,this file was produced from page images at ,google ,books4 ,transcriber's ,note ,this book was transcribed from scans of the original found at ,google ,books4 ,there was no book cover image1 so ,i made one by enlarging a black and white picture of the book from an advertisement found in another ,cole ,morgan title and tried to make it look presentable1 including adding color4 ,the author uses a variant spelling of the word fuselage which ,i have left as is4 ,model ,flying ,machines ,,how ,,to ,,build ,,and ,,fly ,,them ,,by ,a4 ,p4 ,,morgan ,,newark1 ,n4 ,j4 ,,cole ,,morgan #aiac ,,copyright1 #aiac ,by ,,cole ,,morgan ,,introduction4 ,the construction of model aeroplanes is essentially simple and for those wishing to experiment it is an ideal method of gaining practical knowledge of the new science of aeronautics4 ,aside from the utilitarian standpoint1 there is another aspect hardly second or less important4 ,a well balanced little machine which will leave the hand and soar away under its own power is a source of fascination and delight not only to its maker1 but to the spectators of the flight as well4 ,this little volume has been planned to present the material it contains in such a manner that it will aid the judgment of the experimenter and assist him in developing his own ideas4 ,to make it of immediate value to the novice a number of detailed plans for building various machines have been included4 ,for the greater part these machines have been designed rather to fly greater distances than to appear like some man carrying prototype4 ,illustration3 ,,plate ,i4 ,launching a ,model ,aeroplane4 ,,introduction4 4444444444444444444444444444444444444444 4444444444444 ,,chapter ,i4 ,,general ,,principles ,,underlying ,,aeroplane ,,flight4 44444444 ,,chapter ,,ii4 ,,general ,,remarks ,,regarding ,,model ,,aeroplane ,,construction4 ,,the ,,question ,,of ,,resistance4 ,,weight4 ,,stability4 44444444444444444444 ,,chapter ,,iii4 ,,planes ,,and ,,rudders4 ,,elevators ,,and ,,tails4 4444444444444 ,,chapter ,,iv4 ,,the ,,fusellage ,,or ,,framework4 444444444444444444444444444 ,,chapter ,v4 ,,motive ,,power4 4444444444444444444444444444444444444444 44 ,,chapter ,,vi4 ,,screw ,,propellers4 4444444444444444444444444444444444444 ,,chapter ,,vii4 ,,bearings1 ,,thrust ,,blocks ,,and ,,gears4 4444444444444444444 ,,chapter ,,viii4 ,,building ,,and ,,flying ,,model ,,aeroplanes4 444444444444444 ,the ,blerioplane ,flyer4 7,plate ,,ii47 444444444444444444444444444444 ,the ,monoplane ,flyer4 7,plate ,,iii47 4444444444444444444444444444444 ,the ,baby ,racer4 7,plate ,,iv47 4444444444444444444444444444444444444 ,the ,peerless ,racer4 7,plate ,v47 4444444444444444444444444444444444 ,the ,competition ,flyer4 7,plates ,,vi and ,,vii47 444444444444444444444 ,the ,long ,distance ,racer4 7,plates ,,viii and ,,ix47 444444444444444444 ,fleming-,williams ,flyer4 7,plate ,x47 444444444444444444444444444444 ,,flying ,,the ,,models4 4444444444444444444444444444444444444444 444444 ,,plate ,i4 ,launching a ,model ,aeroplane4 44444444444444444444444444444 ,,fig4 #a4 ,diagram showing a kite held in the air by the action of a wind4 ,the dotted lines and arrow heads represent the direction and force of the wind4 4444444444444444444444444444444444444444 44444444 ,,fig4 #b4 ,diagram representing a typical monoplane4 ,the only remaining requisition is that the aeroplane may be guided at will1 caused to rise or fall or be steered to the right and left4 ,the devices used to accomplish this are two rudders called respectively the elevator and the steering rudder4 ,the elevator takes the form of a small surface carried either in front or behind the main supporting surfaces and enables the machine to take an upward1 a horizontal or downward course accordingly as it is adjusted4 ,it acts as a rudder to steer the aeroplane up or down or to hold it to its course in exactly the same manner that a ship's rudder steers it to the right or left4 ,when it is desired to direct the aeroplane upwards1 the front edge of the elevator is raised so as to set it at a greater angle with the horizontal4 ,if the aeroplane's course is required to be downward1 the front edge of the elevator is lowered4 ,,fig #c4 ,diagram showing the makeup of a biplane 7,wright74 4444444444 ,,fig4 #d4 ,two methods of controlling the lateral stability of an aeroplane4 4444444444444444444444444444444444444444 4444444444444444 ,,fig4 #e4 ,the disturbance created in the air by a square object4 ,the arrow points in the direction of motion4 ,the space in the rear of the object is the scene of violent eddy4 44444444444444444444444444 ,,fig4 #f4 ,the disturbance caused by a triangular body moving through the atmosphere4 4444444444444444444444444444444444444444 44444444444 ,plate ,,ii4 4444444444444444444444444444444444444444 44444444444444444 ,,fig4 #g4 ,showing the disturbance created by a small spar on the back of a plane4 4444444444444444444444444444444444444444 444444444444444 ,,fig4 #h4 ,diagram illustrating the ichthyoid shape and how smoothly it slips through the air without creating an eddy4 4444444444444444444 ,,fig4 #i4 ,of the three shapes shown above1 the round one will slip through the air with the least disturbance and resistance4 ,a bar of wood like 7,a71 #b inches square1 showed a drift of #e4af lbs4 when placed in a breeze blowing #di miles per hour4 ,turning it as shown by 7,b7 changed the drift to #e4dg lbs4 ,a round bar1 #b inches in diameter1 like 7,c7 showed #b4ig lbs4 drift under the same conditions4 4444444444444444444444444444444444444444 444444444444444 ,,fig4 #aj4 ,the figures given above each shape show the drift in lbs4 of wooden bars of those shapes when placed in a wind blowing #dj miles an hour4 ,the bars experimented with had a depth of #i inches in the direction of the arrows and were #b inches wide4 444444444444444 ,,fig4 #aa4 ,flat and dihedral planes4 44444444444444444444444444444444 ,,fig4 #ab4 ,the action of the air upon a curved and a flat plane4 ,we have seen that by the effects of the resistance of the air1 an aeroplane may be sustained in the atmosphere4 ,we must now see in what manner we can use these effects to the greatest advantage4 444 ,,fig4 #ac4 ,section of a built-up plane showing how a rib is made4 ,when made small1 they offer greater drift or head resistance than a single curved surface plane and cannot because of the delicate structure necessary to make them light1 withstand hard knocks4 ,they have the further disadvantage of being from a constructional standpoint very hard to make smooth and rigid4 44444444444444444444 ,,plate ,,iii4 4444444444444444444444444444444444444444 4444444444444444 ,,fig4 #ad4 ,how ribs may be joined to the long members4 44444444444444 ,,fig4 #ae4 ,form for bending the planes4 44444444444444444444444444444 ,,fig4 #af4 ,a good method of building a wooden plane4 4444444444444444 ,,fig4 #ag4 ,various shapes a plane may take4 4444444444444444444444444 ,,fig4 #ah4 ,an edgewise view of several planes showing the different ways they may be bent to secure stability4 444444444444444444444444 ,,fig4 #ai4 ,the various ways two planes may be combined to secure stability or form a biplane4 44444444444444444444444444444444444444 ,,fig4 #bj4 ,fins4 4444444444444444444444444444444444444444 444444444444 ,,fig4 #ba4 ,a simple motor base or fusellage4 4444444444444444444444 ,,fig4 #bb4 ,paper ,tube ,fusellage4 ,part of the tube is cutaway to show the rubber skein inside4 4444444444444444444444444444444444444444 44 ,,fig4 #bc4 ,two methods of gearing a propeller4 4444444444444444444444 ,,fig4 #bd4 4444444444444444444444444444444444444444 444444444444444444 ,,fig4 #be4 4444444444444444444444444444444444444444 444444444444444444 ,,fig4 #bf4 ,method of laying out a screw propeller1 that is1 determining the angle of the blades at different points4 4444444444 ,,fig4 #bg4 ,a propeller of the truly helical type delivers a cylinder of air in which all parts move at the same speed as at ,a4 ,a propeller having blades of the same angle throughout their length throws the air as in ,b in which the centre of the cylinder moves more slowly than the outside4 4444444444444444444444444444444444444 ,,fig4 #bh4 ,templets for testing and carving a propeller4 444444444444 ,,fig4 #bi4 ,a simple method of forming a propeller from sheet metal4 4 ,,fig4 #cj4 ,a built-up metal propeller made of aluminum4 4444444444444 ,,fig4 #ca4 ,metal ,propeller4 4444444444444444444444444444444444444444 4 ,,fig4 #cb4 ,method of carving a propeller of the truly helical type4 4 ,,fig4 #cc4 ,methods of fastening propellers to shaft4 4444444444444444 ,,fig4 #cd4 ,method of forming sockets for joining struts1 etc41 by cutting from sheet metal4 4444444444444444444444444444444444444444 4 ,,fig4 #ce4 ,bent wood propellers and the methods of fastening them to the shaft4 4444444444444444444444444444444444444444 4444444444444444 ,,fig4 #cf4 ,propeller blank 7top74 ,carved propeller 7bottom74 44444444 ,,fig4 #cg4 ,langley type propeller 7top74 ,wright type propeller 7bottom74 4444444444444444444444444444444444444444 44444444444444444 ,,fig4 #ch4 ,quasi-helical propeller4 444444444444444444444444444444444 ,,fig4 #ci4 ,blanks for racing 7top7 and chauviere 7bottom7 propellers4 ,,fig4 #dj4 ,the first step in carving a propeller4 ,the blank4 ,hollowing the first blade4 4444444444444444444444444444444444444444 4444444444 ,,fig4 #da4 ,one blade hollowed4 ,hollowing the second blade4 4444444444 ,,fig4 #db ,rounding the back of the first blade4 ,rounding the back of the second blade4 4444444444444444444444444444444444444444 444444444 ,,fig4 #dc4 ,all carving finished4 ,sandpapering to secure a smooth surface4 4444444444444444444444444444444444444444 444444444444444444 ,,fig4 #dd4 ,varnishing4 ,the propeller finished4 4444444444444444444444 ,,fig4 #de4 ,accentricity4 ,the effect of placing the center of gravity too low4 4444444444444444444444444444444444444444 444444444444444444 ,,fig4 #df4 ,simplest method of fitting two propellers to a model aeroplane4 4444444444444444444444444444444444444444 4444444444444444 ,,fig4 #dg4 ,a method of arranging two propellers on the same axis4 444 ,,fig4 #dh4 ,simple bearings4 4444444444444444444444444444444444444444 4 ,,fig4 #di4 ,double bearings4 4444444444444444444444444444444444444444 4 ,,fig4 #ej4 ,simple thrust bearing4 44444444444444444444444444444444444 ,,fig4 #ea4 ,ball thrust bearing4 4444444444444444444444444444444444444 ,,fig4 #eb4 ,hooks4 4444444444444444444444444444444444444444 44444444444 ,plate ,,iv4 4444444444444444444444444444444444444444 44444444444444444 ,plate ,v4 4444444444444444444444444444444444444444 444444444444444444 ,plate ,,vi4 4444444444444444444444444444444444444444 44444444444444444 ,,fig4 #ec4 ,method of holding plane to frame with rubber bands4 444444 ,plate ,,vii4 4444444444444444444444444444444444444444 4444444444444444 ,,fig4 #ed4 ,the ,peerless ,racer4 44444444444444444444444444444444444444 ,plate ,,viii4 4444444444444444444444444444444444444444 444444444444444 ,plate ,,ix4 4444444444444444444444444444444444444444 44444444444444444 ,plate ,x4 4444444444444444444444444444444444444444 444444444444444444 ,,fig4 #ee4 ,racing blank and propeller4 444444444444444444444444444444 ,plate ,,xi4 ,winding a model4 4444444444444444444444444444444444444444 ,,fig4 #ef4 ,a winder made from an egg beater4 444444444444444444444444 ,,chapter ,i4 ,,general ,,principles ,,underlying ,,aeroplane ,,flight4 ,to enter deeply into a discussion of the theory of the aeroplane would not only tire the reader but would waste valuable space in endeavoring to explain that which has been more adequately dealt with in more notable works4 ,in order to gain a clear understanding of the following chapters1 however1 it will be necessary to first grasp the elementary principles underlying the flight of an aeroplane4 ,in setting these forth1 ,i shall try1 as far as possible1 not to hamper or confuse with unnecessary terms or technicalities1 except where such might be of worth in rendering a better conception of that to which they apply4 ,illustration3 ,,fig4 #a4 ,diagram showing a kite held in the air by the action of a wind4 ,the dotted lines and arrow heads represent the direction and force of the wind4 ,an ordinary kite is one of the best examples of the action of an aeroplane4 ,it is scarcely necessary to define the kite2 it is a rigid frame of wooden sticks1 on which is stretched a surface of cloth or paper4 ,a string attached to the kite by means of a bridle serves to hold the apparatus to the ground4 ,in ,fig4 #a is represented a kite against which the wind is blowing as indicated by the dotted lines4 ,the string is so arranged that the kite is inclined at an angle to the wind and thus is sustained in the air by the force of the wind1 viz41 the molecules of air in striking against the slanting surface exert a pressure upon it which both calculation and experiment show to be perpendicular to the surface and tending to lift it4 ,the kite also exerts a strong pull on the string which holds it in position4 ,but on days when there is no breeze or when the wind suddenly dies out2 what is to be done then8 ,wind is not an absolute thing4 ,it is a relative movement of the surrounding air in comparison to a body4 ,the effect is the same1 and the relative movement takes place whether the air is still and the body in motion1 or the air is in motion and the body motionless4 ,it is therefore an easy matter to create a breeze and a kite can be kept in the air providing the person flying the kite and holding the string commences to run4 ,although no wind is blowing1 the pressure of the air through which the kite is moving will cause it to remain in the air4 ,in other words1 the kite would be sustained in the air by virtue of its own relative motion to the wind4 ,in order that the kite may fly1 it makes no difference whether the wind moves against the kite or the kite moves against the wind4 ,an aeroplane1 in fact1 is nothing but a kite which creates its own breeze4 ,if an aeroplane were attached to a strong wire serving as the string in the case of the kite1 it would fly in the same manner as the kite1 providing of course that the wind were sufficiently powerful4 ,if the wind were not blowing at all1 or not blowing hard enough1 the other end of the wire could be attached to an automobile and by driving the automobile fast enough the required relative motion of the air would be produced and the aeroplane would fly4 ,there could be no direct benefit derived1 however1 from an aeroplane which must remain attached to a machine running over the earth and travel in its wake4 ,some other means of producing the required relative motion is necessary so that the aeroplane may be free to fly in any direction and either with or against the wind4 ,this is accomplished by a propeller driven by a motor revolving at high speed in the aeroplane itself4 ,the action of an aerial propeller is similar to that of its marine prototype employed for driving ships through the water4 ,each depends for its action upon the imparting of a sternward motion to a column of fluid1 in the one case air and in the other water4 ,a propeller screws itself forward into the surrounding media in identically the same manner that an ordinary screw forces itself into a block of wood4 ,an aeroplane therefore essentially consists of the wings or supporting surfaces1 also sometimes called planes1 driven through the air in an oblique manner by the propeller and motor4 ,illustration3 ,,fig4 #b4 ,diagram representing a typical monoplane4 ,the only remaining requisition is that the aeroplane may be guided at will1 caused to rise or fall or be steered to the right and left4 ,the devices used to accomplish this are two rudders called respectively the elevator and the steering rudder4 ,the elevator takes the form of a small surface carried either in front or behind the main supporting surfaces and enables the machine to take an upward1 a horizontal or downward course accordingly as it is adjusted4 ,it acts as a rudder to steer the aeroplane up or down or to hold it to its course in exactly the same manner that a ship's rudder steers it to the right or left4 ,when it is desired to direct the aeroplane upwards1 the front edge of the elevator is raised so as to set it at a greater angle with the horizontal4 ,if the aeroplane's course is required to be downward1 the front edge of the elevator is lowered4 ,aeroplanes are usually of two general types1 monoplanes and biplanes4 ,a monoplane1 as its name implies1 is a machine having a single pair of wings or supporting surfaces4 ,the ,bleriot1 ,antoinette and ,santos ,dumont machines are the most prominent representatives of this type of aeroplane4 ,the elevator on a monoplane is usually in the rear of the main supporting surfaces4 ,when in this position it also acts as a tail to furnish longitudinal stability to the machine in the same way that a feather on an arrow steadies its flight4 ,illustration3 ,,fig #c4 ,diagram showing the makeup of a biplane 7,wright74 ,the most prominent machines of the biplane group are the ,voisin1 ,wright1 ,curtiss and ,farman aeroplanes4 ,the old practice of placing the elevator in the front of a biplane is gradually being abandoned and it is safe to say that by the time this book has been printed all these machines will be of the headless variety with the elevator in the rear4 ,the vertical fins shown between the planes of the elevator in the old type of biplane1 counterbalance the effect of gusts of wind striking the vertical rudder from the sides and also act as a pivot for turning to the right and left4 ,together with the steering rudder1 they constitute a sort of keel which keeps the machine straight to its course4 ,in order for an aeroplane to fly in the accepted sense of the word1 it must possess supporting surfaces1 an elevator or tail and a propeller driven by a motor4 ,these are essentially the sustaining1 propelling and steering members of the machine4 ,illustration3 ,,fig4 #d4 ,two methods of controlling the lateral stability of an aeroplane4 ,the machine must1 however1 also possess lateral stability1 that is1 the wings of the apparatus must not incline from the right to left or vice versa during the flight4 ,the machine must be so constructed at it rights itself by its own effort or is under the immediate control of the aviator4 ,this is accomplished by warping the wings1 that is1 the extreme tips of the planes can be moved up and down so as to present a greater or lesser angle and corresponding increase or decrease the lifting capacity of those portions4 ,the same result is also reached by means of small subsidiary moving planes attached to the rear of the main supporting surfaces called aileron4 ,when one aileron is lowered1 the other is raised4 ,the action of the air on the ailerons is to depress the one which is raised and to raise the one which is lowered as shown by the arrows in the illustration4 ,,chapter ,,ii4 ,,general ,,remarks ,,regarding ,,model ,,aeroplane ,,construction4 ,,the ,,question ,,of ,,resistance4 ,,weight4 ,,stability4 99,the first requirement99 of a model aeroplane is that it shall fly4 ,the first essential for a machine to fly well is that it must be simple4 ,simplicity usually insures success and is synonymous with efficiency4 ,a complicated scale model having as its prototype one of the most successful man-carrying machines usually will not fly4 ,if it does fly1 it does not do so well4 ,miniature steam engines1 motors1 etc41 can be constructed to exact scale and will justify their existence by actually working and performing duty1 but in most cases a model aeroplane made to scale will not fly well until it begins to approach full size4 ,the next indispensable feature might be called lightness1 but at the same time it must be borne in mind that strength is also second to none and it would be fatal to sacrifice the one for the other4 ,the hard knocks and battering which a model usually receives at the hands of a novice will soon wreck any flimsy construction4 99,to design model aeroplanes will at first seem like99 robbing ,peter to pay ,paul1 that is1 no one part can be developed to an extreme without seriously affecting the efficiency of the other parts4 ,the successful machine is a sort of happy medium arrived at solely through experiment4 ,a thorough understanding1 however1 of the part played by each individual member of a model and its characteristics will make it possible to avoid much unnecessary work in that connection4 ,it is therefore well to carefully read the following chapters before commencing to carry out any original ideas or to make any radical departure from the designs offered in this book4 ,from these statements it must not be inferred that the successful model aeroplane builder is necessarily an individual possessed of consummate skill in the handling of tools or a person of unusual judgment4 ,a few simple tools and trifling mechanical ability will enable any one to build the simple little machines herein described4 ,the greatest asset required in the work is patience1 patience spelled with a capital ,p4 ,not only patience in building the machines1 but patience in adjusting them and patience in flying them4 ,making haste with a model aeroplane is poor policy4 ,it never pays to use slipshod methods4 ,take the time to make sure every part is the best that you can make it4 ,care with the little details will insure success4 ,model aeroplanes are exasperating to the extreme4 ,a new model will swerve to the right and left or dive with unerring precision to the ground or nearest object4 ,they seem to defy all attempts to make them behave and in the first few flights usually perform a new one every time4 ,this is the point where success comes to the model aeroplanist who possesses patience and perseverance4 ,one must learn to adjust and fly a model aeroplane by practice just as he must also learn to swim or ride a bicycle by repeated trials4 ,a little persuasion will soon make a model soar in a surprising manner4 99,the question of resistance99 is the first consideration of the model aeroplane designer4 ,an aeroplane should pass through the air in such a manner that it leaves that medium in as motionless a state as possible4 ,all motion of the surrounding air represents so much power wasted4 ,it is obvious that a boat with a square prow will offer more resistance than a ship having a sharp bow4 ,the latter causes considerably less disturbance of the fluid in which it moves than the former4 ,illustration3 ,,fig4 #e4 ,the disturbance created in the air by a square object4 ,the arrow points in the direction of motion4 ,the space in the rear of the object is the scene of violent eddy4 ,the resistance of an aeroplane is made up of3 #a4 ,aerodynamic resistance4 #b4 ,head resistance4 #c4 ,surface resistance4 ,the first is offered by the planes of the machine itself and results directly from the pressure of the air supporting the model during flight4 ,the second is set up by the framework1 the edges of the planes1 the wires1 etc41 while the last is caused solely by the air in traveling over the surfaces of the various members composing the machines4 ,illustration3 ,,fig4 #f4 ,the disturbance caused by a triangular body moving through the atmosphere4 ,the head and surface or skin resistance1 as it is sometimes called1 can be reduced1 but the aerodynamical resistance cannot4 ,air is no less a fluid than water1 and the same considerations apply to it1 subject1 of course1 to certain conditions and with due regard for such factors as density1 viscoscity1 etc4 ,illustration3 ,plate ,,ii4 ,when an object1 such as a square stick of wood1 is moved through the air1 the latter flows around it leaving behind a region of dead air4 ,the dead air represents so much waste energy or unnecessary resistance to overcome because it requires an expenditure of power to drag it along4 ,illustration3 ,,fig4 #g4 ,showing the disturbance created by a small spar on the back of a plane4 ,it is obvious then that bodies which are to move through the air with the least resistance possible should be given such a shape that the stream lines of air will flow around it smoothly and not leave a dead region behind4 ,in other words1 the stream line flow of the air shall keep the same contour as the surface4 99,the ichthyoid or fish-like form99 is of such a shape4 ,this is illustrated in ,fig4 #h4 ,its greatest diameter should be about two-fifths of its entire length from the head4 ,all struts1 stanchions1 etc41 should be given this shape4 ,illustration3 ,,fig4 #h4 ,diagram illustrating the ichthyoid shape and how smoothly it slips through the air without creating an eddy4 ,this shape is very interesting because of its probable origin1 for a glance is sufficient to tell that it not only resembles a fish but also the body of a bird4 99,weight99 is an all-important item in model aeroplaning4 ,how to obtain the maximum strength with the minimum of weight is undoubtedly the most difficult problem which the aviator has to solve4 ,weight is a much more important factor in model aeroplanes than in the case of full-size machines because models do not fly fast enough to possess a high weight-carrying capacity4 ,illustration3 ,,fig4 #i4 ,of the three shapes shown above1 the round one will slip through the air with the least disturbance and resistance4 ,a bar of wood like 7,a71 #b inches square1 showed a drift of #e4af lbs4 when placed in a breeze blowing #di miles per hour4 ,turning it as shown by 7,b7 changed the drift to #e4dg lbs4 ,a round bar1 #b inches in diameter1 like 7,c7 showed #b4ig lbs4 drift under the same conditions4 ,it is only by the constant use of a pair of scales and an accurate knowledge of materials with the ability to combine them in the most efficient manner that the weight and strength may be kept in harmony4 ,such knowledge and experience come only with practice4 ,they may1 however1 be acquired by any one4 ,in this regard1 a notebook forms an almost indispensable aid to the experimenter4 ,after a machine has been built an accurate record of every flight and of every alteration or change in material should be made4 ,illustration3 ,,fig4 #aj4 ,the figures given above each shape show the drift in lbs4 of wooden bars of those shapes when placed in a wind blowing #dj miles an hour4 ,the bars experimented with had a depth of #i inches in the direction of the arrows and were #b inches wide4 99,automatic stability99 without doubt has attracted more attention from engineers and aviators than any other one problem connected with aviation4 ,since it is not possible for a model aeroplane to carry a pilot it is much more important that it should be naturally stable than any of its man-carrying prototypes4 ,automatic stability in a model of only two or three feet spread at the most1 is quite a different proposition from that offered by a full-size machine4 ,illustration3 ,,fig4 #aa4 ,flat and dihedral planes4 ,it would at first seem1 that by placing the centre of gravity of the machine very low such stability could be secured4 ,this is accomplished to a certain extent by setting the wings or planes at a dihedral angle4 ,but if the angle is excessive1 the aeroplane will fly with a pitching motion known as accentricity4 ,the centres of gravity1 of pressure and of head resistance should be at the same point4 ,the centre of thrust of the propeller should also pass through this point4 ,in this will be found the secret of the successful model aeroplane4 ,it is only arrived at by careful experiment and calculation4 ,head resistance increases stability while weight and speed lessen it4 ,when an aeroplane is gliding 7traveling downwards7 its stability is greater than when it is rising or flying horizontally4 ,it is the least stable when rising4 ,,chapter ,,iii4 ,,planes ,,and ,,rudders4 ,,elevators ,,and ,,tails4 ,in ,chapter ,i it was explained that an aeroplane is fundamentally composed of a supporting surface1 divided into one or two parts1 usually the planes or wings1 which cut the air in an oblique manner1 driven by a propeller and motor4 ,before going further it is perhaps best to understand more exactly how the planes operate and support the machine in the air than it was possible to explain in the first chapter without confusion4 ,a theoretical aeroplane consists of a flat surface or plane4 ,when the propeller is set into motion the plane is driven through the air in an oblique manner and compels the gaseous molecules to glide under its surface4 ,since the plane is at an angle1 the front edge being higher than the back1 the air must necessarily leave at the rear in a downward direction4 ,the air molecules in traveling under the surface exercise a resistance upon it which is really a pressure against the plane4 ,when this pressure is resolved into its components1 it is found to be made up of two forces1 one horizontal1 tending to retard the forward motion1 and called the drift2 the other1 vertical and tending to lift the plane4 ,the centre of these forces is not as might be supposed at the centre of the plane1 but at a point between the centre and the front edge called the centre of pressure4 ,the centre of pressure approaches the front edge as the angle of the plane with the horizontal becomes less4 ,in order to render a better idea of how it is possible for an aeroplane to gain support in the air consider a skater moving swiftly over very thin ice which would not bear his weight1 but since he is moving so rapidly that any one portion of the ice does not have time to bend to the breaking point1 he is supported4 ,in somewhat the same manner1 the planes pass so rapidly on to new and undisturbed bodies of air1 and stay over one body for so brief an instant that there is no time to completely overcome the inertia of the air and force it downwards4 ,illustration3 ,,fig4 #ab4 ,the action of the air upon a curved and a flat plane4 ,we have seen that by the effects of the resistance of the air1 an aeroplane may be sustained in the atmosphere4 ,we must now see in what manner we can use these effects to the greatest advantage4 ,first of all1 we have been continually speaking of a plane as the supporting surface1 which from the definition of the word would lead one to believe that they were flat4 ,if the wings of a bird are examined1 it will soon be noticed that they are concave underneath4 ,since the first attempts at aviation1 therefore1 machines have been built with planes or wings concave on the underside4 ,the reason for this is very apparent from ,fig4 #ab4 ,the first illustration shows the action of a flat surface moving through the air4 ,the air streams1 as represented by the lines do not follow the surface of the plane1 but leave a considerable region of dead air4 ,this is the reason that a flat plane is very inefficient and not capable of giving so great a lift as the curved plane in the next figure where the lines follow the outline of the plane4 ,the less disturbance a plane causes in the surrounding air1 the closer it is said to approach to stream line form4 ,a correctly curved plane is considerably more effectual than a flat one1 giving at the same time greater lift and less drift4 99,built-up ,planes991 that is1 planes having a double curve approaching true stream line form1 come nearer being the ideal plane than any other from some standpoints1 but do not possess any advantages when used on models of less than four feet spread4 ,illustration3 ,,fig4 #ac4 ,section of a built-up plane showing how a rib is made4 ,when made small1 they offer greater drift or head resistance than a single curved surface plane and cannot because of the delicate structure necessary to make them light1 withstand hard knocks4 ,they have the further disadvantage of being from a constructional standpoint very hard to make smooth and rigid4 ,there are innumerable substances which would at first seem to recommend themselves as material for planes1 but we may immediately thrust the greater portion aside4 ,by all means avoid tracing cloth or linen1 not only because its heavy weight forever precludes it from this use1 but because it wrinkles and cockles so as to be absolutely useless when slightly damp or wet4 99,tissue paper99 wrinkles easily and is not strong enough4 99,jap silk99 is an excellent material for fabric covered planes1 being at once light and strong4 ,however1 by far the most satisfactory plane of this kind is formed by silk bolting cloth which has been coated with collodion4 ,the collodion is brushed on with a fine camel's hair brush after the fabric is in place and it is thereby rendered both waterproof and air-tight4 ,fabrics should always be stretched over the planes from end to end and not front to back or vice versa4 ,make the lap joints or pockets around the end spars as long as possible so that they will not draw dead air and impede the forward motion of the machine4 99,bamboo ,paper99 is one of the best materials for covering the planes of a model aeroplane and is to be highly recommended4 ,it is made in ,japan from bamboo fibre and is very strong4 ,it is usually stretched tightly over the framework and then given two coats of collodion or1 what is much better1 bamboo varnish4 99,the framework99 of the planes may be made of rattan1 split bamboo1 spruce1 or steel piano wire4 ,piano wire is excellent for small machines since it is springy and light and able to withstand shocks4 ,it is easily bent to any shape and offers considerably less head resistance than rattan because of its small diameter4 ,rattan can be bent into almost any shape by wetting4 ,nothing is better for the cross pieces1 ribs1 etc41 of the planes or framework than split bamboo4 ,bulk for bulk it is heavier but infinitely stronger than other woods4 ,it is easily worked and can be bent into all kinds of shapes4 ,bamboo must always be bent while hot4 ,the best source of heat is a spirit lamp or a bunsen burner4 ,always bend toward the hottest side4 ,when bent apply a cold wet rag to cool quickly4 ,if bent more than necessary1 it may be straightened by applying heat again and allowing it to straighten itself4 ,in order to make long bends1 such as the ends of planes1 alighting skids1 etc41 first wind a strip of wet rag around1 the bamboo and allow it to remain on for ten or fifteen minutes4 ,then remove the rag1 heat the bamboo in a flame and bend slowly4 ,illustration3 ,,plate ,,iii4 ,with a little care1 strips several feet long may be easily split from bamboo rods4 ,the best method of accomplishing this is to use a fine saw1 but a sharp knife will often be successful4 ,illustration3 ,,fig4 #ad4 ,how ribs may be joined to the long members4 99,planes99 of any considerable size require ribs to support and hold the fabric in shape4 ,split bamboo is one of the best materials for this purpose4 ,two very good methods of joining the ribs to the long members of the planes are illustrated in ,fig4 #ad4 ,in the first1 a strip of thin sheet aluminum is bent around the rib and spar and fastened by lashing with silk thread4 ,care must be taken to file off all sharp edges on the aluminum which might otherwise cut the thread4 ,the second method is the neatest and probably the best1 since the rib cannot so easily twist or slip out of place4 99,wood ,planes499 ,in spite of the many advantages of fabric planes they cannot approach wooden planes for efficiency on a small machine4 ,wood is strong1 light and does not change its adjustment4 ,whitewood and spruce are the best materials for the purpose4 ,do not endeavor to saw out the wood4 ,use a carpenter's plane as much as possible in the work4 ,a saw tears the fibres of the wood and will make the finished plane full of tiny splits4 ,the wood1 however1 may be sawed down to a thickness of #e_/cb of an inch and then planed down from that4 ,the finished plane should be about #a_/af of an inch thick4 ,when planing down the wood do not butt one end against a bench stop1 because as the wood becomes thin1 the pressure exerted by the plane against the wood will cause it to rise in the middle and thereby become thinner at that part4 ,instead1 use a clamp to fasten the wood at one end to the bench and plane away from the clamp--,plane down to a smooth surface and avoid the use of sand-paper4 ,illustration3 ,,fig4 #ae4 ,form for bending the planes4 99,forming the ,curve99 by steaming and bending the wood is a very poor method4 ,it soon becomes distorted and warped4 ,illustration3 ,,fig4 #af4 ,a good method of building a wooden plane4 ,the best method is illustrated in ,fig #af4 ,a piece of wood of the same length as the completed plane and having a cross section like that at ,a is glued to the forward under edge of a flat plane ,b4 ,after the glue has hardened1 the plane is worked down to the shape shown at ,d which is very close to the stream line form4 ,the plane is then varnished to prevent it from absorbing moisture and losing its shape4 ,the ends may be covered with thin ,jap silk1 carefully glued on to prevent splitting4 ,the ,wright brothers cover the blades of the propellers on their aeroplanes with silk for the same purpose4 ,air does not flow smoothly when changing from an interrupted flow to an uninterrupted flow around a square corner and so by rounding the ends of the planes1 the disturbance at that point is somewhat eliminated4 ,planes having rattan or piano wire edges cannot very well be of any other shape than those which are illustrated in ,fig4 #ag4 ,illustration3 ,,fig4 #ag4 ,various shapes a plane may take4 ,it is a good plan to give wooden planes the shape shown by #c and #d in ,fig4 #ag1 as the disturbances mentioned above are not so marked4 ,illustration3 ,,fig4 #ah4 ,an edgewise view of several planes showing the different ways they may be bent to secure stability4 ,the planes of large man-carrying machines possess the same characteristics1 but not to such an alarming extent as in a model4 ,the ,voisin aeroplanes overcome the objection by the use of vertical panels set between the planes4 ,the angles at which the planes are set may vary from #a in #f to #a in #bj4 ,one in ten might be called the happy medium4 ,if the planes are given too great an angle1 the drift becomes so great that the propeller thrust is severely taxed4 ,the smaller the angle1 the less will be the drift and consequently the greater the speed4 ,however1 if the surface is curved the angle must not be made too small or not much lift will result4 ,illustration3 ,,fig4 #ai4 ,the various ways two planes may be combined to secure stability or form a biplane4 ,the angle of the tail planes should be adjustable4 ,if too great1 the machine will slow down and the tail will drop1 destroying the equilibrium of the machine and consequently the flight4 ,if the lift of the tail is too great1 however1 it will cause that part to rise and the machine will dive downwards4 99,elevators and ,tails99 are usually made of thin wood or fabric stretched over a rattan or wire framework4 ,they are usually rectangular or elliptical in shape4 ,in case they are made of wood one of the best methods of attachment is to fasten the plane to a small stick by means of two or three small rivets4 ,the stick is secured to the framework of the machine by two small rubber bands4 ,then in case the machine strikes head on in alighting1 the band will absorb the shock and permit the elevator to move so that it is not damaged by the fall4 99,vertical ,fins994 ,it is a much mooted question whether or not a vertical fin is of any value on a model aeroplane since a good model should be so designed that it will fly in a straight line without the use of a rudder4 ,it has been the author's experience that it is often of decided advantage in correcting the flight of an erratic machine or in compensating any little difference that there may result in the drift of the two halves of the planes4 ,illustration3 ,,fig4 #bj4 ,fins4 ,the fin should be placed well toward the rear of the machine and1 whenever possible1 stretched both above and below the centre line of the machine1 so that the pressure due to cross winds will be equal both above and below and there will be no tendency for the machine to twist about its longitudinal axis4 ,when it is not possible to place the fin both above and below the centre line it should be placed above rather than below4 ,fins may be made out of thin wood1 sheet aluminum or fabric stretched over a wire or rattan framework4 ,,chapter ,,iv4 ,,the ,,fusellage ,,or ,,framework4 ,by the term fusellage or frames1 that part of the aeroplane which serves as the backbone and to which all the other members are attached is implied4 ,the fusellage above all must be strong4 ,the second requisite is lightness4 ,the simplest frame for a model aeroplane is a long straight stick4 ,the cross section of the stick may vary and be either round or square4 ,a careful workman1 however1 can build them of ,i section like a steel girder4 ,increased lightness and strength is the result4 ,illustration3 ,,fig4 #ba4 ,a simple motor base or fusellage4 ,a single skein of elastic when wound up tends very strongly to twist the framework of the machine out of true4 ,since the tail and elevator are usually attached to the ends1 the adjustment is thrown out to a marked degree and the flight of the machine is liable to be erratic4 ,we have tried building the fusellage of a network of girders such as the ,bleriot and ,voisin aeroplanes employ4 ,nothing could have been prettier than these carefully designed and constructed frames with their little struts and guy wires1 but we soon found that for plain ordinary everyday efficiency1 the simple stick is the best1 provided1 of course1 that it is of the proper size to resist the twist of the rubber4 ,in some cases it is desirable to retain the framework because of the realistic appearance of the model to the larger machines which it gives4 ,the only practical method then is to employ a plain stick backbone to withstand the torque of the rubber and build a false framework around it4 ,the framework need only be strong enough to support the fabric and resist the shocks of landing4 ,this method of construction is best suited to models of the ,bleriot and ,antoinette types4 ,the only type of frame consisting of a single member which will resist the torque of powerful rubber bands successfully is a tube4 ,the rubber skein is placed inside the tube which may be of wood1 paper or aluminum4 ,illustration3 ,,fig4 #bb4 ,paper ,tube ,fusellage4 ,part of the tube is cutaway to show the rubber skein inside4 ,paper tubes are excellent for small machines1 being exceedingly light and very strong4 ,they are formed by wrapping tough1 unglazed paper around a rod of the required inside diameter4 ,the paper is well smeared with glue and wrapped tightly4 ,the rod is afterwards removed4 ,be sure that the glue is thoroughly dry before attempting to use the tube4 ,in larger machines it is preferable to employ some other means of avoiding the nuisance of a single skein rather than to use a tubular frame4 ,there are several ways of accomplishing this1 the best one undoubtedly being to balance the torque of one elastic by an equal torque tending to twist in the opposite direction4 ,illustration3 ,,fig4 #bc4 ,two methods of gearing a propeller4 ,in ,fig4 #bc1 a second skein of elastic is geared to the first with equal sized gear wheels4 ,the second skein is placed immediately underneath the first and is equal in length and strength4 ,placing one skein under the other and not side by side as might be the first tendency allows the propeller to be arranged centrally4 ,the lower part of the same figure illustrates a second method4 ,in this1 the propeller is attached to a long shaft1 the other end of which is fitted with a gear wheel4 ,two elastic skeins of equal length and strength are attached to a second gear which meshes with the first4 ,the only disadvantage of this form of motor is the long propeller shaft required4 ,the objection1 however1 is sometimes outweighed by the fact that it is possible to employ a small gear wheel on the shaft meshing with a large one between the bands so that the action of the elastic is multiplied and a greater number of propeller revolutions secured where the length of the bands is limited and could not be increased in order to bring about the same result4 99,skids499 ,it requires only very little experience with model aeroplanes to prove the need of efficient skids on the machine4 ,after the rubber band motor has run down1 the propeller offers considerable resistance to the forward travel of the machine so that it does not glide properly and causes it to land on its nose1 often damaging the propeller or front planes4 ,at the least1 the framework of the machine is strained by such a shock4 ,illustration3 ,,fig4 #bd4 ,skids of course weigh something and offer a certain amount of resistance1 but the advantages more than outweigh those drawbacks4 ,skids are usually made of piano wire1 split bamboo or rattan4 ,the skids should not be made any larger than is necessary to protect the machine4 ,they do not usually take any special shape but are formed to fit each individual case4 ,,chapter ,v4 ,,motive ,,power4 ,by far the simplest and most efficient form of power which could be installed in a model aeroplane to drive the propeller is a twisted skein of rubber4 ,nothing is lighter1 or more easily handled and repaired4 ,the word elastic1 in physics1 is the name given to the tendency which a body exerts1 when distorted1 to return to its original shape4 ,rubber possesses more elasticity than any other material known1 it being possible to stretch a piece of rubber cord to eight or nine times its original length without fracture4 ,rubber also possesses the added requisite of lightness and will store up more energy than any form of steel spring4 99,the ,simplest ,form of ,motor99 is a single skein of elastic stretched between two hooks1 one fixed and the other to which the propeller is attached1 free to rotate4 ,in some cases it is a decided advantage to divide the motor into one or more parts4 ,one phase of this question has already been considered4 ,the others will be discussed in the following chapter4 99,the type of ,elastic99 which gives at once the longest life and the greatest power is the square rubber1 preferably about #c_/cb x #c_/cb inches1 and not the flat strip4 ,when examined under the microscope the edges of the square rubber show to be cleaner and sharper and not so ragged as those of the flat strips4 ,to be of any value for use in a model aeroplane1 the rubber should be absolutely pure and fresh4 ,there are certain precautions which if observed will add greatly to the power and efficiency of a rubber band motor4 ,always remove the elastic from the machine when the flights are over for the time being4 ,rubber spoils very quickly when kept under tension4 ,it also deteriorates if warm1 so keep in a cool place4 ,strong sunlight causes rubber to harden and lose its elasticity1 due to the presence of the sulphur used in vulcanizing4 ,if talcum powder or finely powdered soapstone is rubbed on the bands from time to time it will prevent them from sticking together4 ,the strands will then run and slip more easily upon each other1 making it possible to store up a greater number of propeller revolutions4 ,in spite of the use of talcum powder1 however1 when a skein of rubber is twisted very tightly1 the strands stick together1 causing it to soon break up4 ,this nuisance may be somewhat alleviated if the strands are lubricated with pure redistilled glycerine free from grease1 etc4 ,such a precaution will not always greatly lengthen the life of the rubber1 but will increase the number of turns which it is possible to give the skein 7and this is a very important advantage in model contests74 ,due to its sticky nature1 however1 the glycerine will cause the rubber to gather dust and particles of dirt which1 if allowed to grind into the rubber1 would soon weaken it4 ,the skein should therefore be washed from time to time in warm soda and water and fresh glycerine applied4 ,by all means1 avoid all oils or substances of a greasy nature1 such as lubricants4 ,they quickly soften and rot the rubber4 99,the ,amount of ,elastic99 required for a model will vary considerably for propellers of the same pitch and diameter4 ,there is always a tendency to use too much rather than too little and this fault should be carefully guarded against4 ,in nine cases out of ten it is the cause of the unsatisfactory behavior of a model4 ,the motor should always be stranded1 that is1 made up of a skein of bands4 ,it is then possible to secure a larger number of turns than if a single strip were used4 ,always start a new machine with a small number of strands and gradually add to the number until the proper amount of power is obtained4 ,the distance between the propeller and the fixed hook should always be as great as possible so as to secure the maximum number of turns4 99,doubling the ,number of ,elastic ,strands99 increases the power of the motor but cuts down the number of turns which it is possible to give the propeller4 ,that is to say1 a certain skein composed of six strands of rubber will take perhaps two hundred and twenty-five turns while a twelve strand skein of he same sized rubber strands strands is only capable of less than half or about one hundred turns before it is wound tight4 ,doubling the number of strands and at the same time keeping them the same length increases the torque more than three times but diminishes the number of turns from one-half to one-third4 99,doubling the length99 of the strands does not materially reduce the torque for the first hundred turns4 ,after two hundred turns have been reached1 the torque is only about one-half as great as it would be in case the length were not doubled4 ,doubling the length of the strands doubles the number of turns it is possible to give the skein4 ,it is easy to see from this why it is always advisable to make the motor as long as possible and to compose it of the fewest number of strands if long flights are desirable4 ,by using several separate skeins geared together so as to apply their energy to one screw1 it is possible to obtain a greatly increased number of turns4 ,the weight of the gearing is very small and hardly a factor1 considering the advantages derived therefrom4 ,since the skeins revolve in opposite directions the frame of the machine is relieved of the harmful twisting effect so often present in a single skein4 ,the gears should be of steel accurately cut and of no larger diameter than is necessary to separate the rubber skeins the requisite distances so that they will not rub4 ,holes may be bored in the gears to lighten them4 ,the gears are easily and conveniently cut out of steel pinion wire4 ,,chapter ,,vi4 ,,screw ,,propellers4 ,we might compare a propeller to an ordinary screw or bolt by likening the thread of the screw to the two blades of the propeller4 ,if the screw penetrates wood or metal nut it will advance a certain distance known as the pitch which is always the same1 namely1 the distance separating two consecutive turns of the threads4 ,the revolving blades of the propeller cut their way through the air in identically the same manner4 ,but since air is a very thin medium as compared to wood or iron the propeller slips a little just like a screw going into an unsteady nut and does not advance the distance it theoretically should considering the angle of the blades4 ,the distance lost in each revolution is called the slip4 ,thus a screw having a ten-foot pitch in actual operation perhaps only advances the aeroplane eight feet4 ,illustration3 ,,fig4 #be4 ,if a propeller blade had a uniform angle throughout its entire length the portions of the blade near the centre would not have as great a pitch as the extreme tips because the diameter of the circle they travel in one revolution is not as great as that at the tips4 ,for this reason it is usual to give the blades an increasing angle as they approach the centre4 ,illustration3 ,,fig4 #bf4 ,method of laying out a screw propeller1 that is1 determining the angle of the blades at different points4 ,fig #bf shows a diagram illustrating the theoretical pitch of a screw1 the angle of the blade varying inversely as its radial distance from the centre of the screw4 ,when a propeller revolves it sets in motion a cylinder of air4 ,if the angle of the blades is uniform throughout their length the air in the centre of the cylinder will move much more slowly than that near the outside as shown by the arrow heads in ,a of ,fig4 #bg4 ,if the blades are given an increasing pitch1 the air in all parts of the cylinder will move away from the propeller at the same speed4 ,from a diagram like this it is very easy to calculate the angle of a blade at any point to secure a certain pitch4 ,suppose that the problem in hand is to design a propeller eight inches in diameter and a pitch of twelve inches4 ,on a sheet of paper draw a vertical line ,,am twelve inches long to represent the pitch4 ,draw a long horizontal line ,,an of indefinite length from the lower end of ,,am and at right angles to it4 ,the diameter of the propeller being eight inches1 the tips of the blades must travel in one revolution #h x #c4adaf 7the circumference of an eight inch circle in inches71 a distance of #cc4a inches4 ,lay off on ,,an the distance ,,ab which is #cc4a inches1 draw the line ,,mb4 ,the angle ,,mb forms with ,,an is the proper angle for the blades at the tips4 ,to find the angle one inch from the tips lay off the distance ,,ac1 which is4 #h - #b x #c4adaf or #bd4h inches4 ,,mc gives the right angle4 ,the angle two inches from the tip would be shown by ,,md where ,,ad is #h - #d x #c4adaf or #ah4h inches4 ,any other points can be located in the same manner4 ,illustration3 ,,fig4 #bg4 ,a propeller of the truly helical type delivers a cylinder of air in which all parts move at the same speed as at ,a4 ,a propeller having blades of the same angle throughout their length throws the air as in ,b in which the centre of the cylinder moves more slowly than the outside4 ,illustration3 ,,fig4 #bh4 ,templets for testing and carving a propeller4 ,if desirable1 a number of small templets having the proper angle may be cut out of sheet tin and fastened to a board as shown in ,fig #bh4 ,when making the propeller it can be frequently laid on the templets to see if the proper angle has been secured yet4 ,there are a great many other ways of making propellers for model aeroplanes1 the simplest and best of which are described below4 99,metal ,propellers99 have advantages and disadvantages which may be summed up only to find that as far as efficiency is concerned the advantages outweigh the disadvantages4 ,illustration3 ,,fig4 #bi4 ,a simple method of forming a propeller from sheet metal4 ,the simplest method of making a small metal propeller is to cut a piece of sheet aluminum into the shape shown by ,a in ,fig4 #bi4 ,fold along the dotted lines so that the result is like ,b in the same illustration4 ,the shaft may be a small piece of piano wire passed through the hole in the centre and bent around as shown4 ,illustration3 ,,fig4 #cj4 ,a built-up metal propeller made of aluminum4 ,another method of making a metal propeller which is more suitable for large machines than that just described is illustrated in ,fig4 #cj4 ,the blades are cut out of sheet aluminum to the shape shown and set in the slots in the end of a small aluminum tube4 ,they are held in position with aluminum solder4 ,ordinary solder will not accomplish the work and cannot be used4 ,the shaft is soldered into a hole in the tube halfway between the two blades4 ,illustration3 ,,fig4 #ca4 ,metal ,propeller4 ,the propeller shown in ,fig4 #ca is extensively used by manufacturers of model aeroplanes because of its simplicity and strength4 ,the propeller is cut out of sheet aluminum and then bent and folded4 ,the shaft is held in place by a brass eyelet riveted firmly over on both sides4 ,illustration3 ,,fig4 #cb4 ,method of carving a propeller of the truly helical type4 99,wooden ,screws994 ,single piece screws cut out of a block of wood are easy to make and very efficient4 ,the propeller is laid out on a square or rectangular strip of wood 7according to the pitch71 cut to the required length4 ,a pocket knife or a wood rasp is used to rough the wood down to the shape shown at ,b4 ,it is then finished down to the form shown at ,c4 ,after rubbing with sand-paper a coat of varnish is applied and allowed to dry4 ,the varnish is then rubbed down to a smooth surface4 ,illustration3 ,,fig4 #cc4 ,methods of fastening propellers to shaft4 ,fig4 #cc shows a very good method of mounting the propeller on the shaft4 ,a piece of stiff brass is soldered to one end of a bicycle spoke and bent around the propeller4 ,a small nut made by cutting a spoke nipple is screwed on the end to hold the propeller in position4 7,the same illustration shows another very good method of fastening the propeller to the shaft4 ,the end of the shaft is filed to a sharp point1 bent into the shape shown in the illustration and then driven into the propeller4 ,a small pin hole should be made in the propeller at the place where the sharp point is to enter in order to avoid the possibility of splitting47 ,illustration3 ,,fig4 #cd4 ,method of forming sockets for joining struts1 etc41 by cutting from sheet metal4 ,there are two methods of making propellers by steaming and bending thin wood4 ,american whitewood and spruce are the best woods for the purpose4 ,after steaming place one end of the strip in a vise and holding the other in the fingers twist it into the right shape4 ,fasten it in position and allow it to remain so until dry4 ,then give it a coat of varnish to prevent the absorption of moisture and consequent warping4 ,the method of fastening the shaft1 which in this case is a piece of piano wire or a bicycle spoke is illustrated in ,fig4 #ce4 ,two small pieces of wood shaped like a half cylinder and having a groove cut on the curved surface are glued on either side at the centre4 ,the shaft is then bent around and twisted4 ,illustration3 ,,fig4 #ce4 ,bent wood propellers and the methods of fastening them to the shaft4 ,illustration3 ,,fig4 #cf4 ,propeller blank 7top74 ,carved propeller 7bottom74 ,in order to make the second type the wood must first be bent into shape4 ,it is steamed and bent along the dotted lines4 ,it is attached to the shaft by means of a piece of sheet brass doubled over the edge and soldered to the end of a bicycle spoke4 ,the only disadvantage of this form of propeller is that it is easily broken4 ,it turns very easily with little expenditure of power4 ,illustration3 ,,fig4 #cg4 ,langley type propeller 7top74 ,wright type propeller 7bottom74 99,size of ,propeller499 ,one bad feature about most of the model aeroplanes offered for sale in toy shops is the propeller4 ,in almost every case it is decidedly too small4 ,in order for a model to fly really well the propeller must usually be out of all proportion to the rest of the machine4 ,in fact its size will make the machine appear very awkward and unsightly4 ,illustration3 ,,fig4 #ch4 ,quasi-helical propeller4 ,the enormous slip of small screw propellers when turning rapidly makes them very inefficient4 ,the thrust of the propeller is dependent upon the volume of air sent backwards4 ,a large propeller naturally deflects more air than a small one and so in order for the latter to equal the work of a large propeller it must either have an increased pitch or revolve more rapidly4 ,illustration3 ,,fig4 #ci4 ,blanks for racing 7top7 and chauviere 7bottom7 propellers4 ,a small pitched propeller is less wasteful of power than one having a high pitch and so it is of no advantage to make a small screw do the work of a larger one4 ,it is not only wasteful of energy but also permits the rubber skein to untwist too rapidly4 ,the advantage therefore lies with a propeller of low pitch driven slowly4 ,illustration3 ,,fig4 #dj4 ,the first step in carving a propeller4 ,the blank4 ,hollowing the first blade4 ,illustration3 ,,fig4 #da4 ,one blade hollowed4 ,hollowing the second blade4 ,the average propeller should have a pitch of from #b-c times its diameter1 that is1 the blade should have an angle at the tips of slightly less than #de degrees4 ,the propeller diameter 7of course this rule is not infallible1 but only a general statement7 should be about one-third the spread of the planes4 ,the edges of the blades should come to a clean edge but not be too sharp4 ,illustration3 ,,fig4 #db ,rounding the back of the first blade4 ,rounding the back of the second blade4 ,one of the best means of determining the efficiency of a propeller is to connect it to a small electric motor which will drive it at high speed and by blowing tobacco smoke around it or holding a piece of burning rag nearby and test whether or not the air is thrown out from the sides by centrifugal force4 ,a correctly designed propeller will pull air in from the sides instead of throwing it out4 ,illustration3 ,,fig4 #dc4 ,all carving finished4 ,sandpapering to secure a smooth surface4 ,calculation in fitting a model with a propeller is almost useless4 ,the experimental error is so large that the empirical or cut and try method is the only reliable one4 ,it is best to make a number of propellers of varying pitch and diameter and give to each a thorough tryout on the machine before making a decision4 99,the ,single ,screw ,machine499 ,a propeller placed in the rear of a machine is usually more efficient than a tractor screw placed in front4 ,a machine drags along considerable air with it 7due to skin friction of the planes1 etc471 and so a screw placed in the rear revolves in air which is really traveling with the machine itself and so the effect is somewhat as though it were traveling with the wind4 ,a further advantage of placing the propeller in the rear of the machine lies in the fact that there is less likelihood of damage in landing4 ,illustration3 ,,fig4 #dd4 ,varnishing4 ,the propeller finished4 ,an aeroplane having a single screw always betrays a marked tendency to turn completely over in a direction opposite to that in which the screw is rotating4 ,action and reaction are always equal and opposite in their effects and so the motor has a tendency to rotate the machine against the resistance of the screw as well as to rotate the screw against the resistance of the machine4 ,one way in overcoming this difficulty is to set the two halves of the plane at a slight angle to one another or at a dihedral angle as it is called4 ,then if the machine tends to twist and turn over the lifting power of the lower wing becomes greater as it approaches the horizontal while that of the other wing grows less4 ,accordingly the machine resists and tends to turn back to its normal position4 ,another method is to keep the weight or centre of gravity as low as possible so that the machine will automatically right itself as soon as it begins to turn4 ,the objection to this1 however1 is that the machine will fly very unsteadily on a gusty day 7and most days are more or less gusty74 ,the effect of placing the centre of gravity low is shown in ,fig4 #de4 ,the dotted line represents the centre of pressure acting against a plane ,p4 ,the weight of the machine is centred at ,w4 ,imagine the machine in flight4 ,then the resistance of the plane ,p acting along the dotted line will tend to stop the machine while ,w tends to still go forward because of its inertia4 ,as a result1 the front of the machine tilts upwards and increases the angle of ,p1 which in turn increases the resistance4 ,the machine therefore slows down but ,w tends to still move forward and tilt the machine further until the thrust of the screw is unable to support the weight and so ,w swings back down and beyond the position shown at ,b4 ,the angle of ,p decreases1 the machine travels forward quickly and gathers sufficient speed for ,w to swing up again4 ,thus the performance is repeated and the machine will have a flight path very much like the dotted line shown in the lower part of the illustration4 ,the motion is slight but is sufficient to considerably shorten the length of the flight4 ,illustration3 ,,fig4 #de4 ,accentricity4 ,the effect of placing the center of gravity too low4 ,if the machine meets wind1 the motion is somewhat increased4 ,in fact the author has seen a small biplane turn completely over and actually loop the loop4 ,when the machine flies with the wind the effect is largely reduced4 ,if the wind is of just the right strength and comes from the rear1 the machine will fly quite steadily4 ,if too strong1 however1 the model will dive to the ground4 ,a tail somewhat dampens the swing while an elevator will slightly increase it4 ,the only other methods of partially mitigating the evils of a single screw are to ballast the machine1 that is1 place a weight on one side or to give one plane an increased sustaining surface4 ,the first may be dismissed immediately because the weight will cause one side of the machine to drop as the elastic runs down and the reaction of the propeller becomes smaller4 ,the last named method is the usual one employed4 ,the wing on that side of the machine opposite to which the propeller is revolving is given a larger surface than the other and so exerts a greater lift on that side4 ,this also has disadvantages1 however1 for by giving one wing a greater lifting power the machine is caused to fly in a long spiral path when the propeller begins to run down and when it stops completely to glide in the same manner4 ,illustration3 ,,fig4 #df4 ,simplest method of fitting two propellers to a model aeroplane4 ,the propeller should be placed as nearly as possible on a level with the planes4 ,the centre of pressure on the planes and the centre of gravity should coincide if true stability is desired4 ,the centre of pressure on a machine having the planes set at a dihedral angle is halfway between the lowest point and the highest providing the planes are the same width all the way along4 ,if they taper towards the ends it is slightly lower while if they are wider at the extremities it is higher4 ,the rubber skein and the propeller are usually placed on top of the fusellage of a dihedral winged machine4 99,the ,double ,propeller ,machine499 ,the best method and the only one which entirely removes the difficulty is to fit the machine with two propellers4 ,a machine having two propellers to the author's mind is the only one worth much attention4 ,fig4 #df illustrates the simplest arrangement for fitting two propellers to a machine4 ,in the first a second propeller is attached to the other end of the skein4 ,at first it might seem in the second arrangement that there would be difficulty in getting the screws to revolve at the same speed4 ,however1 if the propellers are similar and the same number of rubber strands employed to drive each1 the difference will be so small as to be negligible4 ,when the first arrangement is employed the pitch of the screw in the rear must be slightly greater than that in the front because it is revolving in the slip of the latter4 ,placing both propellers on a double shaft on the same axis has the disadvantage of decreasing the efficiency of the propellers because they are operating in each other's draft4 ,illustration3 ,,fig4 #dg4 ,a method of arranging two propellers on the same axis4 ,the first of these methods is undoubtedly the best construction4 ,it is then possible to use the same rubber skein to drive both propellers4 ,also any possible difference in their speed will not so readily cause the machine to change its course as if the propellers were alongside of each other4 ,when two propellers are used in this latter position it is a very good idea to fit them with two small pulleys and a connecting belt so that any tendency for a difference in speed between the two will be immediately equalized4 ,the power absorbed varies directly with the volume of air acted upon and the square of the speed with which it moves away4 ,if the pitch of the propeller or its rate of revolution were doubled1 four times the power previously required would be necessary4 ,vice versa1 decreasing the rate of revolution or the pitch by one-half will make only one-fourth the power previously required necessary4 ,doubling the speed and doubling the diameter requires eight times more power4 ,doubling the diameter1 halving the pitch and halving the speed will give twice the thrust for the same power as in the first case4 ,,chapter ,,vii4 ,,bearings1 ,,thrust ,,blocks ,,and ,,gears4 ,since the power available for driving the model is very limited it is obvious that every precaution should be taken to enable the propeller to absorb every last fraction of energy stored in the motor4 ,with this end in view the bearing or thrust block in which the shaft of the propeller revolves should receive careful attention in order to remove as far as possible all causes which would result in friction4 ,illustration3 ,,fig4 #dh4 ,simple bearings4 ,the simplest form of bearing is a simple piece of sheet brass or aluminum having a hole drilled through it and bent up at right angles so that it may be lasted to the frame as shown in ,fig4 #dh by ,a4 ,single bearings of this type are employed on the model aeroplanes manufactured by toy makers whose only desire is to flood the department stores and toy shops around ,christmas time with their impossible machines4 ,such single bearings are a decidedly poor and unsatisfactory construction4 ,unless the elastic is very short it soon begins to vibrate in unwinding4 ,since the rubber is directly connected to the propeller shaft1 the propeller is set into vibration as shown by the dotted lines in the second part of ,fig4 #dh4 ,the long blades of the propeller considerably magnify the motion and there is a very appreciable loss of power due to the erratic path of the propeller and the increased friction at the bearing4 ,the rubber skein also offers considerably more resistance to the forward travel of the machine than if it were not in vibration4 ,illustration3 ,,fig4 #di4 ,double bearings4 ,the advantage of a double bearing more than offsets the added weight4 ,such a bearing is formed out of a piece of sheet brass bent up at right angles at both ends as in ,fig4 #di4 ,the third method of construction in the accompanying figure makes it possible to employ lighter sheet metal in the construction of the bearing and still resist the pull of the rubber and the thrust of the propeller successfully4 ,illustration3 ,,fig4 #ej4 ,simple thrust bearing4 99,friction is reduced99 and the thrust taken up by placing one or two glass beads between the propeller and the bearing4 ,only those beads which are flat1 with parallel sides and have a round hole in the centre1 should be used4 ,four or five copper washers or rings may be made to serve the same purpose with equally good results4 ,another method is to employ two washers separated by a small spiral spring4 ,such an arrangement is employed on some of the ,french models and might be called a friction thrust4 ,that is1 when the rubber skein is wound up tight and the propeller is released the friction acts as a brake and reduces the speed1 preventing the propeller from racing4 ,as the elastic unwinds1 the tension1 and with it also1 the friction becomes less so that the propeller revolves more rapidly and maintains a somewhat even speed4 ,the importance of preserving as far as possible an even propeller speed can hardly be overestimated and that is why such emphasis has been laid in several places upon the desirability of a model whose propeller is driven by a long skein of rubber composed of the fewest possible number of strands4 ,illustration3 ,,fig4 #ea4 ,ball thrust bearing4 99,ball bearing99 thrusts are by all means the most desirable1 but not all models are large enough to accommodate their size and weight4 ,wherever it is possible1 however1 to use them it should be done4 ,the increased amount of energy available for turning the propeller will make it possible to employ less rubber and so increase the number of turns and consequently the length of the flight4 ,illustration3 ,,fig4 #eb4 ,hooks4 99,the hooks99 at either end of the rubber skein are apt to cut the rubber unless some precautions are taken to prevent it4 ,this can be done by binding with cotton thread or slipping a piece of rubber tubing or aluminum over the hook as shown in ,fig4 #eb4 ,,chapter ,,viii4 ,,building ,,and ,,flying ,,model ,,aeroplanes4 ,the ,blerioplane ,flyer4 7,plate ,,ii47 ,the ,blerioplane ,flyer is of the simple monoplane type and is very easily constructed4 ,it is a remarkable flyer when properly adjusted and will fly over one hundred and fifty feet4 ,the motor base is a piece of #c_/af dowel1 #ab inches long4 ,the edges of the planes are made of fine steel piano wire bent to the shape shown in ,plate ,i4 ,the planes are covered with silk which is carefully turned over at the edges1 around the wires and fastened either by sewing or with bamboo varnish4 ,the dimensions of the planes are clearly shown in the illustration4 ,illustration3 ,plate ,,iv4 ,the propeller is placed at the rear of the machine1 the smaller plane being considered the elevator4 ,the bearing is shown in detail in the accompanying illustration4 ,it is made by folding and bending a piece of sheet brass into the shape shown4 ,a piece of steel piano wire is passed through the forward end of the motor base to act as an anchor hook for the rubber band4 ,the propeller is easily wound up by hand4 ,one side of the main plane will have to be made slightly larger than the other in some cases in order to counteract the twisting action of the propeller by one side of the machine more of a lift than the other4 ,the planes are adjusted by bending the wire edge4 ,they should form a slight dihedral angle4 ,the rubber strands lie along the top of the motor base so as to bring the centre of the propeller thrust coincident with the centre of pressure on the planes4 ,bending the front edge of the planes down will cause the machine to take a downward path while bending them up will cause the aeroplane to fly higher4 ,a little experimental work will determine the proper position4 ,the ,monoplane ,flyer4 7,plate ,,iii47 ,the fusellage or backbone of the machine is formed out of a piece of thin walled aluminum tubing having an outside diameter of one-quarter of an inch and measuring twenty-four inches long4 ,the framework of the planes is formed out of rattan reed1 one-eighth of an inch in diameter4 ,the main plane is #ai inches across from tip to tip4 ,it is #d inches deep at the centre and #e #a_/b inches at the widest point near the tips4 ,the framework is spread near the centre of each wing by a piece of rattan reed #e #a_/d inches long4 ,the ends of the reed are joined by rolling a small piece of copper sheet into a tube and closing it around the reed tightly with a pair of pliers4 ,the reed forming the frame of the plane passes through a hole in the aluminum tube4 ,illustration3 ,plate ,v4 ,the plane forming the tail is almost the same in all respects save that of size as the forward main plane4 ,a small vertical fin #c inches wide and #c #a_/b inches deep is placed below the tail plane1 in line with the backbone to act as a keel or rudder and hold the machine to a straight course4 ,the covering of the planes is ,china silk or bamboo paper coated with bamboo varnish4 ,the bearing is made out of sheet brass bent into the shape shown and fastened to the tube by lashing with a wire4 ,the propeller should be #f inches in diameter4 ,one or two glass beads placed between the bearing and the propeller will reduce the friction4 ,the motive power consists of #h strands of #c_/cb x #c_/cb inch rubber connected at one end to the propeller and at the other to a hook at the rear end of the aluminum tube4 ,the machine is provided with two piano wire skids to protect the propeller in landing4 ,if the aeroplane tends to rise too abruptly when in flight1 bend the rear edge of the main planes up4 ,if on the contrary1 it dips or dives1 bend the rear edge down4 ,the ,baby ,racer4 7,plate ,,iv47 ,this is one of the smallest and simplest machines of the twin propelled racing models4 ,the two main members of the motor base or fusellage are #a_/h x #a_/h in section and #e #a_/b inches long4 ,one end of each is tapered and then glued and bound with strong thread4 ,the opposite ends are held apart by a brace made from flat steel wire4 ,the wire is hammered out flat at the ends and drilled with a small hole to form a propeller bearing4 ,the details of the brace are given in the upper right-hand corner of the plate4 ,the brace is fastened to the sticks by lashing with thread4 ,it is well to place a small wooden brace across the frame about midway of its length4 ,this will serve to considerably stiffen the frame and prevent it from sagging under the tension of the rubber bands4 ,illustration3 ,plate ,,vi4 ,the planes are cut from stiff paper4 ,the main plane is #g #a_/d inches across and the elevation plane #b #c_/d inches4 ,each plane is cut to the shape shown in the drawings and stiffened by gluing a thin wooden strip across the front edges of the planes4 ,a small piece of steel wire is passed around the front end of the frame and bent to form two anchor hooks for the rubber bands4 ,it is then lashed firmly into position and the thread covered with glue so that it will not untwist if broken4 ,the propellers are made from thin whitewood or veneer4 ,they are four inches in diameter and formed by steaming and bending4 ,the shaft is formed out of brass wire by bending it around the centre of the propeller4 ,two small beads are slipped over the shaft to eliminate friction between the propeller and the bearing4 ,the planes are held in position by small rubber bands4 ,the sketches in ,fig4 #ec explain exactly how this is accomplished4 ,illustration3 ,,fig4 #ec4 ,method of holding plane to frame with rubber bands4 ,the sticks glued along the front edges of the planes are sufficient to give them a slight angle4 ,the machine is controlled by moving the planes back and forth so as to shift their lifting effort to the proper position4 ,illustration3 ,plate ,,vii4 ,the motor consists of two strands of #c_/cb x #c_/cb rubber attached to each propeller4 ,the ,peerless ,racer4 7,plate ,v47 ,this excellent flyer is very simple to put together and by carefully following the directions anyone can construct the machine and obtain splendid flights4 ,the two long members of the frame or fusellage1 marked ,a and ,b in the drawing are #cf inches in length4 ,they measure #a_/d x #c_/af in cross section4 ,bevel one #a_/d inch side of one end of each of the two long sticks so that they can be joined to form an angle as shown in the upper right hand corner of the accompanying plate4 ,the tip should not be greater than one quarter inch in width after joining4 ,glue the ends together using plenty of glue and before it has set1 bind with strong linen thread1 starting at the tip and winding back for about one inch4 ,the surplus glue will squeeze out between the threads and when hard prevent them from unwinding if broken4 ,an aluminum brace must be made by flattening the ends of a piece of #a_/h inch aluminum rod4 ,the rod should be about #e #a_/d inches long so that when the brace is placed #e_/h of an inch back from the ends of the sticks1 the distance between them will be about #d #c_/d inches4 ,glue and bind a small wooden cross brace to the frame1 #ab inches from the rear end4 ,the brace should be made #c_/af of an inch wide and #c_/cb of an inch thick4 ,the elevating blocks are #c_/d of an inch long1 #c_/af of an inch thick1 #c_/h of an inch high at the rear and #a_/b inch high at the front4 ,they should be fastened to the machine by gluing and binding six inches back from the tip4 ,the highest part of the blocks should be towards the front of the machine as shown in the illustration4 ,be careful to see that the frame is lined up perfectly true and then lay it aside until the glue dries4 ,illustration3 ,,fig4 #ed4 ,the ,peerless ,racer4 ,the propeller bearings are made from ,no4 #ah hard sheet aluminum4 ,it is cut into a strip #a_/d of an inch wide and then drilled and bent as shown in the accompanying illustrations4 ,the bearings are screwed on the rear ends of the sticks ,a and ,b4 ,it is also a good plan to bind some linen thread around tightly4 ,pass the propellers through the bearings and bend the end of the shaft into the shape of a hook1 being very careful not to twist the bearings during the operation4 ,a bead should be slipped over the propeller shaft previous to passing it through the bearing so that it comes between the bearing and the propeller and lessens the friction4 ,bore a small hole through the frame of the machine #a_/b inch back from the tip1 making the hole pass from side to side4 ,pass a piece of stiff wire through this hole and bend back each end snugly to the frame to form the anchor hooks as illustrated4 ,bind some thread over the anchor hooks to keep them from twisting4 ,bend two small pieces of wire into ,s shaped hooks and slip one over each of the anchor hooks4 ,illustration3 ,plate ,,viii4 ,pass the rubber skein through one of the ,s hooks and back to the hook in the end of the propeller shaft1 weaving it back and forth seven times so that there are seven strands4 ,do the same with the other propeller4 ,the ends of the rubber must be tied to the hook with some strong cotton cord4 ,the cord should be soft and the rubber should be passed loosely around the hook so that it will not easily become cut4 ,the planes are made of hard fibre #a_/cb of an inch thick4 ,the main plane is #bb inches long and #c #a_/b inches wide4 ,the elevating plane is #h inches long and #c #a_/b inches wide4 ,the ends are rounded as shown in the illustration4 ,glue a strip of wood #a_/af x #c_/af inches to the front edge of each plane4 ,the strip for the large main plane should be #ai inches long and that for the elevating plane #e inches4 ,the edges should be smoothed with a piece of fine sandpaper and rubbed down until they are dry4 ,the planes are attached to the frame by rubber bands in the usual manner4 ,the edges of the planes should be squeezed together slightly until they are slightly concave on the under side4 ,the position of the main plane will have to be determined by trial4 ,the front edge of the elevating plane should rest on the elevating blocks4 ,the propeller should be given from #fjj-gjj turns4 ,the propellers should be six inches in diameter and of medium pitch4 ,the ,peerless ,racer is a splendid flyer and will fly over #a1jjj feet if properly adjusted4 ,the ,competition ,flyer4 7,plates ,,vi and ,,vii47 ,the ,competition ,flyer does not differ materially from the ,peerless ,racer just described except in some of the details of construction4 ,the motor base of the machine is composed of two long members #cf inches in length tapered and lashed together at one end in the usual manner4 ,the other ends are held apart by a wooden brace 7marked a7 about #d #g_/h inches long4 ,two other braces 7marked b and c7 are placed at equal distances along the frame4 ,the bearings used on this machine are similar to those used on the ,peerless ,racer and are fastened to the rear end of the frame by three small screws4 ,illustration3 ,plate ,,ix4 ,the planes of this machine are built up planes1 that is1 they are double surfaced4 ,the main plane is #bd inches long and four inches broad4 ,the accompanying illustration shows the details of the planes4 ,the long members of the planes are made of whitewood or spruce and the edges and ribs are split bamboo4 ,the elevating plane is #i #a_/b inches long and five inches wide4 ,the planes are covered with bamboo paper and then given a coat of bamboo varnish4 ,the front plane is tilted upwards by two small elevating blocks similar to those used on the ,peerless ,racer4 ,the machine is fitted with skids made by bending #c_/cb inch square split bamboo into the shape shown and lashing them to the frame4 ,the skids protect the planes and the propeller of the machine from possible damage in landing4 ,the propellers should be of the racing type1 six inches in diameter and carved out from a blank in the method described in the chapter on propellers4 ,the planes are held to the frame of the machine by rubber bands in the usual manner4 ,their exact position will have to be determined by experiment4 ,the ,long ,distance ,racer4 7,plates ,,viii and ,,ix47 ,the ,long ,distance ,racer is a model adapted from the ,competition ,flyer and similar to it in many respects4 ,the drawings show the dimensions and arrangement of the various parts sufficiently well so that little comment is necessary4 ,the planes are of the built-up type1 being made entirely from split bamboo according to the size and shape shown in the drawings4 ,they are covered with bamboo paper and given two coats of bamboo varnish4 ,the propellers are of the racing type and carved from wood in the manner described in the chapter on propellers4 ,illustration3 ,plate ,x4 ,the machine is fitted with skids to prevent possible damage to the propeller and planes4 ,the front plane is bent so as to form a slight dihedral angle4 ,this tends to make the machine keep to a straight course4 ,illustration3 ,,fig4 #ee4 ,racing blank and propeller4 ,the rubber skeins are each composed of #g to #aj strands of #c_/cb x #c_/cb inch rubber4 ,the best number will have to be determined for each particular machine4 ,fleming-,williams ,flyer4 7,plate ,x47 ,the ,fleming-,williams model is a type well known in ,england where it has won many prizes4 ,the motor base is a piece of ,t section wood #dh inches long4 ,the detailed dimensions of the ,t section are given on the plate4 ,a crosspiece ,b1 #e_/af square and #h #a_/b inches long is fastened at one end of the motor by gluing and lashing as shown in the drawing4 ,two braces1 ,c1 ,c1 #a_/h x #a_/d inches in section are lashed near the ends of the cross piece and brought together on the motor base so as to form a triangle4 ,this is covered with bamboo paper to form a triangular shaped plane called the stabilizer4 ,the bearings are simple strips of hard sheet aluminum bent around the ends of the cross brace and fastened into place with several small screws4 ,the main plane is formed by bending #a_/cbnd inch drill rod into the shape shown in the detailed drawing on the plate4 ,mark out the wing form on a board1 and by means of nails driven into the board around the outline1 bend the drill rod into shape1 splicing the ends neatly with some fine wire4 ,then bend the ribs into shape and twist the ends around the wing form4 ,it is a very good plan to solder all joints4 ,cover the frame with bamboo paper and when dry apply two coats of bamboo varnish4 ,drill a hole through the motor base at the front to receive a piece of steel wire4 ,bend the wire to form two anchor hooks4 ,the propellers are each #h inches in diameter4 ,each propeller is driven by a skein composed of #ej feet of #c_/cb x #c_/cb rubber4 ,the main plane is fastened temporarily to the motor base with rubber bands4 ,its normal position is about #ag inches from the tip of the machine1 but its exact position will have to be determined by experiment4 ,after it is formed1 the plane should be fastened into position more securely4 ,the propellers must be of opposite pitch and wound in opposite directions4 ,each should receive from #ejj to #fjj turns4 ,the model is launched by casting from the hand as though it were a spear4 ,,flying ,,the ,,models4 ,a suitable winder of some sort is essential for winding up the strands of a model aeroplane4 ,a winder is most easily made from an egg beater of the dover pattern4 ,the egg beater is dismantled and fitted up in the manner shown in the illustration4 ,the blades are fitted with hooks which engage those on the end of the rubber skein4 ,illustration3 ,plate ,,xi4 ,winding a model4 ,in order to wind a model remove the skeins from the anchor hooks and hook them on the winder4 ,have some one hold the machine at the rear end1 slipping the fingers around the propellers to keep them from untwisting4 ,stretch the skeins out to about twice their normal length and commence to wind4 ,gradually shorten the skein as the winding progresses until1 at the time it is finished1 it is down to its normal length4 ,illustration3 ,,fig4 #ef4 ,a winder made from an egg beater4 ,in winding the machine be careful to do it in such a manner that the machine is not wrenched or twisted4 ,always count the number of turns given the winder so that there will be no danger of twisting them up too tightly and causing them to break4 ,the successful flying of a model aeroplane is an acquired knack just like swimming or bicycle riding4 ,it is usually necessary to make several attempts before the model can be made to fly well4 ,as soon as one gets acquainted with the vagaries of a model aeroplane it is a very easy matter to launch and adjust a machine4 ,the large page in the front of the book shows the right way of launching a model4 ,the fingers are passed over the propellers and the frame grasped firmly1 but gently4 ,the tip of the machine should be raised and pointed slightly upward4 ,then give it a gentle slow push forward and release it4 ,always launch a machine into the wind1 that is against it4 ,the machine will fly forward1 rise rapidly1 turn completely around and race down the wind for a thousand feet or more in the case of some of the larger machines described in this book when properly adjusted4 ,all the models described in this book with the exception of the first three must be flown out of doors because1 when properly handled1 they will travel upwards of one thousand feet4 99,you can not afford to be without99 99,aeronautics99 ,each month it gives articles of value1 based on definite results obtained by the foremost experimenters-propellers surfaces1 general design1 etc4 ,successful aeroplanes involving new features are described in minute detail1 with scale drawings and all dimensions4 ,articles of practical interest in the painting and finishing of woodwork1 making of propellers1 landing chasses1 etc4 ,monthly page of drawings of constructional details of machines all over the world4 ,questions involving principles and experimental data of aerodynamos1 and of motors1 answered in full by an authority4 ,every issue a complete directory of ,american manufacturers of planes and all accessories4 ,exclusive principal articles only are published4 ,a file of ,,aeronautics is more valuable than any book yet written on the subject of ,aeronautics4 ,,aeronautics is the oldest aero journal in ,america2 established #aijg4 ,send for a sample copy and compare it with any other aeronautical magazine4 ,ask any reader of ,,aeronautics for his opinion as to its worth4 ,all aeronautical patents issued in the ,u4 ,s4 are listed monthly4 99,subscription #c4jj yearly499 99,send for ,low ,rate ,combination99 99,offer and ,sample ,copy99 ,any of the ,following ,practical ,books 99will be sent ,at ,once1 ,post-paid on receipt of price499 ,there is very little danger of losing currency in a letter if the following directions are observed3 ,cut a circular hole the diameter of the coin in a piece of cardboard1 of sufficient size to fit closely in the envelope4 ,the cardboard should be no thicker than the coin4 ,insert the coin in the hole and paste a piece of paper on both sides of the cardboard to prevent the coin from falling out4 ,,we ,,have ,,the ,,largest ,,line ,,of ,,twenty-,,five ,,cent ,,books ,,cole ,,morgan ,publishers of the ,arts and ,sciences ,series #ahg ,n4 #aath ,street1 ,,newark1 ,n4 ,j4 ,wireless ,telegraphy and ,telephony ,simply ,explained ,by ,,alfred ,p4 ,,morgan ,a ,,new ,,book by the author of ,wireless ,telegraph ,construction for ,amateurs4 ,this is undoubtedly one of the most complete and comprehensive treatises on the subject ever published1 and a close study of its pages will enable one to master all the details of the wireless transmission of messages4 ,the author has filled a long-felt want and has succeeded in furnishing a lucid1 comprehensible explanation in simple language of the theory and practice of wireless telegraphy and telephony4 ,the book treats the subject from an entirely new standpoint4 ,several very novel and original ideas have been carried out in its making4 ,it is well illustrated by over one hundred and fifty interesting photographs and drawings4 ,all diagrams have been made in perspective showing the instruments as they actually appear in practice4 ,the drawings are carefully keyed and labeled4 ,many of the photographs are accompanied by phantom drawings which reveal the name and purpose of each part4 ,it is a book which the wireless experimenter cannot afford to be without4 ,it will prove even more valuable to the layman4 ,among the contents are3 ,introductory4 ,wireless ,transmission and reception4 ,the ether4 ,electrical ,oscillations4 ,electro-magnetic waves4 ,the means for radiating and intercepting electric waves4 ,aerial ,systems4 ,earth ,connection4 ,the ,transmitting ,apparatus4 ,current ,supply4 ,spark ,coils and ,transformers4 ,condensers4 ,helixes4 ,spark ,gaps4 ,anchor ,gaps4 ,aerial ,switches1 ,etc4 ,the ,receiving ,apparatus4 ,detectors1 etc4 ,tuning ,coils and ,loose ,couplers4 ,variable ,condensers4 ,tuning and ,coupling4 ,directive ,wave ,telegraphy4 ,the ,dignity of ,wireless4 ,its applications and service4 ,wireless in the army and navy4 ,wireless on an aeroplane4 ,how a message is sent and received4 ,the ,wireless ,telephone4 ,the ,ear4 ,how we hear4 ,sound and ,sound ,waves4 ,the ,vocal ,cords4 ,the ,structure of ,speech4 ,the ,telephone ,transmitter and ,receiver4 ,the ,photophone4 ,the ,thermophone4 ,the ,selenium4 ,handsomely bound in cloth with embossed cover 99,postpaid1 #a4jj99 99,build ,your ,own ,wireless ,instruments99 99,complete ,up-to-the-,minute ,authentic ,practical99 ,,wireless ,,telegraph ,,construction ,,for ,,amateurs ,by ,,alfred ,,powell ,,morgan #c;d ,,edition #bbj ,pages #afc ,illustrations 99,price991 #a4ej1 99,postpaid99 99,handsomely ,bound in ,silk ,cloth99 ,thoroughly up to date and unusually complete4 ,gives in minute detail1 full directions for constructing wireless apparatus and various outfits capable of receiving from #ajj to #a1ejj miles and transmitting #c to #ajj miles4 ,also clearly explains the purpose and action of each instrument4 ,directions for ,operating and ,adjusting1 etc4 99,a ,,splendid ,,treatise ,,of ,,wireless ,,along99 99,,constructive ,,lines99 ,price1 #a4ej1 ,postpaid 99,,contents ,,of ,,chapters99 ,i4--,introduction4 ,,ii4--,the ,apparatus4 ,,iii4--,aerials and ,earth ,connections4 ,,iv4--,induction ,coils4 ,v4--,interrupters4 ,,vi4--,transformers4 ,,vii4--,oscillation ,condensers and ,leyden ,jars4 ,,viii4--,spark ,gaps or ,oscillators4 ,,ix4--,transmitting ,helixes4 ,x4--,keys4 ,,xi4--,aerial ,switches and ,anchor ,gaps4 ,,xii4--,hot ,wire ,ammeter4 ,,xiii4--,oscillation ,detectors4 ,,xiv4--,tuning ,coils and ,tuning ,transformers4 ,,xv4--,receiving ,condensers4 ,,xvi4--,telephone ,receivers and ,headbands4 ,,xvii4--,operation4 ,,xviii4--,the ,amateur and the ,wireless ,law4 ,how to ,secure a ,license4 ,oscillation ,helix4 ,quenched ,spark ,gap4 ,rotary ,gaps4 ,kick-,back4 ,the ,variometer4 ,new ,crystal ,detectors4 ,the ,audion4--,appendix4 ,,endorsed ,,by ,,wireless ,,clubs ,,throughout ,,the ,,country ,,as ,,being ,,the ,,most ,,practical ,,book ,,published ,,on ,,wireless4 ,the value of this book has been greatly increased by the addition of much new subject matter and many illustrations of recent interest4 ,the new text explains fully how to build the most recent forms of ,quenched ,gaps1 ,rotary ,gaps1 ,dough-,nut ,tuners1 ,kick-back ,preventers1 ,audion ,detectors and numerous other instruments1 accompanied by dimensioned working drawings4 ,several very interesting and instructive photographs have been included4 99,if you are interested in ,wireless you need this book499 ,,the ,,amateur',s ,,wireless ,,handy ,,book ,,you ,,cannot ,,afford ,,to ,,be ,,without ,,this ,,book ,price #be ,cents1 ,postpaid ,if you want to be an expert and an authority you must surround yourself with all available aids and helps4 ,you have one of the best in the ,,amateur',s ,,wireless ,,handy ,,book4 ,it contains #cf pages of wireless calls1 #aejj in all4 ,the list is complete and thoroughly revised to date and embodies all the wireless land stations in the world1 the ships of the ,merchant ,marine1 the ,u4 ,s4 ,navy1 the ,revenue ,service1 etc4 ,they are all there4 ,all the calls are classified alphabetically4 ,the list is the most reliable and complete in existence4 ,all obsolete stations have been abolished4 ,all corrections and changes have been made from the official lists4 99,,but1 ,,that ,,is ,,not ,,all499 ,pages with spaces to fill in names1 call letters1 etc41 make it possible to keep an accurate record of nearby amateur stations4 ,,the ,,codes1 ,,both ,,morse ,,and ,,continental1 are shown in the form of two large full-page charts printed in heavy black type so that they can be read from a distance4 ,a ,,beginner',s ,,speed ,,chart of both ,codes so arranged that the codes may be quickly learned or consulted is provided4 ,all the ,abbreviations used so constantly by the wireless operator to save time and labor are included4 ,there are a couple of pages of them4 99,and last but not least99 ,and last but not least ,over #ajj large hook-ups of wiring diagrams fully illustrated in a concise and clear manner4 ,loop and straightaway aerials1 grounds1 helixes1 spark gaps1 anchor gaps1 leyden jars1 induction coils1 transformers1 keys1 aerial switches1 tuning coils1 loading coils1 loose couplers1 variometers1 fixed condensers1 silicon1 electrolytic1 carborundum1 perikon and audion detectors1 telephones1 potentiometers1 etc41 you can find them all and how to connect4 ,a hook-up for any set accompanied by full explanation4 ,none are missing4 ,they are all there4 ,there are no two alike4 ,the most complete and reliable data ever collected4 ,the result of thousands of experiments by some of the most famous wireless experts in the country4 ,read now before the supply is exhausted or you forget4 ,you will be sorry if you don't4 99,price1 #be ,cents1 ,postpaid99 ,note3 ,this book is always kept up-to-date by frequently issuing new editions4 ,send for the latest copy4 99,the ,operation of ,wireless ,telegraph ,apparatus99 ,do your ,wireless friends come to you for advice on constructing and operating their apparatus or do you go to them for information8 ,here is a chance for ,,you to become the authority4 99,this book is a necessity to every ,progressive ,experimenter499 99,it shows how to obtain the very highest efficiency from any station1 and how to comply with the law4 ,how to tune1 adjust your detector1 spark gap1 phones1 etc499 ,price1 #be ,cents1 ,postpaid4 ,this book was written for the wireless experimenter who has passed the amateur stage1 but explains how the beginner also can obtain the very best results from his station4 ,it contains much useful information to this end and many kinks4 99,,it ,,shows ,,how99 to receive or send on long or short wave lengths with highest efficiency1 to tune for longest distance reception of messages1 to use the buzzer test1 how to test and connect condensers1 receivers1 etc41 how to use receiving transformers1 variometers1 etc41 all with highest efficiency in view4 99,,it ,,also ,,describes99 the construction and use of a simple1 inexpensive wave meter to tune the station to any desired wave length1 and tells how to obtain a sharp wave and a pure wave4 99,,extracts ,,from ,,the ,,law99 are also given in such a manner that they are easily understood4 ,,the ,,model ,,library ,,series 99#be;c4 ,,books499 99,,electricity499 ,the study of1 and its laws for beginners1 comprising the laws of electric current generation and flow1 ,ohm's law1 galvanism1 magnetism1 induction1 principles of dynamos and motors1 wiring1 with explanations of simple mathematics as applied to electrical calculations4 ,by ,n4 ,h4 ,,schneider4 ,with #ee original illustrations and #f tables4 99,,dry ,,batteries499 ,a practical handbook on the designing1 filling and finishing of dry batteries1 with tables1 for automobiles1 gas engine1 medical and coil work1 electric bells1 alarms1 telephones1 experiments and all purposes requiring a first-rate battery4 ,fully illustrated with #cj original drawings4 99,,electrical ,,circuits ,,and ,,diagrams499 ,being a selection of original up-to-date and practical diagrams for installing annunciators1 alarms1 bells1 electric gas lighting1 telephones1 electric power light and wiring circuits1 induction coils1 gas engine igniters1 dynamos and motors1 armature windings4 ,by ,n4 ,h4 ,,schneider4 99,,electric ,,bells ,,and ,,alarms499 ,how to install them4 ,by ,n4 ,h4 ,,schneider4 ,including batteries1 wire and wiring1 circuits1 pushes1 bells1 burglar alarms1 high and low water alarms1 fire alarms1 ,thermostats1 annunciators1 and the locating and remedying of faults4 ,with #ef original diagrams4 99,,modern ,,primary ,,batteries499 ,their construction1 use and maintenance1 including batteries for telephones1 telegraphs1 motors1 electric lights1 induction coils1 and for all experimental work4 ,by ,n4 ,h4 ,,schneider4 #id pages1 #ee illustrations4 ,the best and latest ,american book on the subject4 99,,experimenting ,,with ,,induction ,,coils499 ,h4 ,s4 ,,norrie1 author of ,induction ,coils and ,coil ,making4 ,a most instructive little book1 full of practical and interesting experiments1 fully explained in plain language with numerous hints and suggestions for evening entertainments4 ,arranged under the following headings3 ,introduction2 ,the ,handling of ,ruhmkorff ,coil2 ,experiments with ,sparks2 ,effects in the ,vacuum2 ,induction and ,wireless ,telegraphy4 ,with #cf original illustrations4 ,in the press 99,,small ,,accumulators499 ,how made and used1 by ,p4 ,marshall4 ,giving full descriptions how to make all the parts1 assemble them1 charge the cells and run them1 with examples of their practical application4 ,useful receipts and memoranda and a glossary of technical terms4 #hj pages1 #dj illustrations1 paper4 99,,electric ,,gas ,,lighting499 ,how to install ,electric gas igniting apparatus including the jump spark and multiple systems for all purposes4 ,also the care and selection of suitable batteries1 wiring and repairs1 by ,h4 ,s4 ,,norrie4 #aja pages1 #eg illustrations1 paper 99,,the ,,wimshurst ,,machine4 ,,how ,,to ,,make ,,and ,,use ,,it499 ,a practical handbook on the construction and working of ,wimshurst machines1 including radiography and wireless telegraphy and other static electrical apparatus4 ,by ,a4 ,w4 ,marshall4 ,second edition1 revised and enlarged4 ,containing a number of sectional drawings and details to scale4 ,contents of chapters3 #a4 ,introductory4 #b4 ,static ,electricity4 #c4 ,the electrophorus4 #d4 ,the ,electroscope4 #e4 ,condensers4 #f4 ,the ,leyden ,jar4 #g4 ,the ,parts of a ,wimshurst ,machine and ,their ,use4 #h4 ,making and ,management of ,wimshurst ,machines4 #i4 ,some ,examples of ,wimshurst ,machines1 small machines4 #aj4 ,complete detailed drawings and particulars for the construction of a #bd-;inch plate machine4 #aa4 ,the ,wimshurst machine for ,x-ray work with detailed drawings4 #ab4 ,experiments for ,wimshurst machine4 #aab pages1 #cj illustrations and plates4 99,,wireless ,,telephone ,,construction499 ,by ,newton ,harrison4 ,a comprehensive explanation of the making of a ,wireless ,telephone ,equipment4 ,both the transmitting and receiving stations fully explained with details of construction sufficient to give an intelligent reader a good start in building a ,wireless ,telephone system and in operating it4 #gd pages and #dc illustrations4 99,,low ,,voltage ,,electric ,,lighting ,,with ,,the ,,storage ,,battery499 ,specially applicable to ,country ,houses1 ,farms1 ,small ,settlements1 ,launches1 ,yachts1 etc4 ,by ,norman ,h4 ,schneider4 ,giving full details and illustrations of the most up-to-date small ,american ,plants4 ,contents of chapters4 #a4 ,introduction4 #b4 ,the ,storage ,battery4 #c4 ,estimating the ,installation4 #d4 ,the ,electric ,plant4 #e4 ,some ,typical ,plants4 #f4 ,installation and ,operation4 #ie pages1 #bg illustrations4 99,,plans ,,and ,,specifications ,,for ,,wireless ,,telegraph ,,sets1 ,part ,,ii991 by ,a4 ,f4 ,collins4 ,complete and detailed data for constructing a five to ten mile set1 also a ten to twenty-five mile set4 #a4 ,a five to ten mile tuned transmitter4 #b4 ,a five to ten mile tuned coherer receptor4 #c4 ,a five to ten mile tuned auto-detector receptor4 #d and #e4 ,a ten to twenty-five mile tuned transmitter4 #f4 ,a ten to twenty-five mile tuned coherer receptor4 #g4 ,a ten to twenty-five mile auto-detector receptor4 #hj pages1 #fc illustrations4 99,,plans ,,and ,,specifications ,,for ,,wireless ,,telegraph ,,sets1 ,part ,i991 by ,a4 ,frederick ,collins4 ,complete and detailed instructions for making an experimental set1 also a one to five mile set4 #a4 ,an experimental transmitter4 ,an experimental receptor4 #c4 ,a one to five mile transmitter4 #d4 ,a one to five miles coherer receptor4 #e4 ,a one to five mile auto-receptor4 #ee pages1 #cg illustrations4 99,,model ,,flying ,,machines1 ,,their ,,design ,,and ,,construction499 ,by ,w4 ,g4 ,aston4 ,contents of chapters3 #a4 ,general principles and their application4 #b4 ,power4 #c4 ,supporting surfaces4 #d4 ,screws1 and how to make them4 #e4 ,tails and elevators4 #f4 ,fins4 #g4 ,designs4 ,with a number of examples of monoplane1 bi-plane1 tandem bi-plane and tri-plane models4 #h4 ,dirigibles4 #i4 ,helicopters4 #aj4 ,ornithopters4 #aa4 ,winding apparatus4 #ab4 ,compressed air motor4 ,a first-rate book for ,model ,makers1 #abe pages1 #ie illustrations1 #abmo4 boards1 postpaid1 for #eej4 99,,model ,,gliders1 ,,birds1 ,,butterflies ,,and ,,aeroplanes499 ,how to ,make and ,fly ,them4 ,a booklet with one large sheet containing twelve butterflies and two birds in colors and material for making a small card-board ,model ,aeroplane ,glider4 ,complete in folder1 postpaid1 for #ee;c4 99,,model ,,aeroplanes1 ,,how ,,to ,,build ,,and ,,fly ,,them499 ,by ,e4 ,w4 ,twining4 ,consisting of one booklet and five large scaled drawings for three ,twining ,models1 two of them being of the ,bi-plane ,glider type4 ,complete in folder1 postpaid1 for #ee;c4 99,,the ,,aeroplane ,,portfolio499 ,by ,d4 ,ross ,kennedy4 ,containing nine sheets of scale drawings of the following celebrated ,aeroplanes3 ,bi-plane type-,wright1 ,farman1 ,voisin1 ,cody1 ,herring-,curtis4 ,monoplanes--,rep4 ,antoinette1 ,santos ,dumont1 and ,bleriot4 ,each of these machines are here shown in ,end ,view1 ,plan and ,elevation4 ,including booklet which contains a description of each machine4 ,this timely set of drawings should prove of value to everyone interested in this important new industry4 ,the complete set in folder1 postpaid1 for #ee;c4 99,,the ,,percy ,,pierce ,,flyer499 ,a large scale drawing of this prize-winning ,monoplane4 ,with all measurements and details showing a front elevation1 a side elevation and a top elevation2 with #h-page descriptive booklet of particulars postpaid1 #ae;c4 99,,how ,,to ,,build ,a #bj-;,,ft ,,biplane ,,gliding ,,machine199 that will carry a man4 ,by ,a4 ,p4 ,morgan4 ,a practical handbook on its construction and management4 ,enabling an intelligent reader to make his first step in the field of aviation with a comprehensive understanding of some of the principles involved4 ,fully illustrated with detailed drawings4 ,contents of chapters3 #a4 ,the frame work assembling and finishing the wood4 #b4 ,covering the planes1 laying out the fabric and fastening it4 #c4 ,trussing1 fastening the tie-rods and trueing the glider4 #d4 ,gliding flight1 the principles involved1 instructions and precautions4 #e4 ,remarks4 #fj pages1 #ca illustrations4 99,,electrician ,,and ,,mechanic99 ,is a magazine which will help you4 ,it is a practical monthly for every one who wants to learn about electricity1 or who uses tools4 ,its articles tell you how to make dynamos1 engines1 wireless telegraph apparatus1 furniture1 models1 etc4 ,it is the only magazine of its kind in the world4 ,,editors3 ,frank ,roy ,frapie1 ,m4 ,sc4 ,chem41 ,f4 ,r4 ,p4 ,s4 ,prof4 ,a4 ,e4 ,watson1 ,e4 ,e41 ,ph4 ,d4 ,m4 ,o4 ,sampson4 99,,characteristic ,,features99 99,electricity499 ,practical and simple articles on electrical science1 new applications and history1 all illustrated4 ,how to make dynamos1 motors1 batteries1 all kinds of electrical apparatus4 ,how to wire for bells and electric lights1 install telephones1 etc4 99,mechanical ,articles499 ,how to use lathes and machine tools4 ,how to build gas engines1 steam engines and other machines4 ,all about gas engines and flying machines4 ,illustrated articles on everything new in mechanical progress4 99,woodworking and ,manual ,training499 ,how to build mission furniture4 ,wood finishing1 staining1 polishing1 etc4 ,woodwork joints and cabinet making4 ,how to make useful and handy articles of wood4 ,mechanical drawing1 etc4 99,wireless ,telegraphy and ,telephony499 ,full information of all that is new in wireless4 ,any one can build a wireless station from our descriptions4 ,our ,wireless ,club has over a thousand members in ,america and even beyond the seas4 ,for seven years the wireless authority in the magazine line4 99,all articles written in simple language for everybody to read4 #a4ej a year1 #c months' trial #be;c499 ,,special ,,offer ,until our stock of back numbers is exhausted1 we offer six back numbers and a full year's subscription for #a4ej4 ,money orders only2 no stamps accepted4 ,,sampson ,,publishing ,,company #afa ,pope ,building ,,boston1 ,,mass4 ,when writing to advertisers1 please mention this book4 ,materials for ,building ,,model ,,aeroplanes will be found listed in our catalog of apparatus and supplies for ,,experimenters 99,,we ,,are ,,headquarters for ,rubber ,strand1 ,bamboo ,sticks99 and all the rest of the things that you need 99,,wireless ,,telegraph ,,apparatus99 ,we manufacture the largest line of ,,reliable wireless ,apparatus in the country ,efficient ,design ,reasonable ,cost ,excellent ,appearance ,skillful ,workmanship and ,unequalled ,efficiency are all yours when you buy ,,amco ,apparatus4 ,,our ,,catalog ,shows1 ,storage ,cells1 ,step ,down ,transformers1 ,rectifiers1 ,induction ,coils1 ,wireless ,instruments1 ,complete ,transmitting and ,receiving ,outfits1 ,telephones1 ,keys1 ,sounders1 ,flashlights1 ,lamps1 ,motors1 ,dynamos1 ,water ,motors1 ,railways1 ,model ,aeroplanes1 ,books1 ,parts and ,supplies4 99,send #d cents in stamps to help cover cost of mailing and ask for a copy of our catalog499 ,,adams - ,,morgan ,,co4 99,the ,experimenters ,supply ,house99 99,box #gb;i ,upper ,montclair1 ,n4 ,j499