,,flying ,,machine3 ,,construction ,,and ,,operation ,by ,w4,j4 ,jackman and ,thos4 ,h4 ,russell ,a ,practical ,book ,which ,shows1 in ,illustrations1 ,working ,plans and ,text1 ,how to ,build and ,navigate the ,modern ,airship4 ,w4,j4 ,,jackman1 ,m4,e41 ,author of ,a ,b ,c of the ,motorcycle1 ,facts for ,motorists1 etc4 etc4 and ,,thos4 ,h4 ,,russell1 ,a4,m41 ,m4,e41 ,charter ,member of the ,aero ,club of ,illinois1 ,author of ,history of the ,automobile1 ,motor ,boats3 ,construction and ,operation1 etc4 etc4 ,with ,introductory ,chapter ,by ,octave ,chanute1 ,c4,e41 ,president ,aero ,club of ,illinois #aiab ,,preface4 ,this book is written for the guidance of the novice in aviation--the man who seeks practical information as to the theory1 construction and operation of the modern flying machine4 ,with this object in view the wording is intentionally plain and non-technical4 ,it contains some propositions which1 so far as satisfying the experts is concerned1 might doubtless be better stated in technical terms1 but this would defeat the main purpose of its preparation4 ,consequently1 while fully aware of its shortcomings in this respect1 the authors have no apologies to make4 ,in the stating of a technical proposition so it may be clearly understood by people not versed in technical matters it becomes absolutely necessary to use language much different from that which an expert would employ1 and this has been done in this volume4 ,no man of ordinary intelligence can read this book without obtaining a clear1 comprehensive knowledge of flying machine construction and operation4 ,he will learn1 not only how to build1 equip1 and manipulate an aeroplane in actual flight1 but will also gain a thorough understanding of the principle upon which the suspension in the air of an object much heavier than the air is made possible4 ,this latter feature should make the book of interest even to those who have no intention of constructing or operating a flying machine4 ,it will enable them to better understand and appreciate the performances of the daring men like the ,wright brothers1 ,curtiss1 ,bleriot1 ,farman1 ,paulhan1 ,latham1 and others1 whose bold experiments have made aviation an actuality4 ,for those who wish to engage in the fascinating pastime of construction and operation it is intended as a reliable1 practical guide4 ,it may be well to explain that the sub-headings in the articles by ,mr4 ,chanute were inserted by the authors without his knowledge4 ,the purpose of this was merely to preserve uniformity in the typography of the book4 ,this explanation is made in justice to ,mr4 ,chanute4 ,,the ,,authors4 ,,in ,,memoriam4 ,octave ,chanute1 the father of the modern flying machine1 died at his home in ,chicago on ,november #bc1 #aiaj1 at the age of #gb years4 ,his last work in the interest of aviation was to furnish the introductory chapter to the first edition of this volume1 and to render valuable assistance in the handling of the various subjects4 ,he even made the trip from his home to the office of the publishers one inclement day last spring1 to look over the proofs of the book and1 at his suggestion1 several important changes were made4 ,all this was a labor of love on ,mr4 ,chanute's part4 ,he gave of his time and talents freely because he was enthusiastic in the cause of aviation1 and because he knew the authors of this book and desired to give them material aid in the preparation of the work--a favor that was most sincerely appreciated4 ,the authors desire to make acknowledgment of many courtesies in the way of valuable advice1 information1 etc41 extended by ,mr4 ,octave ,chanute1 ,c4 ,e41 ,mr4 ,e4 ,l4 ,jones1 ,editor of ,aeronautics1 and the publishers of1 the ,new ,england ,automobile ,journal and ,fly4 ,,contents ,chapter ,i4 ,evolution of the ,two-,surface ,flying ,machine ,introductory ,chapter by ,octave ,chanute1 ,c4 ,e4 ,,ii4 ,theory ,development and ,use ,origin of the ,aeroplane--,developments by ,chanute and the ,wrights--,practical ,uses and ,limits4 ,,iii4 ,mechanical ,bird ,action ,what the ,motor ,does--,puzzle in ,bird ,soaring4 ,,iv4 ,various ,forms of ,flying ,machines ,helicopters1 ,ornithopters and ,aeroplanes-- ,monoplanes1 ,biplanes and ,triplanes4 ,v4 ,constructing a ,gliding ,machine ,plans and ,materials ,required--,estimate of ,cost-- ,sizes and ,preparation of ,various ,parts--,putting the ,parts ,together ,,vi4 ,learning to ,fly ,how to ,use the ,glider--,effect of ,body ,movements --,rules for ,beginners--,safest ,place to ,glide4 ,,vii4 ,putting ,on the ,rudder ,its ,construction1 ,application and ,use4 ,,viii4 ,the ,real ,flying ,machine ,surface ,area ,required--,proper ,size of ,frame and ,auxiliaries--,installation of ,motor--,cost of ,constructing ,machine4 ,,ix4 ,selection of the ,motor ,essential ,features--,multiplicity of ,cylinders--,power ,required--,kind and ,action of ,propellers--,placing of the ,motor ,x4 ,proper ,dimensions of ,machines ,figuring ,out the ,details--,how to ,estimate ,load ,capacity--,distribution of the ,weight--,measurements of ,leading ,machines4 ,,xi4 ,plane and ,rudder ,control ,various ,methods in ,use--,wheels and ,hand and ,foot ,levers ,,xii4 ,how to ,use the ,machine ,rules of ,leading ,aviators--,rising from the ,ground --,reasonable ,altitude--,preserving ,equilibrium-- ,learning to ,steer4 ,,xiii4 ,peculiarities of ,aeroplane ,power ,pressure of the ,wind--,how to ,determine ,upon ,power--,why ,speed ,is ,required--,bird find ,flying ,machine ,areas4 ,,xiv4 ,about ,wind ,currents1 ,etc4 ,uncertainty of ,direct ,force--,trouble ,with ,gusty ,currents--,why ,bird ,action ,is ,imitated4 ,,xv4 ,the ,element of ,danger ,risk ,small ,under ,proper ,conditions--,two ,fields of ,safety--,lessons in ,recent ,accidents4 ,,xvi4 ,radical ,changes ,being ,made ,results of ,recent ,experiments--,new ,dimensions --,increased ,speed--,the ,one ,governing ,rule4 ,,xvii4 ,some of the ,new ,designs ,automatic ,control of ,plane ,stability--,inventor ,herring's ,devices--,novel ,ideas of ,students4 ,,xviii4 ,demand for ,flying ,machines ,wonderful ,results in a ,year--,factories ,over- crowded with ,orders4 ,,xix4 ,law of the ,airship ,rights of ,property ,owners--,some ,legal ,peculiarities--,danger of ,trespass4 ,,xx4 ,soaring ,flight ,,xxi4 ,flying ,machines vs4 ,balloons ,,xxii4 ,problems of ,aerial ,flight ,,xxiii4 ,amateurs ,may ,use ,wright ,patents ,,xxiv4 ,hints on ,propeller ,construction ,,xxv4 ,new ,motors and ,devices ,,xxvi4 ,monoplanes1 ,triplanes1 ,multiplanes ,,xxvii4 ,records of ,various ,kinds ,,flying ,,machines3 ,,construction and ,,operation ,,chapter ,i4 ,,evolution ,,of ,,two-,,surface ,,flying ,,machine4 ,by ,octave ,chanute4 ,i am asked to set forth the development of the two-surface type of flying machine which is now used with modifications by ,wright ,brothers1 ,farman1 #a ,delagrange1 ,herring and others4 ,this type originated with ,mr4 ,f4 ,h4 ,wenham1 who patented it in ,england in #ahff 7,no4 #aega71 taking out provisional papers only4 ,in the abridgment of ,british patent ,aeronautical ,specifications 7#ahic7 it is described as follows3 ,two or more aeroplanes are arranged one above the other1 and support a framework or car containing the motive power4 ,the aeroplanes are made of silk or canvas stretched on a frame by wooden rods or steel ribs4 ,when manual power is employed the body is placed horizontally1 and oars or propellers are actuated by the arms or legs4 ,a start may be obtained by lowering the legs and running down hill or the machine may be started from a moving carriage4 ,one or more screw propellers may be applied for propelling when steam power is employed4 ,on ,june #bg1 #ahff1 ,mr4 ,wenham read before the ,aeronautical ,society of ,great ,britain1 then recently organized1 the ablest paper ever presented to that society1 and thereby breathed into it a spirit which has continued to this day4 ,in this paper he described his observations of birds1 discussed the laws governing flight as to the surfaces and power required both with wings and screws1 and he then gave an account of his own experiments with models and with aeroplanes of sufficient size to carry the weight of a man4 ,second ,wenham ,aeroplane4 ,his second aeroplane was sixteen feet from tip to tip4 ,a trussed spar at the bottom carried six superposed bands of thin holland fabric fifteen inches wide1 connected with vertical webs of holland two feet apart1 thus virtually giving a length of wing of ninety-six feet and one hundred and twenty square feet of supporting surface4 ,the man was placed horizontally on a base board beneath the spar4 ,this apparatus when tried in the wind was found to be unmanageable by reason of the fluttering motions of the fabric1 which was insufficiently stiffened with crinoline steel1 but ,mr4 ,wenham pointed out that this in no way invalidated the principle of the apparatus1 which was to obtain large supporting surfaces without increasing unduly the leverage and consequent weight of spar required1 by simply superposing the surfaces4 ,this principle is entirely sound and it is surprising that it is1 to this day1 not realized by those aviators who are hankering for monoplanes4 ,experiments by ,stringfellow4 ,the next man to test an apparatus with superposed surfaces was ,mr4 ,stringfellow1 who1 becoming much impressed with ,mr4 ,wenham's proposal1 produced a largish model at the exhibition of the ,aeronautical ,society in #ahfh4 ,it consisted of three superposed surfaces aggregating #bh square feet and a tail of #h square feet more4 ,the weight was under #ab pounds and it was driven by a central propeller actuated by a steam engine overestimated at one-third of a horsepower4 ,it ran suspended to a wire on its trials but failed of free flight1 in consequence of defective equilibrium4 ,this apparatus has since been rebuilt and is now in the ,national ,museum of the ,smithsonian ,institution at ,washington4 ,linfield's ,unsuccessful ,efforts4 ,in #ahgh ,mr4 ,linfield tested an apparatus in ,england consisting of a cigar-shaped car1 to which was attached on each side frames five feet square1 containing each twenty-five superposed planes of stretched and varnished linen eighteen inches wide1 and only two inches apart1 thus reminding one of a ,spanish donkey with panniers4 ,the whole weighed two hundred and forty pounds4 ,this was tested by being mounted on a flat car behind a locomotive going #dj miles an hour4 ,when towed by a line fifteen feet long the apparatus rose only a little from the car and exhibited such unstable equilibrium that the experiment was not renewed4 ,the lift was only about one-third of what it would have been had the planes been properly spaced1 say their full width apart1 instead of one-ninth as erroneously devised4 ,renard's ,dirigible ,parachute4 ,in #ahhi ,commandant ,renard1 the eminent superintendent of the ,french ,aeronautical ,department1 exhibited at the ,paris ,exposition of that year1 an apparatus experimented with some years before1 which he termed a dirigible parachute4 ,it consisted of an oviform body to which were pivoted two upright slats carrying above the body nine long superposed flat blades spaced about one-third of their width apart4 ,when this apparatus was properly set at an angle to the longitudinal axis of the body and dropped from a balloon1 it travelled back against the wind for a considerable distance before alighting4 ,the course could be varied by a rudder4 ,no practical application seems to have been made of this device by the ,french ,war ,department1 but ,mr4 ,j4 ,p4 ,holland1 the inventor of the submarine boat which bears his name1 proposed in #ahic an arrangement of pivoted framework attached to the body of a flying machine which combines the principle of ,commandant ,renard with the curved blades experimented with by ,mr4 ,phillips1 now to be noticed1 with the addition of lifting screws inserted among the blades4 ,phillips ,fails on ,stability ,problem4 ,in #ahic ,mr4 ,horatio ,phillips1 of ,england1 after some very interesting experiments with various wing sections1 from which he deduced conclusions as to the shape of maximum lift1 tested an apparatus resembling a ,venetian blind which consisted of fifty wooden slats of peculiar shape1 #bb feet long1 one and a half inches wide1 and two inches apart1 set in ten vertical upright boards4 ,all this was carried upon a body provided with three wheels4 ,it weighed #dbj pounds and was driven at #dj miles an hour on a wooden sidewalk by a steam engine of nine horsepower which actuated a two-bladed screw4 ,the lift was satisfactory1 being perhaps #gj pounds per horsepower1 but the equilibrium was quite bad and the experiments were discontinued4 ,they were taken up again in #aijd with a similar apparatus large enough to carry a passenger1 but the longitudinal equilibrium was found to be defective4 ,then in #aijg a new machine was tested1 in which four sets of frames1 carrying similar sets of slat sustainers were inserted1 and with this arrangement the longitudinal stability was found to be very satisfactory4 ,the whole apparatus1 with the operator1 weighed #fej pounds4 ,it flew about #bjj yards when driven by a motor of #bj to #bb h4p4 at #cj miles an hour1 thus exhibiting a lift of about #cb pounds per h4p41 while it will be remembered that the aeroplane of ,wright ,brothers exhibits a lifting capacity of #ej pounds to the h4p4 ,hargrave's ,kite ,experiments4 ,after experimenting with very many models and building no less than eighteen monoplane flying model machines1 actuated by rubber1 by compressed air and by steam1 ,mr4 ,lawrence ,hargrave1 of ,sydney1 ,new ,south ,wales1 invented the cellular kite which bears his name and made it known in a paper contributed to the ,chicago ,conference on ,aerial ,navigation in #ahic1 describing several varieties4 ,the modern construction is well known1 and consists of two cells1 each of superposed surfaces with vertical side fins1 placed one behind the other and connected by a rod or frame4 ,this flies with great steadiness without a tail4 ,mr4 ,hargrave's idea was to use a team of these kites1 below which he proposed to suspend a motor and propeller from which a line would be carried to an anchor in the ground4 ,then by actuating the propeller the whole apparatus would move forward1 pick up the anchor and fly away4 ,he said3 ,the next step is clear enough1 namely1 that a flying machine with acres of surface can be safely got under way or anchored and hauled to the ground by means of the string of kites4 ,the first tentative experiments did not result well and emphasized the necessity for a light motor1 so that ,mr4 ,hargrave has since been engaged in developing one1 not having convenient access to those which have been produced by the automobile designers and builders4 ,experiments ,with ,glider ,model4 ,and here a curious reminiscence may be indulged in4 ,in #ahhh the present writer experimented with a two-cell gliding model1 precisely similar to a ,hargrave kite1 as will be confirmed by ,mr4 ,herring4 ,it was frequently tested by launching from the top of a three-story house and glided downward very steadily in all sorts of breezes1 but the angle of descent was much steeper than that of birds1 and the weight sustained per square foot was less than with single cells1 in consequence of the lesser support afforded by the rear cell1 which operated upon air already set in motion downward by the front cell1 so nothing more was done with it1 for it never occurred to the writer to try it as a kite and he thus missed the distinction which attaches to ,hargrave's name4 ,sir ,hiram ,maxim also introduced fore and aft superposed surfaces in his wondrous flying machine of #ahic1 but he relied chiefly for the lift upon his main large surface and this necessitated so many guys1 to prevent distortion1 as greatly to increase the head resistance and this1 together with the unstable equilibrium1 made it evident that the design of the machine would have to be changed4 ,how ,lilienthal ,was ,killed4 ,in #ahie1 ,otto ,lilienthal1 the father of modern aviation1 the man to whose method of experimenting almost all present successes are due1 after making something like two thousand glides with monoplanes1 added a superposed surface to his apparatus and found the control of it much improved4 ,the two surfaces were kept apart by two struts or vertical posts with a few guy wires1 but the connecting joints were weak and there was nothing like trussing4 ,this eventually cost his most useful life4 ,two weeks before that distressing loss to science1 ,herr ,wilhelm ,kress1 the distinguished and veteran aviator of ,vienna1 witnessed a number of glides by ,lilienthal with his double-decked apparatus4 ,he noticed that it was much wracked and wobbly and wrote to me after the accident3 ,the connection of the wings and the steering arrangement were very bad and unreliable4 ,i warned ,herr ,lilienthal very seriously4 ,he promised me that he would soon put it in order1 but ,i fear that he did not attend to it immediately4 ,in point of fact1 ,lilienthal had built a new machine1 upon a different principle1 from which he expected great results1 and intended to make but very few more flights with the old apparatus4 ,he unwisely made one too many and1 like ,pilcher1 was the victim of a distorted apparatus4 ,probably one of the joints of the struts gave way1 the upper surface blew back and ,lilienthal1 who was well forward on the lower surface1 was pitched headlong to destruction4 ,experiments by the ,writer4 ,in #ahif1 assisted by ,mr4 ,herring and ,mr4 ,avery1 ,i experimented with several full sized gliding machines1 carrying a man4 ,the first was a ,lilienthal monoplane which was deemed so cranky that it was discarded after making about one hundred glides1 six weeks before ,lilienthal's accident4 ,the second was known as the multiple winged machine and finally developed into five pairs of pivoted wings1 trussed together at the front and one pair in the rear4 ,it glided at angles of descent of #aj or #aa degrees or of one in five1 and this was deemed too steep4 ,then ,mr4 ,herring and myself made computations to analyze the resistances4 ,we attributed much of them to the five front spars of the wings and on a sheet of cross-barred paper ,i at once drew the design for a new three-decked machine to be built by ,mr4 ,herring4 ,being a builder of bridges1 ,i trussed these surfaces together1 in order to obtain strength and stiffness4 ,when tested in gliding flight the lower surface was found too near the ground4 ,it was taken off and the remaining apparatus now consisted of two surfaces connected together by a girder composed of vertical posts and diagonal ties1 specifically known as a ,pratt truss4 ,then ,mr4 ,herring and ,mr4 ,avery together devised and put on an elastic attachment to the tail4 ,this machine proved a success1 it being safe and manageable4 ,over #gjj glides were made with it at angles of descent of #h to #aj degrees1 or one in six to one in seven4 ,first ,proposed by ,wenham4 ,the elastic tail attachment and the trussing of the connecting frame of the superposed wings were the only novelties in this machine1 for the superposing of the surfaces had first been proposed by ,wenham1 but in accordance with the popular perception1 which bestows all the credit upon the man who adds the last touch making for success to the labors of his predecessors1 the machine has since been known by many persons as the ,chanute type of gliders1 much to my personal gratification4 ,it has since been improved in many ways4 ,wright ,brothers1 disregarding the fashion which prevails among birds1 have placed the tail in front of their apparatus and called it a front rudder1 besides placing the operator in horizontal position instead of upright1 as ,i did2 and also providing a method of warping the wings to preserve equilibrium4 ,farman and ,delagrange1 under the very able guidance and constructive work of ,voisin brothers1 then substituted many details1 including a box tail for the dart-like tail which ,i used4 ,this may have increased the resistance1 but it adds to the steadiness4 ,now the tendency in ,france seems to be to go back to the monoplane4 ,monoplane ,idea ,wrong4 ,the advocates of the single supporting surface are probably mistaken4 ,it is true that a single surface shows a greater lift per square foot than superposed surfaces for a given speed1 but the increased weight due to leverage more than counterbalances this advantage by requiring heavy spars and some guys4 ,i believe that the future aeroplane dynamic flier will consist of superposed surfaces1 and1 now that it has been found that by imbedding suitably shaped spars in the cloth the head resistance may be much diminished1 ,i see few objections to superposing three1 four or even five surfaces properly trussed1 and thus obtaining a compact1 handy1 manageable and comparatively light apparatus4 #b ,,chapter ,,ii4 ,,theory1 ,,development1 ,,and ,,use4 ,while every craft that navigates the air is an airship1 all airships are not flying machines4 ,the balloon1 for instance1 is an airship1 but it is not what is known among aviators as a flying machine4 ,this latter term is properly used only in referring to heavier-than-air machines which have no gas-bag lifting devices1 and are made to really fly by the application of engine propulsion4 ,mechanical ,birds4 ,all successful flying machines--and there are a number of them--are based on bird action4 ,the various designers have studied bird flight and soaring1 mastered its technique as devised by ,nature1 and the modern flying machine is the result4 ,on an exaggerated1 enlarged scale the machines which are now navigating the air are nothing more nor less than mechanical birds4 ,origin of the ,aeroplane4 ,octave ,chanute1 of ,chicago1 may well be called the developer of the flying machine4 ,leaving balloons and various forms of gas-bags out of consideration1 other experimenters1 notably ,langley and ,lilienthal1 antedated him in attempting the navigation of the air on aeroplanes1 or flying machines1 but none of them were wholly successful1 and it remained for ,chanute to demonstrate the practicability of what was then called the gliding machine4 ,this term was adopted because the apparatus was1 as the name implies1 simply a gliding machine1 being without motor propulsion1 and intended solely to solve the problem of the best form of construction4 ,the biplane1 used by ,chanute in #ahif1 is still the basis of most successful flying machines1 the only radical difference being that motors1 rudders1 etc41 have been added4 ,character of ,chanute's ,experiments4 ,it was the privilege of the author of this book to be ,mr4 ,chanute's guest at ,millers1 ,indiana1 in #ahif1 when1 in collaboration with ,messrs4 ,herring and ,avery1 he was conducting the series of experiments which have since made possible the construction of the modern flying machine which such successful aviators as the ,wright brothers and others are now using4 ,it was a wild country1 much frequented by eagles1 hawks1 and similar birds4 ,the enthusiastic trio1 ,chanute1 ,herring and ,avery1 would watch for hours the evolutions of some big bird in the air1 agreeing in the end on the verdict1 ,when we master the principle of that bird's soaring without wing action1 we will have come close to solving the problem of the flying machine4 ,aeroplanes of various forms were constructed by ,mr4 ,chanute with the assistance of ,messrs4 ,herring and ,avery until1 at the time of the writer's visit1 they had settled upon the biplane1 or two-surface machine4 ,mr4 ,herring later equipped this with a rudder1 and made other additions1 but the general idea is still the basis of the ,wright1 ,curtiss1 and other machines in which1 by the aid of gasolene motors1 long flights have been made4 ,developments by the ,wrights4 ,in #aijj the ,wright brothers1 ,william and ,orville1 who were then in the bicycle business in ,dayton1 ,ohio1 became interested in ,chanute's experiments and communicated with him4 ,the result was that the ,wrights took up ,chanute's ideas and developed them further1 making many additions of their own1 one of which was the placing of a rudder in front1 and the location of the operator horizontally on the machine1 thus diminishing by four-fifths the wind resistance of the man's body4 ,for three years the ,wrights experimented with the glider before venturing to add a motor1 which was not done until they had thoroughly mastered the control of their movements in the air4 ,limits of the ,flying ,machine4 ,in the opinion of competent experts it is idle to look for a commercial future for the flying machine4 ,there is1 and always will be1 a limit to its carrying capacity which will prohibit its employment for passenger or freight purposes in a wholesale or general way4 ,there are some1 of course1 who will argue that because a machine will carry two people another may be constructed that will carry a dozen1 but those who make this contention do not understand the theory of weight sustentation in the air2 or that the greater the load the greater must be the lifting power 7motors and plane surface71 and that there is a limit to these--as will be explained later on--beyond which the aviator cannot go4 ,some ,practical ,uses4 ,at the same time there are fields in which the flying machine may be used to great advantage4 ,these are3 ,sports--,flying machine races or flights will always be popular by reason of the element of danger4 ,it is a strange1 but nevertheless a true proposition1 that it is this element which adds zest to all sporting events4 ,scientific--,for exploration of otherwise inaccessible regions such as deserts1 mountain tops1 etc4 ,reconnoitering--,in time of war flying machines may be used to advantage to spy out an enemy's encampment1 ascertain its defenses1 etc4 ,,chapter ,,iii4 ,,mechanical ,,bird ,,action ,in order to understand the theory of the modern flying machine one must also understand bird action and wind action4 ,in this connection the following simple experiment will be of interest3 ,take a circular-shaped bit of cardboard1 like the lid of a hat box1 and remove the bent-over portion so as to have a perfectly flat surface with a clean1 sharp edge4 ,holding the cardboard at arm's length1 withdraw your hand1 leaving the cardboard without support4 ,what is the result8 ,the cardboard1 being heavier than air1 and having nothing to sustain it1 will fall to the ground4 ,pick it up and throw it1 with considerable force1 against the wind edgewise4 ,what happens8 ,instead of falling to the ground1 the cardboard sails along on the wind1 remaining afloat so long as it is in motion4 ,it seeks the ground1 by gravity1 only as the motion ceases1 and then by easy stages1 instead of dropping abruptly as in the first instance4 ,here we have a homely1 but accurate illustration of the action of the flying machine4 ,the motor does for the latter what the force of your arm does for the cardboard--imparts a motion which keeps it afloat4 ,the only real difference is that the motion given by the motor is continuous and much more powerful than that given by your arm4 ,the action of the latter is limited and the end of its propulsive force is reached within a second or two after it is exerted1 while the action of the motor is prolonged4 ,another ,simple ,illustration4 ,another simple means of illustrating the principle of flying machine operation1 so far as sustentation and the elevation and depression of the planes is concerned1 is explained in the accompanying diagram4 ,a is a piece of cardboard about #b by #c inches in size4 ,b is a piece of paper of the same size pasted to one edge of ,a4 ,if you bend the paper to a curve1 with convex side up and blow across it as shown in ,figure ,c1 the paper will rise instead of being depressed4 ,the dotted lines show that the air is passing over the top of the curved paper and yet1 no matter how hard you may blow1 the effect will be to elevate the paper1 despite the fact that the air is passing over1 instead of under the curved surface4 ,in ,figure ,d we have an opposite effect4 ,here the paper is in a curve exactly the reverse of that shown in ,figure ,c1 bringing the concave side up4 ,now if you will again blow across the surface of the card the action of the paper will be downward--it will be impossible to make it rise4 ,the harder you blow the greater will be the downward movement4 ,principle ,in ,general ,use4 ,this principle is taken advantage of in the construction of all successful flying machines4 ,makers of monoplanes and biplanes alike adhere to curved bodies1 with the concave surface facing downward4 ,straight planes were tried for a time1 but found greatly lacking in the power of sustentation4 ,by curving the planes1 and placing the concave surface downward1 a sort of inverted bowl is formed in which the air gathers and exerts a buoyant effect4 ,just what the ratio of the curve should be is a matter of contention4 ,in some instances one inch to the foot is found to be satisfactory2 in others this is doubled1 and there are a few cases in which a curve of as much as #c inches to the foot has been used4 ,right here it might be well to explain that the word plane applied to flying machines of modern construction is in reality a misnomer4 ,plane indicates a flat1 level surface4 ,as most successful flying machines have curved supporting surfaces it is clearly wrong to speak of planes1 or aeroplanes4 ,usage1 however1 has made the terms convenient and1 as they are generally accepted and understood by the public1 they are used in like manner in this volume4 ,getting ,under ,headway4 ,a bird1 on first rising from the ground1 or beginning its flight from a tree1 will flap its wings to get under headway4 ,here again we have another illustration of the manner in which a flying machine gets under headway--the motor imparts the force necessary to put the machine into the air1 but right here the similarity ceases4 ,if the machine is to be kept afloat the motor must be kept moving4 ,a flying machine will not sustain itself2 it will not remain suspended in the air unless it is under headway4 ,this is because it is heavier than air1 and gravity draws it to the ground4 ,puzzle in ,bird ,soaring4 ,but a bird1 which is also heavier than air1 will remain suspended1 in a calm1 will even soar and move in a circle1 without apparent movement of its wings4 ,this is explained on the theory that there are generally vertical columns of air in circulation strong enough to sustain a bird1 but much too weak to exert any lifting power on a flying machine1 ,it is easy to understand how a bird can remain suspended when the wind is in action1 but its suspension in a seeming dead calm was a puzzle to scientists until ,mr4 ,chanute advanced the proposition of vertical columns of air4 ,modeled ,closely ,after ,birds4 ,so far as possible1 builders of flying machines have taken what may be called the architecture of birds as a model4 ,this is readily noticeable in the form of construction4 ,when a bird is in motion its wings 7except when flapping7 are extended in a straight line at right angles to its body4 ,this brings a sharp1 thin edge against the air1 offering the least possible surface for resistance1 while at the same time a broad surface for support is afforded by the flat1 under side of the wings4 ,identically the same thing is done in the construction of the flying machine4 ,note1 for instance1 the marked similarity in form as shown in the illustration in ,chapter ,,ii4 ,here ,a is the bird1 and ,b the general outline of the machine4 ,the thin edge of the plane in the latter is almost a duplicate of that formed by the outstretched wings of the bird1 while the rudder plane in the rear serves the same purpose as the bird's tail4 ,,chapter ,,iv4 ,,various ,,forms ,,of ,,flying ,,machines4 ,there are three distinct and radically different forms of flying machines4 ,these are3 ,aeroplanes1 helicopters and ornithopers4 ,of these the aeroplane takes precedence and is used almost exclusively by successful aviators1 the helicopters and ornithopers having been tried and found lacking in some vital features1 while at the same time in some respects the helicopter has advantages not found in the aeroplane4 ,what the ,helicopter ,is4 ,the helicopter gets its name from being fitted with vertical propellers or helices 7see illustration7 by the action of which the machine is raised directly from the ground into the air4 ,this does away with the necessity for getting the machine under a gliding headway before it floats1 as is the case with the aeroplane1 and consequently the helicopter can be handled in a much smaller space than is required for an aeroplane4 ,this1 in many instances1 is an important advantage1 but it is the only one the helicopter possesses1 and is more than overcome by its drawbacks4 ,the most serious of these is that the helicopter is deficient in sustaining capacity1 and requires too much motive power4 ,form of the ,ornithopter4 ,the ornithopter has hinged planes which work like the wings of a bird4 ,at first thought this would seem to be the correct principle1 and most of the early experimenters conducted their operations on this line4 ,it is now generally understood1 however1 that the bird in soaring is in reality an aeroplane1 its extended wings serving to sustain1 as well as propel1 the body4 ,at any rate the ornithoper has not been successful in aviation1 and has been interesting mainly as an ingenious toy4 ,attempts to construct it on a scale that would permit of its use by man in actual aerial flights have been far from encouraging4 ,three ,kinds of ,aeroplanes4 ,there are three forms of aeroplanes1 with all of which more or less success has been attained4 ,these are3 ,the monoplane1 a one-surfaced plane1 like that used by ,bleriot4 ,the biplane1 a two-surfaced plane1 now used by the ,wrights1 ,curtiss1 ,farman1 and others4 ,the triplane1 a three-surfaced plane ,this form is but little used1 its only prominent advocate at present being ,elle ,lavimer1 a ,danish experimenter1 who has not thus far accomplished much4 ,whatever of real success has been accomplished in aviation may be credited to the monoplane and biplane1 with the balance in favor of the latter4 ,the monoplane is the more simple in construction and1 where weight-sustaining capacity is not a prime requisite1 may probably be found the most convenient4 ,this opinion is based on the fact that the smaller the surface of the plane the less will be the resistance offered to the air1 and the greater will be the speed at which the machine may be moved4 ,on the other hand1 the biplane has a much greater plane surface 7double that of a monoplane of the same size7 and consequently much greater weight-carrying capacity4 ,differences in ,biplanes4 ,while all biplanes are of the same general construction so far as the main planes are concerned1 each aviator has his own ideas as to the rigging4 ,wright1 for instance1 places a double horizontal rudder in front1 with a vertical rudder in the rear4 ,there are no partitions between the main planes1 and the bicycle wheels used on other forms are replaced by skids4 ,voisin1 on the contrary1 divides the main planes with vertical partitions to increase stability in turning2 uses a single-plane horizontal rudder in front1 and a big box-tail with vertical rudder at the rear2 also the bicycle wheels4 ,curtiss attaches horizontal stabilizing surfaces to the upper plane2 has a double horizontal rudder in front1 with a vertical rudder and horizontal stabilizing surfaces in rear4 ,also the bicycle wheel alighting gear4 ,,chapter ,v4 ,,constructing ,a ,,gliding ,,machine4 ,first decide upon the kind of a machine you want--monoplane1 biplane1 or triplane4 ,for a novice the biplane will1 as a rule1 be found the most satisfactory as it is more compact and therefore the more easily handled4 ,this will be easily understood when we realize that the surface of a flying machine should be laid out in proportion to the amount of weight it will have to sustain4 ,the generally accepted rule is that #aeb square feet of surface will sustain the weight of an average-sized man1 say #agj pounds4 ,now it follows that if these #aeb square feet of surface are used in one plane1 as in the monoplane1 the length and width of this plane must be greater than if the same amount of surface is secured by using two planes--the biplane4 ,this results in the biplane being more compact and therefore more readily manipulated than the monoplane1 which is an important item for a novice4 ,glider the ,basis of ,success4 ,flying machines without motors are called gliders4 ,in making a flying machine you first construct the glider4 ,if you use it in this form it remains a glider4 ,if you install a motor it becomes a flying machine4 ,you must have a good glider as the basis of a successful flying machine4 ,it will be well for the novice1 the man who has never had any experience as an aviator1 to begin with a glider and master its construction and operation before he essays the more pretentious task of handling a fully-equipped flying machine4 ,in fact1 it is essential that he should do so4 ,plans for ,handy ,glider4 ,a glider with a spread 7advancing edge7 of #bj feet1 and a breadth or depth of #d feet1 will be about right to begin with4 ,two planes of this size will give the #aeb square yards of surface necessary to sustain a man's weight4 ,remember that in referring to flying machine measurements spread takes the place of what would ordinarily be called length1 and invariably applies to the long or advancing edge of the machine which cuts into the air4 ,thus1 a glider is spoken of as being #bj feet spread1 and #d feet in depth4 ,so far as mastering the control of the machine is concerned1 learning to balance one's self in the air1 guiding the machine in any desired direction by changing the position of the body1 etc41 all this may be learned just as readily1 and perhaps more so1 with a #bj-;foot glider than with a larger apparatus4 ,kind of ,material ,required4 ,there are three all-important features in flying machine construction1 viz43 lightness1 strength and extreme rigidity4 ,spruce is the wood generally used for glider frames4 ,oak1 ash and hickory are all stronger1 but they are also considerably heavier1 and where the saving of weight is essential1 the difference is largely in favor of spruce4 ,this will be seen in the following table3 ,weight ,tensile ,compressive per cubic ft4 ,strength ,strength ,wood in lbs4 lbs4 per sq4 in4 lbs4 per sq in4 ,hickory #ec #ab1jjj #h1ejj ,oak #ej #ab1jjj #i1jjj ,ash #ch #ab1jjj #f1jjj ,walnut #ch #h1jjj #f1jjj ,spruce #be #h1jjj #e1jjj ,pine #be #e1jjj #d1ejj ,considering the marked saving in weight spruce has a greater percentage of tensile strength than any of the other woods4 ,it is also easier to find in long1 straight-grained pieces free from knots1 and it is this kind only that should be used in flying machine construction4 ,you will next need some spools or hanks of ,no4 #f linen shoe thread1 metal sockets1 a supply of strong piano wire1 a quantity of closely-woven silk or cotton cloth1 glue1 turnbuckles1 varnish1 etc4 ,names of the ,various ,parts4 ,the long strips1 four in number1 which form the front and rear edges of the upper and lower frames1 are called the horizontal beams4 ,these are each #bj feet in length4 ,these horizontal beams are connected by upright strips1 #d feet long1 called stanchions4 ,there are usually #ab of these1 six on the front edge1 and six on the rear4 ,they serve to hold the upper plane away from the lower one4 ,next comes the ribs4 ,these are #d feet in length 7projecting for a foot over the rear beam71 and while intended principally as a support to the cloth covering of the planes1 also tend to hold the frame together in a horizontal position just as the stanchions do in the vertical4 ,there are forty-one of these ribs1 twenty-one on the upper and twenty on the lower plane4 ,then come the struts1 the main pieces which join the horizontal beams4 ,all of these parts are shown in the illustrations1 reference to which will make the meaning of the various names clear4 ,quantity and ,cost of ,material4 ,for the horizontal beams four pieces of spruce1 #bj feet long1 #a #a_/b inches wide and #c_/d inch thick are necessary4 ,these pieces must be straight-grain1 and absolutely free from knots4 ,if it is impossible to obtain clear pieces of this length1 shorter ones may be spliced1 but this is not advised as it adds materially to the weight4 ,the twelve stanchions should be #d feet long and #g_/h inch in diameter and rounded in form so as to offer as little resistance as possible to the wind4 ,the struts1 there are twelve of them1 are #c feet long by #aa_/d x #a_/b inch4 ,for a #bj-;foot biplane about #bj yards of stout silk or unbleached muslin1 of standard one yard width1 will be needed4 ,the forty-one ribs are each #d feet long1 and #a_/b inch square4 ,a roll of ,no4 #ab piano wire1 twenty-four sockets1 a package of small copper tacks1 a pot of glue1 and similar accessories will be required4 ,the entire cost of this material should not exceed #bj4 ,the wood and cloth will be the two largest items1 and these should not cost more than #aj4 ,this leaves #aj for the varnish1 wire1 tacks1 glue1 and other incidentals4 ,this estimate is made for cost of materials only1 it being taken for granted that the experimenter will construct his own glider4 ,should the services of a carpenter be required the total cost will probably approximate #fj or #gj4 ,application of the ,rudders4 ,the figures given also include the expense of rudders1 but the details of these have not been included as the glider is really complete without them4 ,some of the best flights the writer ever saw were made by ,mr4 ,a4 ,m4 ,herring in a glider without a rudder1 and yet there can be no doubt that a rudder1 properly proportioned and placed1 especially a rear rudder1 is of great value to the aviator as it keeps the machine with its head to the wind1 which is the only safe position for a novice4 ,for initial educational purposes1 however1 a rudder is not essential as the glides will1 or should1 be made on level ground1 in moderate1 steady wind currents1 and at a modest elevation4 ,the addition of a rudder1 therefore1 may well be left until the aviator has become reasonably expert in the management of his machine4 ,putting the ,machine ,together4 ,having obtained the necessary material1 the first move is to have the rib pieces steamed and curved4 ,this curve may be slight1 about #b inches for the #d feet4 ,while this is being done the other parts should be carefully rounded so the square edges will be taken off4 ,this may be done with sand paper4 ,next apply a coat of shellac1 and when dry rub it down thoroughly with fine sand paper4 ,when the ribs are curved treat them in the same way4 ,lay two of the long horizontal frame pieces on the floor #c feet apart4 ,between these place six of the strut pieces4 ,put one at each end1 and each #d #a_/b feet put another1 leaving a #b-;foot space in the center4 ,this will give you four struts #d #a_/b feet apart1 and two in the center #b feet apart1 as shown in the illustration4 ,this makes five rectangles4 ,be sure that the points of contact are perfect1 and that the struts are exactly at right angles with the horizontal frames4 ,this is a most important feature because if your frame skews or twists you cannot keep it straight in the air4 ,now glue the ends of the struts to the frame pieces1 using plenty of glue1 and nail on strips that will hold the frame in place while the glue is drying4 ,the next day lash the joints together firmly with the shoe thread1 winding it as you would to mend a broken gun stock1 and over each layer put a coating of glue4 ,this done1 the other frame pieces and struts may be treated in the same way1 and you will thus get the foundations for the two planes4 ,another ,way of ,placing ,struts4 ,in the machines built for professional use a stronger and more certain form of construction is desired4 ,this is secured by the placing the struts for the lower plane under the frame piece1 and those for the upper plane over it1 allowing them in each instance to come out flush with the outer edges of the frame pieces4 ,they are then securely fastened with a tie plate or clamp which passes over the end of the strut and is bound firmly against the surface of the frame piece by the eye bolts of the stanchion sockets4 ,placing the ,rib ,pieces4 ,take one of the frames and place on it the ribs1 with the arched side up1 letting one end of the ribs come flush with the front edge of the forward frame1 and the other end projecting about a foot beyond the rear frame4 ,the manner of fastening the ribs to the frame pieces is optional4 ,in some cases they are lashed with shoe thread1 and in others clamped with a metal clamp fastened with #a_/b-;inch wood screws4 ,where clamps and screws are used care should be taken to make slight holes in the wood with an awl before starting the screws so as to lessen any tendency to split the wood4 ,on the top frame1 twenty-one ribs placed one foot apart will be required4 ,on the lower frame1 because of the opening left for the operator's body1 you will need only twenty4 ,joining the ,two ,frames4 ,the two frames must now be joined together4 ,for this you will need twenty-four aluminum or iron sockets which may be purchased at a foundry or hardware shop4 ,these sockets1 as the name implies1 provide a receptacle in which the end of a stanchion is firmly held1 and have flanges with holes for eye-bolts which hold them firmly to the frame pieces1 and also serve to hold the guy wires4 ,in addition to these eye-bolt holes there are two others through which screws are fastened into the frame pieces4 ,on the front frame piece of the bottom plane place six sockets1 beginning at the end of the frame1 and locating them exactly opposite the struts4 ,screw the sockets into position with wood screws1 and then put the eye-bolts in place4 ,repeat the operation on the rear frame4 ,next put the sockets for the upper plane frame in place4 ,you are now ready to bring the two planes together4 ,begin by inserting the stanchions in the sockets in the lower plane4 ,the ends may need a little rubbing with sandpaper to get them into the sockets1 but care must be taken to have them fit snugly4 ,when all the stanchions are in place on the lower plane1 lift the upper plane into position1 and fit the sockets over the upper ends of the stanchions4 ,trussing with ,guy ,wires4 ,the next move is to tie the frame together rigidly by the aid of guy wires4 ,this is where the ,no4 #ab piano wire comes in4 ,each rectangle formed by the struts and stanchions with the exception of the small center one1 is to be wired separately as shown in the illustration4 ,at each of the eight corners forming the rectangle the ring of one of the eye-bolts will be found4 ,there are two ways of doing this tieing1 or trussing4 ,one is to run the wires diagonally from eye-bolt to eye-bolt1 depending upon main strength to pull them taut enough1 and then twist the ends so as to hold4 ,the other is to first make a loop of wire at each eye-bolt1 and connect these loops to the main wires with turn-buckles4 ,this latter method is the best1 as it admits of the tension being regulated by simply turning the buckle so as to draw the ends of the wire closer together4 ,a glance at the illustration will make this plain1 and also show how the wires are to be placed4 ,the proper degree of tension may be determined in the following manner3 ,after the frame is wired place each end on a saw-horse so as to lift the entire frame clear of the work-shop floor4 ,get under it1 in the center rectangle and1 grasping the center struts1 one in each hand1 put your entire weight on the structure4 ,if it is properly put together it will remain rigid and unyielding4 ,should it sag ever so slightly the tension of the wires must be increased until any tendency to sag1 no matter how slight it may be1 is overcome4 ,putting on the ,cloth4 ,we are now ready to put on the cloth covering which holds the air and makes the machine buoyant4 ,the kind of material employed is of small account so long as it is light1 strong1 and wind-proof1 or nearly so4 ,some aviators use what is called rubberized silk1 others prefer balloon cloth4 ,ordinary muslin of good quality1 treated with a coat of light varnish after it is in place1 will answer all the purposes of the amateur4 ,cut the cloth into strips a little over #d feet in length4 ,as you have #bj feet in width to cover1 and the cloth is one yard wide1 you will need seven strips for each plane1 so as to allow for laps1 etc4 ,this will give you fourteen strips4 ,glue the end of each strip around the front horizontal beams of the planes1 and draw each strip back1 over the ribs1 tacking the edges to the ribs as you go along1 with small copper or brass tacks4 ,in doing this keep the cloth smooth and stretched tight4 ,tacks should also be used in addition to the glue1 to hold the cloth to the horizontal beams4 ,next1 give the cloth a coat of varnish on the clear1 or upper side1 and when this is dry your glider will be ready for use4 ,reinforcing the ,cloth4 ,while not absolutely necessary for amateur purposes1 reinforcement of the cloth1 so as to avoid any tendency to split or tear out from wind-pressure1 is desirable4 ,one way of doing this is to tack narrow strips of some heavier material1 like felt1 over the cloth where it laps on the ribs4 ,another is to sew slips or pockets in the cloth itself and let the ribs run through them4 ,still another method is to sew #b-;inch strips 7of the same material as the cover7 on the cloth1 placing them about one yard apart1 but having them come in the center of each piece of covering1 and not on the laps where the various pieces are joined4 ,use of ,armpieces4 ,should armpieces be desired1 aside from those afforded by the center struts1 take two pieces of spruce1 #c feet long1 by #a x #a #c_/d inches1 and bolt them to the front and rear beams of the lower plane about #ad inches apart4 ,these will be more comfortable than using the struts1 as the operator will not have to spread his arms so much4 ,in using the struts the operator1 as a rule1 takes hold of them with his hands1 while with the armpieces1 as the name implies1 he places his arms over them1 one of the strips coming under each armpit4 ,frequently somebody asks why the ribs should be curved4 ,the answer is easy4 ,the curvature tends to direct the air downward toward the rear and1 as the air is thus forced downward1 there is more or less of an impact which assists in propelling the aeroplane upwards4 ,,chapter ,,vi4 ,,learning ,,to ,,fly4 ,don't be too ambitious at the start4 ,go slow1 and avoid unnecessary risks4 ,at its best there is an element of danger in aviation which cannot be entirely eliminated1 but it may be greatly reduced and minimized by the use of common sense4 ,theoretically1 the proper way to begin a glide is from the top of an incline1 facing against the wind1 so that the machine will soar until the attraction of gravitation draws it gradually to the ground4 ,this is the manner in which experienced aviators operate1 but it must be kept in mind that these men are experts4 ,they understand air currents1 know how to control the action and direction of their machines by shifting the position of their bodies1 and by so doing avoid accidents which would be unavoidable by a novice4 ,begin on ,level ,ground4 ,make your first flights on level ground1 having a couple of men to assist you in getting the apparatus under headway4 ,take your position in the center rectangle1 back far enough to give the forward edges of the glider an inclination to tilt upward very slightly4 ,now start and run forward at a moderately rapid gait1 one man at each end of the glider assisting you4 ,as the glider cuts into the air the wind will catch under the uplifted edges of the curved planes1 and buoy it up so that it will rise in the air and take you with it4 ,this rise will not be great1 just enough to keep you well clear of the ground4 ,now project your legs a little to the front so as to shift the center of gravity a trifle and bring the edges of the glider on an exact level with the atmosphere4 ,this1 with the momentum acquired in the start1 will keep the machine moving forward for some distance4 ,effect of ,body ,movements4 ,when the weight of the body is slightly back of the center of gravity the edges of the advancing planes are tilted slightly upward4 ,the glider in this position acts as a scoop1 taking in the air which1 in turn1 lifts it off the ground4 ,when a certain altitude is reached--this varies with the force of the wind--the tendency to a forward movement is lost and the glider comes to the ground4 ,it is to prolong the forward movement as much as possible that the operator shifts the center of gravity slightly1 bringing the apparatus on an even keel as it were by lowering the advancing edges4 ,this done1 so long as there is momentum enough to keep the glider moving1 it will remain afloat4 ,if you shift your body well forward it will bring the front edges of the glider down1 and elevate the rear ones4 ,in this way the air will be spilled out at the rear1 and1 having lost the air support or buoyancy1 the glider comes down to the ground4 ,a few flights will make any ordinary man proficient in the control of his apparatus by his body movements1 not only as concerns the elevating and depressing of the advancing edges1 but also actual steering4 ,you will quickly learn1 for instance1 that1 as the shifting of the bodily weight backwards and forwards affects the upward and downward trend of the planes1 so a movement sideways--to the left or the right--affects the direction in which the glider travels4 ,ascends at an ,angle4 ,in ascending1 the glider and flying machine1 like the bird1 makes an angular1 not a vertical flight4 ,just what this angle of ascension may be is difficult to determine4 ,it is probable and in fact altogether likely1 that it varies with the force of the wind1 weight of the rising body1 power of propulsion1 etc4 ,this1 in the language of physicists1 is the angle of inclination1 and1 as a general thing1 under normal conditions 7still air7 should be put down as about one in ten1 or #e #c_/d degrees4 ,this would be an ideal condition1 but it has not1 as vet been reached4 ,the force of the wind affects the angle considerably1 as does also the weight and velocity of the apparatus4 ,in general practice the angle varies from #bc to #de degrees4 ,at more than #de degrees the supporting effort is overcome by the resistance to forward motion4 ,increasing the speed or propulsive force1 tends to lessen the angle at which the machine may be successfully operated because it reduces the wind pressure4 ,most of the modern flying machines are operated at an angle of #bc degrees1 or less4 ,maintaining an ,equilibrium4 ,stable equilibrium is one of the main essentials to successful flight1 and this cannot be preserved in an uncertain1 gusty wind1 especially by an amateur4 ,the novice should not attempt a glide unless the conditions are just right4 ,these conditions are3 ,a clear1 level space1 without obstructions1 such as trees1 etc41 and a steady wind of not exceeding twelve miles an hour4 ,always fly against the wind4 ,when a reasonable amount of proficiency in the handling of the machine on level ground has been acquired the field of practice may be changed to some gentle slope4 ,in starting from a slope it will be found easier to keep the machine afloat1 but the experience at first is likely to be very disconcerting to a man of less than iron nerve4 ,as the glider sails away from the top of the slope the distance between him and the ground increases rapidly until the aviator thinks he is up a hundred miles in the air4 ,if he will keep cool1 manipulate his apparatus so as to preserve its equilibrium1 and let nature take its course1 he will come down gradually and safely to the ground at a considerable distance from the starting place4 ,this is one advantage of starting from an elevation--your machine will go further4 ,but1 if the aviator becomes rattled2 if he loses control of his machine1 serious results1 including a bad fall with risk of death1 are almost certain4 ,and yet this practice is just as necessary as the initial lessons on level ground4 ,when judgment is used1 and haste made slowly1 there is very little real danger4 ,while experimenting with gliders the ,wrights made flights innumerable under all sorts of conditions and never had an accident of any kind4 ,effects of ,wind ,currents4 ,the larger the machine the more difficult it will be to control its movements in the air1 and yet enlargement is absolutely necessary as weight1 in the form of motor1 rudder1 etc41 is added4 ,air currents near the surface of the ground are diverted by every obstruction unless the wind is blowing hard enough to remove the obstruction entirely4 ,take1 for instance1 the case of a tree or shrub1 in a moderate wind of from ten to twelve miles an hour4 ,as the wind strikes the tree it divides1 part going to one side and part going to the other1 while still another part is directed upward and goes over the top of the obstruction4 ,this makes the handling of a glider on an obstructed field difficult and uncertain4 ,to handle a glider successfully the place of operation should be clear and the wind moderate and steady4 ,if it is gusty postpone your flight4 ,in this connection it will be well to understand the velocity of the wind1 and what it means as shown in the following table3 ,miles per hour ,feet per second ,pressure per sq4 foot #aj #ad4g 4#dib #be #cf4g #c4jge #ej #gc4c #ab4cjj #ajj #adf4f #di4bjj ,pressure of wind increases in proportion to the square of the velocity4 ,thus wind at #aj miles an hour has four times the pressure of wind at #e miles an hour4 ,the greater this pressure the large and heavier the object which can be raised4 ,any boy who has had experience in flying kites can testify to this1 ,high winds1 however1 are almost invariably gusty and uncertain as to direction1 and this makes them dangerous for aviators4 ,it is also a self-evident fact that1 beyond a certain stage1 the harder the wind blows the more difficult it is to make headway against it4 ,launching ,device for ,gliders4 ,on page #aie will be found a diagram of the various parts of a launcher for gliders1 designed and patented by ,mr4 ,octave ,chanute4 ,in describing this invention in ,aeronautics1 ,mr4 ,chanute says3 ,in practicing1 the track1 preferably portable1 is generally laid in the direction of the existing wind and the car1 preferably a light platform-car1 is placed on the track4 ,the truck carrying the winding-drum and its motor is placed to windward a suitable distance--say from two hundred to one thousand feet--and is firmly blocked or anchored in line with the portable track1 which is preferably #hj or #ajj feet in length4 ,the flying or gliding machine to be launched with its operator is placed on the platform-car at the leeward end of the portable track4 ,the line1 which is preferably a flexible combination wire-and-cord cable1 is stretched between the winding-drum on the track and detachably secured to the flying or gliding machine1 preferably by means of a trip-hoop1 or else held in the hand of the operator1 so that the operator may readily detach the same from the flying-machine when the desired height is attained4 ,how ,glider ,is ,started4 ,then upon a signal given by the operator the engineer at the motor puts it into operation1 gradually increasing the speed until the line is wound upon the drum at a maximum speed of1 say1 thirty miles an hour4 ,the operator of the flying-machine1 whether he stands upright and carries it on his shoulders1 or whether he sits or lies down prone upon it1 adjusts the aeroplane or carrying surfaces so that the wind shall strike them on the top and press downward instead of upward until the platform-car under action of the winding-drum and line attains the required speed4 ,when the operator judges that his speed is sufficient1 and this depends upon the velocity of the wind as well as that of the car moving against the wind1 he quickly causes the front of the flying-machine to tip upward1 so that the relative wind striking on the under side of the planes or carrying surfaces shall lift the flying machine into the air4 ,it then ascends like a kite to such height as may be desired by the operator1 who then trips the hook and releases the line from the machine4 ,what the ,operator ,does4 ,the operator being now free in the air has a certain initial velocity imparted by the winding-drum and line and also a potential energy corresponding to his height above the ground4 ,if the flying or gliding machine is provided with a motor1 he can utilize that in his further flight1 and if it is a simple gliding machine without motor he can make a descending flight through the air to such distance as corresponds to the velocity acquired and the height gained1 steering meanwhile by the devices provided for that purpose4 ,the simplest operation or maneuver is to continue the flight straight ahead against the wind2 but it is possible to vary this course to the right or left1 or even to return in downward flight with the wind to the vicinity of the starting-point4 ,upon nearing the ground the operator tips upward his carrying-surfaces and stops his headway upon the cushion of increased air resistance so caused4 ,the operator is in no way permanently fastened to his machine1 and the machine and the operator simply rest upon the light platform-car1 so that the operator is free to rise with the machine from the car whenever the required initial velocity is attained4 ,motor ,for the ,launcher4 ,the motor may be of any suitable kind or construction1 but is preferably an electric or gasolene motor4 ,the winding-drum is furnished with any suitable or customary reversing-guide to cause the line to wind smoothly and evenly upon the drum4 ,the line is preferably a cable composed of flexible wire and having a cotton or other cord core to increase its flexibility4 ,the line extends from the drum to the flying or gliding machine4 ,its free end may1 if desired1 be grasped and held by the operator until the flying-machine ascends to the desired height1 when by simply letting go of the line the operator may continue his flight free4 ,the line1 however1 is preferably connected to the flying or gliding machine directly by a trip-hook having a handle or trip lever within reach of the operator1 so that when he ascends to the required height he may readily detach the line from the flying or gliding machine4 ,,chapter ,,vii4 ,,putting ,,on ,,the ,,rudder4 ,gliders as a rule have only one rudder1 and this is in the rear4 ,it tends to keep the apparatus with its head to the wind4 ,unlike the rudder on a boat it is fixed and immovable4 ,the real motor-propelled flying machine1 generally has both front and rear rudders manipulated by wire cables at the will of the operator4 ,allowing that the amateur has become reasonably expert in the manipulation of the glider he should1 before constructing an actual flying machine1 equip his glider with a rudder4 ,cross ,pieces for ,rudder ,beam4 ,to do this he should begin by putting in a cross piece1 #b feet long by #a_/d x #c_/d inches between the center struts1 in the lower plane4 ,this may be fastened to the struts with bolts or braces4 ,the former method is preferable4 ,on this cross piece1 and on the rear frame of the plane itself1 the rudder beam is clamped and bolted4 ,this rudder beam is #h feet #aa inches long4 ,having put these in place duplicate them in exactly the same manner and dimensions from the upper frame ,the cross pieces on which the ends of the rudder beams are clamped should be placed about one foot in advance of the rear frame beam4 ,the ,rudder ,itself4 ,the next step is to construct the rudder itself4 ,this consists of two sections1 one horizontal1 the other vertical4 ,the latter keeps the aeroplane headed into the wind1 while the former keeps it steady--preserves the equilibrium4 ,the rudder beams form the top and bottom frames of the vertical rudder4 ,to these are bolted and clamped two upright pieces1 #c feet1 #aj inches in length1 and #c_/d inch in cross section4 ,these latter pieces are placed about two feet apart4 ,this completes the framework of the vertical rudder4 ,see next page 7#ei74 ,for the horizontal rudder you will require two strips #f feet long1 and four #b feet long4 ,find the exact center of the upright pieces on the vertical rudder1 and at this spot fasten with bolts the long pieces of the horizontal1 placing them on the outside of the vertical strips4 ,next join the ends of the horizontal strips with the #b-;foot pieces1 using small screws and corner braces4 ,this done you will have two of the #b-;foot pieces left4 ,these go in the center of the horizontal frame1 straddling the vertical strips1 as shown in the illustration4 ,the framework is to be covered with cloth in the same manner as the planes4 ,for this about ten yards will be needed4 ,strengthening the ,rudder4 ,to ensure rigidity the rudder must be stayed with guy wires4 ,for this purpose the ,no4 #ab piano wire is the best4 ,begin by running two of these wires from the top eye-bolts of stanchions #c and #d1 page #cg1 to rudder beam where it joins the rudder planes1 fastening them at the bottom4 ,then run two wires from the top of the rudder beam at the same point1 to the bottom eye-bolts of the same stanchions4 ,this will give you four diagonal wires reaching from the rudder beam to the top and bottom planes of the glider4 ,now1 from the outer ends of the rudder frame run four similar diagonal wires to the end of the rudder beam where it rests on the cross piece4 ,you will then have eight truss wires strengthening the connection of the rudder to the main body of the glider4 ,the framework of the rudder planes is then to be braced in the same way1 which will take eight more wires1 four for each rudder plane4 ,all the wires are to be connected at one end with turn-buckles so the tension may be regulated as desired4 ,in forming the rudder frame it will be well to mortise the corners1 tack them together with small nails1 and then put in a corner brace in the inside of each joint4 ,in doing this bear in mind that the material to be thus fastened is light1 and consequently the lightest of nails1 screws1 bolts and corner pieces1 etc41 is necessary4 ,,chapter ,,viii4 ,,the ,,real ,,flying ,,machine4 ,we will now assume that you have become proficient enough to warrant an attempt at the construction of a real flying machine--one that will not only remain suspended in the air at the will of the operator1 but make respectable progress in whatever direction he may desire to go4 ,the glider1 it must be remembered1 is not steerable1 except to a limited extent1 and moves only in one direction--against the wind4 ,besides this its power of flotation--suspension in the air--is circumscribed4 ,larger ,surface ,area ,required4 ,the real flying machine is the glider enlarged1 and equipped with motor and propeller4 ,the first thing to do is to decide upon the size required4 ,while a glider of #bj foot spread is large enough to sustain a man it could not under any possible conditions1 be made to rise with the weight of the motor1 propeller and similar equipment added4 ,as the load is increased so must the surface area of the planes be increased4 ,just what this increase in surface area should be is problematical as experienced aviators disagree1 but as a general proposition it may be placed at from three to four times the area of a #bj-;foot glider4 #c ,some ,practical ,examples4 ,the ,wrights used a biplane #da feet in spread1 and #f #a_/b ft4 deep4 ,this1 for the two planes1 gives a total surface area of #ech square feet1 inclusive of auxiliary planes4 ,this sustains the engine equipment1 operator1 etc41 a total weight officially announced at #a1jgj pounds4 ,it shows a lifting capacity of about two pounds to the square foot of plane surface1 as against a lifting capacity of about #a_/b pound per square foot of plane surface for the #bj-;foot glider4 ,this same ,wright machine is also reported to have made a successful flight1 carrying a total load of #a1ajj pounds1 which would be over two pounds for each square foot of surface area1 which1 with auxiliary planes1 is #ech square feet4 ,to attain the same results in a monoplane1 the single surface would have to be #fj feet in spread and #i feet deep4 ,but1 while this is the mathematical rule1 ,bleriot has demonstrated that it does not always hold good4 ,on his record-breaking trip across the ,english channel1 ,july #beth1 #aiji1 the ,frenchman was carried in a monoplane #bd #a_/b feet in spread1 and with a total sustaining surface of #aej #a_/b square feet4 ,the total weight of the outfit1 including machine1 operator and fuel sufficient for a three-hour run1 was only #ffj pounds4 ,with an engine of 7nominally7 #be horsepower the distance of #ba miles was covered in #cg minutes4 ,which is the ,best8 ,right here an established mathematical quantity is involved4 ,a small plane surface offers less resistance to the air than a large one and consequently can attain a higher rate of speed4 ,as explained further on in this chapter speed is an important factor in the matter of weight-sustaining capacity4 ,a machine that travels one-third faster than another can get along with one-half the surface area of the latter without affecting the load4 ,see the closing paragraph of this chapter on this point4 ,in theory the construction is also the simplest1 but this is not always found to be so in practice4 ,the designing and carrying into execution of plans for an extensive area like that of a monoplane involves great skill and cleverness in getting a framework that will be strong enough to furnish the requisite support without an undue excess of weight4 ,this proposition is greatly simplified in the biplane and1 while the speed attained by the latter may not be quite so great as that of the monoplane1 it has much larger weight-carrying capacity4 ,proper ,sizes ,for ,frame4 ,allowing that the biplane form is selected the construction may be practically identical with that of the #bj-;foot glider described in ,chapter ,v41 except as to size and elimination of the armpieces4 ,in size the surface planes should be about twice as large as those of the #bj-;foot glider1 viz3 #dj feet spread instead of #bj1 and #f feet deep instead of #c4 ,the horizontal beams1 struts1 stanchions1 ribs1 etc41 should also be increased in size proportionately4 ,while care in the selection of clear1 straight-grained timber is important in the glider1 it is still more important in the construction of a motor-equipped flying machine as the strain on the various parts will be much greater4 ,how to ,splice ,timbers4 ,it is practically certain that you will have to resort to splicing the horizontal beams as it will be difficult1 if not impossible1 to find #dj-;foot pieces of timber totally free from knots and worm holes1 and of straight grain4 ,if splicing is necessary select two good #bj-;foot pieces1 #c inches wide and #a #a_/b inches thick1 and one #aj-;foot long1 of the same thickness and width4 ,plane off the bottom sides of the #aj-;foot strip1 beginning about two feet back from each end1 and taper them so the strip will be about #c_/d inch thick at the extreme ends4 ,lay the two #bj-;foot beams end to end1 and under the joint thus made place the #aj-;foot strip1 with the planed-off ends downward4 ,the joint of the #bj-;foot pieces should be directly in the center of the #aj-;foot piece4 ,bore ten holes 7with a #a_/d-;inch augur7 equi-distant apart through the #bj-;foot strips and the #aj-;foot strip under them4 ,through these holes run #a_/d-;inch stove bolts with round1 beveled heads4 ,in placing these bolts use washers top and bottom1 one between the head and the top beam1 and the other between the bottom beam and the screw nut which holds the bolt4 ,screw the nuts down hard so as to bring the two beams tightly together1 and you will have a rigid #dj-;foot beam4 ,splicing with ,metal ,sleeves4 ,an even better way of making a splice is by tonguing and grooving the ends of the frame pieces and enclosing them in a metal sleeve1 but it requires more mechanical skill than the method first named4 ,the operation of tonguing and grooving is especially delicate and calls for extreme nicety of touch in the handling of tools1 but if this dexterity is possessed the job will be much more satisfactory than one done with a third timber4 ,as the frame pieces are generally about #a #a_/b inch in diameter1 the tongue and the groove into which the tongue fits must be correspondingly small4 ,begin by sawing into one side of one of the frame pieces about #d inches back from the end4 ,make the cut about #a_/b inch deep4 ,then turn the piece over and duplicate the cut4 ,next saw down from the end to these cuts4 ,when the sawed-out parts are removed you will have a tongue in the end of the frame timber #d inches long and #a_/b inch thick4 ,the next move is to saw out a #e_/h-;inch groove in the end of the frame piece which is to be joined4 ,you will have to use a small chisel to remove the #e_/h-;inch bit4 ,this will leave a groove into which the tongue will fit easily4 ,joining the ,two ,pieces4 ,take a thin metal sleeve--this is merely a hollow tube of aluminum or brass open at each end--#h inches long1 and slip it over either the tongued or grooved end of one of the frame timbers4 ,it is well to have the sleeve fit snugly1 and this may necessitate a sand-papering of the frame pieces so the sleeve will slip on4 ,push the sleeve well back out of the way4 ,cover the tongue thoroughly with glue1 and also put some on the inside of the groove4 ,use plenty of glue4 ,now press the tongue into the groove1 and keep the ends firmly together until the glue is thoroughly dried4 ,rub off the joint lightly with sand-paper to remove any of the glue which may have oozed out1 and slip the sleeve into place over the joint4 ,tack the sleeve in position with small copper tacks1 and you will have an ideal splice4 ,the same operation is to be repeated on each of the four frame pieces4 ,two #bj-;foot pieces joined in this way will give a substantial frame1 but when suitable timber of this kind can not be had1 three pieces1 each #f feet #aa inches long1 may be used4 ,this would give #bj feet #i inches1 of which #h inches will be taken up in the two joints1 leaving the frame #bj feet #a inch long4 ,installation of ,motor4 ,next comes the installation of the motor4 ,the kinds and efficiency of the various types are described in the following chapter 7,,ix74 ,all we are interested in at this point is the manner of installation4 ,this varies according to the personal ideas of the aviator4 ,thus one man puts his motor in the front of his machine1 another places it in the center1 and still another finds the rear of the frame the best4 ,all get good results1 the comparative advantages of which it is difficult to estimate4 ,where one man1 as already explained1 flies faster than another1 the one beaten from the speed standpoint has an advantage in the matter of carrying weight1 etc4 ,the ideas of various well-known aviators as to the correct placing of motors may be had from the following3 ,wrights--,in rear of machine and to one side4 ,curtiss--,well to rear1 about midway between upper and lower planes4 ,raich--,in rear1 above the center4 ,brauner-,smith--,in exact center of machine4 ,van ,anden--,in center4 ,herring-,burgess--,directly behind operator4 ,voisin--,in rear1 and on lower plane4 ,bleriot--,in front4 ,r4 ,e4 ,p4--,in front4 ,the ,one ,chief ,object4 ,an even distribution of the load so as to assist in maintaining the equilibrium of the machine1 should be the one chief object in deciding upon the location of the motor4 ,it matters little what particular spot is selected so long as the weight does not tend to overbalance the machine1 or to throw it off an even keel4 ,it is just like loading a vessel1 an operation in which the expert seeks to so distribute the weight of the cargo as to keep the vessel in a perfectly upright position1 and prevent a list or leaning to one side4 ,the more evenly the cargo is distributed the more perfect will be the equilibrium of the vessel and the better it can be handled4 ,sometimes1 when not properly stowed1 the cargo shifts1 and this at once affects the position of the craft4 ,when a ship lists to starboard or port a preponderating weight of the cargo has shifted sideways2 if bow or stern is unduly depressed it is a sure indication that the cargo has shifted accordingly4 ,in either event the handling of the craft becomes not only difficult1 but extremely hazardous4 ,exactly the same conditions prevail in the handling of a flying machine4 ,shape of ,machine a ,factor4 ,in placing the motor you must be governed largely by the shape and construction of the flying machine frame4 ,if the bulk of the weight of the machine and auxiliaries is toward the rear1 then the natural location for the motor will be well to the front so as to counterbalance the excess in rear weight4 ,in the same way if the preponderance of the weight is forward1 then the motor should be placed back of the center4 ,as the propeller blade is really an integral part of the motor1 the latter being useless without it1 its placing naturally depends upon the location selected for the motor4 ,rudders and ,auxiliary ,planes4 ,here again there is great diversity of opinion among aviators as to size1 location and form4 ,the striking difference of ideas in this respect is well illustrated in the choice made by prominent makers as follows3 ,voisin--horizontal rudder1 with two wing-like planes1 in front2 box-like longitudinal stability plane in rear1 inside of which is a vertical rudder4 ,wright--large biplane horizontal rudder in front at considerable distance--about #aj feet--from the main planes2 vertical biplane rudder in rear2 ends of upper and lower main planes made flexible so they may be moved4 ,curtiss--horizontal biplane rudder1 with vertical damping plane between the rudder planes about #aj feet in front of main planes2 vertical rudder in rear2 stabilizing planes at each end of upper main plane4 ,bleriot--,v-shaped stabilizing fin1 projecting from rear of plane1 with broad end outward2 to the broad end of this fin is hinged a vertical rudder2 horizontal biplane rudder1 also in rear1 under the fin4 ,these instances show forcefully the wide diversity of opinion existing among experienced aviators as to the best manner of placing the rudders and stabilizing1 or auxiliary planes1 and make manifest how hopeless would be the task of attempting to select any one form and advise its exclusive use4 ,rudder and ,auxiliary ,construction4 ,the material used in the construction of the rudders and auxiliary planes is the same as that used in the main planes--spruce for the framework and some kind of rubberized or varnished cloth for the covering4 ,the frames are joined and wired in exactly the same manner as the frames of the main planes1 the purpose being to secure the same strength and rigidity4 ,dimensions of the various parts depend upon the plan adopted and the size of the main plane4 ,no details as to exact dimensions of these rudders and auxiliary planes are obtainable4 ,the various builders1 while willing enough to supply data as to the general measurements1 weight1 power1 etc41 of their machines1 appear to have overlooked the details of the auxiliary parts1 thinking1 perhaps1 that these were of no particular import to the general public4 ,in the ,wright machine1 the rear horizontal and front vertical rudders may be set down as being about one-quarter 7probably a little less7 the size of the main supporting planes4 ,arrangement of ,alighting ,gear4 ,most modern machines are equipped with an alighting gear1 which not only serves to protect the machine and aviator from shock or injury in touching the ground1 but also aids in getting under headway4 ,all the leading makes1 with the exception of the ,wright1 are furnished with a frame carrying from two to five pneumatic rubber-tired bicycle wheels4 ,in the ,curtiss and ,voisin machines one wheel is placed in front and two in the rear4 ,in the ,bleriot and other prominent machines the reverse is the rule--two wheels in front and one in the rear4 ,farman makes use of five wheels1 one in the extreme rear1 and four1 arranged in pairs1 a little to the front of the center of the main lower plane4 ,in place of wheels the ,wright machine is equipped with a skid-like device consisting of two long beams attached to the lower plane by stanchions and curving up far in front1 so as to act as supports to the horizontal rudder4 ,why ,wood ,is ,favored4 ,a frequently asked question is3 ,why is not aluminum1 or some similar metal1 substituted for wood4 ,wood1 particularly spruce1 is preferred because1 weight considered1 it is much stronger than aluminum1 and this is the lightest of all metals4 ,in this connection the following table will be of interest3 ,compressive ,weight ,tensile ,strength ,strength per cubic foot per sq4 inch per sq4 inch ,material in lbs4 in lbs4 in lbs4 ,spruce4444 #be #h1jjj #e1jjj ,aluminum #afb #af1jjj 444444 ,brass 7sheet7 #eaj #bc1jjj #ab1jjj ,steel 7tool7 #dij #ajj1jjj #dj1jjj ,copper 7sheet7 #edh #cj1jjj #dj1jjj ,as extreme lightness1 combined with strength1 especially tensile strength1 is the great essential in flying-machine construction1 it can be readily seen that the use of metal1 even aluminum1 for the framework1 is prohibited by its weight4 ,while aluminum has double the strength of spruce wood it is vastly heavier1 and thus the advantage it has in strength is overbalanced many times by its weight4 ,the specific gravity of aluminum is #b4ej2 that of spruce is only #j4djc4 ,things to ,be ,considered4 ,in laying out plans for a flying machine there are five important points which should be settled upon before the actual work of construction is started4 ,these are3 ,first--,approximate weight of the machine when finished and equipped4 ,second--,area of the supporting surface required4 ,third--,amount of power that will be necessary to secure the desired speed and lifting capacity4 ,fourth--,exact dimensions of the main framework and of the auxiliary parts4 ,fifth--,size1 speed and character of the propeller4 ,in deciding upon these it will be well to take into consideration the experience of expert aviators regarding these features as given elsewhere4 7,see ,chapter ,x47 ,estimating the ,weights ,involved4 ,in fixing upon the probable approximate weight in advance of construction much1 of course1 must be assumed4 ,this means that it will be a matter of advance estimating4 ,if a two-passenger machine is to be built we will start by assuming the maximum combined weight of the two people to be #cej pounds4 ,most of the professional aviators are lighter than this4 ,taking the medium between the weights of the ,curtiss and ,wright machines we have a net average of #hej pounds for the framework1 motor1 propeller1 etc4 ,this1 with the two passengers1 amounts to #a1aij pounds4 ,as the machines quoted are in successful operation it will be reasonable to assume that this will be a safe basis to operate on4 ,what the ,novice ,must ,avoid4 ,this does not mean1 however1 that it will be safe to follow these weights exactly in construction1 but that they will serve merely as a basis to start from4 ,because an expert can turn out a machine1 thoroughly equipped1 of #hej pounds weight1 it does not follow that a novice can do the same thing4 ,the expert's work is the result of years of experience1 and he has learned how to construct frames and motor plants of the utmost lightness and strength4 ,it will be safer for the novice to assume that he can not duplicate the work of such men as ,wright and ,curtiss without adding materially to the gross weight of the framework and equipment minus passengers4 ,how to ,distribute the ,weight4 ,let us take #a1jcj pounds as the net weight of the machine as against the same average in the ,wright and ,curtiss machines4 ,now comes the question of distributing this weight between the framework1 motor1 and other equipment4 ,as a general proposition the framework should weigh about twice as much as the complete power plant 7this is for amateur work74 ,the word framework indicates not only the wooden frames of the main planes1 auxiliary planes1 rudders1 etc41 but the cloth coverings as well--everything in fact except the engine and propeller4 ,on the basis named the framework would weigh #fhf pounds1 and the power plant #cdd4 ,these figures are liberal1 and the results desired may be obtained well within them as the novice will learn as he makes progress in the work4 ,figuring on ,surface ,area4 ,it was ,prof4 ,langley who first brought into prominence in connection with flying machine construction the mathematical principle that the larger the object the smaller may be the relative area of support4 ,as explained in ,chapter ,,xiii1 there are mechanical limits as to size which it is not practical to exceed1 but the main principle remains in effect4 ,take two aeroplanes of marked difference in area of surface4 ,the larger will1 as a rule1 sustain a greater weight in relative proportion to its area than the smaller one1 and do the work with less relative horsepower4 ,as a general thing well-constructed machines will average a supporting capacity of one pound for every one-half square foot of surface area4 ,accepting this as a working rule we find that to sustain a weight of #a1bjj pounds--machine and two passengers--we should have #fjj square feet of surface4 ,distributing the ,surface ,area4 ,the largest surfaces now in use are those of the ,wright1 ,voisin and ,antoinette machines--#ech square feet in each4 ,the actual sustaining power of these machines1 so far as known1 has never been tested to the limit2 it is probable that the maximum is considerably in excess of what they have been called upon to show4 ,in actual practice the average is a little over one pound for each one-half square foot of surface area4 ,allowing that #fjj square feet of surface will be used1 the next question is how to distribute it to the best advantage4 ,this is another important matter in which individual preference must rule4 ,we have seen how the professionals disagree on this point1 some using auxiliary planes of large size1 and others depending upon smaller auxiliaries with an increase in number so as to secure on a different plan virtually the same amount of surface4 ,in deciding upon this feature the best thing to do is to follow the plans of some successful aviator1 increasing the area of the auxiliaries in proportion to the increase in the area of the main planes4 ,thus1 if you use #fjj square feet of surface where the man whose plans you are following uses #ejj1 it is simply a matter of making your planes one-fifth larger all around4 ,the ,cost of ,production4 ,cost of production will be of interest to the amateur who essays to construct a flying machine4 ,assuming that the size decided upon is double that of the glider the material for the framework1 timber1 cloth1 wire1 etc41 will cost a little more than double4 ,this is because it must be heavier in proportion to the increased size of the framework1 and heavy material brings a larger price than the lighter goods4 ,if we allow #bj as the cost of the glider material it will be safe to put down the cost of that required for a real flying machine framework at #fj1 provided the owner builds it himself4 ,as regards the cost of motor and similar equipment it can only be said that this depends upon the selection made4 ,there are some reliable aviation motors which may be had as low as #ejj1 and there are others which cost as much as #b1jjj4 ,services of ,expert ,necessary4 ,no matter what kind of a motor may be selected the services of an expert will be necessary in its proper installation unless the amateur has considerable genius in this line himself4 ,as a general thing #be should be a liberal allowance for this work4 ,no matter how carefully the engine may be placed and connected it will be largely a matter of luck if it is installed in exactly the proper manner at the first attempt4 ,the chances are that several alterations1 prompted by the results of trials1 will have to be made4 ,if this is the case the expert's bill may readily run up to #ej4 ,if the amateur is competent to do this part of the work the entire item of #ej may1 of course1 be cut out4 ,as a general proposition a fairly satisfactory flying machine1 one that will actually fly and carry the operator with it1 may be constructed for #gej1 but it will lack the better qualities which mark the higher priced machines4 ,this computation is made on the basis of #fj for material1 #ej for services of expert1 #fjj for motor1 etc41 and an allowance of #dj for extras4 ,no man who has the flying machine germ in his system will be long satisfied with his first moderate price machine1 no matter how well it may work4 ,it's the old story of the automobile bug over again4 ,the man who starts in with a modest #a1jjj automobile invariably progresses by easy stages to the #d1jjj or #e1jjj class4 ,the natural tendency is to want the biggest and best attainable within the financial reach of the owner4 ,it's exactly the same way with the flying machine convert4 ,the more proficient he becomes in the manipulation of his car1 the stronger becomes the desire to fly further and stay in the air longer than the rest of his brethren4 ,this necessitates larger1 more powerful1 and more expensive machines as the work of the germ progresses4 ,speed ,affects ,weight ,capacity4 ,don't overlook the fact that the greater speed you can attain the smaller will be the surface area you can get along with4 ,if a machine with #ejj square feet of sustaining surface1 traveling at a speed of #dj miles an hour1 will carry a weight of #a1bjj pounds1 we can cut the sustaining surface in half and get along with #bej square feet1 provided a speed of #fj miles an hour can be obtained4 ,at #ajj miles an hour only #hj square feet of surface area would be required4 ,in both instances the weight sustaining capacity will remain the same as with the #ejj square feet of surface area--#a1bjj pounds4 ,one of these days some mathematical genius will figure out this problem with exactitude and we will have a dependable table giving the maximum carrying capacity of various surface areas at various stated speeds1 based on the dimensions of the advancing edges4 ,at present it is largely a matter of guesswork so far as making accurate computation goes4 ,much depends upon the shape of the machine1 and the amount of surface offering resistance to the wind1 etc4 ,,chapter ,,ix4 ,,selection ,,of ,,the ,,motor4 ,motors for flying machines must be light in weight1 of great strength1 productive of extreme speed1 and positively dependable in action4 ,it matters little as to the particular form1 or whether air or water cooled1 so long as the four features named are secured4 ,there are at least a dozen such motors or engines now in use4 ,all are of the gasolene type1 and all possess in greater or lesser degree the desired qualities4 ,some of these motors are3 ,renault--#h-;cylinder1 air-cooled2 #ej horse power2 weight #cgd pounds4 ,fiat--#h-;cylinder1 air-cooled2 #ej horse power2 weight #aej pounds4 ,farcot--#h-;cylinder1 air-cooled2 from #cj to #ajj horse power1 according to bore of cylinders2 weight of smallest1 #hd pounds4 ,r4 ,e4 ,p4--#aj-;cylinder1 air-cooled2 #aej horse power2 weight #bae pounds4 ,gnome--#g and #ad cylinders1 revolving type1 air-cooled2 #ej and #ajj horse power2 weight #aej and #cjj pounds4 ,darracq--#b to #ad cylinders1 water cooled2 #cj to #bjj horse power2 weight of smallest #ajj pounds4 ,wright--#d-;cylinder1 water-cooled2 #be horse power2 weight #bjj pounds4 ,antoinette--#h and #af-;cylinder1 water-cooled2 #ej and #ajj horse power2 weight #bej and #ejj pounds4 ,e4 ,n4 ,v4--#h-;cylinder1 water-cooled2 from #cj to #hj horse power1 according to bore of cylinder2 weight #aej to #djj pounds4 ,curtiss--#h-;cylinder1 water-cooled2 #fj horse power2 weight #cjj pounds4 ,average ,weight ,per ,horse ,power4 ,it will be noticed that the ,gnome motor is unusually light1 being about three pounds to the horse power produced1 as opposed to an average of #d #a_/b pounds per horse power in other makes4 ,this result is secured by the elimination of the fly-wheel1 the engine itself revolving1 thus obtaining the same effect that would be produced by a fly-wheel4 ,the ,farcot is even lighter1 being considerably less than three pounds per horse power1 which is the nearest approach to the long-sought engine equipment that will make possible a complete flying machine the total weight of which will not exceed one pound per square foot of area4 ,how ,lightness ,is ,secured4 ,thus far foreign manufacturers are ahead of ,americans in the production of light-weight aerial motors1 as is evidenced by the ,gnome and ,farcot engines1 both of which are of ,french make4 ,extreme lightness is made possible by the use of fine1 specially prepared steel for the cylinders1 thus permitting them to be much thinner than if ordinary forms of steel were used4 ,another big saving in weight is made by substituting what are known as auto lubricating alloys for bearings4 ,these alloys are made of a combination of aluminum and magnesium4 ,still further gains are made in the use of alloy steel tubing instead of solid rods1 and also by the paring away of material wherever it can be done without sacrificing strength4 ,this plan1 with the exclusive use of the best grades of steel1 regardless of cost1 makes possible a marked reduction in weight4 ,multiplicity of ,cylinders4 ,strange as it may seem1 multiplicity of cylinders does not always add proportionate weight4 ,because a #d-;cylinder motor weighs say #ajj pounds1 it does not necessarily follow that an #h-;cylinder equipment will weigh #bjj pounds4 ,the reason of this will be plain when it is understood that many of the parts essential to a #d-;cylinder motor will fill the requirements of an #h-;cylinder motor without enlargement or addition4 ,neither does multiplying the cylinders always increase the horsepower proportionately4 ,if a #d-;cylinder motor is rated at #be horsepower it is not safe to take it for granted that double the number of cylinders will give #ej horsepower4 ,generally speaking1 eight cylinders1 the bore1 stroke and speed being the same1 will give double the power that can be obtained from four1 but this does not always hold good4 ,just why this exception should occur is not explainable by any accepted rule4 ,horse ,power and ,speed4 ,speed is an important requisite in a flying-machine motor1 as the velocity of the aeroplane is a vital factor in flotation4 ,at first thought1 the propeller and similar adjuncts being equal1 the inexperienced mind would naturally argue that a #ej-;horsepower engine should produce just double the speed of one of #be-;horsepower4 ,that this is a fallacy is shown by actual performances4 ,the ,wrights1 using a #be-;horsepower motor1 have made #dd miles an hour1 while ,bleriot1 with a #ej-;horsepower motor1 has a record of a short-distance flight at the rate of #eb miles an hour4 ,the fact is that1 so far as speed is concerned1 much depends upon the velocity of the wind1 the size and shape of the aeroplane itself1 and the size1 shape and gearing of the propeller4 ,the stronger the wind is blowing the easier it will be for the aeroplane to ascend1 but at the same time the more difficult it will be to make headway against the wind in a horizontal direction4 ,with a strong head wind1 and proper engine force1 your machine will progress to a certain extent1 but it will be at an angle4 ,if the aviator desired to keep on going upward this would be all right1 but there is a limit to the altitude which it is desirable to reach--from #ajj to #ejj feet for experts--and after that it becomes a question of going straight ahead4 ,great ,waste of ,power4 ,one thing is certain--even in the most efficient of modern aerial motors there is a great loss of power between the two points of production and effect4 ,the ,wright outfit1 which is admittedly one of the most effective in use1 takes one horsepower of force for the raising and propulsion of each #ej pounds of weight4 ,this1 for a #be-;horsepower engine1 would give a maximum lifting capacity of #abej pounds4 ,it is doubtful if any of the higher rated motors have greater efficiency4 ,as an #h-;cylinder motor requires more fuel to operate than a #d-;cylinder1 it naturally follows that it is more expensive to run than the smaller motor1 and a normal increase in capacity1 taking actual performances as a criterion1 is lacking4 ,in other words1 what is the sense of using an #h-;cylinder motor when one of #d cylinders is sufficient8 ,what the ,propeller ,does4 ,much of the efficiency of the motor is due to the form and gearing of the propeller4 ,here again1 as in other vital parts of flying-machine mechanism1 we have a wide divergence of opinion as to the best form4 ,a fish makes progress through the water by using its fins and tail2 a bird makes its way through the air in a similar manner by the use of its wings and tail4 ,in both instances the motive power comes from the body of the fish or bird4 ,in place of fins or wings the flying machine is equipped with a propeller1 the action of which is furnished by the engine4 ,fins and wings have been tried1 but they don't work4 ,while operating on the same general principle1 aerial propellers are much larger than those used on boats4 ,this is because the boat propeller has a denser1 more substantial medium to work in 7water71 and consequently can get a better hold1 and produce more propulsive force than one of the same size revolving in the air4 ,this necessitates the aerial propellers being much larger than those employed for marine purposes4 ,up to this point all aviators agree1 but as to the best form most of them differ4 ,kinds of ,propellers ,used4 ,one of the most simple is that used by ,curtiss4 ,it consists of two pear-shaped blades of laminated wood1 each blade being #e inches wide at its extreme point1 tapering slightly to the shaft connection4 ,these blades are joined at the engine shaft1 in a direct line4 ,the propeller has a pitch of #e feet1 and weighs1 complete1 less than #aj pounds4 ,the length from end to end of the two blades is #f #a_/b feet4 ,wright uses two wooden propellers1 in the rear of his biplane1 revolving in opposite directions4 ,each propeller is two-bladed4 ,bleriot also uses a two-blade wooden propeller1 but it is placed in front of his machine4 ,the blades are each about #c #a_/b feet long and have an acute twist4 ,santos-,dumont uses a two-blade wooden propeller1 strikingly similar to the ,bleriot4 ,on the ,antoinette monoplane1 with which good records have been made1 the propeller consists of two spoon-shaped pieces of metal1 joined at the engine shaft in front1 and with the concave surfaces facing the machine4 ,the propeller on the ,voisin biplane is also of metal1 consisting of two aluminum blades connected by a forged steel arm4 ,maximum thrust1 or stress--exercise of the greatest air-displacing force--is the object sought4 ,this1 according to experts1 is best obtained with a large propeller diameter and reasonably low speed4 ,the diameter is the distance from end to end of the blades1 which on the largest propellers ranges from #f to #h feet4 ,the larger the blade surface the greater will be the volume of air displaced1 and1 following this1 the greater will be the impulse which forces the aeroplane ahead4 ,in all centrifugal motion there is more or less tendency to disintegration in the form of flying off from the center1 and the larger the revolving object is the stronger is this tendency4 ,this is illustrated in the many instances in which big grindstones and fly-wheels have burst from being revolved too fast4 ,to have a propeller break apart in the air would jeopardize the life of the aviator1 and to guard against this it has been found best to make its revolving action comparatively slow4 ,besides this the slow motion 7it is only comparatively slow7 gives the atmosphere a chance to refill the area disturbed by one propeller blade1 and thus have a new surface for the next blade to act upon4 ,placing of the ,motor4 ,as on other points1 aviators differ widely in their ideas as to the proper position for the motor4 ,wright locates his on the lower plane1 midway between the front and rear edges1 but considerably to one side of the exact center4 ,he then counter-balances the engine weight by placing his seat far enough away in the opposite direction to preserve the center of gravity4 ,this leaves a space in the center between the motor and the operator in which a passenger may be carried without disturbing the equilibrium4 ,bleriot1 on the contrary1 has his motor directly in front and preserves the center of gravity by taking his seat well back1 this1 with the weight of the aeroplane1 acting as a counter-balance4 ,on the ,curtiss machine the motor is in the rear1 the forward seat of the operator1 and weight of the horizontal rudder and damping plane in front equalizing the engine weight4 ,no ,perfect ,motor as ,yet4 ,engine makers in the ,united ,states1 ,england1 ,france and ,germany are all seeking to produce an ideal motor for aviation purposes4 ,many of the productions are highly creditable1 but it may be truthfully said that none of them quite fill the bill as regards a combination of the minimum of weight with the maximum of reliable maintained power4 ,they are all1 in some respects1 improvements upon those previously in use1 but the great end sought for has not been fully attained4 ,one of the motors thus produced was made by the ,french firm of ,darracq at the suggestion of ,santos ,dumont1 and on lines laid down by him4 ,santos ,dumont wanted a #b-;cylinder horizontal motor capable of developing #cj horsepower1 and not exceeding #d #a_/b pounds per horsepower in weight4 ,there can be no question as to the ability and skill of the ,darracq people1 or of their desire to produce a motor that would bring new credit and prominence to the firm4 ,neither could anything radically wrong be detected in the plans4 ,but the motor1 in at least one important requirement1 fell short of expectations4 ,it could not be depended upon to deliver an energy of #cj horsepower continuously for any length of time4 ,its maximum power could be secured only in spurts4 ,this tends to show how hard it is to produce an ideal motor for aviation purposes4 ,santos ,dumont1 of undoubted skill and experience as an aviator1 outlined definitely what he wanted2 one of the greatest designers in the business drew the plans1 and the famous house of ,darracq bent its best energies to the production4 ,but the desired end was not fully attained4 ,features of ,darracq ,motor4 ,horizontal motors were practically abandoned some time ago in favor of the vertical type1 but ,santos ,dumont had a logical reason for reverting to them4 ,he wanted to secure a lower center of gravity than would be possible with a vertical engine4 ,theoretically his idea was correct as the horizontal motor lies flat1 and therefore offers less resistance to the wind1 but it did not work out as desired4 ,at the same time it must be admitted that this ,darracq motor is a marvel of ingenuity and exquisite workmanship4 ,the two cylinders1 having a bore of #e #a-aj inches and a stroke of #d #g-aj inches1 are machined out of a solid bar of steel until their weight is only #h #d-e pounds complete4 ,the head is separate1 carrying the seatings for the inlet and exhaust valves1 is screwed onto the cylinder1 and then welded in position4 ,a copper water-jacket is fitted1 and it is in this condition that the weight of #h #d-e pounds is obtained4 ,on long trips1 especially in regions where gasolene is hard to get1 the weight of the fuel supply is an important feature in aviation4 ,as a natural consequence flying machine operators favor the motor of greatest economy in gasolene consumption1 provided it gives the necessary power4 ,an ,american inventor1 ,ramsey by name1 is working on a motor which is said to possess great possibilities in this line4 ,its distinctive features include a connecting rod much shorter than usual1 and a crank shaft located the length of the crank from the central axis of the cylinder4 ,this has the effect of increasing the piston stroke1 and also of increasing the proportion of the crank circle during which effective pressure is applied to the crank4 ,making the connecting rod shorter and leaving the crank mechanism the same would introduce excessive cylinder friction4 ,this ,ramsey overcomes by the location of his crank shaft4 ,the effect of the long piston stroke thus secured1 is to increase the expansion of the gases1 which in turn increases the power of the engine without increasing the amount of fuel used4 ,propeller ,thrust ,important4 ,there is one great principle in flying machine propulsion which must not be overlooked4 ,no matter how powerful the engine may be unless the propeller thrust more than overcomes the wind pressure there can be no progress forward4 ,should the force of this propeller thrust and that of the wind pressure be equal the result is obvious4 ,the machine is at a stand-still so far as forward progress is concerned and is deprived of the essential advancing movement4 ,speed not only furnishes sustentation for the airship1 but adds to the stability of the machine4 ,an aeroplane which may be jerky and uncertain in its movements1 so far as equilibrium is concerned1 when moving at a slow gait1 will readily maintain an even keel when the speed is increased4 ,designs for ,propeller ,blades4 ,it is the object of all men who design propellers to obtain the maximum of thrust with the minimum expenditure of engine energy4 ,with this purpose in view many peculiar forms of propeller blades have been evolved4 ,in theory it would seem that the best effects could be secured with blades so shaped as to present a thin 7or cutting7 edge when they come out of the wind1 and then at the climax of displacement afford a maximum of surface so as to displace as much air as possible4 ,while this is the form most generally favored there are others in successful operation4 ,there is also wide difference in opinion as to the equipment of the propeller shaft with two or more blades4 ,some aviators use two and some four4 ,all have more or less success4 ,as a mathematical proposition it would seem that four blades should give more propulsive force than two1 but here again comes in one of the puzzles of aviation1 as this result is not always obtained4 ,difference in ,propeller ,efficiency4 ,that there is a great difference in propeller efficiency is made readily apparent by the comparison of effects produced in two leading makes of machines--the ,wright and the ,voisin4 ,in the former a weight of from #a1ajj to #a1bjj pounds is sustained and advance progress made at the rate of #dj miles an hour and more1 with half the engine speed of a #be horse-power motor4 ,this would be a sustaining capacity of #dh pounds per horsepower4 ,but the actual capacity of the ,wright machine1 as already stated1 is #ej pounds per horsepower4 ,the ,voisin machine1 with aviator1 weighs about #a1cgj pounds1 and is operated with a so-horsepower motor4 ,allowing it the same speed as the ,wright we find that1 with double the engine energy1 the lifting capacity is only #bg #a_/b pounds per horsepower4 ,to what shall we charge this remarkable difference8 ,the surface of the planes is exactly the same in both machines so there is no advantage in the matter of supporting area4 ,comparison of ,two ,designs4 ,on the ,wright machine two wooden propellers of two blades each 7each blade having a decided twist7 are used4 ,as one #be horsepower motor drives both propellers the engine energy amounts to just one-half of this for each1 or #ab #a_/b horsepower4 ,and this energy is utilized at one-half the normal engine speed4 ,on the ,voisin a radically different system is employed4 ,here we have one metal two-bladed propeller with a very slight twist to the blade surfaces4 ,the full energy of a #ej-;horsepower motor is utilized4 ,experts ,fail to ,agree4 ,why should there be such a marked difference in the results obtained8 ,who knows8 ,some experts maintain that it is because there are two propellers on the ,wright machine and only one on the ,voisin1 and consequently double the propulsive power is exerted4 ,but this is not a fair deduction1 unless both propellers are of the same size4 ,propulsive power depends upon the amount of air displaced1 and the energy put into the thrust which displaces the air4 ,other experts argue that the difference in results may be traced to the difference in blade design1 especially in the matter of twist4 ,the fact is that propeller results depend largely upon the nature of the aeroplanes on which they are used4 ,a propeller1 for instance1 which gives excellent results on one type of aeroplane1 will not work satisfactorily on another4 ,there are some features1 however1 which may be safely adopted in propeller selection4 ,these are3 ,as extensive a diameter as possible2 blade area #aj to #ae per cent of the area swept2 pitch four-fifths of the diameter2 rotation slow4 ,the maximum of thrust effort will be thus obtained4 ,,chapter ,x4 ,,proper ,,dimensions ,,of ,,machines4 ,in laying out plans for a flying machine the first thing to decide upon is the size of the plane surfaces4 ,the proportions of these must be based upon the load to be carried4 ,this includes the total weight of the machine and equipment1 and also the operator4 ,this will be a rather difficult problem to figure out exactly1 but practical approximate figures may be reached4 ,it is easy to get at the weight of the operator1 motor and propeller1 but the matter of determining1 before they are constructed1 what the planes1 rudders1 auxiliaries1 etc41 will weigh when completed is an intricate proposition4 ,the best way is to take the dimensions of some successful machine and use them1 making such alterations in a minor way as you may desire4 ,dimensions of ,leading ,machines4 ,in the following tables will be found the details as to surface area1 weight1 power1 etc41 of the nine principal types of flying machines which are now prominently before the public3 ,,monoplanes4 ,surface area ,spread in ,depth in ,make ,passengers sq4 feet linear feet linear feet ,santos-,dumont44 #a #aaj #af4j #bf4j ,bleriot44444 #a #aej4f #bd4f #bb4j ,r4 ,e4 ,p44444 #a #bae #cd4a #bh4i ,bleriot44444 #b #bcf #cb4i #bc4j ,antoinette4444 #b #ech #da4b #cg4i ,no4 of ,weight ,without ,propeller ,make ,cylinders ,horse ,power ,operator ,diameter ,santos-,dumont44 #b #cj #bej #e4j ,bleriot44444 #c #be #fhj #f4i ,r4 ,e4 ,p44444 #g #ce #ijj #f4f ,bleriot44444 #g #ej #a1bdj #h4a ,antoinette444 #h #ej #a1jdj #g4b ,,biplanes4 ,surface ,area ,spread in ,depth in ,make ,passengers sq4 feet linear feet linear feet ,curtiss444 #b #beh #bi4j #bh4g ,wright4444 #b #ech #da4j #cj4g ,farman4444 #b #dcj #cb4i #ci4f ,voisin4444 #b #ech #cg4i #ci4f ,no4 of ,weight ,without ,propeller ,make ,cylinders ,horse ,power ,operator ,diameter ,curtiss444 #h #ej #fjj #f4j ,wright4444 #d #be #a1ajj #h4a ,farman4444 #g #ej #a1bjj #h4i ,voisin4444 #h #ej #a1bjj #f4f ,in giving the depth dimensions the length over all--from the extreme edge of the front auxiliary plane to the extreme tip of the rear is stated4 ,thus while the dimensions of the main planes of the ,wright machine are #da feet spread by #f #a_/b feet in depth1 the depth over all is #cj4g4 ,figuring ,out the ,details4 ,with this data as a guide it should be comparatively easy to decide upon the dimensions of the machine required4 ,in arriving at the maximum lifting capacity the weight of the operator must be added4 ,assuming this to average #agj pounds the method of procedure would be as follows3 ,add the weight of the operator to the weight of the complete machine4 ,the new ,wright machine complete weighs #ijj pounds4 ,this1 plus #agj1 the weight of the operator1 gives a total of #a1jgj pounds4 ,there are #ech square feet of supporting surface1 or practically one square foot of surface area to each two pounds of load4 ,there are some machines1 notably the ,bleriot1 in which the supporting power is much greater4 ,in this latter instance we find a surface area of #aej #a_/b square feet carrying a load of #fhj plus #agj1 or an aggregate of #hej pounds4 ,this is the equivalent of five pounds to the square foot4 ,this ratio is phenomenally large1 and should not be taken as a guide by amateurs4 ,the ,matter of ,passengers4 ,these deductions are based on each machine carrying one passenger1 which is admittedly the limit at present of the monoplanes like those operated for record-making purposes by ,santos-,dumont and ,bleriot4 ,the biplanes1 however1 have a two-passenger capacity1 and this adds materially to the proportion of their weight-sustaining power as compared with the surface area4 ,in the following statement all the machines are figured on the one-passenger basis4 ,curtiss and ,wright have carried two passengers on numerous occasions1 and an extra #agj pounds should therefore be added to the total weight carried1 which would materially increase the capacity4 ,even with the two-passenger load the limit is by no means reached1 but as experiments have gone no further it is impossible to make more accurate figures4 ,average ,proportions of ,load4 ,it will be interesting1 before proceeding to lay out the dimension details1 to make a comparison of the proportion of load effect with the supporting surfaces of various well-known machines4 ,here are the figures3 ,santos-,dumont--,a trifle under four pounds per square foot4 ,bleriot--,five pounds4 ,r4 ,e4 ,p4--,five pounds4 ,antoinette--,about two and one-quarter pounds4 ,curtiss--,about two and one-half pounds4 ,wright--,two and one-quarter pounds4 ,farman--,a trifle over three pounds4 ,voisin--,a little under two and one-half pounds4 ,importance of ,engine ,power4 ,while these figures are authentic1 they are in a way misleading1 as the important factor of engine power is not taken into consideration4 ,let us recall the fact that it is the engine power which keeps the machine in motion1 and that it is only while in motion that the machine will remain suspended in the air4 ,hence1 to attribute the support solely to the surface area is erroneous4 ,true1 that once under headway the planes contribute largely to the sustaining effect1 and are absolutely essential in aerial navigation--the motor could not rise without them--still1 when it comes to a question of weight-sustaining power1 we must also figure on the engine capacity4 ,in the ,wright machine1 in which there is a lifting capacity of approximately #b #a_/d pounds to the square foot of surface area1 an engine of only #be horsepower is used4 ,in the ,curtiss1 which has a lifting capacity of #b #a_/b pounds per square foot1 the engine is of #ej horsepower4 ,this is another of the peculiarities of aerial construction and navigation4 ,here we have a gain of #a_/d pound in weight-lifting capacity with an expenditure of double the horsepower4 ,it is this feature which enables ,curtiss to get along with a smaller surface area of supporting planes at the expense of a big increase in engine power4 ,proper ,weight of ,machine4 ,as a general proposition the most satisfactory machine for amateur purposes will be found to be one with a total weight-sustaining power of about #a1bjj pounds4 ,deducting #agj pounds as the weight of the operator1 this will leave #a1jcj pounds for the complete motor-equipped machine1 and it should be easy to construct one within this limit4 ,this implies1 of course1 that due care will be taken to eliminate all superfluous weight by using the lightest material compatible with strength and safety4 ,this plan will admit of #fhf pounds weight in the frame work1 coverings1 etc41 and #cdd for the motor1 propeller1 etc41 which will be ample4 ,just how to distribute the weight of the planes is a matter which must be left to the ingenuity of the builder4 ,comparison of ,bird ,power4 ,there is an interesting study in the accompanying illustration4 ,note that the surface area of the albatross is much smaller than that of the vulture1 although the wing spread is about the same4 ,despite this the albatross accomplishes fully as much in the way of flight and soaring as the vulture4 ,why8 ,because the albaboss is quicker and more powerful in action4 ,it is the application of this same principle in flying machines which enables those of great speed and power to get along with less supporting surface than those of slower movement4 ,measurements of ,curtiss ,machine4 ,some idea of framework proportion may be had from the following description of the ,curtiss machine4 ,the main planes have a spread 7width7 of #bi feet1 and are #d #a_/b feet deep4 ,the front double surface horizontal rudder is #fx#b feet1 with an area of #bd square feet4 ,to the rear of the main planes is a single surface horizontal plane #fx#b feet1 with an area of #ab square feet4 ,in connection with this is a vertical rudder #b #a_/b feet square4 ,two movable ailerons1 or balancing planes1 are placed at the extreme ends of the upper planes4 ,these are #fx#b feet1 and have a combined area of #bd square feet4 ,there is also a triangular shaped vertical steadying surface in connection with the front rudder4 ,thus we have a total of #aie square feet1 but as the official figures are #beh1 and the size of the triangular-shaped steadying surface is unknown1 we must take it for granted that this makes up the difference4 ,in the matter of proportion the horizontal double-plane rudder is about one-tenth the size of the main plane1 counting the surface area of only one plane1 the vertical rudder one-fortieth1 and the ailerons one-twentieth4 ,,chapter ,,xi4 ,,plane ,,and ,,rudder ,,control4 ,having constructed and equipped your machine1 the next thing is to decide upon the method of controlling the various rudders and auxiliary planes by which the direction and equilibrium and ascending and descending of the machine are governed4 ,the operator must be in position to shift instantaneously the position of rudders and planes1 and also to control the action of the motor4 ,this latter is supposed to work automatically and as a general thing does so with entire satisfaction1 but there are times when the supply of gasolene must be regulated1 and similar things done4 ,airship navigation calls for quick action1 and for this reason the matter of control is an important one--it is more than important2 it is vital4 ,several ,methods of ,control4 ,some aviators use a steering wheel somewhat after the style of that used in automobiles1 and by this not only manipulate the rudder planes1 but also the flow of gasolene4 ,others employ foot levers1 and still others1 like the ,wrights1 depend upon hand levers4 ,curtiss steers his aeroplane by means of a wheel1 but secures the desired stabilizing effect with an ingenious jointed chair-back4 ,this is so arranged that by leaning toward the high point of his wing planes the aeroplane is restored to an even keel4 ,the steering post of the wheel is movable backward and forward1 and by this motion elevation is obtained4 ,the ,wrights for some time used two hand levers1 one to steer by and warp the flexible tips of the planes1 the other to secure elevation4 ,they have now consolidated all the functions in one lever4 ,bleriot also uses the single lever control4 ,farman employs a lever to actuate the rudders1 but manipulates the balancing planes by foot levers4 ,santos-,dumont uses two hand levers with which to steer and elevate1 but manipulates the planes by means of an attachment to the back of his outer coat4 ,connection ,with the ,levers4 ,no matter which particular method is employed1 the connection between the levers and the object to be manipulated is almost invariably by wire4 ,for instance1 from the steering levers 7or lever7 two wires connect with opposite sides of the rudder4 ,as a lever is moved so as to draw in the right-hand wire the rudder is drawn to the right and vice versa4 ,the operation is exactly the same as in steering a boat4 ,it is the same way in changing the position of the balancing planes4 ,a movement of the hands or feet and the machine has changed its course1 or1 if the equilibrium is threatened1 is back on an even keel4 ,simple as this seems it calls for a cool head1 quick eye1 and steady hand4 ,the least hesitation or a false movement1 and both aviator and craft are in danger4 ,which ,method is ,best8 ,it would be a bold man who would attempt to pick out any one of these methods of control and say it was better than the others4 ,as in other sections of aeroplane mechanism each method has its advocates who dwell learnedly upon its advantages1 but the fact remains that all the various plans work well and give satisfaction4 ,what the novice is interested in knowing is how the control is effected1 and whether he has become proficient enough in his manipulation of it to be absolutely dependable in time of emergency4 ,no amateur should attempt a flight alone1 until he has thoroughly mastered the steering and plane control4 ,if the services and advice of an experienced aviator are not to be had the novice should mount his machine on some suitable supports so it will be well clear of the ground1 and1 getting into the operator's seat1 proceed to make himself well acquainted with the operation of the steering wheel and levers4 ,some ,things to ,be ,learned4 ,he will soon learn that certain movements of the steering gear produce certain effects on the rudders4 ,if1 for instance1 his machine is equipped with a steering wheel1 he will find that turning the wheel to the right turns the aeroplane in the same direction1 because the tiller is brought around to the left4 ,in the same way he will learn that a given movement of the lever throws the forward edge of the main plane upward1 and that the machine1 getting the impetus of the wind under the concave surfaces of the planes1 will ascend4 ,in the same way it will quickly become apparent to him that an opposite movement of the lever will produce an opposite effect--the forward edges of the planes will be lowered1 the air will be spilled out to the rear1 and the machine will descend4 ,the time expended in these preliminary lessons will be well spent4 ,it would be an act of folly to attempt to actually sail the craft without them4 ,,chapter ,,xii4 ,,how ,,to ,,use ,,the ,,machine4 ,it is a mistaken idea that flying machines must be operated at extreme altitudes4 ,true1 under the impetus of handsome prizes1 and the incentive to advance scientific knowledge1 professional aviators have ascended to considerable heights1 flights at from #ejj to #a1ejj feet being now common with such experts as ,farman1 ,bleriot1 ,latham1 ,paulhan1 ,wright and ,curtiss4 ,the altitude record at this time is about #d1afe feet1 held by ,paulhan4 ,one of the instructions given by experienced aviators to pupils1 and for which they insist upon implicit obeyance1 is3 ,if your machine gets more than #cj feet high1 or comes closer to the ground than #f feet1 descend at once4 ,such men as ,wright and ,curtiss will not tolerate a violation of this rule4 ,if their instructions are not strictly complied with they decline to give the offender further lessons4 ,why ,this ,rule ,prevails4 ,there is good reason for this precaution4 ,the higher the altitude the more rarefied 7thinner7 becomes the air1 and the less sustaining power it has4 ,consequently the more difficult it becomes to keep in suspension a given weight4 ,when sailing within #cj feet of the ground sustentation is comparatively easy and1 should a fall occur1 the results are not likely to be serious4 ,on the other hand1 sailing too near the ground is almost as objectionable in many ways as getting up too high4 ,if the craft is navigated too close to the ground trees1 shrubs1 fences and other obstructions are liable to be encountered4 ,there is also the handicap of contrary air currents diverted by the obstructions referred to1 and which will be explained more fully further on4 ,how to ,make a ,start4 ,taking it for granted that the beginner has familiarized himself with the manipulation of the machine1 and especially the control mechanism1 the next thing in order is an actual flight4 ,it is probable that his machine will be equipped with a wheeled alighting gear1 as the skids used by the ,wrights necessitate the use of a special starting track4 ,in this respect the wheeled machine is much easier to handle so far as novices are concerned as it may be easily rolled to the trial grounds4 ,this1 as in the case of the initial experiments1 should be a clear1 reasonably level place1 free from trees1 fences1 rocks and similar obstructions with which there may be danger of colliding4 ,the beginner will need the assistance of three men4 ,one of these should take his position in the rear of the machine1 and one at each end4 ,on reaching the trial ground the aviator takes his seat in the machine and1 while the men at the ends hold it steady the one in the rear assists in retaining it until the operator is ready4 ,in the meantime the aviator has started his motor4 ,like the glider the flying machine1 in order to accomplish the desired results1 should be headed into the wind4 ,when the ,machine ,rises4 ,under the impulse of the pushing movement1 and assisted by the motor action1 the machine will gradually rise from the ground--provided it has been properly proportioned and put together1 and everything is in working order4 ,this is the time when the aviator requires a cool head1 ,at a modest distance from the ground use the control lever to bring the machine on a horizontal level and overcome the tendency to rise4 ,the exact manipulation of this lever depends upon the method of control adopted1 and with this the aviator is supposed to have thoroughly familiarized himself as previously advised in ,chapter ,,xi4 ,it is at this juncture that the operator must act promptly1 but with the perfect composure begotten of confidence4 ,one of the great drawbacks in aviation by novices is the tendency to become rattled1 and this is much more prevalent than one might suppose1 even among men who1 under other conditions1 are cool and confident in their actions4 ,there is something in the sensation of being suddenly lifted from the ground1 and suspended in the air that is disconcerting at the start1 but this will soon wear off if the experimenter will keep cool4 ,a few successful flights no matter how short they may be1 will put a lot of confidence into him4 ,make ,your ,flights ,short4 ,be modest in your initial flights4 ,don't attempt to match the records of experienced men who have devoted years to mastering the details of aviation4 ,paulhan1 ,farman1 ,bleriot1 ,wright1 ,curtiss1 and all the rest of them began1 and practiced for years1 in the manner here described1 being content to make just a little advancement at each attempt4 ,a flight of #aej feet1 cleanly and safely made1 is better as a beginning than one of #djj yards full of bungling mishaps4 ,and yet these latter have their uses1 provided the operator is of a discerning mind and can take advantage of them as object lessons4 ,but1 it is not well to invite them4 ,they will occur frequently enough under the most favorable conditions1 and it is best to have them come later when the feeling of trepidation and uncertainty as to what to do has worn off4 ,above all1 don't attempt to fly too high4 ,keep within a reasonable distance from the ground--about #be or #cj feet4 ,this advice is not given solely to lessen the risk of serious accident in case of collapse1 but mainly because it will assist to instill confidence in the operator4 ,it is comparatively easy to learn to swim in shallow water1 but the knowledge that one is tempting death in deep water begets timidity4 ,preserving the ,equilibrium4 ,after learning how to start and stop1 to ascend and descend1 the next thing to master is the art of preserving equilibrium1 the knack of keeping the machine perfectly level in the air--on an even keel1 as a sailor would say4 ,this simile is particularly appropriate as all aviators are in reality sailors1 and much more daring ones than those who course the seas4 ,the latter are in craft which are kept afloat by the buoyancy of the water1 whether in motion or otherwise and1 so long as normal conditions prevail1 will not sink4 ,aviators sail the air in craft in which constant motion must be maintained in order to ensure flotation4 ,the man who has ridden a bicycle or motorcycle around curves at anything like high speed1 will have a very good idea as to the principle of maintaining equilibrium in an airship4 ,he knows that in rounding curves rapidly there is a marked tendency to change the direction of the motion which will result in an upset unless he overcomes it by an inclination of his body in an opposite direction4 ,this is why we see racers lean well over when taking the curves4 ,it simply must be done to preserve the equilibrium and avoid a spill4 ,how ,it ,works ,in the ,air4 ,if the equilibrium of an airship is disturbed to an extent which completely overcomes the center of gravity it falls according to the location of the displacement4 ,if this displacement1 for instance1 is at either end the apparatus falls endways2 if it is to the front or rear1 the fall is in the corresponding direction4 ,owing to uncertain air currents--the air is continually shifting and eddying1 especially within a hundred feet or so of the earth--the equilibrium of an airship is almost constantly being disturbed to some extent4 ,even if this disturbance is not serious enough to bring on a fall it interferes with the progress of the machine1 and should be overcome at once4 ,this is one of the things connected with aerial navigation which calls for prompt1 intelligent action4 ,frequently1 when the displacement is very slight1 it may be overcome1 and the craft immediately righted by a mere shifting of the operator's body4 ,take1 for illustration1 a case in which the extreme right end of the machine becomes lowered a trifle from the normal level4 ,it is possible to bring it back into proper position by leaning over to the left far enough to shift the weight to the counter-balancing point4 ,the same holds good as to minor front or rear displacements4 ,when ,planes ,must ,be ,used4 ,there are other displacements1 however1 and these are the most frequent1 which can be only overcome by manipulation of the stabilizing planes4 ,the method of procedure depends upon the form of machine in use4 ,the ,wright machine1 as previously explained1 is equipped with plane ends which are so contrived as to admit of their being warped 7position changed7 by means of the lever control4 ,these flexible tip planes move simultaneously1 but in opposite directions4 ,as those on one end rise1 those on the other end fall below the level of the main plane4 ,by this means air is displaced at one point1 and an increased amount secured in another4 ,this may seem like a complicated system1 but its workings are simple when once understood4 ,it is by the manipulation or warping of these flexible tips that transverse stability is maintained1 and any tendency to displacement endways is overcome4 ,longitudinal stability is governed by means of the front rudder4 ,stabilizing planes of some form are a feature1 and a necessary feature1 on all flying machines1 but the methods of application and manipulation vary according to the individual ideas of the inventors4 ,they all tend1 however1 toward the same end--the keeping of the machine perfectly level when being navigated in the air4 ,when to ,make a ,flight4 ,a beginner should never attempt to make a flight when a strong wind is blowing4 ,the fiercer the wind1 the more likely it is to be gusty and uncertain1 and the more difficult it will be to control the machine4 ,even the most experienced and daring of aviators find there is a limit to wind speed against which they dare not compete4 ,this is not because they lack courage1 but have the sense to realize that it would be silly and useless4 ,the novice will find a comparatively still day1 or one when the wind is blowing at not to exceed #ae miles an hour1 the best for his experiments4 ,the machine will be more easily controlled1 the trip will be safer1 and also cheaper as the consumption of fuel increases with the speed of the wind against which the aeroplane is forced4 ,,chapter ,,xiii4 ,,peculiarities ,,of ,,airship ,,power4 ,as a general proposition it takes much more power to propel an airship a given number of miles in a certain time than it does an automobile carrying a far heavier load4 ,automobiles with a gross load of #d1jjj pounds1 and equipped with engines of #cj horsepower1 have travelled considerable distances at the rate of #ej miles an hour4 ,this is an equivalent of about #acd pounds per horsepower4 ,for an average modern flying machine1 with a total load1 machine and passengers1 of #a1bjj pounds1 and equipped with a #ej-;horsepower engine1 #ej miles an hour is the maximum4 ,here we have the equivalent of exactly #bd pounds per horsepower4 ,why this great difference8 ,no less an authority than ,mr4 ,octave ,chanute answers the question in a plain1 easily understood manner4 ,he says3 ,in the case of an automobile the ground furnishes a stable support2 in the case of a flying machine the engine must furnish the support and also velocity by which the apparatus is sustained in the air4 ,pressure of the ,wind4 ,air pressure is a big factor in the matter of aeroplane horsepower4 ,allowing that a dead calm exists1 a body moving in the atmosphere creates more or less resistance4 ,the faster it moves1 the greater is this resistance4 ,moving at the rate of #fj miles an hour the resistance1 or wind pressure1 is approximately #ej pounds to the square foot of surface presented4 ,if the moving object is advancing at a right angle to the wind the following table will give the horsepower effect of the resistance per square foot of surface at various speeds4 ,horse ,power ,miles per ,hour per sq4 foot #aj #j4jac #ae #j #jdd #bj #j4aje #be #j4bje #cj #j4ced #dj #j4hd #ej #a4fd #fj #b4hc #hj #f4gb #ajj #ac4ab ,while the pressure per square foot at #fj miles an hour1 is only #a4fd horsepower1 at #ajj miles1 less than double the speed1 it has increased to #ac4ab horsepower1 or exactly eight times as much4 ,in other words the pressure of the wind increases with the square of the velocity4 ,wind at #aj miles an hour has four times more pressure than wind at #e miles an hour4 ,how to ,determine ,upon ,power4 ,this element of air resistance must be taken into consideration in determining the engine horsepower required4 ,when the machine is under headway sufficient to raise it from the ground 7about #bj miles an hour71 each square foot of surface resistance1 will require nearly nine-tenths of a horsepower to overcome the wind pressure1 and propel the machine through the air4 ,as shown in the table the ratio of power required increases rapidly as the speed increases until at #fj miles an hour approximately #c horsepower is needed4 ,in a machine like the ,curtiss the area of wind-exposed surface is about #ae square feet4 ,on the basis of this resistance moving the machine at #dj miles an hour would require #ab horsepower4 ,this computation covers only the machine's power to overcome resistance4 ,it does not cover the power exerted in propelling the machine forward after the air pressure is overcome4 ,to meet this important requirement ,mr4 ,curtiss finds it necessary to use a #ej-;horsepower engine4 ,of this power1 as has been already stated1 #ab horsepower is consumed in meeting the wind pressure1 leaving #ch horsepower for the purpose of making progress4 ,the flying machine must move faster than the air to which it is opposed4 ,unless it does this there can be no direct progress4 ,if the two forces are equal there is no straight-ahead advancement4 ,take1 for sake of illustration1 a case in which an aeroplane1 which has developed a speed of #cj miles an hour1 meets a wind velocity of equal force moving in an opposite direction4 ,what is the result8 ,there can be no advance because it is a contest between two evenly matched forces4 ,the aeroplane stands still4 ,the only way to get out of the difficulty is for the operator to wait for more favorable conditions1 or bring his machine to the ground in the usual manner by manipulation of the control system4 ,take another case4 ,an aeroplane1 capable of making #ej miles an hour in a calm1 is met by a head wind of #be miles an hour4 ,how much progress does the aeroplane make8 ,obviously it is #be miles an hour over the ground4 ,put the proposition in still another way4 ,if the wind is blowing harder than it is possible for the engine power to overcome1 the machine will be forced backward4 ,wind ,pressure a ,necessity4 ,while all this is true1 the fact remains that wind pressure1 up to a certain stage1 is an absolute necessity in aerial navigation4 ,the atmosphere itself has very little real supporting power1 especially if inactive4 ,if a body heavier than air is to remain afloat it must move rapidly while in suspension4 ,one of the best illustrations of this is to be found in skating over thin ice4 ,every school boy knows that if he moves with speed he may skate or glide in safety across a thin sheet of ice that would not begin to bear his weight if he were standing still4 ,exactly the same proposition obtains in the case of the flying machine4 ,the non-technical reason why the support of the machine becomes easier as the speed increases is that the sustaining power of the atmosphere increases with the resistance1 and the speed with which the object is moving increases this resistance4 ,with a velocity of #ab miles an hour the weight of the machine is practically reduced by #bcj pounds4 ,thus1 if under a condition of absolute calm it were possible to sustain a weight of #ggj pounds1 the same atmosphere would sustain a weight of #a1jjj pounds moving at a speed of #ab miles an hour4 ,this sustaining power increases rapidly as the speed increases4 ,while at #ab miles the sustaining power is figured at #bcj pounds1 at #bd miles it is four times as great1 or #ibj pounds4 ,supporting ,area of ,birds4 ,one of the things which all producing aviators seek to copy is the motive power of birds1 particularly in their relation to the area of support4 ,close investigation has established the fact that the larger the bird the less is the relative area of support required to secure a given result4 ,this is shown in the following table3 ,supporting ,weight ,surface ,horse area ,bird in lbs4 in sq4 feet power per lb4 ,pigeon #a4jj #j4g #j4jab #j4g ,wild ,goose #i4jj #b4fe #j4jbf #j4bhcc ,buzzard #e4jj #e4jc #j4jae #a4jf ,condor #ag4jj #i4he #j4jdc #j4eg ,so far as known the condor is the largest of modern birds4 ,it has a wing stretch of #aj feet from tip to tip1 a supporting area of about #aj square feet1 and weighs #ag pounds4 ,it4 is capable of exerting perhaps #a-cj horsepower4 7,these figures are1 of course1 approximate47 ,comparing the condor with the buzzard with a wing stretch of #f feet1 supporting area of #e square feet1 and a little over #a-ajj horsepower1 it may be seen that1 broadly speaking1 the larger the bird the less surface area 7relatively7 is needed for its support in the air4 ,comparison ,with ,aeroplanes4 ,if we compare the bird figures with those made possible by the development of the aeroplane it will be readily seen that man has made a wonderful advance in imitating the results produced by nature4 ,here are the figures3 ,supporting ,weight ,surface ,horse area ,machine in lbs4 in sq4 feet power per lb4 ,santos-,dumont44 #cej #aaj4jj #cj #j4cad ,bleriot44444 #gjj #aej4jj #be #j4bad ,antoinette4444 #a1bjj #ech4jj #ej #j4ddh ,curtiss44444 #gjj #beh4jj #fj #j4cfh ,wright44444#d #a1ajj #ech4jj #be #j4dhi ,farman444444 #a1bjj #dcj4jj #ej #j4ceh ,voisin444444 #a1bjj #ech4jj #ej #j4ddh ,while the average supporting surface is in favor of the aeroplane1 this is more than overbalanced by the greater amount of horsepower required for the weight lifted4 ,the average supporting surface in birds is about three-quarters of a square foot per pound4 ,in the average aeroplane it is about one-half square foot per pound4 ,on the other hand the average aeroplane has a lifting capacity of #bd pounds per horsepower1 while the buzzard1 for instance1 lifts #e pounds with #ae-ajj of a horsepower4 ,if the ,wright machine--which has a lifting power of #ej pounds per horsepower--should be alone considered the showing would be much more favorable to the aeroplane1 but it would not be a fair comparison4 ,more ,surface1 ,less ,power4 ,broadly speaking1 the larger the supporting area the less will be the power required4 ,wright1 by the use of #ech square feet of supporting surface1 gets along with an engine of #be horsepower4 ,curtiss1 who uses only #beh square feet of surface1 finds an engine of #ej horsepower is needed4 ,other things1 such as frame1 etc41 being equal1 it stands to reason that a reduction in the area of supporting surface will correspondingly reduce the weight of the machine4 ,thus we have the ,curtiss machine with its #beh square feet of surface1 weighing only #fjj pounds 7without operator71 but requiring double the horsepower of the ,wright machine with #ech square feet of surface and weighing #a1ajj pounds4 ,this demonstrates in a forceful way the proposition that the larger the surface the less power will be needed4 ,but there is a limit1 on account of its bulk and awkwardness in handling1 beyond which the surface area cannot be enlarged4 ,otherwise it might be possible to equip and operate aeroplanes satisfactorily with engines of #ae horsepower1 or even less4 ,the ,fuel ,consumption ,problem4 ,fuel consumption is a prime factor in the production of engine power4 ,the veriest mechanical tyro knows in a general way that the more power is secured the more fuel must be consumed1 allowing that there is no difference in the power-producing qualities of the material used4 ,but few of us understand just what the ratio of increase is1 or how it is caused4 ,this proposition is one of keen interest in connection with aviation4 ,let us cite a problem which will illustrate the point quoted3 ,allowing that it takes a given amount of gasolene to propel a flying machine a given distance1 half the way with the wind1 and half against it1 the wind blowing at one-half the speed of the machine1 what will be the increase in fuel consumption8 ,increase of ,thirty ,per ,cent4 ,on the face of it there would seem to be no call for an increase as the resistance met when going against the wind is apparently offset by the propulsive force of the wind when the machine is travelling with it4 ,this1 however1 is called faulty reasoning4 ,the increase in fuel consumption1 as figured by ,mr4 ,f4 ,w4 ,lanchester1 of the ,royal ,society of ,arts1 will be fully #cj per cent over the amount required for a similar operation of the machine in still air4 ,if the journey should be made at right angles to the wind under the same conditions the increase would be #ae per cent4 ,in other words ,mr4 ,lanchester maintains that the work done by the motor in making headway against the wind for a certain distance calls for more engine energy1 and consequently more fuel by #cj per cent1 than is saved by the helping force of the wind on the return journey4 ,,chapter ,,xiv4 ,,about ,,wind ,,currents1 ,,etc4 ,one of the first difficulties which the novice will encounter is the uncertainty of the wind currents4 ,with a low velocity the wind1 some distance away from the ground1 is ordinarily steady4 ,as the velocity increases1 however1 the wind generally becomes gusty and fitful in its action4 ,this1 it should be remembered1 does not refer to the velocity of the machine1 but to that of the air itself4 ,in this connection ,mr4 ,arthur ,t4 ,atherholt1 president of the ,aero ,club of ,pennsylvania1 in addressing the ,boston ,society of ,scientific ,research1 said3 ,probably the whirlpools of ,niagara contain no more erratic currents than the strata of air which is now immediately above us1 a fact hard to realize on account of its invisibility4 ,changes ,in ,wind ,currents4 ,while ,mr4 ,atherholt's experience has been mainly with balloons it is all the more valuable on this account1 as the balloons were at the mercy of the wind and their varying directions afforded an indisputable guide as to the changing course of the air currents4 ,in speaking of this he said3 ,in the many trips taken1 varying in distance traversed from twenty-five to #ijj miles1 it was never possible except in one instance to maintain a straight course4 ,these uncertain currents were most noticeable in the ,gordon-,bennett race from ,st4 ,louis in #aijg4 ,of the nine aerostats competing in that event1 eight covered a more or less direct course due east and southeast1 whereas the writer1 with ,major ,henry ,b4 ,hersey1 first started northwest1 then north1 northeast1 east1 east by south1 and when over the center of ,lake ,erie were again blown northwest notwithstanding that more favorable winds were sought for at altitudes varying from #ajj to #c1jjj meters1 necessitating a finish in ,canada nearly northeast of the starting point4 ,these nine balloons1 making landings extending from ,lake ,ontario1 ,canada1 to ,virginia1 all started from one point within the same hour4 ,the single exception to these roving currents occurred on ,october #bast1 of last year 7#aiji7 when1 starting from ,philadelphia1 the wind shifted more than eight degrees1 the greatest variation being at the lowest altitudes1 yet at no time was a height of over a mile reached4 ,throughout the entire day the sky was overcast1 with a thermometer varying from fifty-seven degrees at #cjj feet to forty-four degrees1 ,fahrenheit at #e1jjj feet1 at which altitude the wind had a velocity of #dc miles an hour1 in clouds of a cirro-cumulus nature1 a landing finally being made near ,tannersville1 ,new ,york1 in the ,catskill mountains1 after a voyage of five and one-half hours4 ,i have no knowledge of a recorded trip of this distance and duration1 maintained in practically a straight line from start to finish4 ,this wind disturbance is more noticeable and more difficult to contend with in a balloon than in a flying machine1 owing to the bulk and unwieldy character of the former4 ,at the same time it is not conducive to pleasant1 safe or satisfactory sky-sailing in an aeroplane4 ,this is not stated with the purpose of discouraging aviation1 but merely that the operator may know what to expect and be prepared to meet it4 ,not only does the wind change its horizontal course abruptly and without notice1 but it also shifts in a vertical direction1 one second blowing up1 and another down4 ,no man has as yet fathomed the why and wherefore of this erratic action2 it is only known that it exists4 ,the most stable currents will be found from #ej to #ajj feet from the earth1 provided the wind is not diverted by such objects as trees1 rocks1 etc4 ,that there are equally stable currents higher up is true1 but they are generally to be found at excessive altitudes4 ,how a ,bird ,meets ,currents4 ,observe a bird in action on a windy day and you will find it continually changing the position of its wings4 ,this is done to meet the varying gusts and eddies of the air so that sustentation may be maintained and headway made4 ,one second the bird is bending its wings1 altering the angle of incidence2 the next it is lifting or depressing one wing at a time4 ,still again it will extend one wing tip in advance of the other1 or be spreading or folding1 lowering or raising its tail4 ,all these motions have a meaning1 a purpose4 ,they assist the bird in preserving its equilibrium4 ,without them the bird would be just as helpless in the air as a human being and could not remain afloat4 ,when the wind is still1 or comparatively so1 a bird1 having secured the desired altitude by flight at an angle1 may sail or soar with no wing action beyond an occasional stroke when it desires to advance4 ,but1 in a gusty1 uncertain wind it must use its wings or alight somewhere4 ,trying to ,imitate the ,bird4 ,writing in ,fly1 ,mr4 ,william ,e4 ,white says3 ,the bird's flight suggests a number of ways in which the equilibrium of a mechanical bird may be controlled4 ,each of these methods of control may be effected by several different forms of mechanism4 ,placing the two wings of an aeroplane at an angle of three to five degrees to each other is perhaps the oldest way of securing lateral balance4 ,this way readily occurs to anyone who watches a sea gull soaring4 ,the theory of the dihedral angle is that when one wing is lifted by a gust of wind1 the air is spilled from under it2 while the other wing1 being correspondingly depressed1 presents a greater resistance to the gust and is lifted restoring the balance4 ,a fixed angle of three to five degrees1 however1 will only be sufficient for very light puffs of wind and to mount the wings so that the whole wing may be moved to change the dihedral angle presents mechanical difficulties which would be better avoided4 ,the objection of mechanical impracticability applies to any plan to preserve the balance by shifting weight or ballast4 ,the center of gravity should be lower than the center of the supporting surfaces1 but cannot be made much lower4 ,it is a common mistake to assume that complete stability will be secured by hanging the center of gravity very low on the principle of the parachute4 ,an aeroplane depends upon rapid horizontal motion for its support1 and if the center of gravity be far below the center of support1 every change of speed or wind pressure will cause the machine to turn about its center of gravity1 pitching forward and backward dangerously4 ,preserving ,longitudinal ,balance4 ,the birds maintain longitudinal1 or fore and aft balance1 by elevating or depressing their tails4 ,whether this action is secured in an aeroplane by means of a horizontal rudder placed in the rear1 or by deflecting planes placed in front of the main planes1 the principle is evidently the same4 ,a horizontal rudder placed well to the rear as in the ,antoinette1 ,bleriot or ,santos-,dumont monoplanes1 will be very much safer and steadier than the deflecting planes in front1 as in the ,wright or ,curtiss biplanes1 but not so sensitive or prompt in action4 ,the natural fore and aft stability is very much strengthened by placing the load well forward4 ,the center of gravity near the front and a tail or rudder streaming to the rear secures stability as an arrow is balanced by the head and feathering4 ,the adoption of this principle makes it almost impossible for the aeroplane to turn over4 ,the ,matter of ,lateral ,balance4 ,all successful aeroplanes thus far have maintained lateral balance by the principle of changing the angle of incidence of the wings4 ,other ways of maintaining the lateral balance1 suggested by observation of the flight of birds are--extending the wing tips and spilling the air through the pinions2 or1 what is the same thing1 varying the area of the wings at their extremities4 ,extending the wing tips seems to be a simple and effective solution of the problem4 ,the tips may be made to swing outward upon a vertical axis placed at the front edge of the main planes2 or they may be hinged to the ends of the main plane so as to be elevated or depressed through suitable connections by the aviator2 or they may be supported from a horizontal axis parallel with the ends of the main planes so that they may swing outward1 the aviator controlling both tips through one lever so that as one tip is extended the other is retracted4 ,the elastic wing pinions of a bird bend easily before the wind1 permitting the gusts to glance off1 but presenting always an even and efficient curvature to the steady currents of the air4 ,high ,winds ,threaten ,stability4 ,to ensure perfect stability1 without control1 either human or automatic1 it is asserted that the aeroplane must move faster than the wind is blowing4 ,so long as the wind is blowing at the rate of #cj miles an hour1 and the machine is traveling #dj or more1 there will be little trouble as regards equilibrium so far as wind disturbance goes1 provided the wind blows evenly and does not come in gusts or eddying currents4 ,but when conditions are reversed--when the machine travels only #cj miles an hour and the wind blows at the rate of #ej1 look out for loss of equilibrium4 ,one of the main reasons for this is that high winds are rarely steady2 they seldom blow for any length of time at the same speed4 ,they are usually gusty1 the gusts being a momentary movement at a higher speed4 ,tornadic gusts are also formed by the meeting of two opposing currents1 causing a whirling motion1 which makes stability uncertain4 ,besides1 it is not unusual for wind of high speed to suddenly change its direction without warning4 ,trouble ,with ,vertical ,columns4 ,vertical currents--columns of ascending air--are frequently encountered in unexpected places and have more or less tendency1 according to their strength1 to make it difficult to keep the machine within a reasonable distance from the ground4 ,these vertical currents are most generally noticeable in the vicinity of steep cliffs1 or deep ravines4 ,in such instances they are usually of considerable strength1 being caused by the deflection of strong winds blowing against the face of the cliffs4 ,this deflection exerts a back pressure which is felt quite a distance away from the point of origin1 so that the vertical current exerts an influence in forcing the machine upward long before the cliff is reached4 ,,chapter ,,xv4 ,,the ,,element ,,of ,,danger4 ,that there is an element of danger in aviation is undeniable1 but it is nowhere so great as the public imagines4 ,men are killed and injured in the operation of flying machines just as they are killed and injured in the operation of railways4 ,considering the character of aviation the percentage of casualties is surprisingly small4 ,this is because the results following a collapse in the air are very much different from what might be imagined4 ,instead of dropping to the ground like a bullet an aeroplane1 under ordinary conditions will1 when anything goes wrong1 sail gently downward like a parachute1 particularly if the operator is cool-headed and nervy enough to so manipulate the apparatus as to preserve its equilibrium and keep the machine on an even keel4 ,two ,fields of ,safety4 ,at least one prominent aviator has declared that there are two fields of safety--one close to the ground1 and the other well up in the air4 ,in the first-named the fall will be a slight one with little chance of the operator being seriously hurt4 ,from the field of high altitude the the descent will be gradual1 as a rule1 the planes of the machine serving to break the force of the fall4 ,with a cool-headed operator in control the aeroplane may be even guided at an angle 7about #a to #h7 in its descent so as to touch the ground with a gliding motion and with a minimum of impact4 ,such an experience1 of course1 is far from pleasant1 but it is by no means so dangerous as might appear4 ,there is more real danger in falling from an elevation of #ge or #ajj feet than there is from #a1jjj feet1 as in the former case there is no chance for the machine to serve as a parachute--its contact with the ground comes too quickly4 ,lesson in ,recent ,accidents4 ,among the more recent fatalities in aviation are the deaths of ,antonio ,fernandez and ,leon ,delagrange4 ,the former was thrown to the ground by a sudden stoppage of his motor1 the entire machine seeming to collapse4 ,it is evident there were radical defects1 not only in the motor1 but in the aeroplane framework as well4 ,at the time of the stoppage it is estimated that ,fernandez was up about #a1ejj feet1 but the machine got no opportunity to exert a parachute effect1 as it broke up immediately4 ,this would indicate a fatal weakness in the structure which1 under proper testing1 could probably have been detected before it was used in flight4 ,it is hard to say it1 but ,delagrange appears to have been culpable to great degree in overloading his machine with a motor equipment much heavier than it was designed to sustain4 ,he was #fe feet up in the air when the collapse occurred1 resulting in his death4 ,as in the case of ,fernandez common-sense precaution would doubtless have prevented the fatality4 ,aviation ,not ,extra ,hazardous4 ,all told there have been1 up to the time of this writing 7,april1 #aiaj71 just five fatalities in the history of power-driven aviation4 ,this is surprisingly low when the nature of the experiments1 and the fact that most of the operators were far from having extended experience1 is taken into consideration4 ,men like the ,wrights1 ,curtiss1 ,bleriot1 ,farman1 ,paulhan and others1 are now experts1 but there was a time1 and it was not long ago1 when they were unskilled4 ,that they1 with numerous others less widely known1 should have come safely through their many experiments would seem to disprove the prevailing idea that aviation is an extra hazardous pursuit4 ,in the hands of careful1 quick-witted1 nervy men the sailing of an airship should be no more hazardous than the sailing of a yacht4 ,a vessel captain with common sense will not go to sea in a storm1 or navigate a weak1 unseaworthy craft4 ,neither should an aviator attempt to sail when the wind is high and gusty1 nor with a machine which has not been thoroughly tested and found to be strong and safe4 ,safer ,than ,railroading4 ,statistics show that some #ab1jjj people are killed and #gb1jjj injured every year on the railroads of the ,united ,states4 ,come to think it over it is small wonder that the list of fatalities is so large4 ,trains are run at high speeds1 dashing over crossings at which collisions are liable to occur1 and over bridges which often collapse or are swept away by floods4 ,still1 while the number of casualties is large1 the actual percentage is small considering the immense number of people involved4 ,it is so in aviation4 ,the number of casualties is remarkably small in comparison with the number of flights made4 ,in the hands of competent men the sailing of an airship should be1 and is1 freer from risk of accident than the running of a railway train4 ,there are no rails to spread or break1 no bridges to collapse1 no crossings at which collisions may occur1 no chance for some sleepy or overworked employee to misunderstand the dispatcher's orders and cause a wreck4 ,two ,main ,causes of ,trouble4 ,the two main causes of trouble in an airship leading to disaster may be attributed to the stoppage of the motor1 and the aviator becoming rattled so that he loses control of his machine4 ,modern ingenuity is fast developing motors that almost daily become more and more reliable1 and experience is making aviators more and more self-confident in their ability to act wisely and promptly in cases of emergency4 ,besides this a satisfactory system of automatic control is in a fair way of being perfected4 ,occasionally even the most experienced and competent of men in all callings become careless and by foolish action invite disaster4 ,this is true of aviators the same as it is of railroaders1 men who work in dynamite mills1 etc4 ,but in nearly every instance the responsibility rests with the individual2 not with the system4 ,there are some men unfitted by nature for aviation1 just as there are others unfitted to be railway engineers4 ,,chapter ,,xvi4 ,,radical ,,changes ,,being ,,made4 ,changes1 many of them extremely radical in their nature1 are continually being made by prominent aviators1 and particularly those who have won the greatest amount of success4 ,wonderful as the results have been few of the aviators are really satisfied4 ,their successes have merely spurred them on to new endeavors1 the ultimate end being the development of an absolutely perfect aircraft4 ,among the men who have been thus experimenting are the ,wright ,brothers1 who last year 7#aiji7 brought out a craft totally different as regards proportions and weight from the one used the preceding year4 ,one marked result was a gain of about #c #a_/b miles an hour in speed4 ,dimensions of #aijh ,machine4 ,the #aijh model aeroplane was #dj by #bi feet over all4 ,the carrying surfaces1 that is1 the two aerocurves1 were #dj by #f feet1 having a parabolical curve of one in twelve4 ,with about #gj square feet of surface in the rudders1 the total surface given was about #eej square feet4 ,the engine1 which is the invention of the ,wright brothers1 weighed1 approximately1 #bjj pounds1 and gave about #be horsepower at #a1djj revolutions per minute4 ,the total weight of the aeroplane1 exclusive of passenger1 but inclusive of engine1 was about #a1aej pounds4 ,this result showed a lift of a fraction over #b #a_/d pounds to the square foot of carrying surface4 ,the speed desired was #dj miles an hour1 but the machine was found to make only a scant #ci miles an hour4 ,the upright struts were about #g_/h-;inch thick1 the skids1 #b #a_/b by #a #a_/d inches thick4 ,dimensions of #aiji ,machine4 ,the #aiji aeroplane was built primarily for greater speed1 and relatively heavier2 to be less at the mercy of the wind4 ,this result was obtained as follows3 ,the aerocurves1 or carrying surfaces1 were reduced in dimensions from #dj by #f feet to #cf by #e #a_/b feet1 the curve remaining the same1 one in twelve4 ,the upright struts were cut from seven-eighths inch to five-eighths inch1 and the skids from two and one-half by one and one-quarter to two and one-quarter by one and three-eighths inches4 ,this result shows that there were some #ha square feet of carrying surface missing over that of last year's model4 and some #be pounds loss of weight4 ,relatively1 though1 the #aiji model aeroplane1 while actually #be pounds lighter1 is really some #aej pounds heavier in the air than the #aijh model1 owing to the lesser square feet of carrying surface4 ,some of the ,results ,obtained4 ,reducing the carrying surfaces from #f to #e #a_/b feet gave two results--first1 less carrying capacity2 and1 second1 less head-on resistance1 owing to the fact that the extent of the parabolic curve in the carrying surfaces was shortened4 ,the head-on resistance is the retardance the aeroplane meets in passing through the air1 and is counted in square feet4 ,in the #aijh model the curve being one in twelve and #f feet deep1 gave #f inches of head-on resistance4 ,the plane being #dj feet spread1 gave #f inches by #dj feet1 or #bj square feet of head-on resistance4 ,increasing this figure by a like amount for each plane1 and adding approximately #aj square feet for struts1 skids and wiring1 we have a total of approximately1 #ej square feet of surface for head-on resistance4 ,in the #aiji aeroplane1 shortening the curve #f inches at the parabolic end of the curve took off #a inch of head-on resistance4 ,shortening the spread of the planes took off between #c and #d square feet of head-on resistance4 ,add to this the total of #g square feet1 less curve surface and about #a square foot1 less wire and woodwork resistance1 and we have a grand total of1 approximately1 #ab square feet of less head-on resistance over the #aijh model4 ,changes in ,engine ,action4 ,the engine used in #aiji was the same one used in #aijh1 though some minor changes were made as improvements2 for instance1 a make and break spark was used1 and a nine-tooth1 instead of a ten-tooth magneto gear-wheel was used4 ,this increased the engine revolutions per minute from #a1bjj to #a1djj1 and the propeller revolutions per minute from #cej to #cga1 giving a propeller thrust of1 approximately1 #agj foot pounds instead of #aec1 as was had last year4 ,more ,speed and ,same ,capacity4 ,one unsatisfactory feature of the #aiji model over that of #aijh1 apparently1 was the lack of inherent lateral stability4 ,this was caused by the lesser surface and lesser extent of curvatures at the portions of the aeroplane which were warped4 ,this defect did not show so plainly after ,mr4 ,orville ,wright had become fully proficient in the handling of the new machine1 and with skillful management1 the #aiji model aeroplane will be just as safe and secure as the other though it will take a little more practice to get that same degree of skill4 ,to sum up3 ,the aeroplane used in #aiji was #be pounds lighter1 but really about #aej pounds heavier in the air1 had less head-on resistance1 and greater propeller thrust4 ,the speed was increased from about #ci miles per hour to #db #a_/b miles per hour4 ,the lifting capacity remained about the same1 about #dej pounds capacity passenger-weight1 with the #aijh machine4 ,in this respect1 the loss of carrying surface was compensated for by the increased speed4 ,during the first few flights it was plainly demonstrated that it would need the highest skill to properly handle the aeroplane1 as first one end and then the other would dip and strike the ground1 and either tear the canvas or slew the aeroplane around and break a skid4 ,wrights ,adopt ,wheeled ,gears4 ,in still another important respect the ,wrights1 so far as the output of one of their companies goes1 have made a radical change4 ,all the aeroplanes turned out by the ,deutsch ,wright ,gesellschaft1 according to the ,german publication1 ,automobil-,welt1 will hereafter be equipped with wheeled running gears and tails4 ,the plan of this new machine is shown in the illustration on page #ade4 ,the wheels are three in number1 and are attached one to each of the two skids1 just under the front edge of the planes1 and one forward of these1 attached to a cross-member4 ,it is asserted that with these wheels the teaching of purchasers to operate the machines is much simplified1 as the beginners can make short flights on their own account without using the starting derrick4 ,this is a big concession for the ,wrights to make1 as they have hitherto adhered stoutly to the skid gear4 ,while it is true they do not control the ,german company producing their aeroplanes1 yet the nature of their connection with the enterprise is such that it may be taken for granted no radical changes in construction would be made without their approval and consent4 ,only ,three ,dangerous ,rivals4 ,official trials with the #aiji model smashed many records and leave the ,wright brothers with only three dangerous rivals in the field1 and with basic patents which cover the curve1 warp and wing-tip devices found on all the other makes of aeroplanes4 ,these three rivals are the ,curtiss and ,voisin biplane type and the ,bleriot monoplane pattern4 ,the ,bleriot monoplane is probably the most dangerous rival1 as this make of machine has a record of #ed miles per hour1 has crossed the ,english channel1 and has lifted two passengers besides the operator4 ,the latest type of this machine only weighs #gga4fa pounds complete1 without passengers1 and will lift a total passenger weight of #dfb4ig pounds1 which is a lift of #e4ba pounds to the square foot4 ,this is a better result than those published by the ,wright brothers1 the best noted being #d4be pounds per square foot4 ,other ,aviators at ,work4 ,the ,wrights1 however1 are not alone in their efforts to promote the efficiency of the flying machine4 ,other competent inventive aviators1 notably ,curtiss1 ,voisin1 ,bleriot and ,farman1 are close after them4 ,the ,wrights1 as stated1 have a marked advantage in the possession of patents covering surface plane devices which have thus far been found indispensable in flying machine construction4 ,numerous law suits growing out of alleged infringements of these patents have been started1 and others are threatened4 ,what effect these actions will have in deterring aviators in general from proceeding with their experiments remains to be seen4 ,in the meantime the four men named--,curtiss1 ,voisin1 ,bleriot and ,farman--are going ahead regardless of consequences1 and the inventive genius of each is so strong that it is reasonable to expect some remarkable developments in the near future4 ,smallest of ,flying ,machines4 ,to ,santos ,dumont must be given the credit of producing the smallest practical flying machine yet constructed4 ,true1 he has done nothing remarkable with it in the line of speed1 but he has demonstrated the fact that a large supporting surface is not an essential feature4 ,this machine is named ,la ,demoiselle4 ,it is a monoplane of the dihedral type1 with a main plane on each side of the center4 ,these main planes are of #ah foot spread1 and nearly #f #a_/b feet in depth1 giving approximately #aae feet of surface area4 ,the total weight is #bdb pounds1 which is #ceh pounds less than any other machine which has been successfully used4 ,the total depth from front to rear is #bf feet4 ,the framework is of bamboo1 strengthened and held taut with wire guys4 ,have ,one ,rule in ,mind4 ,in this struggle for mastery in flying machine efficiency all the contestants keep one rule in mind1 and this is3 ,the carrying capacity of an aeroplane is governed by the peripheral curve of its carrying surfaces1 plus the speed2 and the speed is governed by the thrust of the propellers1 less the 'head-on' resistance4 ,their ideas as to the proper means of approaching the proposition may1 and undoubtedly are1 at variance1 but the one rule in solving the problem of obtaining the greatest carrying capacity combined with the greatest speed1 obtains in all instances4 ,,chapter ,,xvii4 ,,some ,,of ,,the ,,new ,,designs4 ,spurred on by the success attained by the more experienced and better known aviators numerous inventors of lesser fame are almost daily producing practical flying machines varying radically in construction from those now in general use4 ,one of these comparatively new designs is the ,van ,anden biplane1 made by ,frank ,van ,anden of ,islip1 ,long ,island1 a member of the ,new ,york ,aeronautic ,society4 ,while his machine is wholly experimental1 many successful short flights were made with it last fall 7#aiji74 ,one flight1 made ,october #aith1 #aiji1 is of particular interest as showing the practicability of an automatic stabilizing device installed by the inventor4 ,the machine was caught in a sudden severe gust of wind and keeled over1 but almost immediately righted itself1 thus demonstrating in a most satisfactory manner the value of one new attachment4 ,features of ,van ,anden ,model4 ,in size the surfaces of the main biplane are #bf feet in spread1 and #d feet in depth from front to rear4 ,the upper and lower planes are #d feet apart4 ,silkolene coated with varnish is used for the coverings4 ,ribs 7spruce7 are curved one inch to the foot1 the deepest part of the curve 7#d inches7 being one foot back from the front edge of the horizontal beam4 ,struts 7also of spruce1 as is all the framework7 are elliptical in shape4 ,the main beams are in three sections1 nearly half round in form1 and joined by metal sleeves4 ,there is a two-surface horizontal rudder1 #bx#bx#d feet1 in front4 ,this is pivoted at its lateral center #h feet from the front edge of the main planes4 ,in the rear is another two-surface horizontal rudder #bx#bx#b #a_/b feet1 pivoted in the same manner as the front one1 #ae feet from the rear edges of the main planes4 ,hinged to the rear central strut of the rear rudder is a vertical rudder #b feet high by #c feet in length4 ,the ,method of ,control4 ,in the operation of these rudders--both front and rear--and the elevation and depression of the main planes1 the ,curtiss system is employed4 ,pushing the steering-wheel post outward depresses the front edges of the planes1 and brings the machine downward2 pulling the steering-wheel post inward elevates the front edges of the planes and causes the machine to ascend4 ,turning the steering wheel itself to the right swings the tail rudder to the left1 and the machine1 obeying this like a boat1 turns in the same direction as the wheel is turned4 ,by like cause turning the wheel to the left turns the machine to the left4 ,automatic ,control of ,wings4 ,there are two wing tips1 each of #f feet spread 7length7 and #b feet from front to rear4 ,these are hinged half way between the main surfaces to the two outermost rear struts4 ,cables run from these to an automatic device working with power from the engine1 which automatically operates the tips with the tilting of the machine4 ,normally the wing tips are held horizontal by stiff springs introduced in the cables outside of the device4 ,it was the successful working of this device which righted the ,van ,anden craft when it was overturned in the squall of ,october #aith1 #aiji4 ,previous to that occurrence ,mr4 ,van ,anden had looked upon the device as purely experimental1 and had admitted that he had grave uncertainty as to how it would operate in time of emergency4 ,he is now quoted as being thoroughly satisfied with its practicability4 ,it is this automatic device which gives the ,van ,anden machine at least one distinctively new feature4 ,while on this subject it will not be amiss to add that ,mr4 ,curtiss does not look kindly on automatic control4 ,i would rather trust to my own action than that of a machine1 he says4 ,this is undoubtedly good logic so far as ,mr4 ,curtiss is concerned1 but all aviators are not so cool-headed and resourceful4 ,motive ,power of ,van ,anden4 ,a #ej-;horsepower ,h-,f water cooled motor drives a laminated wood propeller #f feet in diameter1 with a #ag degree pitch at the extremities1 increasing toward the hub4 ,the rear end of the motor is about #f inches back from the rear transverse beam and the engine shaft is in a direct line with the axes of the two horizontal rudders4 ,an ,r4 ,i4 ,v4 ball bearing carries the shaft at this point4 ,flying1 the motor turns at about #hjj revolutions per minute1 delivering #ahj pounds pull4 ,a test of the motor running at #a1bjj showed a pull of #bej pounds on the scales4 ,still ,another ,new ,aeroplane4 ,another new aeroplane is that produced by ,a4 ,m4 ,herring 7an old-timer7 and ,w4 ,s4 ,burgess1 under the name of the ,herring-,burgess4 ,this is also equipped with an automatic stability device for maintaining the balance transversely4 ,the curvature of the planes is also laid out on new lines4 ,that this new plan is effective is evidenced by the fact that the machine has been elevated to an altitude of #dj feet by using one-half the power of the #cj-;horsepower motor4 ,the system of rudder and elevation control is very simple4 ,the aviator sits in front of the lower plane1 and extending his arms1 grasps two supports which extend down diagonally in front4 ,on the under side of these supports just beneath his fingers are the controls which operate the vertical rudder1 in the rear4 ,thus1 if he wishes to turn to the right1 he presses the control under the fingers of his right hand2 if to the left1 that under the fingers of his left hand4 ,the elevating rudder is operated by the aviator's right foot1 the control being placed on a foot-rest4 ,motor ,is ,extremely ,light4 ,not the least notable feature of the craft is its motor4 ,although developing1 under load1 #cj-;horsepower1 or that of an ordinary automobile1 it weighs1 complete1 hardly #ajj pounds4 ,having occasion to move it a little distance for inspection1 ,mr4 ,burgess picked it up and walked off with it--cylinders1 pistons1 crankcase and all1 even the magneto1 being attached4 ,there are not many #cj-;horsepower engines which can be so handled4 ,everything about it is reduced to its lowest terms of simplicity1 and hence1 of weight4 ,a single camshaft operates not only all of the inlet and exhaust valves1 but the magneto and gear water pump1 as well4 ,the motor is placed directly behind the operator1 and the propeller is directly mounted on the crankshaft4 ,this weight of less than #ajj pounds1 it must be remembered1 is not for the motor alone2 it includes the entire power plant equipment4 ,the thrust of the propeller is also extraordinary1 being between #bej and #bfj pounds4 ,the force of the wind displacement is strong enough to knock down a good-sized boy as one youngster ascertained when he got behind the propeller as it was being tested4 ,he was not only knocked down but driven for some distance away from the machine4 ,the propeller has four blades which are but little wider than a lath4 ,machine ,built by ,students4 ,students at the ,university of ,pennsylvania1 headed by ,laurence ,j4 ,lesh1 a protege of ,octave ,chanute1 have constructed a practical aeroplane of ordinary maximum size1 in which is incorporated many new ideas4 ,the most unique of these is to be found in the steering gear1 and the provision made for the accommodation of a pupil while taking lessons under an experienced aviator4 ,immediately back of the aviator is an extra seat and an extra steering wheel which works in tandem style with the front wheel4 ,by this arrangement a beginner may be easily and quickly taught to have perfect control of the machine4 ,these tandem wheels are also handy for passengers who may wish to operate the car independently of one another1 it being understood1 of course1 that there will be no conflict of action4 ,frame ,size and ,engine ,power4 ,the frame has #cf feet spread and measures #ce feet from the front edge to the end of the tail in the rear4 ,it is equipped with two rear propellers operated by a ,ramsey #h-;cylinder motor of #ej horsepower1 placed horizontally across the lower plane1 with the crank shaft running clear through the engine4 ,the ,pennsylvania ,i is the first two-propeller biplane chainless car1 this scheme having been adopted in order to avoid the crossing of chains4 ,the lateral control is by a new invention by ,octave ,chanute and ,laurence ,j4 ,lesh1 for which ,lesh is now applying for a patent4 ,the device was worked out before the ,wright brothers' suit was begun1 and is said to be superior to the ,wright warping or the ,curtiss ailerons4 ,the landing device is also new in design4 ,this aeroplane will weigh about #a1ejj pounds1 and will carry fuel for a flight of #aej miles1 and it is expected to attain a speed of at least #de miles an hour4 ,there are others1 lots of them1 too numerous in fact to admit of mention in a book of this size4 ,,chapter ,,xviii4 ,,demand ,,for ,,flying ,,machines4 ,as a commercial proposition the manufacture and sale of motor-equipped aeroplanes is making much more rapid advance than at first obtained in the similar handling of the automobile4 ,great1 and even phenomenal1 as was the commercial development of the motor car1 that of the flying machine is even greater4 ,this is a startling statement1 but it is fully warranted by the facts4 ,it is barely more than a year ago 7#aiji7 that attention was seriously attracted to the motor-equipped aeroplane as a vehicle possible of manipulation by others than professional aviators4 ,up to that time such actual flights as were made were almost exclusively with the sole purpose of demonstrating the practicability of the machine1 and the merits of the ideas as to shape1 engine power1 etc41 of the various producers4 ,results of ,bleriot's ,daring4 ,it was not until ,bleriot flew across the straits of ,dover on ,july #beth1 #aiji1 that the general public awoke to a full realization of the fact that it was possible for others than professional aviators to indulge in aviation4 ,bleriot's feat was accepted as proof that at last an absolutely new means of sport1 pleasure and research1 had been practically developed1 and was within the reach of all who had the inclination1 nerve and financial means to adopt it4 ,from this event may be dated the birth of the modern flying machine into the world of business4 ,the automobile was taken up by the general public from the very start because it was a proposition comparatively easy of demonstration4 ,there was nothing mysterious or uncanny in the fact that a wheeled vehicle could be propelled on solid1 substantial roads by means of engine power4 ,and yet it took 7comparatively speaking7 a long time to really popularize the motor car4 ,wonderful ,results in a ,year4 ,men of large financial means engaged in the manufacture of automobiles1 and expended fortunes in attracting public attention to them through the medium of advertisements1 speed and road contests1 etc4 ,by these means a mammoth business has been built up1 but bringing this business to its present proportions required years of patient industry and indomitable pluck4 ,at this writing1 less than a year from the day when ,bleriot crossed the channel1 the actual sales of flying machines outnumber the actual sales of automobiles in the first year of their commercial development4 ,this may appear incredible1 but it is a fact as statistics will show4 ,in this connection we should take into consideration the fact that up to a year ago there was no serious intention of putting flying machines on the market2 no preparations had been made to produce them on a commercial scale2 no money had been expended in advertisements with a view to selling them4 ,some of the ,actual ,results4 ,today flying machines are being produced on a commercial basis1 and there is a big demand for them4 ,the people making them are overcrowded with orders4 ,some of the producers are already making arrangements to enlarge their plants and advertise their product for sale the same as is being done with automobiles1 while a number of flying machine motor makers are already promoting the sale of their wares in this way4 ,here are a few actual figures of flying machine sales made by the more prominent producers since ,july #beth1 #aiji4 ,santos ,dumont1 #ij machines2 ,bleriot1 #bjj2 ,farman1 #acj2 ,clemenceau-,wright1 #hj2 ,voisin1 #ajj2 ,antoinette1 #ajj4 ,many of these orders have been filled by delivery of the machines1 and in others the construction work is under way4 ,the foregoing are all of foreign make4 ,in this country ,curtiss and the ,wrights are engaged in similar work1 but no actual figures of their output are obtainable4 ,larger ,plants ,are ,necessary4 ,and this situation exists despite the fact that none of the producers are really equipped with adequate plants for turning out their machines on a modern1 business-like basis4 ,the demand was so sudden and unexpected that it found them poorly prepared to meet it4 ,this1 however1 is now being remedied by the erection of special plants1 the enlargement of others1 and the introduction of new machinery and other labor-saving conveniences4 ,companies1 with large capitalization1 to engage in the exclusive production of airships are being organized in many parts of the world4 ,one notable instance of this nature is worth quoting as illustrative of the manner in which the production of flying machines is being commercialized4 ,this is the formation at ,frankfort1 ,germany1 of the ,flugmaschine ,wright1 ,g4 m4 b4 ,h41 with a capital of #aai1jjj1 the ,krupps1 of ,essen1 being interested4 ,prices at ,which ,machines ,sell4 ,this wonderful demand from the public has come notwithstanding the fact that the machines1 owing to lack of facilities for wholesale production1 are far from being cheap4 ,such definite quotations as are made are on the following basis3 ,santos ,dumont--,list price #a1jjj1 but owing to the rush of orders agents are readily getting from #a1cjj to #a1ejj4 ,this is the smallest machine made4 ,bleriot--,list price #b1ejj4 ,this is for the cross-channel type1 with ,anzani motor4 ,antoinette--,list price from #d1jjj to #e1jjj1 according to size4 ,wright--,list price #e1fjj4 ,curtiss--,list price #e1jjj4 ,there is1 however1 no stability in prices as purchasers are almost invariably ready to pay a considerable premium to facilitate delivery4 ,the motor is the most expensive part of the flying machine4 ,motor prices range from #ejj to #b1jjj1 this latter amount being asked for the ,curtiss engine4 ,systematic ,instruction of ,amateurs4 ,in addition to the production of flying machines many of the experienced aviators are making a business of the instruction of amateurs4 ,curtiss and the ,wrights in this country have a number of pupils1 as have also the prominent foreigners4 ,schools of instruction are being opened in various parts of the world1 not alone as private money-making ventures1 but in connection with public educational institutions4 ,one of these latter is to be found at the ,university of ,barcelona1 ,spain4 ,the flying machine agent1 the man who handles the machines on a commission1 has also become a known quantity1 and will soon be as numerous as his brother of the automobile4 ,the sign ,john ,bird1 agent for ,skimmer's ,flying ,machine1 is no longer a curiosity4 ,yes1 the ,airship ,is ,here4 ,from all of which we may well infer that the flying machine in practical form has arrived1 and that it is here to stay4 ,it is no exaggeration to say that the time is close at hand when people will keep flying machines just as they now keep automobiles1 and that pleasure jaunts will be fully as numerous and popular4 ,with the important item of practicability fully demonstrated1 ,come1 take a trip in my airship1 will have more real significance than now attaches to the vapid warblings of the vaudeville vocalist4 ,as a further evidence that the airship is really here1 and that its presence is recognized in a business way1 the action of life and accident insurance companies is interesting4 ,some of them are reconstructing their policies so as to include a special waiver of insurance by aviators4 ,anything which compels these great corporations to modify their policies cannot be looked upon as a mere curiosity or toy4 ,it is some consolation to know that the movement in this direction is not thus far widespread4 ,moreover it is more than probable that the competition for business will eventually induce the companies to act more liberally toward aviators1 especially as the art of aviation advances4 ,,chapter ,,xix4 ,,law ,,of ,,the ,,airship4 ,successful aviation has evoked some peculiar things in the way of legal action and interpretation of the law4 ,it is well understood that a man's property cannot be used without his consent4 ,this is an old established principle in common law which holds good today4 ,the limits of a man's property lines1 however1 have not been so well understood by laymen4 ,according to eminent legal authorities such as ,blackstone1 ,littleton and ,coke1 the fathers of the law1 the owner of realty also holds title above and below the surface1 and this theory is generally accepted without question by the courts4 ,rights of ,property ,owners4 ,in other words the owner of realty also owns the sky above it without limit as to distance4 ,he can dig as deep into his land1 or go as high into the air as he desires1 provided he does not trespass upon or injure similar rights of others4 ,the owner of realty may resist by force1 all other means having failed1 any trespass upon1 or invasion of his property4 ,other people1 for instance1 may not enter upon it1 or over or under it1 without his express permission and consent4 ,there is only one exception1 and this is in the case of public utility corporations such as railways which1 under the law of eminent domain1 may condemn a right of way across the property of an obstinate owner who declines to accept a fair price for the privilege4 ,privilege ,sharply ,confined4 ,the law of eminent domain may be taken advantage of only by corporations which are engaged in serving the public4 ,it is based upon the principle that the advancement and improvement of a community is of more importance and carries with it more rights than the interests of the individual owner4 ,but even in cases where the right of eminent domain is exercised there can be no confiscation of the individual's property4 ,exercising the right of eminent domain is merely obtaining by public purchase what is held to be essential to the public good1 and which cannot be secured by private purchase4 ,when eminent domain proceedings are resorted to the court appoints appraisers who determine upon the value of the property wanted1 and this value 7in money7 is paid to the owner4 ,how ,it ,affects ,aviation4 ,it should be kept in mind that this privilege of the right of eminent domain is accorded only to corporations which are engaged in serving the public4 ,individuals cannot take advantage of it4 ,thus far all aviation has been conducted by individuals2 there are no flying machine or airship corporations regularly engaged in the transportation of passengers1 mails or freight4 ,this leads up to the question ,what would happen if realty owners generally1 or in any considerable numbers1 should prohibit the navigation of the air above their holdings8 ,it is idle to say such a possibility is ridiculous--it is already an actuality in a few individual instances4 ,one property owner in ,new ,jersey1 a justice of the peace1 maintains a large sign on the roof of his house warning aviators that they must not trespass upon his domain4 ,that he is acting well within his rights in doing this is conceded by legal authorities4 ,hard to ,catch ,offenders4 ,but1 suppose the alleged trespass is committed1 what is the property owner going to do about it8 ,he must first catch the trespasser and this would be a pretty hard job4 ,he certainly could not overtake him1 unless he kept a racing aeroplane for this special purpose4 ,it would be equally difficult to identify the offender after the offense had been committed1 even if he were located1 as aeroplanes carry no license numbers4 ,allowing that the offender should be caught the only recourse of the realty owner is an action for damages4 ,he may prevent the commission of the offense by force if necessary1 but after it is committed he can only sue for damages4 ,and in doing this he would have a lot of trouble4 ,points to ,be ,proven4 ,one of the first things the plaintiff would be called upon to prove would be the elevation of the machine4 ,if it were reasonably close to the ground there would1 of course1 be grave risk of damage to fences1 shrubbery1 and other property1 and the court would be justified in holding it to be a nuisance that should be suppressed4 ,if1 on the other hand2 the machine was well up in the air1 but going slowly1 or hovering over the plaintiff's property1 the court might be inclined to rule that it could not possibly be a nuisance1 but right here the court would be in serious embarrassment4 ,by deciding that it was not a nuisance he would virtually override the law against invasion of a man's property without his consent regardless of the nature of the invasion4 ,by the same decision he would also say in effect that1 if one flying machine could do this a dozen or more would have equal right to do the same thing4 ,while one machine hovering over a certain piece of property may be no actual nuisance a dozen or more in the same position could hardly be excused4 ,difficult to ,fix ,damages4 ,such a condition would tend to greatly increase the risk of accident1 either through collision1 or by the carelessness of the aviators in dropping articles which might cause damages to the people or property below4 ,in such a case it would undoubtedly be a nuisance1 and in addition to a fine1 the offender would also be liable for the damages4 ,taking it for granted that no actual damage is done1 and the owner merely sues on account of the invasion of his property1 how is the amount of compensation to be fixed upon8 ,the owner has lost nothing2 no part of his possessions has been taken away2 nothing has been injured or destroyed2 everything is left in exactly the same condition as before the invasion4 ,and yet1 if the law is strictly interpreted1 the offender is liable4 ,right of ,way for ,airships4 ,somebody has suggested the organization of flying-machine corporations as common carriers1 which would give them the right of eminent domain with power to condemn a right of way4 ,but what would they condemn8 ,there is nothing tangible in the air4 ,railways in condemning a right of way specify tangible property 7realty7 within certain limits4 ,how would an aviator designate any particular right of way through the air a certain number of feet in width1 and a certain distance from the ground8 ,and yet1 should the higher courts hold to the letter of the law and decide that aviators have no right to navigate their craft over private property1 something will have to be done to get them out of the dilemma1 as aviation is too far advanced to be discarded4 ,fortunately there is little prospect of any widespread antagonism among property owners so long as aviators refrain from making nuisances of themselves4 ,possible ,solution ,offered4 ,one possible solution is offered and that is to confine the path of airships to the public highways so that nobody's property rights would be invaded4 ,in addition1 as a matter of promoting safety for both operators and those who may happen to be beneath the airships as they pass over a course1 adoption of the ,french rules are suggested4 ,these are as follows3 ,aeroplanes1 when passing1 must keep to the right1 and pass at a distance of at least #aej feet4 ,they are free from this rule when flying at altitudes of more than #ajj feet4 ,every machine when flying at night or during foggy weather must carry a green light on the right1 and a red light on the left1 and a white headlight on the front4 ,these are sensible rules1 but may be improved upon by the addition of a signal system of some kind1 either horn1 whistle or bell4 ,responsibility of ,aviators4 ,mr4 ,jay ,carver ,bossard1 in recent numbers of ,fly1 brings out some curious and interesting legal points in connection with aviation1 among which are the following3 ,private parties who possess aerial craft1 and desire to operate the same in aerial territory other than their own1 must obtain from land owners special permission to do so1 such permission to be granted only by agreement1 founded upon a valid consideration4 ,otherwise1 passing over another's land will in each instance amount to a trespass4 ,leaving this highly technical side of the question1 let us turn to another view3 the criminal and tort liability of owners and operators to airship passengers4 ,if ,a invites ,b to make an ascension with him in his machine1 and ,b1 knowing that ,a is merely an enthusiastic amateur and far from being an expert1 accepts and is through ,a's innocent negligence injured1 he has no grounds for recovery4 ,but if ,a contracts with ,b1 to transport him from one place to another1 for a consideration1 and ,b is injured by the poor piloting of ,a1 ,a would be liable to ,b for damages which would result4 ,now in order to safeguard such people as ,b1 curious to the point of recklessness1 the law will have to require all airship operators to have a license1 and to secure this license airship pilots will have to meet certain requirements4 ,here again is a question4 ,who is going to say whether an applicant is competent to pilot a balloon or airship8 ,fine for an ,aeronaut4 ,an aeroplane while maneuvering is suddenly caught by a treacherous gale and swept to the ground4 ,a crowd of people hasten over to see if the aeronaut is injured1 and in doing so trample over ,tax-payer ,smith's garden1 much to the detriment of his growing vegetables and flowers4 ,who is liable for the damages8 ,queer as it may seem1 a case very similar to this was decided in #ahbc1 in the ,new ,york supreme court1 and it was held that the aeronaut was liable upon the following grounds3 ',to render one man liable in trespass for the acts of others1 it must appear either that they acted in concert1 or that the act of the one1 ordinarily and naturally produced the acts of the others1 ,ascending in a balloon is not an unlawful act1 but it is certain that the aeronaut has no control over its motion horizontally1 but is at the sport of the wind1 and is to descend when and how he can4 ,his reaching the earth is a matter of hazard4 ,if his descent would according to the circumstances draw a crowd of people around him1 either out of curiosity1 or for the purpose of rescuing him from a perilous situation1 all this he ought to have foreseen1 and must be responsible for4' ,air ,not ,really ,free4 ,the general belief among people is1 that the air is free4 ,not only free to breathe and enjoy1 but free to travel in1 and that no one has any definite jurisdiction over1 or in any part of it4 ,now suppose this were made a legal doctrine4 ,would a murder perpetrated above the clouds have to go unpunished8 ,undoubtedly4 ,for felonies committed upon the high seas ample provision is made for their punishment1 but new provisions will have to be made for crimes committed in the air4 ,relations of ,owner and ,employee4 ,it is a general rule of law that a master is bound to provide reasonably safe tools1 appliances and machines for his servant4 ,how this rule is going to be applied in cases of aeroplanes1 remains to be seen4 ,the aeroplane owner who hires a professional aeronaut1 that is1 one who has qualified as an expert1 owes him very little legal duty to supply him with a perfect aeroplane4 ,the expert is supposed to know as much regarding the machine as the owner1 if not more1 and his acceptance of his position relieves the owner from liability4 ,when the owner hires an amateur aeronaut to run the aeroplane1 and teaches him how to manipulate it1 even though the prescribed manner of manipulation will make flight safe1 nevertheless if the machine is visibly defective1 or known to be so1 any injury which results to the aeronaut the owner is liable for4 ,as to ,aeroplane ,contracts4 ,at the present time there are many orders being placed with aeroplane manufacturing companies4 ,there are some unique questions to be raised here under the law of contract4 ,it is an elementary principle of law that no one can be compelled to complete a contract which in itself is impossible to perform4 ,for instance1 a contract to row a boat across the ,atlantic in two weeks1 for a consideration1 could never be enforced because it is within judicial knowledge that such an undertaking is beyond human power4 ,again1 contracts formed for the doing of acts contrary to nature are never enforcible1 and here is where our difficulty comes in4 ,is it possible to build a machine or species of craft which will transport a person or goods through the air8 ,the courts know that balloons are practical2 that is1 they know that a bag filled with gas has a lifting power and can move through the air at an appreciable height4 ,therefore1 a contract to transport a person in such manner is a good contract1 and the conditions being favorable could undoubtedly be enforced4 ,but the passengers' right of action for injury would be very limited4 ,no ,redress for ,purchasers4 ,in the case of giving warranties on aeroplanes1 we have yet to see just what a court is going to say4 ,it is easy enough for a manufacturer to guarantee to build a machine of certain dimensions and according to certain specifications1 but when he inserts a clause in the contract to the effect that the machine will raise itself from the surface of the earth1 defy the laws of gravity1 and soar in the heavens at the will of the aviator1 he is to say the least contracting to perform a miracle4 ,until aeroplanes have been made and accepted as practical1 no court will force a manufacturer to turn out a machine guaranteed to fly4 ,so purchasers can well remember that if their machines refuse to fly they have no redress against the maker1 for he can always say1 ',the industry is still in its experimental stage4' ,in contracting for an engine no builder will guarantee that the particular engine will successfully operate the aeroplane4 ,in fact he could never be forced to live up to such an agreement1 should he agree to a stipulation of that sort4 ,the best any engine maker will guarantee is to build an engine according to specifications4 ,,chapter ,,xx4 ,,soaring ,,flight4 ,by ,octave ,chanute4 #e ,there is a wonderful performance daily exhibited in southern climes and occasionally seen in northerly latitudes in summer1 which has never been thoroughly explained4 ,it is the soaring or sailing flight of certain varieties of large birds who transport themselves on rigid1 unflapping wings in any desired direction2 who in winds of #f to #bj miles per hour1 circle1 rise1 advance1 return and remain aloft for hours without a beat of wing1 save for getting under way or convenience in various maneuvers4 ,they appear to obtain from the wind alone all the necessary energy1 even to advancing dead against that wind4 ,this feat is so much opposed to our general ideas of physics that those who have not seen it sometimes deny its actuality1 and those who have only occasionally witnessed it subsequently doubt the evidence of their own eyes4 ,others1 who have seen the exceptional performances1 speculate on various explanations1 but the majority give it up as a sort of negative gravity4 ,soaring ,power of ,birds4 ,the writer of this paper published in the ,aeronautical ,annual for #ahif and #ahig an article upon the sailing flight of birds1 in which he gave a list of the authors who had described such flight or had advanced theories for its explanation1 and he passed these in review4 ,he also described his own observations and submitted some computations to account for the observed facts4 ,these computations were correct as far as they went1 but they were scanty4 ,it was1 for instance1 shown convincingly by analysis that a gull weighing #b4ahh pounds1 with a total supporting surface of #b4jae square feet1 a maximum body cross-section of #j4abf square feet and a maximum cross-section of wing edges of #j4jih square feet1 patrolling on rigid wings 7soaring7 on the weather side of a steamer and maintaining an upward angle or attitude of #e degrees to #g degrees above the horizon1 in a wind blowing #ab4gh miles an hour1 which was deflected upward #aj degrees to #bj degrees by the side of the steamer 7these all being carefully observed facts71 was perfectly sustained at its own relative speed of #ag4hh miles per hour and extracted from the upward trend of the wind sufficient energy to overcome all the resistances1 this energy amounting to #f4dd foot-pounds per second4 ,great ,power of ,gulls4 ,it was shown that the same bird in flapping flight in calm air1 with an attitude or incidence of #c degrees to #e degrees above the horizon and a speed of #bj4d miles an hour was well sustained and expended #e4hh foot-pounds per second1 this being at the rate of #bjd pounds sustained per horsepower4 ,it was stated also that a gull in its observed maneuvers1 rising up from a pile head on unflapping wings1 then plunging forward against the wind and subsequently rising higher than his starting point1 must either time his ascents and descents exactly with the variations in wind velocities1 or must meet a wind billow rotating on a horizontal axis and come to a poise on its crest1 thus availing of an ascending trend4 ,but the observations failed to demonstrate that the variations of the wind gusts and the movements of the bird were absolutely synchronous1 and it was conjectured that the peculiar shape of the soaring wing of certain birds1 as differentiated from the flapping wing1 might1 when experimented upon1 hereafter account for the performance4 ,mystery to be ,explained4 ,these computations1 however satisfactory they were for the speed of winds observed1 failed to account for the observed spiral soaring of buzzards in very light winds and the writer was compelled to confess3 ,now1 this spiral soaring in steady breezes of #e to #aj miles per hour which are apparently horizontal1 and through which the bird maintains an average speed of about #bj miles an hour1 is the mystery to be explained4 ,it is not accounted for1 quantitatively1 by any of the theories which have been advanced1 and it is the one performance which has led some observers to claim that it was done through 'aspiration4' i1 e41 that a bird acted upon by a current1 actually drew forward into that current against its exact direction of motion4 ,buzzards ,soar in ,dead ,calm4 ,a still greater mystery was propounded by the few observers who asserted that they had seen buzzards soaring in a dead calm1 maintaining their elevation and their speed4 ,among these observers was ,mr4 ,e4 ,c4 ,huffaker1 at one time assistant experimenter for ,professor ,langley4 ,the writer believed and said then that he must in some way have been mistaken1 yet1 to satisfy himself1 he paid several visits to ,mr4 ,huffaker1 in ,eastern ,tennessee and took along his anemometer4 ,he saw quite a number of buzzards sailing at a height of #ge to #ajj feet in breezes measuring #e or #f miles an hour at the surface of the ground1 and once he saw one buzzard soaring apparently in a dead calm4 ,the writer was fairly baffled4 ,the bird was not simply gliding1 utilizing gravity or acquired momentum1 he was actually circling horizontally in defiance of physics and mathematics4 ,it took two years and a whole series of further observations to bring those two sciences into accord with the facts4 ,results of ,close ,observations4 ,curiously enough the key to the performance of circling in a light wind or a dead calm was not found through the usual way of gathering human knowledge1 i4 e41 through observations and experiment4 ,these had failed because ,i did not know what to look for4 ,the mystery was1 in fact1 solved by an eclectic process of conjecture and computation1 but once these computations indicated what observations should be made1 the results gave at once the reasons for the circling of the birds1 for their then observed attitude1 and for the necessity of an independent initial sustaining speed before soaring began4 ,both ,mr4 ,huffaker and myself verified the data many times and ,i made the computations4 ,these observations disclosed several facts3 #ast4--,that winds blowing five to seventeen miles per hour frequently had rising trends of #aj degrees to #ae degrees1 and that upon occasions when there seemed to be absolutely no wind1 there was often nevertheless a local rising of the air estimated at a rate of four to eight miles or more per hour4 ,this was ascertained by watching thistledown1 and rising fogs alongside of trees or hills of known height4 ,everyone will readily realize that when walking at the rate of four to eight miles an hour in a dead calm the relative wind is quite inappreciable to the senses and that such a rising air would not be noticed4 #bnd4--,that the buzzard1 sailing in an apparently dead horizontal calm1 progressed at speeds of fifteen to eighteen miles per hour1 as measured by his shadow on the ground4 ,it was thought that the air was then possibly rising #h4h feet per second1 or six miles per hour4 #crd4--,that when soaring in very light winds the angle of incidence of the buzzards was negative to the horizon--i4 e41 that when seen coming toward the eye1 the afternoon light shone on the back instead of on the breast1 as would have been the case had the angle been inclined above the horizon4 #dth4--,that the sailing performance only occurred after the bird had acquired an initial velocity of at least fifteen or eighteen miles per hour1 either by industrious flapping or by descending from a perch4 ,an ,interesting ,experiment4 #eth4--,that the whole resistance of a stuffed buzzard1 at a negative angle of #c degrees in a current of air of #ae4eb miles per hour1 was #j4bg pounds4 ,this test was kindly made for the writer by ,professor ,a4 ,f4 ,zahm in the wind tunnel of the ,catholic ,university at ,washington1 ,d4 ,c41 who1 moreover1 stated that the resistance of a live bird might be less1 as the dried plumage could not be made to lie smooth4 ,this particular buzzard weighed in life #d4be pounds1 the area of his wings and body was #d4eg square feet1 the maximum cross-section of his body was #j4aaj square feet1 and that of his wing edges when fully extended was #j4bdd square feet4 ,with these data1 it became surprisingly easy to compute the performance with the coefficients of ,lilienthal for various angles of incidence and to demonstrate how this buzzard could soar horizontally in a dead horizontal calm1 provided that it was not a vertical calm1 and that the air was rising at the rate of four or six miles per hour1 the lowest observed1 and quite inappreciable without actual measuring4 ,some ,data on ,bird ,power4 ,the most difficult case is purposely selected4 ,for if we assume that the bird has previously acquired an initial minimum speed of seventeen miles an hour 7#bd4ic feet per second1 nearly the lowest measured71 and that the air was rising vertically six miles an hour 7#h4hj feet per second71 then we have as the trend of the relative wind encountered3 #f -- #j4cec1 or the tangent of #ai degrees #bf'4 #ag which brings the case into the category of rising wind effects4 ,but the bird was observed to have a negative angle to the horizon of about #c degrees1 as near as could be guessed1 so that his angle of incidence to the relative wind was reduced to #af degrees #bf'4 ,the relative speed of his soaring was therefore3 ,velocity square root of 7#ag squared #f squared7 #ah4jc miles per hour4 ,at this speed1 using the ,langley co-efficient recently practically confirmed by the accurate experiments of ,mr4 ,eiffel1 the air pressure would be3 #ah4jc squared ,x #j4jjcbg #a4jfc pounds per square foot4 ,if we apply ,lilienthal's co-efficients for an angle of #f degrees #bf'1 we have for the force in action3 ,normal3 #d4eg ,x #a4jfc ,x #j4iab #d4db pounds4 ,tangential3 #d4eg ,x #a4jfc ,x #j4jgd - #j4cei pounds1 which latter1 being negative1 is a propelling force4 ,results ,astonish ,scientists4 ,thus we have a bird weighing #d4be pounds not only thoroughly supported1 but impelled forward by a force of #j4cei pounds1 at seventeen miles per hour1 while the experiments of ,professor ,a4 ,f4 ,zahm showed that the resistance at #ae4eb miles per hour was only #j4bg pounds1 #ag squared or #j4bg ,x ------- #j4cbd pounds1 at seventeen miles an #ae4eb squared hour4 ,these are astonishing results from the data obtained1 and they lead to the inquiry whether the energy of the rising air is sufficient to make up the losses which occur by reason of the resistance and friction of the bird's body and wings1 which1 being rounded1 do not encounter air pressures in proportion to their maximum cross-section4 ,we have no accurate data upon the co-efficients to apply and estimates made by myself proved to be much smaller than the #j4bg pounds resistance measured by ,professor ,zahm1 so that we will figure with the latter as modified4 ,as the speed is seventeen miles per hour1 or #bd4ic feet per second1 we have for the work3 ,work done1 #j4cbd ,x #bd4ic #h4jg foot pounds per second4 ,endorsed by ,prof4 ,marvin4 ,corresponding energy of rising air is not sufficient at four miles per hour4 ,this amounts to but #b4aj foot pounds per second1 but if we assume that the air was rising at the rate of seven miles per hour 7#aj4bf feet per second71 at which the pressure with the ,langley coefficient would be #j4af pounds per square foot1 we have on #d4eg square feet for energy of rising air3 #d4eg ,x #j4af ,x #aj4bf #g4ej foot pounds per second1 which is seen to be still a little too small1 but well within the limits of error1 in view of the hollow shape of the bird's wings1 which receive greater pressure than the flat planes experimented upon by ,langley4 ,these computations were chiefly made in ,january1 #ahii1 and were communicated to a few friends1 who found no fallacy in them1 but thought that few aviators would understand them if published4 ,they were then submitted to ,professor ,c4 ,f4 ,marvin of the ,weather ,bureau1 who is well known as a skillful physicist and mathematician4 ,he wrote that they were1 theoretically1 entirely sound and quantitatively1 probably1 as accurate as the present state of the measurements of wind pressures permitted4 ,the writer determined1 however1 to withhold publication until the feat of soaring flight had been performed by man1 partly because he believed that1 to ensure safety1 it would be necessary that the machine should be equipped with a motor in order to supplement any deficiency in wind force4 ,conditions ,unfavorable for ,wrights4 ,the feat would have been attempted in #aijb by ,wright brothers if the local circumstances had been more favorable4 ,they were experimenting on ,kill ,devil ,hill1 near ,kitty ,hawk1 ,n4 ,c4 ,this sand hill1 about #ajj feet high1 is bordered by a smooth beach on the side whence come the sea breezes1 but has marshy ground at the back4 ,wright brothers were apprehensive that if they rose on the ascending current of air at the front and began to circle like the birds1 they might be carried by the descending current past the back of the hill and land in the marsh4 ,their gliding machine offered no greater head resistance in proportion than the buzzard1 and their gliding angles of descent are practically as favorable1 but the birds performed higher up in the air than they4 ,langley's ,idea of ,aviation4 ,professor ,langley said in concluding his paper upon ,the ,internal ,work of the ,wind3 ,the final application of these principles to the art of aerodromics seems1 then1 to be1 that while it is not likely that the perfected aerodrome will ever be able to dispense altogether with the ability to rely at intervals on some internal source of power1 it will not be indispensable that this aerodrome of the future shall1 in order to go any distance--even to circumnavigate the globe without alighting--need to carry a weight of fuel which would enable it to perform this journey under conditions analogous to those of a steamship1 but that the fuel and weight need only be such as to enable it to take care of itself in exceptional moments of calm4 ,now that dynamic flying machines have been evolved and are being brought under control1 it seems to be worth while to make these computations and the succeeding explanations known1 so that some bold man will attempt the feat of soaring like a bird4 ,the theory underlying the performance in a rising wind is not new1 it has been suggested by ,penaud and others1 but it has attracted little attention because the exact data and the maneuvers required were not known and the feat had not yet been performed by a man4 ,the puzzle has always been to account for the observed act in very light winds1 and it is hoped that by the present selection of the most difficult case to explain--i4 e41 the soaring in a dead horizontal calm--somebody will attempt the exploit4 ,requisites for ,soaring ,flights4 ,the following are deemed to be the requisites and maneuvers to master the secrets of soaring flight3 #ast--,develop a dynamic flying machine weighing about one pound per square foot of area1 with stable equilibrium and under perfect control1 capable of gliding by gravity at angles of one in ten 7#e #c_/d degrees7 in still air4 #bnd4--,select locations where soaring birds abound and occasions where rising trends of gentle winds are frequent and to be relied on4 #crd4--,obtain an initial velocity of at least #be feet per second before attempting to soar4 #dth4--,so locate the center of gravity that the apparatus shall assume a negative angle1 fore and aft1 of about #c degrees4 ,calculations show1 however1 that sufficient propelling force may still exist at #j degrees1 but disappears entirely at #d degrees4 #eth4--,circle like the bird4 ,simultaneously with the steering1 incline the apparatus to the side toward which it is desired to turn1 so that the centrifugal force shall be balanced by the centripetal force4 ,the amount of the required inclination depends upon the speed and on the radius of the circle swept over4 #fth4--,rise spirally like the bird4 ,steer with the horizontal rudder1 so as to descend slightly when going with the wind and to ascend when going against the wind4 ,the bird circles over one spot because the rising trends of wind are generally confined to small areas or local chimneys1 as pointed out by ,sir ,h4 ,maxim and others4 #gth4--,once altitude is gained1 progress may be made in any direction by gliding downward by gravity4 ,the bird's flying apparatus and skill are as yet infinitely superior to those of man1 but there are indications that within a few years the latter may evolve more accurately proportioned apparatus and obtain absolute control over it4 ,it is hoped1 therefore1 that if there be found no radical error in the above computations1 they will carry the conviction that soaring flight is not inaccessible to man1 as it promises great economies of motive power in favorable localities of rising winds4 ,the writer will be grateful to experts who may point out any mistake committed in data or calculations1 and will furnish additional information to any aviator who may wish to attempt the feat of soaring4 ,,chapter ,,xxi4 ,,flying ,,machines ,,vs4 ,,balloons4 ,while wonderful success has attended the development of the dirigible 7steerable7 balloon the most ardent advocates of this form of aerial navigation admit that it has serious drawbacks4 ,some of these may be described as follows3 ,expense and ,other ,items4 ,great ,initial ,expense4--,the modern dirigible balloon costs a fortune4 ,the ,zeppelin1 for instance1 costs more than #ajj1jjj 7these are official figures74 ,expense of ,inflation4--,gas evaporates rapidly1 and a balloon must be re-inflated1 or partially re-inflated1 every time it is used4 ,the ,zeppelin holds #dfj1jjj cubic feet of gas which1 even at #a per thousand1 would cost #dfj4 ,difficulty of ,obtaining ,gas4--,if a balloon suddenly becomes deflated1 by accident or atmospheric conditions1 far from a source of gas supply1 it is practically worthless4 ,gas must be piped to it1 or the balloon carted to the gas house--an expensive proceeding in either event4 ,lack of ,speed and ,control4 ,lack of ,speed4--,under the most favorable conditions the maximum speed of a balloon is #cj miles an hour4 ,its great bulk makes the high speed attained by flying machines impossible4 ,difficulty of ,control4--,while the modern dirigible balloon is readily handled in calm or light winds1 its bulk makes it difficult to control in heavy winds4 ,the ,element of ,danger4--,numerous balloons have been destroyed by lightning and similar causes4 ,one of the largest of the ,zeppelins was thus lost at ,stuttgart in #aijh4 ,some ,balloon ,performances4 ,it is only a matter of fairness to state that1 under favorable conditions1 some very creditable records have been made with modern balloons1 viz3 ,november #bc;d1 #aijg1 the ,french dirigible ,patrie1 travelled #ahg miles in #f hours and #de minutes against a light wind4 ,this was a little over #bh miles an hour4 ,the ,clement-,bayard1 another ,french machine1 sold to the ,russian government1 made a trip of #abe miles at a rate of #bg miles an hour4 ,zeppelin ,no4 #c1 carrying eight passengers1 and having a total lifting capacity of #e1ejj pounds of ballast in addition to passengers1 weight of equipment1 etc41 was tested in ,october1 #aijf1 and made #fg miles in #b hours and #ag minutes1 about #cj miles an hour4 ,these are the best balloon trips on record1 and show forcefully the limitations of speed1 the greatest being not over #cj miles an hour4 ,speed of ,flying ,machines4 ,opposed to the balloon performances we have flying machine trips 7of authentic records7 as follows3 ,bleriot--monoplane--in #aijh--eb miles an hour4 ,delagrange--,june #bb1 #aijh--aj #a_/b miles in #af minutes1 approximately #db miles an hour4 ,wrights--,october1 #aije--the machine was then in its infancy--#bd miles in #ch minutes1 approximately #dd miles an hour4 ,on ,december #ca1 #aijh1 the ,wrights made #gg miles in #b hours and #bj minutes4 ,lambert1 a pupil of the ,wrights1 and using a ,wright biplane1 on ,october #ah1 #aiji1 covered #bi4hb miles in #di minutes and #ci seconds1 being at the rate of #cf miles an hour4 ,this flight was made at a height of #a1cab feet4 ,latham--,october #ba1 #aiji--made a short flight1 about #aa minutes1 in the teeth of a #dj mile gale1 at ,blackpool1 ,eng4 ,he used an ,antoniette monoplane1 and the official report says3 ,this exhibition of nerve1 daring and ability is unparalled in the history of aviation4 ,farman--,october #bj1 #aiji--was in the air for #a hour1 #cb min41 #af seconds1 travelling #dg miles1 #a1ahd yards1 a duration record for ,england4 ,paulhan--,january #ah1 #aija--dg #a_/b miles at the rate of #de miles an hour1 maintaining an altitude of from #a1jjj to #b1jjj feet4 ,expense of ,producing ,gas4 ,gas is indispensable in the operation of dirigible balloons1 and gas is expensive4 ,besides this it is not always possible to obtain it in sufficient quantities even in large cities1 as the supply on hand is generally needed for regular customers4 ,such as can be had is either water or coal gas1 neither of which is as efficient in lifting power as hydrogen4 ,hydrogen is the lightest and consequently the most buoyant of all known gases4 ,it is secured commercially by treating zinc or iron with dilute sulphuric or hydrochloric acid4 ,the average cost may be safely placed at #aj per #a1jjj feet so that1 to inflate a balloon of the size of the ,zeppelin1 holding #dfj1jjj cubic feet1 would cost #d1fjj4 ,proportions of ,materials ,required4 ,in making hydrogen gas it is customary to allow #bj per cent for loss between the generation and the introduction of the gas into the balloon4 ,thus1 while the formula calls for iron #bh times heavier than the weight of the hydrogen required1 and acid #di times heavier1 the real quantities are #bj per cent greater4 ,hydrogen weighs about #j4ji ounce to the cubic foot4 ,consequently if we need say #dej1jjj cubic feet of gas we must have #b1eca4be pounds in weight4 ,to produce this1 allowing for the #bj percent loss1 we must have #ce times its weight in iron1 or over #dd tons4 ,of acid it would take #fj times the weight of the gas1 or nearly #gf tons4 ,in ,time of ,emergency4 ,these figures are appalling1 and under ordinary conditions would be prohibitive1 but there are times when the balloon operator1 unable to obtain water or coal gas1 must foot the bills4 ,in military maneuvers1 where the field of operation is fixed1 it is possible to furnish supplies of hydrogen gas in portable cylinders1 but on long trips where sudden leakage or other cause makes descent in an unexpected spot unavoidable1 it becomes a question of making your own hydrogen gas or deserting the balloon4 ,and when this occurs the balloonist is up against another serious proposition--can he find the necessary zinc or iron8 ,can he get the acid8 ,balloons for ,commercial ,use4 ,despite all this the balloon has its uses4 ,if there is to be such a thing as aerial navigation in a commercial way--the carrying of freight and passengers--it will come through the employment of such monster balloons as ,count ,zeppelin is building4 ,but even then the carrying capacity must of necessity be limited4 ,the latest ,zeppelin creation1 a monster in size1 is #dej feet long1 and #db #a_/b feet in diameter4 ,the dimensions are such as to make all other balloons look like pigmies2 even many ocean-going steamers are much smaller1 and yet its passenger capacity is very small4 ,on its #cf-;hour flight in ,may1 #aiji1 the ,zeppelin1 carried only eight passengers4 ,the speed1 however1 was quite respectable1 #hej miles being covered in the #cf hours1 a trifle over #bc miles an hour4 ,the reserve buoyancy1 that is the total lifting capacity aside from the weight of the airship and its equipment1 is estimated at three tons4 ,,chapter ,,xxii4 ,,problems ,,of ,,aerial ,,flight4 ,in a lecture before the ,royal ,society of ,arts1 reported in ,engineering1 ,f4 ,w4 ,lanchester took the position that practical flight was not the abstract question which some apparently considered it to be1 but a problem in locomotive engineering4 ,the flying machine was a locomotive appliance1 designed not merely to lift a weight1 but to transport it elsewhere1 a fact which should be sufficiently obvious4 ,nevertheless one of the leading scientific men of the day advocated a type in which this1 the main function of the flying machine1 was overlooked4 ,when the machine was considered as a method of transport1 the vertical screw type1 or helicopter1 became at once ridiculous4 ,it had1 nevertheless1 many advocates who had some vague and ill-defined notion of subsequent motion through the air after the weight was raised4 ,helicopter ,type ,useless4 ,when efficiency of transport was demanded1 the helicopter type was entirely out of court4 ,almost all of its advocates neglected the effect of the motion of the machine through the air on the efficiency of the vertical screws4 ,they either assumed that the motion was so slow as not to matter1 or that a patch of still air accompanied the machine in its flight4 ,only one form of this type had any possibility of success4 ,in this there were two screws running on inclined axles--one on each side of the weight to be lifted4 ,the action of such inclined screw was curious1 and in a previous lecture he had pointed out that it was almost exactly the same as that of a bird's wing4 ,in high-speed racing craft such inclined screws were of necessity often used1 but it was at a sacrifice of their efficiency4 ,in any case the efficiency of the inclined-screw helicopter could not compare with that of an aeroplane1 and that type might be dismissed from consideration so soon as efficiency became the ruling factor of the design4 ,must ,compete ,with ,locomotive4 ,to justify itself the aeroplane must compete1 in some regard or other1 with other locomotive appliances1 performing one or more of the purposes of locomotion more efficiently than existing systems4 ,it would be no use unless able to stem air currents1 so that its velocity must be greater than that of the worst winds liable to be encountered4 ,to illustrate the limitations imposed on the motion of an aeroplane by wind velocity1 ,mr4 ,lanchester gave the diagrams shown in ,figs4 #a to #d4 ,the circle in each case was1 he said1 described with a radius equal to the speed of the aeroplane in still air1 from a center placed down-wind from the aeroplane by an amount equal to the velocity of the wind4 ,fig4 #a therefore represented the case in which the air was still1 and in this case the aeroplane represented by ,a had perfect liberty of movement in any direction ,in ,fig4 #b the velocity of the wind was half that of the aeroplane1 and the latter could still navigate in any direction1 but its speed against the wind was only one-third of its speed with the wind4 ,in ,fig4 #c the velocity of the wind was equal to that of the aeroplane1 and then motion against the wind was impossible2 but it could move to any point of the circle1 but not to any point lying to the left of the tangent ,a ,b4 ,finally1 when the wind had a greater speed than the aeroplane1 as in ,fig4 #d1 the machine could move only in directions limited by the tangents ,a ,c and ,a ,d4 ,matter of ,fuel ,consumption4 ,taking the case in which the wind had a speed equal to half that of the aeroplane1 ,mr4 ,lanchester said that for a given journey out and home1 down wind and back1 the aeroplane would require #cj per cent more fuel than if the trip were made in still air2 while if the journey was made at right angles to the direction of the wind the fuel needed would be #ae per cent more than in a calm4 ,this #cj per cent extra was quite a heavy enough addition to the fuel2 and to secure even this figure it was necessary that the aeroplane should have a speed of twice that of the maximum wind in which it was desired to operate the machine4 ,again1 as stated in the last lecture1 to insure the automatic stability of the machine it was necessary that the aeroplane speed should be largely in excess of that of the gusts of wind liable to be encountered4 ,eccentricities of the ,wind4 ,there was1 ,mr4 ,lanchester said1 a loose connection between the average velocity of the wind and the maximum speed of the gusts4 ,when the average speed of the wind was #dj miles per hour1 that of the gusts might be equal or more4 ,at one moment there might be a calm or the direction of the wind even reversed1 followed1 the next moment1 by a violent gust4 ,about the same minimum speed was desirable for security against gusts as was demanded by other considerations4 ,sixty miles an hour was the least figure desirable in an aeroplane1 and this should be exceeded as much as possible4 ,actually1 the ,wright machine had a speed of #ch miles per hour1 while ,farman's ,voisin machine flew at #de miles per hour4 ,both machines were extremely sensitive to high winds1 and the speaker1 in spite of newspaper reports to the contrary1 had never seen either flown in more than a gentle breeze4 ,the damping out of the oscillations of the flight path1 discussed in the last lecture1 increased with the fourth power of the natural velocity of flight1 and rapid damping formed the easiest1 and sometimes the only1 defense against dangerous oscillations4 ,a machine just stable at #ce miles per hour would have reasonably rapid damping if its speed were increased to #fj miles per hour4 ,thinks ,use ,is ,limited4 ,it was1 the lecturer proceeded1 inconceivable that any very extended use should be made of the aeroplane unless the speed was much greater than that of the motor car4 ,it might in special cases be of service1 apart from this increase of speed1 as in the exploration of countries destitute of roads1 but it would have no general utility4 ,with an automobile averaging #be to #ce miles per hour1 almost any part of ,europe1 ,russia excepted1 was attainable in a day's journey4 ,a flying machine of but equal speed would have no advantages1 but if the speed could be raised to #ij or #ajj miles per hour1 the whole continent of ,europe would become a playground1 every part being within a daylight flight of ,berlin4 ,further1 some marine craft now had speeds of #dj miles per hour1 and efficiently to follow up and report movements of such vessels an aeroplane should travel at #fj miles per hour at least4 ,hence from all points of view appeared the imperative desirability of very high velocities of flight4 ,the difficulties of achievement were1 however1 great4 ,weight of ,lightest ,motors4 ,as shown in the first lecture of his course1 the resistance to motion was nearly independent of the velocity1 so that the total work done in transporting a given weight was nearly constant4 ,hence the question of fuel economy was not a bar to high velocities of flight1 though should these become excessive1 the body resistance might constitute a large proportion of the total4 ,the horsepower required varied as the velocity1 so the factor governing the maximum velocity of flight was the horsepower that could be developed on a given weight4 ,at present the weight per horsepower of feather-weight motors appeared to range from #b #a_/d pounds up to #g pounds per brake horsepower1 some actual figures being as follows3 ,antoinette44444444 #e lbs4 ,fiat44444444444444 #c lbs4 ,gnome4444444 ,under #c lbs4 ,metallurgic4444444 #h lbs4 ,renault44444444444 #g lbs4 ,wright4444444444444#f lbs4 ,automobile engines1 on the other hand1 commonly weighed #ab pounds to #ac pounds per brake horsepower4 ,for short flights fuel economy was of less importance than a saving in the weight of the engine4 ,for long flights1 however1 the case was different4 ,thus1 if the gasolene consumption was #a_/b pound per horsepower hour1 and the engine weighed #c pounds per brake horsepower1 the fuel needed for a six-hour flight would weigh as much as the engine1 but for half an hour's flight its weight would be unimportant4 ,best ,means of ,propulsion4 ,the best method of propulsion was by the screw1 which acting in air was subject to much the same conditions as obtained in marine work4 ,its efficiency depended on its diameter and pitch and on its position1 whether in front of or behind the body propelled4 ,from this theory of dynamic support1 ,mr4 ,lanchester proceeded1 the efficiency of each element of a screw propeller could be represented by curves such as were given in his first lecture before the society1 and from these curves the over-all efficiency of any proposed propeller could be computed1 by mere inspection1 with a fair degree of accuracy4 ,these curves showed that the tips of long-bladed propellers were inefficient1 as was also the portion of the blade near the root4 ,in actual marine practice the blade from boss to tip was commonly of such a length that the over-all efficiency was #ie per cent of that of the most efficient element of it4 ,advocates ,propellers in ,rear4 ,from these curves the diameter and appropriate pitch of a screw could be calculated1 and the number of revolutions was then fixed4 ,thus1 for a speed of #hj feet per second the pitch might come out as #h feet1 in which case the revolutions would be #fjj per minute1 which might1 however1 be too low for the motor4 ,it was then necessary either to gear down the propeller1 as was done in the ,wright machine1 or1 if it was decided to drive it direct1 to sacrifice some of the efficiency of the propeller4 ,an analogous case arose in the application of the steam turbine to the propulsion of cargo boats1 a problem as yet unsolved4 ,the propeller should always be aft1 so that it could abstract energy from the wake current1 and also so that its wash was clear of the body propelled4 ,the best possible efficiency was about #gj per cent1 and it was safe to rely upon #ff per cent4 ,benefits of ,soaring ,flight4 ,there was1 ,mr4 ,lanchester proceeded1 some possibility of the aeronaut reducing the power needed for transport by his adopting the principle of soaring flight1 as exemplified by some birds4 ,there were1 he continued1 two different modes of soaring flight4 ,in the one the bird made use of the upward current of air often to be found in the neighborhood of steep vertical cliffs4 ,these cliffs deflected the air upward long before it actually reached the cliff1 a whole region below being thus the seat of an upward current4 ,darwin has noted that the condor was only to be found in the neighborhood of such cliffs4 ,along the south coast also the gulls made frequent use of the up currents due to the nearly perpendicular chalk cliffs along the shore4 ,in the tropics up currents were also caused by temperature differences4 ,cumulus clouds1 moreover1 were nearly always the terminations of such up currents of heated air1 which1 on cooling by expansion in the upper regions1 deposited their moisture as fog4 ,these clouds might1 perhaps1 prove useful in the future in showing the aeronaut where up currents were to be found4 ,another mode of soaring flight was that adopted by the albatross1 which took advantage of the fact that the air moved in pulsations1 into which the bird fitted itself1 being thus able to extract energy from the wind4 ,whether it would be possible for the aeronaut to employ a similar method must be left to the future to decide4 ,main ,difficulties in ,aviation4 ,in practical flight difficulties arose in starting and in alighting4 ,there was a lower limit to the speed at which the machine was stable1 and it was inadvisable to leave the ground till this limit was attained4 ,similarly1 in alighting it was inexpedient to reduce the speed below the limit of stability4 ,this fact constituted a difficulty in the adoption of high speeds1 since the length of run needed increased in proportion to the square of the velocity4 ,this drawback could1 however1 be surmounted by forming starting and alighting grounds of ample size4 ,he thought it quite likely in the future that such grounds would be considered as essential to the flying machine as a seaport was to an ocean-going steamer or as a road was to the automobile4 ,requisites of ,flying ,machine4 ,flying machines were commonly divided into monoplanes and biplanes1 according as they had one or two supporting surfaces4 ,the distinction was not1 however1 fundamental4 ,to get the requisite strength some form of girder framework was necessary1 and it was a mere question of convenience whether the supporting surface was arranged along both the top and the bottom of this girder1 or along the bottom only4 ,the framework adopted universally was of wood braced by ties of pianoforte wire1 an arrangement giving the stiffness desired with the least possible weight4 ,some kind of chassis was also necessary4 ,,chapter ,,xxiii4 ,,amateurs ,,may ,,use ,,wright ,,patents4 ,owing to the fact that the ,wright brothers have enjoined a number of professional aviators from using their system of control1 amateurs have been slow to adopt it4 ,they recognize its merits1 and would like to use the system1 but have been apprehensive that it might involve them in litigation4 ,there is no danger of this1 as will be seen by the following statement made by the ,wrights3 ,what ,wright ,brothers ,say4 ,any amateur1 any professional who is not exhibiting for money1 is at liberty to use our patented devices4 ,we shall be glad to have them do so1 and there will be no interference on our part1 by legal action1 or otherwise4 ,the only men we proceed against are those who1 without our permission1 without even asking our consent1 coolly appropriate the results of our labors and use them for the purpose of making money4 ,curtiss1 ,delagrange1 ,voisin1 and all the rest of them who have used our devices have done so in money-making exhibitions4 ,so long as there is any money to be made by the use of the products of our brains1 we propose to have it ourselves4 ,it is the only way in which we can get any return for the years of patient work we have given to the problem of aviation4 ,on the other hand1 any man who wants to use these devices for the purpose of pleasure1 or the advancement of science1 is welcome to do so1 without money and without price4 ,this is fair enough1 is it not8 ,basis of the ,wright ,patents4 ,in a flying machine a normally flat aeroplane having lateral marginal portions capable of movement to different positions above or below the normal plane of the body of the aeroplane1 such movement being about an axis transverse to the line of flight1 whereby said lateral marginal portions may be moved to different angles relatively to the normal plane of the body of the aeroplane1 so as to present to the atmosphere different angles of incidence1 and means for so moving said lateral marginal portions1 substantially as described4 ,application of vertical struts near the ends having flexible joints4 ,means for simultaneously imparting such movement to said lateral portions to different angles relatively to each other4 ,refers to the movement of the lateral portions on the same side to the same angle4 ,means for simultaneously moving vertical rudder so as to present to the wind that side thereof nearest the side of the aeroplane having the smallest angle of incidence4 ,lateral stability is obtained by warping the end wings by moving the lever at the right hand of the operator1 connection being made by wires from the lever to the wing tips4 ,the rudder may also be curved or warped in similar manner by lever action4 ,wrights ,obtain an ,injunction4 ,in ,january1 #aiaj1 ,judge ,hazel1 of the ,united ,states ,circuit ,court1 granted a preliminary injunction restraining the ,herring-,curtiss ,co41 and ,glenn ,h4 ,curtiss1 from manufacturing1 selling1 or using for exhibition purposes the machine known as the ,curtiss aeroplane4 ,the injunction was obtained on the ground that the ,curtiss machine is an infringement upon the ,wright patents in the matter of wing warping and rudder control4 ,it is not the purpose of the authors to discuss the subject pro or con4 ,such discussion would have no proper place in a volume of this kind4 ,it is enough to say that ,curtiss stoutly insists that his machine is not an infringement of the ,wright patents1 although ,judge ,hazel evidently thinks differently4 ,what the ,judge ,said4 ,in granting the preliminary injunction the judge said3 ,defendants claim generally that the difference in construction of their apparatus causes the equilibrium or lateral balance to be maintained and its aerial movement secured upon an entirely different principle from that of complainant2 the defendants' aeroplanes are curved1 firmly attached to the stanchions and hence are incapable of twisting or turning in any direction2 that the supplementary planes or so-called rudders are secured to the forward stanchion at the extreme lateral ends of the planes and are adjusted midway between the upper and lower planes with the margins extending beyond the edges2 that in moving the supplementary planes equal and uniform angles of incidence are presented as distinguished from fluctuating angles of incidence4 ,such claimed functional effects1 however1 are strongly contradicted by the expert witness for complainant4 ,similar to ,plan of ,wrights4 ,upon this contention it is sufficient to say that the affidavits for the complainant so clearly define the principle of operation of the flying machines in question that ,i am reasonably satisfied that there is a variableness of the angle of incidence in the machine of defendants which is produced when a supplementary plane on one side is tilted or raised and the other stimultaneously tilted or lowered4 ,i am also satisfied that the rear rudder is turned by the operator to the side having the least angle of incidence and that such turning is done at the time the supplementary planes are raised or depressed to prevent tilting or upsetting the machine4 ,on the papers presented ,i incline to the view1 as already indicated1 that the claims of the patent in suit should be broadly construed2 and when given such construction1 the elements of the ,wright machine are found in defendants' machine performing the same functional result4 ,there are dissimilarities in the defendants' structure--changes of form and strengthening of parts--which may be improvements1 but such dissimilarities seem to me to have no bearing upon the means adopted to preserve the equilibrium1 which means are the equivalent of the claims in suit and attain an identical result4 ,variance ,from ,patent ,immaterial4 ,defendants further contend that the curved or arched surfaces of the ,wright aeroplanes in commercial use are departures from the patent1 which describes 'substantially flat surfaces1' and that such a construction would be wholly impracticable4 ,the drawing1 ,fig4 #c1 however1 attached to the specification1 shows a curved line inward of the aeroplane with straight lateral edges1 and considering such drawing with the terminology of the specification1 the slight arching of the surface is not thought a material departure2 at any rate1 the patent in issue does not belong to the class of patents which requires narrowing to the details of construction4 ,june ,bug ,first ,infringement4 ,referring to the matter of priority1 the judge said3 ,indeed1 no one interfered with the rights of the patentees by constructing machines similar to theirs until in ,july1 #aijh1 when ,curtiss exhibited a flying machine which he called the ',june ,bug4' ,he was immediately notified by the patentees that such machine with its movable surfaces at the tips of wings infringed the patent in suit1 and he replied that he did not intend to publicly exhibit the machine for profit1 but merely was engaged in exhibiting it for scientific purposes as a member of the ,aerial ,experiment ,association4 ,to this the patentees did not object4 ,subsequently1 however1 the machine1 with supplementary planes placed midway between the upper and lower aeroplanes1 was publicly exhibited by the defendant corporation and used by ,curtiss in aerial flights for prizes and emoluments4 ,it further appears that the defendants now threaten to continue such use for gain and profit1 and to engage in the manufacture and sale of such infringing machines1 thereby becoming an active rival of complainant in the business of constructing flying machines embodying the claims in suit1 but such use of the infringing machines it is the duty of this court1 on the papers presented1 to enjoin4 ,the requirements in patent causes for the issuance of an injunction pendente lite--the validity of the patent1 general acquiescence by the public and infringement by the defendants--are so reasonably clear that ,i believe if not probable the complainant may succeed at final hearing1 and therefore1 status quo should be preserved and a preliminary injunction granted4 ,so ordered4 ,points ,claimed ,by ,curtiss4 ,that the ,herring-,curtiss ,co4 will appeal is a certainty4 ,mr4 ,emerson ,r4 ,newell1 counsel for the company1 states its case as follows3 ,the ,curtiss machine has two main supporting surfaces1 both of which are curved 99 99 99 and are absolutely rigid at all times and cannot be moved1 warped or distorted in any manner4 ,the front horizontal rudder is used for the steering up or down1 and the rear vertical rudder is used only for steering to the right or left1 in the same manner as a boat is steered by its rudder4 ,the machine is provided at the rear with a fixed horizontal surface1 which is not present in the machine of the patent1 and which has a distinct advantage in the operation of defendants' machine1 as will be hereafter discussed4 ,does ,not ,warp ,main ,surface4 ,defendants' machine does not use the warping of the main supporting surfaces in restoring the lateral equilibrium1 but has two comparatively small pivoted balancing surfaces or rudders4 ,when one end of the machine is tipped up or down from the normal1 these planes may be thrown in opposite directions by the operator1 and so steer each end of the machine up or down to its normal level1 at which time tension upon them is released and they are moved back by the pressure of the wind to their normal position4 ,rudder ,used ,only ,for ,steering4 ,when defendants' balancing surfaces are moved they present equal angles of incidence to the normal rush of air and equal resistances1 at each side of the machine1 and there is therefore no tendency to turn around a vertical axis as is the case of the machine of the patent1 consequently no reason or necessity for turning the vertical rear rudder in defendants' machine to counteract any such turning tendency4 ,at any rate1 whatever may be the theories in regard to this matter1 the fact is that the operator of defendants' machine does not at any time turn his vertical rudder to counteract any turning tendency clue to the side balancing surfaces1 but only uses it to steer the machine the same as a boat is steered4 ,aero ,club ,recognizes ,wrights4 ,the ,aero ,club of ,america has officially recognized the ,wright patents4 ,this course was taken following a conference held ,april #ith1 #aiaj1 participated in by ,william ,wright and ,andrew ,freedman1 representing the ,wright ,co41 and the ,aero ,club's committee1 of ,philip ,t4 ,dodge1 ,w4 ,w4 ,miller1 ,l4 ,l4 ,gillespie1 ,wm4 ,h4 ,page and ,cortlandt ,f4 ,bishop4 ,at this meeting arrangements were made by which the ,aero ,club recognizes the ,wright patents and will not give its section to any open meet where the promoters thereof have not secured a license from the ,wright ,company4 ,the substance of the agreement was that the ,aero ,club of ,america recognizes the rights of the owners of the ,wright patents under the decisions of the ,federal courts and refuses to countenance the infringement of those patents as long as these decisions remain in force4 ,in the meantime1 in order to encourage aviation1 both at home and abroad1 and in order to permit foreign aviators to take part in aviation contests in this country it was agreed that the ,aero ,club of ,america1 as the ,american representative of the ,international ,aeronautic ,federation1 should approve only such public contests as may be licensed by the ,wright ,company and that the ,wright ,company1 on the other hand1 should encourage the holding of open meets or contests where ever approved as aforesaid by the ,aero ,club of ,america by granting licenses to promoters who make satisfactory arrangements with the company for its compensation for the use of its patents4 ,at such licensed meet any machine of any make may participate freely without securing any further license or permit4 ,the details and terms of all meets will be arranged by the committee having in charge the interests of both organizations4 ,,chapter ,,xxiv4 ,,hints ,,on ,,propeller ,,construction4 ,every professional aviator has his own ideas as to the design of the propeller1 one of the most important features of flying-machine construction4 ,while in many instances the propeller1 at a casual glance1 may appear to be identical1 close inspection will develop the fact that in nearly every case some individual idea of the designer has been incorporated4 ,thus1 two propellers of the two-bladed variety1 while of the same general size as to length and width of blade1 will vary greatly as to pitch and twist or curvature4 ,what the ,designers ,seek4 ,every designer is seeking for the same result--the securing of the greatest possible thrust1 or air displacement1 with the least possible energy4 ,the angles of any screw propeller blade having a uniform or true pitch change gradually for every increased diameter4 ,in order to give a reasonably clear explanation1 it will be well to review in a primary way some of the definitions or terms used in connection with and applied to screw propellers4 ,terms in ,general ,use4 ,pitch4--,the term pitch1 as applied to a screw propeller1 is the theoretical distance through which it would travel without slip in one revolution1 and as applied to a propeller blade it is the angle at which the blades are set so as to enable them to travel in a spiral path through a fixed distance theoretically without slip in one revolution4 ,pitch speed4--,the term pitch speed of a screw propeller is the speed in feet multiplied by the number of revolutions it is caused to make in one minute of time4 ,if a screw propeller is revolved #fjj times per minute1 and if its pitch is #g ft41 then the pitch speed of such a propeller would be #gx#fjj revolutions1 or #dbjj ft4 per minute4 ,uniform pitch4--,a true pitch screw propeller is one having its blades formed in such a manner as to enable all of its useful portions1 from the portion nearest the hub to its outer portion1 to travel at a uniform pitch speed4 ,or1 in other words1 the pitch is uniform when the projected area of the blade is parallel along its full length and at the same time representing a true sector of a circle4 ,all screw propellers having a pitch equal to their diameters have the same angle for their blades at their largest diameter4 ,when ,pitch ,is ,not ,uniform4 ,a screw propeller not having a uniform pitch1 but having the same angle for all portions of its blades1 or some arbitrary angle not a true pitch1 is distinguished from one having a true pitch in the variation of the pitch speeds that the various portions of its blades are forced to travel through while traveling at its maximum pitch speed4 ,on this subject ,mr4 ,r4 ,w4 ,jamieson says in ,aeronautics3 ,take for example an #h-;foot screw propeller having an #h-;foot pitch at its largest diameter4 ,if the angle is the same throughout its entire blade length1 then all the porions of its blades approaching the hub from its outer portion would have a gradually decreasing pitch4 ,the #b-;foot portion would have a #b-;foot pitch2 the #c-;foot portion a #c-;foot pitch1 and so on to the #h-;foot portion which would have an #h-;foot pitch4 ,when this form of propeller is caused to revolve1 say #ejj r4p4m41 the #h-;foot portion would have a calculated pitch speed of #h feet by #ejj revolutions1 or #d1jjj feet per min42 while the #b-;foot portion would have a calculated pitch speed of #ejj revolutions by #b feet1 or #a1jjj feet per minute4 ,effect of ,non-,uniformity4 ,now1 as all of the portions of this type of screw propeller must travel at some pitch speed1 which must have for its maximum a pitch speed in feet below the calculated pitch speed of the largest diameter1 it follows that some portions of its blades would perform useful work while the action of the other portions would be negative--resisting the forward motion of the portions having a greater pitch speed4 ,the portions having a pitch speed below that at which the screw is traveling cease to perform useful work after their pitch speed has been exceeded by the portions having a larger diameter and a greater pitch speed4 ,we might compare the larger and smaller diameter portions of this form of screw propeller1 to two power-driven vessels connected with a line1 one capable of traveling #bj miles per hour1 the other #aj miles per hour4 ,it can be readily understood that the boat capable of traveling #aj miles per hour would have no useful effect to help the one traveling #bj miles per hour1 as its action would be such as to impose a dead load upon the latter's progress4 ,the term slip1 as applied to a screw propeller1 is the distance between its calculated pitch speed and the actual distance it travels through under load1 depending upon the efficiency and proportion of its blades and the amount of load it has to carry4 ,the action of a screw propeller while performing useful work might be compared to a nut traveling on a threaded bolt2 little resistance is offered to its forward motion while it spins freely without load1 but give it a load to carry2 then it will take more power to keep up its speed2 if too great a load is applied the thread will strip1 and so it is with a screw propeller gliding spirally on the air4 ,a propeller traveling without load on to new air might be compared to the nut traveling freely on the bolt4 ,it would consume but little power and it would travel at nearly its calculated pitch speed1 but give it work to do and then it will take power to drive it4 ,there is a reaction caused from the propeller projecting air backward when it slips1 which1 together with the supporting effect of the blades1 combine to produce useful work or pull on the object to be carried4 ,a screw propeller working under load approaches more closely to its maximum efficiency as it carries its load with a minimum amount of slip1 or nearing its calculated pitch speed4 ,why ,blades ,are ,curved4 ,it has been pointed out by experiment that certain forms of curved surfaces as applied to aeroplanes will lift more per horse power1 per unit of square foot1 while on the other hand it has been shown that a flat surface will lift more per horse power1 but requires more area of surface to do it4 ,as a true pitch screw propeller is virtually a rotating aeroplane1 a curved surface may be advantageously employed when the limit of size prevents using large plane surfaces for the blades4 ,care should be exercised in keeping the chord of any curve to be used for the blades at the proper pitch angle1 and in all cases propeller blades should be made rigid so as to preserve the true angle and not be distorted by centrifugal force or from any other cause1 as flexibility will seriously affect their pitch speed and otherwise affect their efficiency4 ,how to ,determine ,angle4 ,to find the angle for the proper pitch at any point in the diameter of a propeller1 determine the circumference by multiplying the diameter by #c4adaf1 which represent by drawing a line to scale in feet4 ,at the end of this line draw another line to represent the desired pitch in feet4 ,then draw a line from the point representing the desired pitch in feet to the beginning of the circumference line4 ,for example3 ,if the propeller to be laid out is #g feet in diameter1 and is to have a #g-;foot pitch1 the circumference will be #ba4ii feet4 ,draw a diagram representing the circumference line and pitch in feet4 ,if this diagram is wrapped around a cylinder the angle line will represent a true thread #g feet in diameter and #g feet long1 and the angle of the thread will be #ag #c_/d degrees4 ,relation of ,diameter to ,circumference4 ,since the areas of circles decrease as the diameter lessens1 it follows that if a propeller is to travel at a uniform pitch speed1 the volume of its blade displacement should decrease as its diameter becomes less1 so as to occupy a corresponding relation to the circumferences of larger diameters1 and at the same time the projected area of the blade must be parallel along its full length and should represent a true sector of a circle4 ,let us suppose a #g-;foot circle to be divided into #bj sectors1 one of which represents a propeller blade4 ,if the pitch is to be #g feet1 then the greatest depth of the angle would be #a_/bj part of the pitch1 or #d #b_/aj inch4 ,if the line representing the greatest depth of the angle is kept the same width as it approaches the hub1 the pitch will be uniform4 ,if the blade is set at an angle so its projected area is #a_/bj part of the pitch1 and if it is moved through #bj divisions for one revolution1 it would have a travel of #g feet4 ,,chapter ,,xxv4 ,,new ,,motors ,,and ,,devices4 ,since the first edition of this book was printed1 early in #aiaj1 there has been a remarkable advance in the construction of aeroplane motors1 which has resulted in a wonderful decrease in the amount of surface area from that formerly required4 ,marked gain in lightness and speed of the motor has enabled aviators to get along1 in some instances1 with one-quarter of the plane supporting area previously used4 ,the first ,wright biplane1 propelled by a motor of #be h4p41 productive of a fair average speed of #cj miles an hour1 had a plane surface of #ech square feet4 ,now1 by using a specially designed motor of #fe h4 p41 capable of developing a speed of from #gj to #hj miles an hour1 the ,wrights are enabled to successfully navigate a machine the plane area of which is about #acj square feet4 ,this apparatus is intended to carry only one person 7the operator74 ,at ,belmont ,park1 ,n4 ,y41 the ,wrights demonstrated that the small-surfaced biplane is much faster1 easier to manage in the hands of a skilled manipulator1 and a better altitude climber than the large and cumbersome machines with #ech square feet of surface heretofore used by them4 ,in this may be found a practical illustration of the principle that increased speed permits of a reduction in plane area in mathematical ratio to the gain in speed4 ,the faster any object can be made to move through the air1 the less will be the supporting surface required to sustain a given weight4 ,but1 there is a limit beyond which the plane surface cannot be reduced with safety4 ,regard must always be had to the securing of an ample sustaining surface so that in case of motor stoppage there will be sufficient buoyancy to enable the operator to descend safely4 ,the baby ,wright used at the ,belmont ,park 7,n4 ,y47 aviation meet in the fall of #aiaj1 had a plane length of #ai feet #f inches1 and an extreme breadth of #ba feet #f inches1 with a total surface area of #adf square feet4 ,it was equipped with a new ,wright #h-;cylinder motor of #fj h4 p41 and two ,wright propellers of #h feet #f inches diameter and #ejj r4 p4 m4 ,it was easily the fastest machine at the meet4 ,after the tests1 ,wilbur ,wright said3 ,it is our intention to put together a machine with specially designed propellers1 specially designed gears and a motor which will give us #fe horsepower at least4 ,we will then be able1 after some experimental work we are doing now1 to send forth a machine that will make a new speed record4 ,in the new ,wright machines the front elevating planes for up-and-down control have been eliminated1 and the movements of the apparatus are now regulated solely by the rear1 or tail control4 ,a ,powerful ,light ,motor4 ,another successful ,american aviation motor is the aeromotor1 manufactured by the ,detroit ,aeronautic ,construction4 ,aeromotors are made in four models as follows3 ,model #a4--d-;cylinder1 #cj-dj h4 p41 weight #bjj pounds4 ,model #b4--d-;cylinder1 7larger stroke and bore7 #dj-ej h4 p41 weight #bbe pounds4 ,model #c4--f-;cylinder4 #ej-fj h4 p41 weight #baj pounds4 ,model #d4--f-;cylinder1 #fj-ge h4 p41 weight #bge pounds4 ,this motor is of the #d-;cycle1 vertical1 water-cooled type4 ,roberts ,aviation ,motor4 ,one of the successful aviation motors of ,american make1 is that produced by the ,roberts ,motor ,co41 of ,sandusky1 ,ohio4 ,it is designed by ,e4 ,w4 ,roberts1 ,m4 ,e41 who was formerly chief assistant and designer for ,sir ,hiram ,maxim1 when the latter was making his celebrated aeronautical experiments in ,england in #ahid-ie4 ,this motor is made in both the #d- and #f-;cylinder forms4 ,the #d-;cylinder motor weighs complete with ,bosch magneto and carbureter #afe pounds1 and will develop #dj actual brake h4 p4 at #a1jjj r4 p4 m41 #df h4 p4 at #a1bjj and #eb h4 p4 at #a1djj4 ,the #f-;cylinder weighs #bbj pounds and will develop #fj actual brake h4 p4 at #a1jjj r4 p4 m41 #fi h4 p4 at #a1bjj and #gh h4 p4 at #a1ejj4 ,extreme lightness has been secured by doing away with all superfluous parts1 rather than by a shaving down of materials to a dangerous thinness4 ,for example1 there is neither an intake or exhaust manifold on the motor4 ,the distributing valve forms a part of the crankcase as does the water intake1 and the gear pump4 ,magnalium takes the place of aluminum in the crankcase1 because it is not only lighter but stronger and can be cast very thin4 ,the crankshaft is #b #a_/b-;inch diameter with a #b #a_/d-;inch hole1 and while it would be strong enough in ordinary #dj per cent carbon steel it is made of steel twice the strength of that customarily employed4 ,similar care has been exercised on other parts and the result is a motor weighing #d pounds per h4 p4 ,the ,rinek ,motor4 ,the ,rinek aviation motor1 constructed by the ,rinek ,aero ,mfg4 ,co41 of ,easton1 ,pa41 is another that is meeting with favor among aviators4 ,type ,b-#h is an #h-;cylinder motor1 the cylinders being set at right angles1 on a ,v-shaped crank case4 ,it is water cooled1 develops #ej-fj h4 p41 the minimum at #a1bbj r4 p4 m41 and weighs #bhj pounds with all accessories4 ,type ,b-#d1 a #d-;cylinder motor1 develops #cj h4 p4 at #a1hjj r4 p4 m41 and weighs #acj pounds complete4 ,the cylinders in both motors are made of cast iron with copper water jackets4 ,the ,overhead ,camshaft ,boulevard4 ,the overhead camshaft ,boulevard is still another form of aviation motor which has been favorably received4 ,this is the product of the ,boulevard ,engine ,co41 of ,st4 ,louis4 ,it is made with #d and #h cylinders4 ,the former develops #cj-ce h4 p4 at #a1bjj r4 p4 m41 and weighs #acj pounds4 ,the #h-;cylinder motor gives #fj-gj h4 p4 at #a1bjj r4 p4 m41 and weighs #bjj pounds4 ,simplicity of construction is the main feature of this motor1 especially in the manipulation of the valves4 ,,chapter ,,xxvi4 ,,monoplanes1 ,,triplanes1 ,,multiplanes4 ,until recently1 ,american aviators had not given serious attention to any form of flying machines aside from biplanes4 ,of the twenty-one monoplanes competing at the ,international meet at ,belmont ,park1 ,n4 ,y41 in ,november1 #aiaj1 only three makes were handled by ,americans4 ,moissant and ,drexel navigated ,bleriot machines1 ,harkness an ,antoinette1 and ,glenn ,curtiss a single decker of his own construction4 ,on the other hand the various foreign aviators who took part in the meet unhesitatingly gave preference to monoplanes4 ,whatever may have been the cause of this seeming prejudice against the monoplane on the part of ,american air sailors1 it is slowly being overcome4 ,when a man like ,curtiss1 who has attained great success with biplanes1 gives serious attention to the monoplane form of construction and goes so far as to build and successfully operate a single surface machine1 it may be taken for granted that the monoplane is a fixture in this country4 ,dimensions of ,monoplanes4 ,the makes1 dimensions and equipment of the various monoplanes used at ,belmont ,park are as follows3 ,bleriot--7,moissant1 operator7--plane length #bc feet1 extreme breadth #bh feet1 surface area #afj square feet1 #g-;cylinder1 #ej h4 p4 ,gnome engine1 ,chauviere propeller1 #g feet #f inches diameter1 #a1bjj r4 p4 m4 ,bleriot--7,drexel1 operator7--exactly the same as ,moissant's machine4 ,antoinette--7,harkness1 operator7--plane length #db feet1 extreme breadth #df feet1 surface area #cgg square feet1 ,emerson #f-;cylinder1 #ej h4 p4 motor1 ,antoinette propeller1 #g feet #f inches diameter1 #a1bjj r4 p4 m4 ,curtiss--7,glenn ,h4 ,curtiss1 operator7--plane length #be feet1 extreme breadth #bf feet1 surface area #acj square feet1 ,curtiss #h-;cylinder1 #fj h4 p4 motor1 ,paragon propeller1 #g feet in diameter1 #a1bjj r4 p4 m4 ,with one exception ,curtiss had the smallest machine of any of those entering into competition4 ,the smallest was ,la ,demoiselle1 made by ,santos-,dumont1 the proportions of which were3 plane length #bj feet1 extreme breadth #ah feet1 surface area #ajj square feet1 ,clement-,bayard #b-;cylinder1 #cj h4 p4 motor1 ,chauviere propeller1 #f feet #f inches in diameter1 #a1ajj r4 p4 m4 ,winnings ,made with ,monoplanes4 ,operators of monoplanes won a fair share of the cash prizes4 ,they won #cj1bhc out of a total of #fc1bej1 to say nothing about ,grahame-,white's winnings4 ,the latter won #ac1fjj1 but part of his winning flights were made in a ,bleriot monoplane1 and part in a ,farman machine4 ,aside from ,grahame-,white the winnings were divided as follows3 ,moissant 7,bleriot7 #ac1cej2 ,latham 7,antoinette7 #h1ahc2 ,aubrun 7,bleriot7 #b1djj2 ,de ,lesseps 7,bleriot7 #b1cjj2 ,drexel 7,bleriot7 #a1gjj2 ,radley 7,bleriot7 #a1cjj2 ,simon 7,bleriot7 #gej2 ,andemars 7,clement-,bayard7 #ajj2 ,barrier 7,bleriot7 #ajj4 ,out of a total of #cj1bhc1 operators of ,bleriot machines won #ba1ijj1 again omitting ,grahame-,white's share4 ,if the winnings with monoplane and biplane could be divided so as to show the amount won with each type of machine the credit side of the ,bleriot account would be materially enlarged4 ,the ,most ,popular ,monoplanes4 ,while the number of successful monoplanes is increasing rapidly1 and there is some feature of advantage in nearly all the new makes1 interest centers chiefly in the ,santos-,dumont1 ,antoinette and ,bleriot machines4 ,this is because more has been accomplished with them than with any of the others1 possibly because they have had greater opportunities4 ,for the guidance of those who may wish to build a machine of the monoplane type after the ,santos-,dumont or ,bleriot models1 the following details will be found useful4 ,santos-,dumont--,the latest production of this maker is called the ,no4 #bj ,baby4 ,it is of #ah feet spread1 and #bj feet over all in depth4 ,it stands #d feet #b inches in height1 not counting the propeller4 ,when this latter is in a vertical position the extreme height of the machine is #g feet #e inches4 ,it is strictly a one-man apparatus4 ,the total surface area is #aae square feet4 ,the total weight of the monoplane with engine and propeller is #ceb pounds4 ,santos-,dumont weighs #aaj pounds1 so the entire weight carried while in flight is #dfb pounds1 or about #c4f pounds per square foot of surface4 ,bamboo is used in the construction of the body frame1 and also for the frame of the tail4 ,the body frame consists of three bamboo poles about #b inches in diameter at the forward end and tapering to about #a inch at the rear4 ,these poles are jointed with brass sockets near the rear of the main plane so they may be taken apart easily for convenience in housing or transportation4 ,the main plane is built upon four transverse spars of ash1 set at a slight dihedral angle1 two being placed on each side of the central bamboo4 ,these spars are about #b inches wide by #a #a_/h-;inch deep for a few feet each side of the center of the machine1 and from there taper down to an inch in depth at the center bamboo1 and at their outer ends1 but the width remains the same throughout their entire length4 ,the planes are double surfaced with silk and laced above and below the bamboo ribs which run fore and aft under the main spars and terminate in a forked clip through which a wire is strung for lacing on the silk4 ,the tail consists of a horizontal and vertical surface placed on a universal joint about #aj feet back of the rear edge of the main plane4 ,both of these surfaces are flat and consist of a silk covering stretched upon bamboo ribs4 ,the horizontal surface is #f feet #e inches across1 and #d feet #i inches from front to back4 ,the vertical surface is of the same width 7#f feet #e inches7 but is only #c feet #g inches from front to back4 ,all the details of construction are shown in the accompanying illustration4 ,power is furnished by a very light 7#aaj pounds7 ,darracq motor1 of the double-opposed-cylinder type4 ,it has a bore of #d4aah inches1 and stroke of #d4gbd inches1 runs at #a1hjj r4 p4 m41 and with a #f #a_/b-;foot propeller develops a thrust of #bdb #a_/b pounds when the monoplane is held steady4 ,bleriot--,no4 ,,xi1 the latest of the ,bleriot productions1 and the greatest record maker of the lot1 is #bh feet in spread of main plane1 and depth of #f feet in largest part4 ,this would give a main surface of #afh square feet1 but as the ends of the plane are sharply tapered from the rear1 the actual surface is reduced to #aej square feet4 ,projecting from the main frame is an elongated tail 7shown in the illustration7 which carries the horizontal and vertical rudders4 ,the former is made in three sections4 ,the center piece is #f feet #a inch in spread1 and #b feet #aj inches in depth1 containing #ag square feet of surface4 ,the end sections1 which are made movable for warping purposes1 are each #b feet #aj inches square1 the combined surface area in the entire horizontal rudder being #cc square feet4 ,the vertical rudder contains #d #a_/b square feet of surface1 making the entire supporting area #ahg #a_/b square feet4 ,from the outer end of the propeller shaft in front to the extreme rear edge of the vertical rudder1 the machine is #be feet deep4 ,deducting the #f-;foot depth of the main plane leaves #ai feet as the length of the rudder beam and rudders4 ,the motor equipment consists of a #c-;cylinder1 air-cooled engine of about #cj h4 p4 placed at the front end of the body frame1 and carrying on its crankshaft a two-bladed propeller #f feet #h inches in diameter4 ,the engine speed is about #a1bej r4 p4 m4 at which the propeller develops a thrust of over #bjj pounds4 ,the ,bleriot ,,xi complete weighs #dhd pounds1 and with operator and fuel supply ready for a #be- or #cj-mile flight1 #gae pounds4 ,one peculiarity of the ,bleriot construction is that1 while the ribs of the main plane are curved1 there is no preliminary bending of the pieces as in other forms of construction4 ,bleriot has his rib pieces cut a little longer than required and1 by springing them into place1 secures the necessary curvature4 ,a good view of the ,bleriot plane framework is given on page #fc4 ,combined ,triplane and ,biplane4 ,at ,norwich1 ,conn41 the ,stebbins-,geynet ,co41 after several years of experiment1 has begun the manufacture of a combination triplane and biplane machine4 ,the center plane1 which is located about midway between the upper and lower surfaces1 is made removable4 ,the change from triplane to biplane1 or vice versa1 may be readily made in a few minutes4 ,the constructors claim for this type of air craft a large supporting surface area with the minimum of dimensions in planes4 ,although this machine has only #bd-;foot spread and is only #bf feet over all1 its total amount of supporting area is #djj square feet2 weight1 #fjj pounds in flying order1 and lifting capacity approximately #gjj pounds more4 ,the frame is made entirely of a selected grade of ,oregon spruce1 finished down to a smooth surface and varnished4 ,all struts are fish-shaped and set in aluminum sockets1 which are bolted to top and lower beams with special strong bolts of small diameter4 ,the middle plane is set inside the six uprights and held in place by aluminum castings4 ,a flexible twisted seven-strand wire cable and ,stebbins-,geynet turnbuckles are used for trussing4 ,the top plane is in three sections1 laced together4 ,it has a #bd-;foot spread and is #g feet in depth4 ,the middle plane is in two sections each of #g #a_/b feet spread and #f feet in depth4 ,the center ends of the middle plane sections do not come within #e feet of joining1 this open space being left for the engine4 ,the bottom plane is of #af feet spread and #e feet in depth4 ,it will thus be seen that the planes overhang one another in depth1 the bottom one being the smallest in this respect4 ,the planes are set at an angle of #i degrees1 and there is a clear space of #c #a_/b feet between each1 making the total distance from the bottom to the top plane a trifle over #g feet4 ,the total supporting surface in the main planes is #cej square feet4 ,by arranging the three plane surfaces at an angle as described and varying their size1 the greatest amount of lifting area is secured above the center of gravity1 and the greatest weight carried below4 ,the ribs are made of laminated spruce1 finished down to #a_/bx#c_/d-;inch cross section dimensions1 with a curvature of about #a in #bj1 and fastened to the beams with special aluminum castings4 ,number #b ,naiad aeroplane cloth is used in covering the planes1 with pockets sewn in for the ribs4 ,two combination elevating rudders are set up well in front1 each having #ah square feet of supporting area4 ,these rudders are arranged to work in unison1 independently1 or in opposite directions4 ,in the ,model ,b machine1 there are also two small rear elevating rudders1 which work in unison with the front rudders4 ,one vertical rudder of #aj square feet is suspended in the rear of a small stationary horizontal plane in ,model ,a1 while the vertical rudder on ,model ,b is only #f square feet in size4 ,the elevating rudders are arranged so as to act as stabilizing planes when the machine is in flight4 ,the wing tips are held in place with a special two-piece casting which forms a hinge1 and makes a quick detachable joint4 ,wing tips are also used in balancing4 ,model ,a is equipped with a ,cameron #be-cj h4 p41 #d-;cylinder1 air-cooled motor4 ,on ,model ,b a ,holmes rotary #g-;cylinder motor of #dx#d-;inch bore and stroke is used4 ,positive control is secured by use of the ,stebbins-,geynet auto-control system4 ,a pull or push movement operates the elevating rudders1 while the balancing is done by means of side movements or slight turns4 ,the rear vertical rudder is manipulated by means of a foot lever4 ,new ,cody ,biplane4 ,among the comparatively new biplanes is one constructed by ,willard ,f4 ,cody1 of ,london1 ,eng41 the principal distinctive feature of which is an automatic control which works independently of the hand levers4 ,for the other control a long lever carrying a steering wheel furnishes all the necessary control movements1 there being no footwork at all4 ,the lever is universally jointed and when moved fore and aft operates the two ailerons as if they were one2 when the shaft is rotated it moves the tail as a whole4 ,the horizontal tail component is immovable4 ,when the lever is moved from side to side it works not only the ailerons and the independent elevators1 but also through a peculiar arrangement1 the vertical rear rudder as well4 ,the spread of the planes is #df feet #f inches and the width #f feet #f inches4 ,the ailerons jut out #a foot #f inches on each side of the machine and are #ac feet #f inches long4 ,the cross-shaped tail is supported by an outrigger composed of two long bamboos and of this the vertical plane is #i feet by #d feet1 while the horizontal plane is #h feet by #d feet4 ,the over-all length of the machine is #cf feet4 ,the lifting surface is #heg square feet4 ,it will weigh1 with a pilot1 #a1dej pounds4 ,the distance between the main planes is #h feet #f inches1 which is a rather notable feature in this flyer4 ,the propeller has a diameter of #aa feet and #b inches with a #ac-;foot #f-;inch pitch2 it is driven at #efj revolutions by a chain1 and the gear reduction between the chain and propeller shaft is two to one4 ,the machine from elevator to tail plane bristles in original points4 ,the hump in the ribs has been cut away entirely1 so that although the plane is double surfaced1 the surfaces are closest together at a point which approximates the center of pressure4 ,the plane is practically of two stream-line forms1 of which one is the continuation of the other4 ,this construction1 claims the inventor1 will give increased lift1 and decreased head resistance4 ,the trials substantiate this1 as the angle of incidence in flying is only about one in twenty-six4 ,the ribs in the main planes are made of strips of silver spruce one-half by one-half inch1 while those in the ailerons are solid and one-fourth inch thick4 ,in the main planes the fabric is held down with thin wooden fillets4 ,cody's planes are noted for their neatness1 rigidity and smoothness4 ,pegamoid fabric is used throughout4 ,pressey ,automatic ,control4 ,another ingenious system of automatic control has been perfected by ,dr4 ,j4 ,b4 ,pressey1 of ,newport ,news1 ,va4 ,the aeroplane is equipped with a manually operated1 vertical rudder1 7#c71 at the stern1 and a horizontal1 manually operated1 front control1 7#d71 in front4 ,at the ends of the main plane1 and about midway between the upper and lower sections thereof1 there are supplemental planes1 7#e74 ,in connection with these supplemental planes 7#e71 there is employed a gravity influenced weight1 the aviator in his seat1 for holding them in a horizontal1 or substantially horizontal1 position when the main plane is traveling on an even keel2 and for causing them to tip when the main plane dips laterally1 to port or starboard1 the planes 7#e7 having a lifting effect upon the depressed end of the main plane1 and a depressing effect upon the lifted end of the main plane1 so as to correct such lateral dip of the main plane1 and restore it to an even keel4 ,to the forward1 upper edge of planes 7#e7 connection is made by means of rod 7#ac7 to one arm of a bellcrank lever1 7#ad7 the latter being pivotally mounted upon a fore and aft pin 7#ae71 supported from the main plane2 and the other arms of the port and starboard bellcrank levers 7#af71 are connected by rod 7#ag71 which has an eye 7#ah71 for receiving the segmental rod 7#ai71 secured to and projecting from cross bar on seat supporting yoke 7#g74 ,when1 therefore1 the main plane tips downwardly on the starboard side1 the rod 7#ag7 will be moved bodily to starboard1 and the starboard balancing plane 7#e7 will be inclined so as to raise its forward edge and depress its rear edge1 while1 at the same time1 the port balancing plane 7#e71 will be inclined so as to depress its forward edge1 and raise its rear edge1 thereby causing the starboard balancing plane to exert a lifting effect1 and the port balancing plane to exert a depressing effect upon the main plane1 with the result of restoring the main plane to an even keel1 at which time the balancing planes 7#e71 will have resumed their normal1 horizontal position4 ,when the main plane dips downwardly on the port side1 a reverse action takes place1 with the like result of restoring the main plane to an even keel4 ,in order to correct forward and aft dip of the main plane1 fore and aft balancing planes 7#bj7 and 7#bc7 are provided4 ,these planes are carried by transverse rock shafts1 which may be pivotally mounted in any suitable way1 upon structures carried by main plane4 ,in the present instance1 the forward balancing plane is pivotally mounted in extensions 7#ba7 of the frame 7#bb7 which carries the forward1 manually operated1 horizontal ascending and descending plane ,it is absolutely necessary1 in making a turn with an aeroplane1 if that turn is to be made in safety1 that the main plane shall be inclined1 or banked1 to a degree proportional to the radius of the curve and to the speed of the aeroplane4 ,each different curve1 at the same speed1 demands a different inclination1 as is also demanded by each variation in speed in rounding like curves4 ,this invention gives the desired result with absolute certainty4 ,the ,sellers' ,multiplane4 ,another innovation is a multiplane1 or four-surfaced machine1 built and operated by ,m4 ,b4 ,sellers1 formerly of ,grahn1 ,ky41 but now located at ,norwood1 ,ga4 ,aside from the use of four sustaining surfaces1 the novelty in the ,sellers machine lies in the fact that it is operated successfully with an #h h4 p4 motor1 which is the smallest yet used in actual flight4 ,in describing his work1 ,mr4 ,sellers says his purpose has been to develop the efficiency of the surfaces to a point where flight may be obtained with the minimum of power and1 judging by the results accomplished1 he has succeeded4 ,in a letter written to the authors of this book1 ,mr4 ,sellers says3 ,i dislike having my machine called a quadruplane1 because the number of planes is immaterial2 the distinctive feature being the arrangement of the planes in steps2 a better name would be step aeroplane1 or step plane4 ,the machine as patented1 comprises two or more planes arranged in step form1 the highest being in front4 ,the machine ,i am now using has four planes #c ft4 x #ah ft42 total about #bjj square feet2 camber 7arch7 #a in #af4 ,the vertical keel is for lateral stability2 the rudder for direction4 ,this is the first machine 7so far as ,i know7 to have a combination of wheels and runners or skids 7,oct4 #aijh74 ,the wheels rise up automatically when the machine leaves the ground1 so that it may alight on the runners4 ,a ,duthirt ,chalmers #b-;cylinder opposed1 #c #a_/h-;inch engine was used first1 and several hundred short flights were made4 ,the engine gave four brake h4 p41 which was barely sufficient for continued flight4 ,the aeroplane complete with this engine weighed #gh pounds4 ,the engine now used is a ,bates #c #e_/h-;inch1 #b-;cylinder opposed1 showing #h h4 p41 and apparently giving plenty of power4 ,the weight of aeroplane with this engine is now #aaj pounds4 ,owing to poor grounds only short flights have been made1 the longest to date 7,dec4 #ca1 #aiaj7 being about #a1jjj feet4 ,in building the present machine1 my object was to produce a safe1 slow1 light1 and small h4 p4 aeroplane1 a purpose which ,i have accomplished4 ,,chapter ,,xxvii4 #aiaa ,,aeroplane ,,records4 ,,the ,,world ,,at ,,large4 ,greatest ,speed ,per ,hour1 ,whatever ,length of ,flight1 ,aviator ,alone--,e4 ,nieuport1 ,mourmelon1 ,france1 ,june #ba1 ,nieuport ,machine1 #hb4gb miles2 with one passenger1 ,e4 ,nieuport1 ,moumlelon1 ,france1 ,june #ab1 ,nieuport ,machine1 #fg4aa miles2 with two passengers1 ,e4 ,nieuport1 ,mourmelon1 ,france1 ,march #i1 ,nieuport ,machine1 #fc4ia miles2 with three passengers1 ,g4 ,busson1 ,rheims1 ,france1 ,march #aj1 ,deperdussin ,machine1 #ei4hd miles2 with four passengers1 ,g4 ,busson1 ,rheims1 ,france1 ,march #aj1 ,deperdussin ,machine1 #ed4ba miles4 ,greatest ,distance ,aviator ,alone--,g4 ,fourny1 no stops1 ,buc1 ,france1 ,september #b1 ,m4 ,farman ,machine1 #ddg4ja miles2 ,e4 ,helen1 three stops1 ,etampes1 ,france1 ,september #h1 ,nieuport ,machine1 #ggh4de miles2 with one passenger1 ,lieut4 ,bier1 ,austria1 ,october #b1 ,etrich ,machine1 #aee4cd miles2 with two passengers1 ,lieut4 ,bier1 ,austria1 ,october #d1 ,etrich ,machine1 #fi4ei miles2 with three passengers1 ,g4 ,busson1 ,rheims1 ,france1 ,march #aj1 ,deperdussin ,machine1 #ca4jf miles2 with four passengers1 ,g4 ,busson1 ,rheims1 ,france1 ,march #aj1 ,deperdussin ,machine1 #ae4ii miles4 ,greatest ,duration ,aviator ,alone--,g4 ,fourny1 no stops1 ,buc1 ,france1 ,september #b1 ,m4 ,farman ,machine1 #aa hours1 #a minute1 #bi seconds1 ,e4 ,helen1 three stops1 ,etampes1 ,france1 ,september #h1 ,nieuport ,machine1 #ad hours1 #g minutes1 #ej seconds1 #ac hours1 #ag minutes net time2 with one passenger1 ,suvelack1 ,johannisthal1 ,germany1 ,december #h1 #d hours1 #bc minutes2 with two passengers1 ,t4 de ,w4 ,milling1 ,nassau ,boulevard1 ,new ,york1 ,september #bf1 ,burgess-,wright ,machine1 #a hour1 #ed minutes1 #db #c-e seconds2 with three passengers1 ,warchalowski1 ,wiener-,neustadt1 ,aust41 ,october #cj1 #de minutes1 #df seconds2 with four passengers1 ,g4 ,busson1 ,rheims1 ,france1 ,march #aj1 ,deperdussin ,machine1 #ag minutes1 #bh #a-e seconds4 ,greatest ,altitude ,aviator ,alone--,garros1 ,st4 ,malo1 ,france1 ,september #d1 ,bleriot ,machine1 #ac1cfb feet2 with one passenger1 ,prevost1 ,courcy1 ,france1 ,december #b1 #i1hdj feet2 with two passengers1 ,lieut4 ,bier1 ,austria1 ,etrich ,machine1 #d1jaj feet4 ,,american ,,records4 ,greatest ,speed ,per ,hour1 ,whatever ,length of ,flight1 ,aviator ,alone--,a4 ,leblanc1 ,belmont ,park1 ,n4 ,y41 ,october #bi1 ,bleriot ,machine1 #fg4hg miles2 with one passenger1 ,c4 ,grahame-,white1 ,squantum1 ,mass41 ,september #d1 ,nieuport ,machine1 #fc4bc miles2 with two passengers1 ,t4 ,o4 ,m4 ,sopwith1 ,chicago1 ,ill41 ,august #ae1 ,wright ,machine1 #cd4if miles4 ,greatest ,distance ,aviator ,alone--,st4 ,croix ,johnstone1 ,mineola1 ,n4 ,y41 ,july #bg1 ,moisant 7,bleriot ,type7 ,machine1 #agf4bc miles4 ,greatest ,duration ,aviator ,alone--,howard ,w4 ,gill1 ,kinloch1 ,mo41 ,october #ai1 ,wright ,machine1 #d hours1 #af minutes1 #ce seconds2 with one passenger1 ,g4 ,w4 ,beatty1 ,chicago1 ,ill41 ,august #ai1 ,wright ,machine1 #c hours1 #db minutes1 #bb #a-e seconds2 with two passengers1 ,t4 de ,w4 ,milling1 ,nassau ,boulevard1 ,n4 ,y41 ,september #bf1 ,burgess-,wright ,machine1 #a hour1 #ed minutes1 #db #c-e seconds4 ,greatest ,altitude ,aviator ,alone--,l4 ,beachy1 ,chicago1 ,ill41 ,august #bj1 ,curtiss ,machine1 #aa1fdb feet2 with one passenger1 ,c4 ,grahame-,white1 ,nassau ,boulevard1 ,n4 ,y41 ,september #cj1 ,nieuport ,machine1 #c1cdg feet4 ,weight ,carrying--,p4 ,o4 ,parmelee1 ,chicago1 ,,iii41 ,august #ai1 ,wright ,machine1 #deh lbs4 ,,aviation ,,development4 ,the wonderful progress made in the science of aviation during the year #aiaa far surpasses any twelve months' advancement recorded4 ,the advancement has not been confined to any country or continent1 since every part of the world is taking its part in aviation history making4 ,the rapidly increasing interest in aviation has brought forth schools for the instruction of flying in both the old and new world1 and licensed air pilots before they receive their sanctions from the governing aero clubs of their country are required to pass an extremely trying examination in actual flights4 ,exhibition flights and races were common in all parts of the world during #aiaa1 and touring aviators visited ,india1 ,china1 ,japan1 ,south ,africa1 ,australia and ,south ,america1 giving exhibitions and instruction4 ,europe was the scene of a number of cross-country races in which entries ranging from ten to twenty aviators flew from city to city around a given circuit1 which in some instances exceeded #a1jjj miles in distance4 ,cross-country flights with and without passengers became so common that those of less than two hours' duration attracted little attention4 ,there were fewer attempts at high altitude soaring1 although the world's record in this department of aviation was bettered several times4 ,in place of these high flights1 the aviators devoted more attention to speed1 duration and spectacular manoeuvres1 which appeared to satisfy the spectators4 ,the prize money won during #aiaa exceeded #a1jjj1jjj1 but owing to the increased number of aviators the individual winnings were not as large as in #aiaj4 ,it is estimated that within the past twelve months more than #cjj1jjj miles have been covered in aeroplane flights and more than seven thousand persons1 classed either as aviators or passengers1 taken up into the air4 ,the aeroplane of today ranges through monoplane1 biplane1 triplane and even quadraplane1 and more than two hundred types of these machines are in use4 ,aeroplanes are becoming a factor of international commerce4 ,the records of the ,bureau of ,statistics show that more than #ej1jjj worth of aeroplanes were imported into1 and exported from1 the ,united ,states in the months of ,july1 ,august and ,september1 #aiaa4 ,the ,bureau of ,statistics only began the maintenance of a separate record of this comparatively new article of commerce with the opening of the fiscal year #aiaa-ab4 ,two of the prominent developments of #aiaa were the introduction of the hydro-aeroplane and the motorless glider experiments of the ,wright brothers at ,killdevil ,hills1 ,n4 ,c41 where during the two weeks' experiments numerous flights with and against the wind were made1 culminating in the establishing of a record by ,orville ,wright on ,october #be1 #aiaa1 when in a #eb-mile per hour blow he reached an elevation of #bbe feet and remained in the air #aj minutes and #cd seconds4 ,the search for the secret of automatic stability still continues1 and though some remarkable progress has been made the solution has not yet been reached4 ,,notable ,,cross-,,country ,,flights ,,of #aiaa4 ,one of the important features of #aiaa in aviation was the rapid increase in the number and distance of cross-country flights made either for the purpose of exhibition1 testing1 instruction or pleasure4 ,flights between cities in almost every country of the world became common occurrences4 ,so great was the number that only those of more than ordinary importance because of speed1 distance or duration are recorded4 ,the flights of ,harry ,n4 ,atwood from ,boston to ,washington and from ,st4 ,louis to ,new ,york1 and ,c4 ,p4 ,rodgers from ,new ,york to ,los ,angeles were the most important events of the kind in this country4 ,the ,st ,louis to ,new ,york flight was a distance by air route1 #a1bff miles4 ,duration of flight1 #ab days4 ,net flying time1 #bh hours #ec minutes4 ,average daily flight1 #aje4e miles4 ,average speed1 #dc4i miles per hour4 ,transcontinental ,flight of ,calbraith ,p4 ,rodgers4--,all world records for cross-country flying were broken during the ,new ,york to ,los ,angeles flight of ,calbraith ,p4 ,rodgers1 who left ,sheepshead ,bay1 ,n4 ,y41 on ,sunday1 ,september #ag1 #aiaa1 and completed his flight to the ,pacific ,coast on ,sunday1 ,november #e1 at ,pasadena1 ,cal4 ,rodgers flew a ,wright biplane1 and during his long trip the machine was repeatedly repaired1 so great was the strain of the long journey in the air4 ,rodgers is estimated to have covered #d1bca miles1 although the actual route as mapped out was but #d1jag miles4 ,elapsed time to ,pasadena1 ,cal41 #di days2 actual time in the air1 #d1ibd minutes1 equivalent to #c days #aj hours #d minutes2 average speed approximating #ea miles per hour4 ,rodgers' longest flight in one day was from ,sanderson to ,sierra ,blanca1 ,texas1 on ,october #bh1 when he covered #bca miles4 ,on ,november #ab1 ,rodgers fell at ,compton1 ,cal41 and was badly injured1 causing a delay of #bh days4 ,european ,circuit ,race4--,started from ,paris on ,june #ah1 #aiaa4 ,distance1 #a1jgc miles1 via ,paris to ,liege2 ,liege to ,spa to ,liege2 ,liege to ,utrecht1 ,holland2 ,utrecht to ,brussels1 ,belgium2 ,brussels to ,roubaix2 ,roubaix to ,calais2 ,calais to ,london2 ,london to ,calais and ,calais to ,paris4 ,three aeronauts were killed either at the start or shortly after the race was in progress4 ,they were ,capt4 ,princetau1 ,m4 ,le ,martin and ,m4 ,lendron4 ,three others were injured by falls4 ,seven hundred thousand spectators witnessed the start from the aviation field at ,vincennes1 near ,paris4 ,there were more than forty starters1 of which eight finished4 ,the winner1 ,lieut4 ,jean ,conneau1 who flies under the name of ,andre ,beaumont1 completed the circuit on ,july #g2 his actual net flying time for the distance being #eh;h4 #chm4 #d-es4 ,circuit of ,england ,race--#a1jaj ,miles in ,five ,sections4-- ,start1 ,july #bb4 ,finish1 ,july #bf4 ,prize1 #ej1jjj4 ,twenty-eight entries and eighteen starters4 ,seventeen finished the first section from ,brooklands to ,hendon1 a distance of twenty miles4 ,five reached ,edinburgh1 the second section1 a distance of #cdc miles1 and four completed the entire circuit4 ,paris to ,madrid ,race4--,this race was started at the ,paris aviation held at ,issy-les-,moulineaux on ,sunday1 ,may #ba4 ,there were twenty-one entrants1 and fully #cjj1jjj spectators gathered to witness the initial flight of the aerial races4 ,the race was divided into three stages as follows3 ,paris to ,angouleme1 #bdh miles2 ,angouleme to ,st4 ,sebastian1 #bjh miles1 and from ,st4 ,sebastian to ,madrid1 #chf miles1 a total distance of #hdb miles4 ,after three of the entrants had safely left the field1 ,aviator ,train lost control of his plane1 and in falling struck and killed ,m4 ,berteaux1 the ,french ,minister of ,war1 and seriously injured ,premier ,monis4 ,the accident caused the withdrawal of all but six of the original entrants1 and of these but one finished4 ,the race called for a flight over the ,pyrenees ,mountains1 and ,vedrines1 the winner1 had to rise to a height of more than #g1jjj feet to pass the mountain barrier near ,somosierra ,pass4 ,both ,vedrines and ,gibert1 another competitor1 were attacked by eagles during the latter stages of the flight4 ,vedrines1 who started from ,paris on ,monday1 ,may #bb1 finished the long and perilous race at #h3jf a4 m4 ,friday1 ,may #bf4 ,vedrines net flying time1 all controls and enforced stops subtracted1 was #ad;h4 #eem4 #ahs4 ,the various prizes to the winner aggregated #cj1jjj4 ,the ,paris-,rome-,turin ,race4--,the conditions of this race called for a flight between the cities of ,paris1 ,rome and ,turin1 covering a distance of #a1cjj miles4 ,the aviators were permitted by the rules to alight whenever and wherever they desired and the time limit was set from ,may #bh to ,june #ae4 ,a prize of #ajj1jjj was offered the winner1 but the contest was never finished1 as one after another the aviators dropped out until ,frey fell near ,roncigilione1 ,france1 breaking both arms and legs and unofficially ending the contest4 ,there were twenty-one entries and twelve actual starters4 ,international ,speed ,cup ,race4--,the third annual international ,james ,gordon ,bennett speed cup race was held at ,eastchurch1 ,england1 on ,july #a1 #aiaa1 and for the second time was won by an ,american aviator1 ,c4 ,t4 ,weymann1 in a ,french racing aeroplane4 ,the distance was #aej kilometres equivalent to #id miles1 and the winner's time of #a;h4 #aam4 #cfs4 showed an average speed of #gh4gg miles per hour4 ,the first race was held in #aiji and was won by ,glenn ,curtiss1 who flew the twenty kilometres 7#ab4d miles7 in #ae minutes #ej #b-e seconds at an average speed of #dg miles per hour4 ,in #aiaj the winner was ,grahame-,white1 who covered #ajj kilometres 7#fb miles7 at ,belmont ,park1 ,l4 ,i41 in #fj minutes #dg #c-e seconds1 an average speed of #fa4c miles per hour4 ,in the #aiaa race there were six starters3 three from ,france1 two from ,great ,britain and one from the ,united ,states4 ,milan to ,turin to ,milan ,race4--,this race which was started from ,milan1 ,italy1 on ,october #bi1 was restricted to ,italian aviators and had six starters4 ,the distance was approximately #agg miles and won by ,manissero in a ,bleriot machine in #c;h4 #afm4 #b #d-es4 ,new ,york to ,philadelphia ,race4--,the first intercity aeroplane race ever held in the ,united ,states was started from ,new ,york ,city on ,august #e1 and finished in ,philadelphia the same day4 ,the prize of #e1jjj was offered by a commercial concern with stores in the two cities3 ,three entrants competed from the ,curtiss ,exhibition ,company4 ,the distance was approximately #hc miles and won by ,l4 ,beachey in a ,curtiss machine in #a;h4 #ejm4 at an average speed of #de miles per hour4 ,tri-,state ,race4--,the tri-state race was the feature event of the ,harvard ,aviation ,society meet held at ,squantum1 ,mass41 ,august #bf to ,september #f4 ,it was held ,labor ,day1 ,september #d1 over a course of #agd miles1 from ,boston to ,nashua to ,worcester to ,providence to ,boston4 ,four competitors started1 of which two finished1 the winner1 ,e4 ,ovington1 in a ,bleriot machine4 ,ovington's net flying time1 #c;h4 #fm4 #bb #a-es4 ,winner's prize1 #aj1jjj4 ,,aeroplanes ,,and ,,dirigible ,,balloons ,,in ,,warfare4 ,wonderful progress has been made in the development of the aeroplane in this country and in ,europe since #aijc1 and within the last two or three years the leading powers of the world have entered upon extensive tests and experiments to determine its availability and usefulness in land and naval warfare4 ,at the present time all the great powers are building or purchasing aeroplanes on an extensive scale4 ,they have established government schools for the instruction of their army and navy officers and for experimental work4 ,so-called ,airship ,fleets have been constructed and placed in commission as auxiliaries to the armies and navies4 ,the fleets of ,france and ,germany are about equal and are larger by far than those of any of the other powers4 ,the length of the dirigibles composing these fleets runs from #aej to #ejj feet2 they are equipped with engines of from #ej to #ejj horse-power1 with a rate of speed ranging from #bj to #cj miles per hour4 ,their approximate range is from #bjj to #ijj miles2 the longest actual run 7made by the ,zeppelin ,,ii1 ,germany7 is #hjj miles4 ,a ,british naval airship1 one of the largest yet built1 was completed last summer4 ,it has cost over #bjj1jjj1 and it was in course of designing and construction two years4 ,it is #eaj feet long2 can carry #bb persons1 and has a lift of #ba tons4 ,the relative value of the dirigible balloon and the aeroplane in actual war is yet to be determined4 ,the dirigible is considered to be the safer1 yet several large balloons of this class in ,germany and ,france have met with disaster1 involving loss of lives4 ,the capacity of the dirigible for longer flights and its superior facilities for carrying apparatus and operators for wireless telegraphy are distinct advantages4 ,there has not yet been much opportunity to test the airship in actual warfare4 ,the aeroplane has been used by the ,italians in ,tripoli for scouting and reconnoitering and is said to have justified expectations4 ,on several occasions the ,italian military aviators followed the movements of the enemy1 in one instance as far as forty miles inland4 ,at the time of the attack by the ,turks a skillful aeroplane reconnaissance revealed the approach of a large ,turkish force1 believed to be at the time sixty miles away in the mountains4 ,aeroplanes and airships1 as they exist today1 would doubtless render very valuable service in a time of war1 both over land and water1 in scouting1 reconnoitering1 carrying dispatches1 and as some experts believe1 in locating submarines and mines placed by the enemy in channels of exits from ports4 ,a coast aeroplane could fly out #cj or #dj miles from land1 and rising to a great height1 descry any hostile ships on the distant horizon1 observe their number1 strength1 formation and direction1 and return within two hours with a report to obtain which would require several swift torpedo-boat destroyers and a much greater time4 ,the question as to whether it would be practicable to bombard an enemy on land or sea with explosive bombs dropped or discharged from flying machines or airships1 is one which is much discussed but hardly yet determined4 ,aeroplanes have been constructed with floats in the place of runners and several attempts have been made1 in some cases successfully1 to light with them on and to rise from the water4 ,mr4 ,curtiss did this at ,san ,francisco1 in ,january1 #aiaa4 ,attempts have also been made with the aeroplane to alight on and to take flight from the deck of a warship4 ,toward the end of #aiaj ,aviator ,ely flew to land from the cruiser ,birmingham1 and in ,january1 #aiaa1 he flew from land and alighted on the cruiser ,pennsylvania4 ,but in these cases special arrangements were made which would be hardly practicable in a time of actual war4 ,in ,november1 #aiaa1 a test was made at ,newport1 ,r4 ,i41 by ,lieut4 ,rodgers1 of the navy1 of a hydro-areoplane as an auxiliary to a battleship4 ,the idea of the test was to alight alongside of the ship1 hoist the machine aboard1 put out to sea and launch the machine again with the use of a crane4 ,lieut4 ,rodgers came down smoothly alongside the ,ohio1 his machine was easily drawn aboard with a crane1 and the ,ohio steamed down to the open sea1 where it was blowing half a gale4 ,but1 owing to the misjudgment of the ship's headway1 one of the wings of the machine when it struck the water after being released from the crane1 went under the water and was snapped off4 ,lieut4 ,rodgers was convinced that this method was too risky and that some other must be devised4 ,,chapter ,,xxviii4 ,,glossary ,,of ,,aeronautical ,,terms4 ,aerodrome4--,literally a machine that runs in the air4 ,aerofoil4--,the advancing transverse section of an aeroplane4 ,aeroplane4--,a flying machine of the glider pattern1 used in contra-distinction to a dirigible balloon4 ,aeronaut4--,a person who travels in the air4 ,aerostat4--,a machine sustaining weight in the air4 ,a balloon is an aerostat4 ,aerostatic4--,pertaining to suspension in the air2 the art of aerial navigation4 ,ailerons4--,small stabilizing planes attached to the main planes to assist in preserving equilibrium4 ,angle of ,incidence4--,angle formed by making comparison with a perpendicular line or body4 ,angle of ,inclination4--,angle at which a flying machine rises4 ,this angle1 like that of incidence1 is obtained by comparison with an upright1 or perpendicular line4 ,auxiliary ,planes4--,minor plane surfaces1 used in conjunction with the main planes for stabilizing purposes4 ,biplane4--,a flying-machine of the glider type with two surface planes4 ,blade ,twist4--,the angle of twist or curvature on a propeller blade4 ,cambered4--,curve or arch in plane1 or wing from port to starboard4 ,chassis4--,the under framework of a flying machine2 the framework of the lower plane4 ,control4--,system by which the rudders and stabilizing planes are manipulated4 ,dihedral4--,having two sides and set at an angle1 like dihedral planes1 or dihedral propeller blades4 ,dirigible4--,obedient to a rudder2 something that may be steered or directed4 ,helicopter4--,flying machine the lifting power of which is furnished by vertical propellers4 ,lateral ,curvature4--,parabolic form in a transverse direction4 ,lateral ,equilibrium or ,stability4--,maintenance of the machine on an even keel transversely4 ,if the lateral equilibrium is perfect the extreme ends of the machine will be on a dead level4 ,longitudinal ,equilibrium or ,stability4--,maintenance of the machine on an even keel from front to rear4 ,monoplane4--,flying machine with one supporting1 or surface plane4 ,multiplane4--,flying machine with more than three surface planes4 ,ornithopter4--,flying machine with movable bird-like wings4 ,parabolic ,curves4--,having the form of a parabola--a conic section4 ,pitch of ,propeller ,blade4--,see ,twist4 ,ribs4--,the pieces over which the cloth covering is stretched4 ,spread4--,the distance from end to end of the main surface2 the transverse dimension4 ,stanchions4--,upright pieces connecting the upper and lower frames4 ,struts4--,the pieces which hold together longitudinally the main frame beams4 ,superposed4--,placed one over another4 ,surface ,area4--,the amount of cloth-covered supporting surface which furnishes the sustaining quality4 ,sustentation4--,suspension in the air4 ,power of sustentation2 the quality of sustaining a weight in the air4 ,triplane4--,flying machine with three surface planes4 ,thrust of ,propeller4--,power with which the blades displace the air4 ,width4--,the distance from the front to the rear edge of a flying machine4 ,wind ,pressure4--,the force exerted by the wind when a body is moving against it4 ,there is always more or less wind pressure1 even in a calm4 ,wing ,tips4--,the extreme ends of the main surface planes4 ,sometimes these are movable parts of the main planes1 and sometimes separate auxiliary planes4 ,footnotes3 ,footnote #a3 ,now dead4 ,footnote #b3 ,aeronautics4 ,footnote #c3 ,see ,chapter ,,xxv4 ,footnote #d3 ,the ,wrights' new machine weighs only #ijj pounds4 ,footnote #e3 ,aeronautics4