,this file was produced from page images at ,google ,books4 ,transcriber's ,note ,this book was transcribed from a scan of the original found at ,google ,books4 ,i have rotated some images and have corrected the misspelling of aileron that appeared many times in the original text4 ,illustration3 ,a model aeroplane rising from the water4 ,,the ,,second ,,boys' ,,book ,,of ,,model ,,aeroplanes ,,by ,,francis ,a4 ,,collins ,,author ,,of ,,the ,,boys' ,,book ,,of ,,model ,,aeroplanes ,,illustrated ,,with ,,many ,,photographs ,,and ,,diagrams ,,by ,,the ,,author ,,new ,,york ,,the ,,century ,,co4 #aiaa ,copyright #aiaa1 by ,the ,century ,co4 ,published ,october1 #aiaa ,,the ,,second ,,boys' ,,book ,,of ,,model ,,aeroplanes ,,foreword ,it is assumed that the reader is familiar with ,the ,boys' ,book of ,model ,aeroplanes4 ,some knowledge of the history of aviation and the early models1 big and little1 will be found helpful1 but not essential1 as a preparation for the present volume4 ,within the year so much has been learned of the science of model aeroplane construction that an entirely new and more detailed treatment of the subject seems to be justified4 ,since the length of model aeroplane flights has been increased ten times1 their improvement is comparable to that of the large man-carrying machines4 ,the science has become more exact1 and the chance of failure reduced1 until to-day successful flights are within the reach of all4 ,in the preparation of this volume thanks are due to the ,new ,york ,model ,aero ,club1 to ,mr4 ,edward ,durrant1 ,percy ,pierce1 ,cecil ,peoli1 ,w4 ,s4 ,howells1 ,jr41 and to the young gentlemen whose models are illustrated herewith1 who1 singly and collectively1 are doing much for the development of the science in ,america4 ,,the ,,second ,,boys' ,,book ,,of ,,model ,,aeroplanes 4444444444444444444444444 ,,foreword 4444444444444444444444444444444444444444 4444444444444444 ,,list ,,of ,,illustrations 4444444444444444444444444444444444444444 444 ,,chapter ,i ,,model ,,aeroplanes ,,of #aiaa 444444444444444444444444444444 ,,chapter ,,ii ,,model ,,aeroplane ,,tournaments 44444444444444444444444444 ,,chapter ,,iii ,,parlor ,,aviation 4444444444444444444444444444444444444 ,,chapter ,,iv ,,tools ,,and ,,materials 4444444444444444444444444444444444 ,,chapter ,v ,,theory ,,and ,,practice ,,of ,,plane ,,construction 4444444444444 ,,chapter ,,vi ,,scientific ,,propeller ,,building 444444444444444444444444 ,,chapter ,,vii ,,assembling ,,the ,,motors 4444444444444444444444444444444 ,,chapter ,,viii ,,directional ,,control 44444444444444444444444444444444 ,,chapter ,,ix ,,model ,,aeroplane ,,designs 444444444444444444444444444444 ,,chapter ,x ,,designing ,,the ,,skids 44444444444444444444444444444444444 ,,chapter ,,xi ,,geared ,,motors 4444444444444444444444444444444444444444 ,,chapter ,,xii ,,lessons ,,of ,,the ,,man-,,carrying ,,aeroplanes 44444444444444 ,,chapter ,,xiii ,,selected ,,questions ,,for ,,beginners 4444444444444444444 ,,chapter ,,xiv ,,among ,,the ,,model ,,builders 4444444444444444444444444444 ,,chapter ,,xv ,,curiosities ,,of ,,the ,,air 4444444444444444444444444444444 ,,chapter ,,xvi ,,rules ,,for ,,conducting ,,model ,,aeroplane ,,contests 4444444 ,,constitution ,,and ,,by-,,laws ,,of ,a ,,model ,,aeroplane ,,club 44444444444444 ,,dictionary ,,of ,,aeronautical ,,terms 44444444444444444444444444444444 ,the ,full ,project ,gutenberg ,license 44444444444444444444444444444444 ,section #a4 ,general ,terms of ,use ,redistributing ,project ,gutenberg electronic works 4444444444444444444444444444444444444 ,section #b4 ,information about the ,mission of ,project ,gutenberg 44 ,section #c4 ,information about the ,project ,gutenberg ,literary ,archive ,foundation 4444444444444444444444444444444444444444 444444 ,section #d4 ,information about ,donations to the ,project ,gutenberg ,literary ,archive ,foundation 4444444444444444444444444444444444444 ,section #e4 ,general ,information ,about ,project ,gutenberg electronic works4 4444444444444444444444444444444444444444 444444444444444444 ,,list ,,of ,,illustrations ,a model aeroplane rising from the water4 44444444444444444444444444 ,a good specimen of plane building4 44444444444444444444444444444444 ,finish one end of the blade before cutting away the opposite end4 ,model aeroplane4 ,designed by ,cecil ,peoli4 4444444444444444444444444 ,a variation on a familiar form4 44444444444444444444444444444444444 ,an excellent model designed and built by ,h4 ,wakkins4 44444444444444 ,an original design by ,harry ,mc,allister 4444444444444444444444444444 ,an interesting experiment in stability 4444444444444444444444444444 ,an early model built by ,e4,g4 ,halpine 444444444444444444444444444444 ,an interesting experiment in stability 4444444444444444444444444444 ,an early model built by ,monroe ,jacobs4 ,note the ,ailerons4 444444444 ,a ,simple ,model ,glider 4444444444444444444444444444444444444444 44444 ,an effective glider built by ,r4,s4 ,barnaby 4444444444444444444444444 ,an efficient sling-shot glider built by ,john ,roche 4444444444444444 ,designs for ,sling-,shot ,gliders4 44444444444444444444444444444444444 ,paper ,gliders4 ,antoinette ,monoplane and ,wright ,biplane 444444444444 ,an excellent glider with wooden planes 4444444444444444444444444444 ,a covered-frame sling-shot glider 444444444444444444444444444444444 ,percy ,pierce launching a model 444444444444444444444444444444444444 ,a ,french model built of aluminium 444444444444444444444444444444444 ,diagram for making the planes 4444444444444444444444444444444444444 ,working drawing of the ,flemming ,williams model 44444444444444444444 ,an imported ,flemming ,williams model4 ,english record #bfjj feet4 4444 ,storing energy for a long distance flight 4444444444444444444444444 ,a geared model built by ,leslie ,v4 ,robinson 444444444444444444444444 ,an ingenious biplane 4444444444444444444444444444444444444444 444444 ,a well-proportioned model built by ,reginald ,overton 444444444444444 ,a good model intended for long distance work built by ,a4 ,c4 ,odom 44 ,a beautiful monoplane built by ,r4 ,mungokee 444444444444444444444444 ,detail of a model built by ,r4 ,mungokee 4444444444444444444444444444 ,an ingenious application of the dihedral angle 44444444444444444444 ,diagram ,showing ,how ,to ,make ,a ,propeller ,from ,a ,wooden ,blank 4444444 ,design of ,metal ,propeller 4444444444444444444444444444444444444444 4 ,a test of high aspect ratio planes 44444444444444444444444444444444 ,a modified ,bleriot built by ,cecil ,peoli 444444444444444444444444444 ,langley ,propeller ,blade 4444444444444444444444444444444444444444 444 ,a combination of several interesting features 444444444444444444444 ,a skilful adjustment of the front plane and skid built by ,percy ,pierce 4444444444444444444444444444444444444444 44444444444444444444 ,wright ,propeller ,blade 4444444444444444444444444444444444444444 4444 ,an efficient model1 showing excellent construction1 designed by ,john ,caresi 4444444444444444444444444444444444444444 44444444444444444444 ,one of the best minimum plane models of #aiaa 4444444444444444444444 ,a ,metal ,motor ,anchorage 4444444444444444444444444444444444444444 444 ,a ,metal ,motor ,anchorage 4444444444444444444444444444444444444444 444 ,a notable model possessing unusual stability4 ,built by ,w4,s4 ,howell1 ,jr4 4444444444444444444444444444444444444444 44444444444444444444444 ,front view of model built by ,w4,s4 ,howell1 ,jr4 444444444444444444444 ,a ,metal ,skid 4444444444444444444444444444444444444444 44444444444444 ,an ingenious adjustment of ailerons 4444444444444444444444444444444 ,tuning up the model for a flight4 444444444444444444444444444444444 ,showing ,construction ,and ,mounting ,of ,propeller ,and ,axle4 4444444444 ,an excellent monoplane capable of long flights4 4444444444444444444 ,long-distance model built by ,percy ,pierce4 444444444444444444444444 ,showing ,an ,excellent ,way ,of ,fastening ,the ,propellers ,to ,the ,framework4 4444444444444444444444444444444444444444 4444444444444444 ,model built by ,rutledge ,barry1 winner of spectacular flight contest4 ,a model by ,percy ,pierce1 winner of the indoor long-distance record4 ,a ,motor ,anchorage 4444444444444444444444444444444444444444 444444444 ,a serviceable model showing excellent workmanship built by ,cecil ,peoli 4444444444444444444444444444444444444444 444444444444444444444 ,a serviceable model showing excellent workmanship built by ,cecil ,peoli 4444444444444444444444444444444444444444 444444444444444444444 ,various ,steering ,devices4 a and b1 simple aileron forms4 ,a novel fin on ,vinet plane4 ,b ,l-shaped aileron4 ,c vertical rudder 7,bleriot type74 ,d ,blinkers1 an effective rudder4 ,e stability planes not unlike the runners of a sleigh4 444444444444444444444444 ,an excellent piece of workmanship4 ,model by ,r4 ,mungokee 44444444444 ,model with minimum plane surface4 ,built by ,a4 ,c4 ,odom 4444444444444 ,a -- ,the ,famous one ,ouncer4 ,b -- ,a ,small ,experimental ,model4 ,c -- ,a ,modified ,burgess ,webb ,model4 44444444444444444444444444444444444444 ,model ,with ,minimum ,plane ,surface4 444444444444444444444444444444444 ,an ,american ,fleming ,williams built by ,c4 ,mc,queen 444444444444444444 ,one of the earlier models built by ,cecil ,peoli 44444444444444444444 ,a ,model ,with ,adjustable ,stabilizer4 4444444444444444444444444444444 ,an ,efficient ,three-ounce ,model4 44444444444444444444444444444444444 ,an ,all-metal ,model ,frame4 4444444444444444444444444444444444444444 4 ,one of the best models of the year1 built by ,john ,caresi 4444444444 ,an excellent model1 showing careful attention to details4 ,built by ,l4 ,v4 ,brooks 4444444444444444444444444444444444444444 44444444444444 ,a model with limited plane area built by ,r4 ,barry 44444444444444444 ,an interesting experiment in metal frame building by ,r4 ,fisher 4444 ,an aeroplane of simple construction that flies remarkably well1 built by ,r4 ,s4 ,barnaby 4444444444444444444444444444444444444444 4444 ,percy ,pierce1 winner of the distance record 44444444444444444444444 ,a well-proportioned model1 capable of long flights 4444444444444444 ,a well designed aeroplane built by ,james ,mac,pherson 444444444444444 ,a beautiful model built by ,stewart ,easter 4444444444444444444444444 ,a successful model of #aiaj built by ,e4 ,g4 ,halpine4 ,note contrast in plane area 4444444444444444444444444444444444444444 4444444444444444 ,percy ,pierce launching a prize-winning model 4444444444444444444444 ,launching the sling-shot gliders 4444444444444444444444444444444444 ,a tractor with large plane forward built by ,f4 ,w4 ,curtis 4444444444 ,model built by ,william ,robinson 44444444444444444444444444444444444 ,front view of the ,de ,lion model 44444444444444444444444444444444444 ,two of the earlier ,peoli models 44444444444444444444444444444444444 ,,chapter ,i ,,model ,,aeroplanes ,,of #aiaa ,for the average boy there is no more stirring music than the brisk1 whirring note of his model aeroplane4 ,let the propellers spin steadily for ten glorious seconds1 and the journey spans a couple hundred feet or more4 ,double the time and the flight becomes a triumph4 ,out of the ingenuity of thousands of boy aviators1 the world over1 has come a surprising development of the model aeroplane4 ,the experimental stage is passed4 ,any bright boy may now build a model aeroplane which is certain to give results4 ,the distance qualities of your model may even rival your endurance as a runner in keeping pace with it4 ,working along different lines1 the builders of model aeroplanes1 widely scattered1 seem to be gradually developing much the same type of air craft4 ,the tendency is toward the construction of much lighter and more logical models than last year4 ,in place of the complicated models supported by several broad planes1 we find the most successful amateur aviators expending all their ingenuity upon simple monoplane forms4 ,the biplane forms are being abandoned by model builders1 as well as the biplane form of elevating planes4 ,in place of the models made from fifty or more members1 we now find excellent models1 capable of much longer flights1 formed of but a dozen pieces4 ,the builders of model aeroplanes are keeping pace with the development of the man-carrying machines1 if they are not passing them1 in developing the flying machine of the future4 ,improvement in the distance qualities of the model aeroplanes1 in the past few months1 has been remarkable4 ,at one of the first model aeroplane tournaments1 held in ,new ,york1 less than two years since1 the longest flight was under sixty feet4 ,in less than one year1 flights of more than #bjj feet had become common4 ,to-day the improved racing model aeroplanes have flown more than #b1ejj feet4 ,as a result of the labors of the boy aviators1 it is much easier to build a successful model flying machine to-day than it was a year ago4 ,what may be called the #aiaa type of model aeroplane looks every inch a racer4 ,every unnecessary stick and string has been cut away4 ,when skids are used they are of the lightest possible material and the simplest construction4 ,the miniature rubber-tired wheels1 with ball bearings1 which made many of last year's models so attractive1 are rarely used4 ,the plane surface has been reduced fully one half4 ,one great secret of success is in the cutting down of weight4 ,when your propeller has but half the work to do1 the length of the flight is1 of course1 greatly increased4 ,our amateur aviators are attacking one great problem of aviation which the pilots of man-carrying crafts are perhaps neglecting4 ,model aeroplanes are built to maintain their equilibrium in the air automatically4 ,they must not only rise from the ground1 prepared for a long flight1 but must be contrived to resist all manner of baffling air currents aloft4 ,watch the successful model as it gains its altitude1 settles down to a horizontal flight1 is perhaps knocked off its course by a cross current1 and steadies itself with a graceful curve and proceeds on its way4 ,all these problems must be anticipated4 ,the young aviator must ingeniously arrange his planes and ballast in advance4 ,the regular sky pilot1 on the other hand1 meets the problems of the air as he encounters them1 by flexing his wings against disturbing currents or by banking to maintain an even keel at a turn4 ,if the man-carrying airship had to be prepared to meet all these problems before it left the ground1 the problem would be1 of course1 much more complicated4 ,in other words1 if the motor of a large machine were started and the aeroplane launched without a pilot1 would its chances of flight be as good1 in proportion to its size1 as those of our best model aeroplanes8 ,a model aeroplane which flies #cjj feet performs as remarkable a feat as would a large machine flying1 unguided1 a mile or more4 ,the progress in the construction of model aeroplanes1 in brief1 already deserves serious scientific consideration4 ,the last twelve months have brought out a surprising number of new aeroplanes1 while notable progress has been made in the standard types4 ,to realize the immense strides or flights forward in the construction of heavier-than-air machines1 one need only set the #aiaa models beside the aeroplanes of a year or two years since4 ,even to the eye of the layman in such matters1 the older machines are beginning to appear obsolete4 ,in a previous volume1 it was suggested that within a few years the aeroplane of to-day would appear like cumbersome stage coaches to one familiar with racing automobiles1 and certainly the prophecy is being quickly realized4 ,the general tendency is in the direction of greater simplicity in design in passenger-carrying craft1 as in model aeroplanes4 ,both the monoplane and biplane types are being developed side by side1 and each continues to have its enthusiastic advocates4 ,the increase in the passenger-carrying qualities is realizing the most sanguine hopes4 ,aeroplanes have carried fifteen passengers for several miles4 ,the speed qualities of machines have developed correspondingly4 ,if the development of model aeroplanes leads the way in perfecting heavier-than-air machines1 as many believe1 the monoplane form seems destined to replace all multiplane types4 ,during the past year practically all of the biplane forms have been abandoned by model builders4 ,as a result of wide experiments1 it has been found that the monoplane exerts more sustension per unit of surface than any two or three-plane machines4 ,in theory1 it is1 of course1 possible to increase the sustained force by setting one plane above another1 but in practice it has been found that the planes must be set so far apart that the arrangement is impracticable4 ,when planes are separated1 they must1 of course1 be stayed and trussed to keep them rigid1 and all this adds to the weight and complexity of the machine4 ,illustration3 ,a good specimen of plane building4 ,illustration3 ,finish one end of the blade before cutting away the opposite end4 ,illustration3 ,model aeroplane4 ,designed by ,cecil ,peoli4 ,the builder of model aeroplanes has a great advantage over the designer of man-carrying crafts4 ,the spread of the wings of his model is comparatively small1 and the problem of staying and trussing is greatly simplified4 ,the monoplane1 especially in a model1 requires practically no staying at all4 ,then again the skin friction is greatly reduced in the monoplane form4 ,simple as it is1 there are great possibilities in the arrangement of these surfaces4 ,the effect of outline upon resistance again may be more closely observed in the monoplane than in the multiplane forms4 ,in other words1 if your model goes wrong1 it is far easier to locate the fault and rectify it than in the more complicated arrangement of planes4 ,the flights of the ,english models this year are longer than those made in ,america1 but1 on the other hand1 we are solving many practical problems of aviation1 in our model building1 which the ,english have not attempted4 ,even in the case of our single-stick frames built in ,america1 the tendency is toward more stable construction than abroad4 ,the best ,english models would not qualify for an ,american model tournament1 since they could not rise from the ground4 ,the best ,american models1 on the other hand1 would be outdistanced in an ,english meet1 but their flights would show them to have far greater automatic stability than their ,english rivals4 ,it is extremely interesting to speculate whether the ,american or ,english types of model aeroplanes will survive1 and which is contributing more to the solving of the great mysteries of aviation1 but1 after all1 it is a question which only time can answer4 ,compare typical flights of the ,american and ,english models1 and the contrast becomes obvious4 ,the ,english model is usually held and thrown forward4 ,the starter thus gives it its altitude and direction4 ,being extremely light1 they gain a great deal from the wind4 ,their flights are usually in straight lines1 or in slightly undulating curves4 ,under favorable conditions1 their distance qualities are remarkable4 ,flights of six or eight hundred feet are common1 while the present record is over #b1ejj feet or nearly half a mile4 ,in an ,american model tournament1 the models are set upon the ground and left to themselves4 ,as a rule1 it is not even permitted to give them a slight push4 ,the motor must be powerful enough to carry them onward and upward unassisted4 ,in many cases they must be clear of the ground within twenty feet or the flight is disqualified4 ,it is1 of course1 obvious that the motors must be far stronger than in the case of the ,english models1 and that their frames must therefore be correspondingly heavier to support the weight4 ,the plane surface1 in turn1 must be increased to support this weight4 ,the average ,english models1 even with ,american skids1 would not leave the ground at all4 ,once in the air1 the behavior of the ,american model1 again1 is entirely different from its ,english rival4 ,our aeroplanes are off with a rush4 ,the first part of the flight is at a more or less sharply drawn angle of elevation4 ,it usually rises to an altitude of from ten to twenty feet in a straight line4 ,to secure a good rise requires a much more scientific adjustment of the planes and weighting than in the case of the ,english models4 ,as it reaches its altitude1 it adjusts itself1 and here the problem of stability comes in4 ,the marvelous little craft balances itself with the least possible loss of time and power1 comes to a horizontal position1 and is off on its flight4 ,if its adjustment is not all it should be1 it will1 of course1 fail to right itself and fall backward1 or1 as the phrase goes sit on its tail4 ,it is estimated that one-third of the power of the motors is used up in leaving the ground and rising to its maximum altitude4 ,our ,american model builders believe that their flights are far more scientific than in the case of a hand-launched model1 and that they are doing more for the actual development of the art of aviation than their ,english cousins4 ,whether one prefers to watch an ,american or ,english tournament is1 of course1 largely a matter of taste2 certainly both are fascinating4 ,much has been learned about motors4 ,it has been found that the rubber motor is capable of great development4 ,since a flight of one-half a mile may be made by twisted bands of rubber1 the average model builder may be content to let clock work and miniature gasoline engines take care of themselves4 ,by building and flying thousands of models1 we have found what form of rubber strand is best1 just how heavy the strands should be1 and the most efficient point of winding4 ,instead of short heavy bands1 we now use much longer and more slender motors4 ,the efficiency of rubber motors has been greatly increased by arranging them in series and connecting them up by gear wheels4 ,it is even possible to buy miniature gasoline motors suitable for model aeroplanes4 ,flights of more than one mile have been made in this way4 ,all the best models this year are equipped with twin propellers4 ,it is very little more trouble to build two motors than one1 and the model thus equipped will not only travel much further1 but will insure much more stable flights4 ,a common trouble in model building has been the lack of stability4 ,your model has been likely to capsize1 even under favorable conditions1 spoiling the flight1 while a chance gust of wind would knock it out of its course in spite of everything you could do4 ,to overcome this tendency1 the surface of the planes might be increased1 but this added to the weight of the model1 thus cutting down the length of the flights4 ,the twin propellers cut at the root of the problem4 ,they balance the thrust1 thus making the flight even and stable4 ,the planes may also be made much smaller with a gain in weight which1 in turn1 lengthens the flight4 ,illustration3 ,a variation on a familiar form4 ,illustration3 ,an excellent model designed and built by ,h4 ,wakkins4 ,,chapter ,,ii ,,model ,,aeroplane ,,tournaments ,within the year1 exhibitions and contests of model aeroplane flights have become an established form of entertainment4 ,the attractions of the flights of man-carrying machines are borrowed in a large measure by the model aeroplanes4 ,the building of models has progressed so rapidly1 bringing the little air-craft under such control1 that a definite program of flights may now be carried out4 ,the programs may be considerably varied to include distance flights1 weight-lifting contests1 and spectacular flights in which the models loop the loop and perform other amazing feats4 ,the first formal exhibition or professional appearance of the model aeroplane in public as an entertainment was made in connection with the first aviation meet held at ,asbury ,park1 ,new ,jersey4 ,two of the most successful model builders1 ,percy ,pierce and ,frank ,schoeber1 of the ,new ,york ,model ,aero ,club1 were engaged to give exhibition flights for one hour a day in the intervals between the flights of ,arch ,hoxey1 ,johnston and other aviators of the ,wright ,brothers staff4 ,illustration3 ,an original design by ,harry ,mc,allister ,illustration3 ,an interesting experiment in stability ,illustration3 ,an early model built by ,e4,g4 ,halpine ,the models were flown for more than #bjj feet and were enthusiastically applauded4 ,the aeroplanes in miniature imitated the flights of the man-carrying craft with wonderful fidelity1 rising from the ground and soaring aloft in long1 graceful curves4 ,they came as a very welcome variety1 and could be watched without breaking one's neck gazing aloft1 or the unpleasant possibility of a serious accident4 ,the applause of the thousands gathered for the meet may be said to have definitely established the model aeroplane as a feature of these tournaments4 ,the model aeroplane has one great advantage over the man-carrying machines4 ,it makes possible indoor aviation1 and may be enjoyed the year round1 and is especially effective for evening entertainment4 ,the fortnightly meets in one of the great ,new ,york armories1 some time since1 attracted the attention of the officers1 and the boys were invited to give exhibition flights in connection with athletic games4 ,the first of these meets was held under the auspices of the ,new ,york ,model ,aero ,club1 in connection with the ,greek athletic games1 in the interval between the games and the ball which followed4 ,an audience of fully #c1jjj people1 crowding the armory1 witnessed the flights4 ,some twenty members of the club entered the contest4 ,in a public contest of this kind1 much depends upon the system of flying4 ,the floor must be kept clear and the flights follow one another so quickly that the interest will not lag for a moment1 and the audience have no opportunity to tire4 ,the flights on this occasion went with a rush and proved in every way so successful that the rules which made this program are given in full on another page4 ,few in the audience had ever seen a model flight1 and the contest held the great crowd's attention more closely than had any of the evening's athletic events1 which had come before4 ,there was a breathless moment of suspense when the whistle had sounded for the first flight4 ,a beautiful white monoplane led off1 but in the excitement of the moment1 it had not been properly adjusted1 and failing to get its altitude1 spun daintily across the floor4 ,the second model yawed sharply and flew into the crowd at the side4 ,the third model found itself1 however1 rose perhaps twenty feet and1 settling down to a steady horizontal1 darted across the arena4 ,every eye followed it4 ,a burst of handclapping greeted its graceful rise1 which increased in volume1 and as it reached the farthest corner of the great armory1 more than #bjj feet distant1 there was a perfectly spontaneous cheer4 ,the program was so well organized and carried on that the flights followed rapidly without a break4 ,there was scarcely a moment when an aeroplane was not aloft1 and the interest never faltered4 ,there were ,scores of excellent straight-away flights of #bjj feet or more1 at various altitudes4 ,occasionally a model would fly wild1 even refuse to rise1 but the flights followed one another so continuously that a failure was quickly forgotten in the delight of watching the next flight4 ,the rapid development of the model aeroplane was shown particularly in the spectacular flights4 ,the thrilling volplanes and daring aerial feats of the famous air pilots were imitated by the model aeroplanes4 ,the models were made to dart about at unexpected angles1 and1 while keeping clear of the ground1 perform many astonishing feats4 ,the prize for these spectacular flights was won by ,henry ,ragot whose aeroplane actually looped the loop repeatedly1 in obedience to skilful adjustment of the planes and weights4 ,in launching the model for this flight1 the model was held well above the ground and launched at a sharp upward angle4 ,it rose with astonishing speed1 in a vertical line1 fully twenty feet1 when it turned and descended with accelerated speed4 ,the crowd naturally expected a bad smash1 but with a good clearance of the ground the model suddenly swept around in a narrow semicircle1 rose and repeated the performance4 ,it seemed to many spectators that the model was enjoying a miracle of good luck1 but they were mistaken4 ,the flight was repeated several times4 ,indoor aviation was an instantaneous success4 ,unless well-thought-out rules are carefully observed1 a public exhibition may fall into confusion1 and be seriously marred4 ,a large audience grows quickly impatient of delays between flights4 ,there is1 of course1 the danger that the models will follow each other too quickly1 perhaps collide in the air4 ,the distance and spectacular flights again must be kept separate4 ,the rules followed by the ,new ,york ,model ,aero ,club in these exhibitions worked well in practice4 ,first of all1 the floor was kept absolutely clear except for the director of the flights1 who took up a position at the center4 ,the distance flights started from one corner only1 and the spectacular nights from the center of one side1 the weight-lifting contest from another corner4 ,an official starter1 a measurer1 and an entry clerk are stationed at each point from which the flights are started4 ,when a model was wound up ready for a flight1 a starter waved a small flag to attract the attention of the director out on the floor4 ,from his vantage point1 the director could see if the floor was clear and signaled to the starter to go ahead4 ,he blew a whistle by way of signal1 one blast for the start of a weight-lifting contest1 two for a distance flight1 and three for a spectacular flight4 ,instantly the whistle sounded1 the model signaled was released without a moment's delay4 ,in this way no two models were ever started at the same time1 and all confusion was avoided4 ,the whistle was clearly heard in all parts of the hall1 and the audience quickly learned to recognize the signals and look to the point from which the start took place4 ,in the distance flights the one flying the model and the measurer alone were allowed to go after the machine4 ,this was done on the run4 ,it is important that any delay be avoided in measuring1 since this does not interest the public in the least1 and may make the exhibition drag4 ,illustration3 ,an interesting experiment in stability ,illustration3 ,an early model built by ,monroe ,jacobs4 ,note the ,ailerons4 ,the only other person allowed on the floor while the flights were in progress was the owner of the model1 who must follow it and bring it back4 ,he was allowed to cross the floor1 but once he had secured his model1 he must carry it quickly to the nearest point at the side1 and find his way back to the starting point along the outer lines4 ,it is confusing both to the flyer and the spectators to have a single unnecessary figure on the floor during the flights4 ,the crowd is kept back by members of the club1 wearing the club colors4 ,the regular fortnightly model aeroplane meets held in ,new ,york are doubtless the most largely-attended and best-organized meets of the kind in the world4 ,the #bbnd ,regiment armory1 a spacious structure admirably suited for indoor aviation1 has very courteously been thrown open for the purpose on every other ,saturday afternoon4 ,throughout the season1 each of these meets brings together several hundred boys and spectators1 and on the average about #ajj model aeroplanes4 ,the meet is conducted with intelligence and sympathy by the ,y4 ,m4 ,c4 ,a41 and is open to all4 ,of late these exhibitions have become so popular that the crowds actually threaten the convenience of the flyers1 and the boys have been required to present credentials on entering1 consisting simply of a model aeroplane4 ,there are few more animated spectacles than the model aeroplane tournament4 ,there is a great sunlit floor1 measuring #bej by #aej feet1 roofed with glass4 ,the aviation fields are reproduced here in miniature1 without loss of animation4 ,along the sides are continuous lines of camps1 corresponding to the hangars where scores of boys are busy tuning up their machines4 ,they have brought tools and a variety of extra materials1 planes1 propellers1 motors1 and strips1 which are spread about them4 ,in each camp the machines1--and there are no two alike1--are being assembled or repaired4 ,groups of the boys' friends and admirers are gathered about each camp1 earnestly discussing the merits of a particular model and its chances in the approaching contest4 ,to stroll down the line of camps is in itself a liberal education in aeronautics4 ,the records of all flights are carefully preserved1 to be counted against the several important trophies which will be awarded at the end of the season4 ,any one of the scores of contestants can tell you at any moment how the score stands4 ,during this tuning up process1 the galleries have filled and an enthusiastic audience is assured4 ,one of the great beauties of indoor aviation is that it is entirely independent of the weather4 ,the air of the great armory is practically at rest1 and the aeroplanes escape the baffling side currents and air gusts4 ,in ,england1 for instance1 indoor aviation is practically unknown4 ,a whistle sounds above the hum of many voices1 and at the signal everyone scurries to the sides1 leaving the broad floor clear4 ,the judge1 starter1 and measurer take their positions1 and the aviators1 with their models tuned up to concert pitch1 stand ready at the starting line4 ,the starter announces whether the flight is official and if it is to be counted in the competition for the trophies1 or is merely a practice or exhibition flight4 ,the start is made from the extreme corner diagonally across the armory4 ,only last year the start was made from a point well out in the middle of the floor1 but that was when the flights were much shorter4 ,to-day the boys have actually outgrown the armory1 and even by flying from corner to corner there is not enough room4 ,the aeroplanes are no longer launched from the hand or even pushed along the ground4 ,they are required to start without assistance and rise in the air without being touched4 ,official flight4 ,everyone's attention is attracted by the announcement4 ,hundreds of boys crowd to the lines4 ,the starter is doubtless known to all1 as well as his record and standing in the various competitions4 ,hundreds of critical eyes are upon the model4 ,it is a thrilling moment4 ,the propellers are released1 and the aeroplane starts forward under its own power4 ,some leap into the air1 others take the full twenty feet permitted them in getting off the ground4 ,there are surprisingly few failures4 ,the length of the take-off1 the angle at which it rises1 the altitude in the first rise1 are critically observed by the young experts4 ,to the whir of the propellers1 which form two blurred circles in the air1 the model quickly climbs upward1 rights itself and speeds away on its long flight4 ,the young aviator's skill is revealed to every eye by the angle of the ascent1 the altitude and the ability to gain equilibrium aloft4 ,the more you know about aviation1 the more absorbing is your interest in a flight4 ,a good rise is usually observed in silence4 ,by the time the model has reached the middle of the armory1 more than one hundred feet from the starting line1 enthusiasm is aroused4 ,when two-thirds the distance has been covered1 the applause begins4 ,let the model continue without swerving to the farthest corner1 and a perfectly spontaneous cheer sweeps the crowd4 ,it is a well-deserved reward of hours of patient effort4 ,the official measurers take the floor on the run1 dragging their tape after them4 ,the crowd overruns the floor to gain a closer view of the model1 and the young aviator receives congratulations4 ,the distance is announced at once1 and there are more cheers4 ,there is never a dull moment at the meets4 ,one or more machines are almost always aloft4 ,it is as thrilling as a three-ringed circus4 ,,chapter ,,iii ,,parlor ,,aviation ,a model glider1 or aeroplane without a motor1 will be found perhaps as entertaining a toy as the power-driven machine4 ,it is much simpler1 of course1 to build and adjust a successful glider even than the most elementary model aeroplane4 ,with the problem of the motor and propeller removed1 the cost of construction besides is reduced to practically nothing4 ,here is excellent entertainment for those who have not the time or patience for model building4 ,a graceful glide of successive waving lines makes a beautiful spectacle4 ,incidentally it is a good plan to work out the designs of large models in this way4 ,fascinating little paper models1 reproducing the famous man-carrying machines1 the ,wright1 ,bleriot1 and others1 may be put together in a few minutes4 ,with a little adjustment1 they may be made to fly from fifty to one hundred times their length4 ,a paper ,bleriot biplane six inches in length1 for instance1 may be made to sail for from twenty-five to fifty feet1 and so on4 ,this will be the actual horizontal distance traversed2 the actual distance measured in long1 undulating curves may be considerably more4 ,such flights do not consist merely of a long diagonal to earth1 but of several surprising upward sweeps1 well worth the trouble of construction4 ,it is interesting to note the remarkable stability of their gliders4 ,illustration3 ,a ,simple ,model ,glider ,an hour's entertainment1 no less interesting than instructive1 may be enjoyed with a series of these paper gliders4 ,a different model might be prepared for each guest1 and a prize or favor offered for the longest or best spectacular flight4 ,the little gliders will cross a large room before coming down4 ,the various aeroplanes nowadays are so familiar that in any gathering will be found several who favor1 for instance1 a ,wright over a ,curtiss take a lively interest in the rivalry of the various models4 ,illustration3 ,an effective glider built by ,r4,s4 ,barnaby ,illustration3 ,an efficient sling-shot glider built by ,john ,roche ,begin with a very simple model4 ,you will soon learn the trick of judging the size of the supporting surfaces and the spacing4 ,the ,antoinette aeroplane is probably the easiest one to imitate4 ,from a sheet of ordinary writing paper1 cardboard or fine wood1 cut the form indicated4 ,if the paper be rather heavy1 it may be made six inches in length4 ,by folding the paper and making one cutting1 it will be found much easier to make the wings even and symmetrical4 ,the two sides should be fixed at a broad dihedral angle4 ,to keep the little glider on an even keel you will need to add a weight to the front4 ,a large pin or paper clip will answer4 ,launch the glider by holding it horizontally and throwing slightly forward4 ,if it darts downward1 lighten the ballast4 ,if it falls backward1 sitting on its tail1 add more weight at the front or bend the tail up4 ,your glider will1 of course1 travel to the ground along the line of least resistance1 and the trick is to adjust the center of gravity and center of pressure that this descent may be as gradual as possible4 ,the center of gravity should come a little in front of the center of pressure4 ,the gliding angle1 as it is called1 or the angle between the course of the model in flight with the ground should be about one in twelve4 ,in other words1 the glider descends one foot for every twelve feet it travels forward4 ,practically all the famous monoplanes may be reproduced in this way4 ,a variety of gliders may be made in a general arrow form4 ,these arrows1 or darts1 as they are called1 may be made about a foot in length and three or four inches in width4 ,the horizontal surface1 it should be borne in mind1 is the supporting surface1 while the vertical surface gives the flight direction4 ,these gliders will also require weighting at the forward end4 ,they should be thrown forward with rather more force than in the case of the ,antoinette4 ,the biplanes such as the ,wright and ,curtiss aeroplanes may be reproduced very easily in paper4 ,they fly best when made about six inches in length4 ,cut the two sheets of paper for the main planes one inch by six inches and round off the corners on one side4 ,two similar sheets1 one by three inches1 will be required for the smaller plane in the rear4 ,the planes are held in position by a series of paper struts1 or toothpicks1 and should be separated by a distance equal to their width1 in this case one inch4 ,cut the slips of paper to form the struts one and one-half inches in length and bend over the corners at right angles1 one-quarter of an inch from either end4 ,these should be pasted in position1 always keeping the edge of the struts lengthwise so that they will offer the least resistance in flight4 ,connect the two biplanes by strips of paper six inches in length pasted on the lower planes or main deck of the little aeroplane4 ,the forward planes should be fixed at a slightly elevated angle by running struts from the connecting strips to the upper plane4 ,the accompanying picture will show how simple this all is4 ,the biplanes as a rule require no weighing4 ,to launch them1 hold them high in the air and merely let go4 ,they fly best with their smaller planes forward4 ,by varying the angle of the front plane1 you can soon bring it to an even keel4 ,a vertical rudder placed three inches behind the main plane will increase the model's directional stability4 ,an amazingly clever little glider may be made of a piece of reed or cane1 say five inches in length1 and a sheet of writing paper4 ,with a pair of scissors cut two planes1 one three by one inch and the second two by half an inch4 ,you will also need a vertical rudder one inch square4 ,round off the corners slightly and glue the planes at either end of the stick and exactly on a level4 ,now fasten the rudder at right angles to the planes beneath the larger plane4 ,if it dips1 the front plane is too far back1 while if it rises too quickly and settles back1 the front plane must be brought back4 ,the paper gliders form an excellent kindergarten preparation to the study of aviation1 leading up to the construction of large model gliders4 ,you will thus gain a skill in adjusting the planes and fixing the centers of gravity and of pressure1 which will prove valuable later on4 ,the possibilities of glider building come as a surprise to the laymen in such matters4 ,,the ,,sling-,,shot ,,glider4 ,a fascinating field of experiment is opened by combining the sling-shot principle with the ordinary glider4 ,the speed with which one can launch a glider from the hand is1 of course1 limited4 ,now use a small strand of rubber to launch the planes1 and the increased speed will not only lengthen the flight surprisingly but make possible a really remarkable spectacular flight4 ,a small glider may be made to return to the starting point or even loop the loop two or three times before touching the ground4 ,by a simple adjustment of the planes1 these curves may be varied indefinitely4 ,illustration3 ,designs for ,sling-,shot ,gliders4 ,when you have adjusted your glider to fly well1 try the same arrangement of planes on a piece of reed1 say eight inches in length1 and bend the end over in the form of a hook4 ,by heating the cane over a flame1 you can make it turn without breaking and hold its position4 ,now loop a single rubber band over your thumb and forefinger1 and passing the hook over the rubber1 pull back exactly as you would use a sling shot4 ,as you release the glider1 pull your other hand quickly out of range4 ,by using a heavier paper1 one which will hold its shape1 and turning the forward edges up slightly1 the glider may be made to travel upward in a variety of graceful curves4 ,illustration3 ,paper ,gliders4 ,antoinette ,monoplane and ,wright ,biplane ,illustration3 ,an excellent glider with wooden planes ,illustration3 ,a covered-frame sling-shot glider ,the best glider for launching on the sling-shot principle is made from planes cut from thin metal sheets4 ,aluminum is the best material1 but a very thin wood will answer4 ,a one-foot model glider will be found the easiest size to manage4 ,cut one plane eight inches in length by three in width1 and the second five inches by two inches4 ,round off the corners on one side of each plane1 leaving a straight line for the front or entering edge4 ,mount the planes on a strip of reed1 cane or bamboo about eighteen inches in length4 ,in all these gliders the forward plane is made the smaller1 thereby reducing the head resistance as far as possible4 ,the metal planes should be slightly flexed by bending them to a slight concave above the horizontal and just back of the front edge4 ,the forward end of the stick should be bent into a large hook by heating or first soaking in water4 ,if your glider falls quickly to the ground bend the frame a trifle upward4 ,since your glider is intended to travel at a comparatively high speed1 the planes may be mounted much further apart than in the case of a glider launched from the hand4 ,try them first ten inches apart and afterwards adjust them to suit4 ,the rubber used for launching the glider should be fairly heavy1 say three strands of one-eighth inch rubber or its equivalent4 ,the end of the hook may need adjusting so that it will escape from the rubber on being released4 ,it will be found an easy matter to obtain long1 graceful glides from this model from the first4 ,by launching it upward1 it may rise to a considerable height4 ,when you have caught the trick of launching your glider with sufficient force1 try a spectacular flight4 ,set your forward plane at an angle by inserting a block of wood between the stick4 ,in the case of metal planes1 bend up the front edge4 ,a very slight upward elevation will answer4 ,gradually increase this angle until the model sweeps upward and turns on itself4 ,you will soon be able to make the glider describe a complete circle or loop the loop twice before landing4 ,when traveling at such a high rate of speed1 your glider is likely to be dangerous and might inflict a bad cut1 and the flight should only be attempted where one has plenty of room4 ,these flights may be still further varied by adjusting the rear edge of the vertical plane or rudder4 ,by turning the rudder to the right1 for instance1 the glider may be made to travel to the right or the direction may be reversed4 ,in this way the glider may be made to describe a complete horizontal circle or several circles4 ,by launching the glider upward with this adjustment1 it may be made to fly in a graceful spiral4 ,the success of a glider depends more upon its modeling and finish of its planes than in the case of the model aeroplane4 ,it must gain as much support as possible from the air1 since it has no motive power to keep it aloft4 ,its head resistance must also be cut down4 ,the ordinary cloth-covered planes1 which serve well enough for an ordinary model aeroplane1 will not carry a glider far4 ,the planes must1 therefore1 be of metal or wood1 or when built-up planes are used they must be of the most careful workmanship4 ,the simplest form of glider1 excepting1 of course1 the paper model1 is made entirely of wood4 ,a glider two feet in length will be found a good size to experiment with4 ,the model should be much heavier than an aeroplane so that one need not take the care in its construction to reduce weight which may make the construction of a model tedious4 ,a glider of this size may weigh upward of one pound4 ,under favorable conditions1 it will glide for two hundred feet1 when launched from the hand1 while if it is thrown from an elevation1 an upper window or a hill top1 it may travel considerably further4 ,select a stout stick for your base1 one inch square and two feet in length4 ,the main plane should measure fifteen inches in width by six in depth1 and the smaller plane ten inches by four inches4 ,a thin board about three-sixteenths of an inch thick may be used for the planes4 ,the front corners should be slightly rounded1 and the rear edges cut sharply away4 ,these planes may be flexed by steaming4 ,hold the section to be bent over the spout of a tea kettle until the wood is soft and pliable enough to bend4 ,if it does not soften sufficiently1 immerse the wood in boiling water4 ,the plane should be flexed slightly upward just back of the forward edge4 ,a good curve may be obtained by heating the under surface over a flame4 ,to hold it in position until it has dried and assumed shape1 bend it over a stick laid on a board and fasten the plane down by driving brads around the edges and bending them over to keep it down4 ,leave it in this position until it is dry and hard4 ,your glider will fly better with a vertical rudder1 as in the case of the paper models4 ,the rudder should be cut from a thin board of the same material about six inches square4 ,round off one corner and plane or sandpaper this front edge1 which will be the entering edge4 ,the entering edges of the front plane should be prepared in the same way to reduce the head resistance as much as possible4 ,nail this rudder to the side of the stick directly beneath the rear or larger plane4 ,it will be still better if you mortise it neatly into the center of the stick4 ,the glider is thrown with the smaller end forward4 ,for the trial flight1 mount the smaller plane at the extreme forward end and then move it backward as you test it out1 until the glider moves on an even keel4 ,to launch the glider1 grasp the central stick from beneath at the point where it balances1 and throw it forward with all your might4 ,since it travels at a much higher speed than a power-driven model aeroplane1 it requires much less supporting surface1 while the planes may be spaced much further apart4 ,when you have adjusted the planes1 try throwing your glider at an upward angle of say forty-five degrees4 ,it should rise swiftly to a height of upwards of fifty feet1 turn backward on itself1 and even describe a graceful upward curve before coming down4 ,now try throwing it into the wind or against a moderately strong breeze4 ,its course is likely to be very irregular4 ,it will dip and rise at many unexpected angles1 and probably travel several hundred feet in all before landing4 ,during the past year1 a model glider has been built by ,mr4 ,w4 ,h4 ,howell1 ,jr41 to glide a horizontal distance of #fej feet1 while the actual length of the flights has been upwards of #b1jjj feet4 ,,chapter ,,iv ,,tools ,,and ,,materials ,a well-stocked tool chest will be of great assistance to the builder of model aeroplanes1 but it is by no means essential4 ,a few simple tools1 easily obtained1 will be found to answer4 ,first of these comes a serviceable pair of nippers4 ,you will need them to bend the axles of your propellers1 in adjusting the motors1 and for a score of uses4 ,a pair of nippers with a cutting edge is best4 ,always be sure to slip these in your pocket before flying your model1 for you are sure to need them4 ,a fine gimlet1 or a needle drill1 will be found useful in a score of ways4 ,they cost but a few cents4 ,a handle which may be adjusted to drills of different size is best4 ,a drill one thirty-second of an inch in diameter will be found especially useful4 ,the parts of your model are likely to be delicate and easily split1 even while driving a small brad4 ,you can avoid the danger of splitting by first using the needle drill1 even for small brads1 and then enlarging the hole1 if necessary1 with a larger drill or a gimlet4 ,illustration3 ,percy ,pierce launching a model ,illustration3 ,a ,french model built of aluminium ,a fine saw will be found very useful1--the finer the better4 ,the timber used for the frame is so light and soft that it is likely to split4 ,a gig saw will be found just the thing for cutting out propeller blanks and other parts1 but it is not essential4 ,if your model be made of metal1 a small soldering iron will1 of course1 be found indispensable1--the smaller the better4 ,the metal parts are very delicate1 and the iron should have as fine a point as possible4 ,such an iron can be obtained at a hardware store for a few cents4 ,if you do not know how to solder neatly consult some tinsmith4 ,illustration3 ,diagram for making the planes ,in addition to good cutting tools1 a good half-inch chisel is most important4 ,a concave chisel will be found handy in carving propellers4 ,some of the best propellers have been whittled out with an ordinary penknife1 and sometimes a dull one at that1 so that after all a good penknife is the most essential tool of all4 ,with this little handful of tools1 you will find you can build up the most delicate models4 ,the world has been ransacked for material which will give the greatest possible strength for its weight4 ,the use of aluminum is1 of course1 familiar4 ,the search has also brought out the comparatively unknown metal1 magnalium1 which1 although a trifle heavier1 is believed to be much more desirable on account of its greater strength4 ,in a search for strong1 light wood the builders of aeroplanes have searched the tropics4 ,one of their discoveries has been balsic wood1 which is of a feather weight4 ,it is exceedingly soft and easily worked1 but has the drawback of being rather pithy and easily split4 ,a severe jar is likely to discover some weak point4 ,it will be found valuable1 however1 for the shorter members of the model4 ,some model builders use balsic wood as a filling for hollow sticks4 ,the wood may be strengthened by covering with cloth glued firmly about it4 ,it is also used as a filling for thin aluminum tubing4 ,in all the search for materials nothing has been found to compare with bamboo for lightness and strength4 ,a number of successful model aeroplanes have been built this year in which the central sticks and frames are built entirely of bamboo4 ,bamboo is especially valuable in constructing the smaller members4 ,it can be bent either by the dry-heat process1 described elsewhere1 or by steaming4 ,bear in mind that the strongest part of the stick lies just beneath the hard glazed outer surface4 ,the only drawback of bamboo is a tendency to split at the ends4 ,the extreme lightness of the material on the other hand makes it possible to make rigid joints by glueing and winding with fine thread touched with glue4 ,illustration3 ,working drawing of the ,flemming ,williams model ,illustration3 ,an imported ,flemming ,williams model4 ,english record #bfjj feet4 ,the lighter woods1 whitewood and poplar1 are much used by model builders4 ,they are easy to work1 especially whitewood1 because of its freedom from knots and cross grains4 ,some builders prefer ash on account of its strength4 ,beech has rather less strength1 some fifteen per cent1 while spruce is little more than half as strong as ash4 ,the quality of the wood varies considerably according to its nearness to the bark of the tree4 ,the wood used for model aeroplanes should be well seasoned2 a year is not too long4 ,motor bases are of two general divisions4 ,the single stickers1 or bases consisting of one member1 are commonly called spars1 while the more complicated frameworks are designated as built-up frames4 ,the spar type is1 of course1 the simplest to construct1 and1 as many believe1 the most efficient of all forms4 ,the simpler the design1 as a rule1 the less chance will there be of breakage4 ,for the beginner the use of plain1 honest sticks is1 of course1 to be recommended4 ,the built-up motor bases1 on the other hand1 make a more attractive model to the eye4 ,there is besides an opportunity to reduce the weight of the frame while retaining the same strength4 ,an examination of the models illustrated elsewhere will show to what an art such construction has been brought4 ,by ingenious bracing it is possible to construct motor bases of strips one-sixteenth of an inch1 or even less1 in width1 and yet render the whole sufficiently rigid to withstand the pull of powerful twin motors4 ,your frame may be considerably lightened by using hollow sticks or shafts in place of solid members4 ,a stick three-fourths of an inch wide formed of light lath one-eighth of an inch thick will weigh no more than a solid piece one quarter of an inch square4 ,such a member is stronger than the small1 solid stick2 it bends less readily under the pull of your motors1 and renders the entire frame far more rigid4 ,it will also be found much more satisfactory to mount the planes upon such a frame4 ,a little practice will enable you to make a very satisfactory stick of this pattern4 ,secure a light strip one-eighth of an inch thick and of a width one-eighth of an inch less than that of the stick you intend to build4 ,a one-inch stick is probably larger than you will need4 ,the following directions are intended for a stick three-fourths of an inch square4 ,first cut three square plugs one-half an inch square and one-fourth of an inch thick1 and placing one at either end and one in the middle to form a core1 build your frame about them4 ,the edges should overlap and be glued continuously together1 and the plugs fastened in position with brads driven from the middle of the four sides4 ,when dry1 cut away the glue1 sandpaper and varnish4 ,some model builders prefer a ,t-section-shaped spar1 which is almost as light as the hollow stick1 besides being easier to construct4 ,we assume that you are working with eight-inch strips1 which will prove heavy enough for ordinary purposes4 ,prepare one strip one-half an inch wide1 the desired length of your base1 and the second strip three-eighths of an inch wide1 the thickness and length being the same4 ,now fasten the smaller strip at the center of the long strip1 glueing it first in position4 ,when dry1 drive a series of fine brads along the center of the back of the larger strip4 ,cut away the glue and sandpaper4 ,the ,t-shaped stick will be found strong enough for all ordinary demands4 ,the rubber strands of your motor may be carried either above or below it4 ,the ,h-shaped-section stick is rather more difficult to build1 but it will be found somewhat stronger1 weight for weight4 ,if you are using one-eighth strips1 cut two lengths one-half an inch wide1 and a third length three-eighths of an inch wide4 ,fasten the smaller pieces to the middle of one of these strips1 as in the case of the ,t stick1 with glue and brads4 ,when dry1 attach the remaining strip opposite1 glueing and nailing as before4 ,some builders prepare these strips by cutting out the grooves with a chisel1 thus making a one-piece strip4 ,this requires very careful workmanship1 however1 and is scarcely worth the trouble4 ,the motor frame may be still further lightened by using a trussed frame4 ,the weight of this member may be cut in two in this way without sacrificing its strength4 ,to build such a part secure two strips of wood one-eighth of an inch thick1 one inch in width1 and cut to the desired length4 ,now from the same material cut six blocks1 one-half an inch in length1 and set these at regular intervals along one side of the strip4 ,they may be glued or nailed in position1 or both4 ,a small brad will hold them in place4 ,in working with such delicate material it will be well to first drill the holes with a fine drill4 ,next fasten the second strip above them1 nailing and glueing as before4 ,illustration3 ,storing energy for a long distance flight ,,chapter ,v ,,theory ,,and ,,practice ,,of ,,plane ,,construction ,,the planes of your model aeroplane need no longer be a blind experiment whose merits or defects may only be learned by actual test4 ,the science of wing-building is much better understood to-day than a year ago4 ,without going into the complicated equations dealing with aspect ratio1 pressure1 and gravity1 it is important that one bear in mind a few definite rules in designing even the simplest planes4 ,a great many useless experiments may be avoided4 ,in a previous volume1 it was pointed out that a narrow plane1 or one with a high aspect ratio1 driven with its broader side forward1 would yield greater support than a square surface of the same area4 7,the aspect ratio1 it may be well to repeat1 is the relation between the width and depth of the plane4 ,a wing1 for instance1 whose width is five times its depth1 is said to have an aspect ratio of five47 ,it has been found that on small planes the center of pressure is situated about one-third the distance back from its front or entering edge4 ,the center of pressure in flexed planes occupies about the same position4 ,as long as a plane remains horizontal1 or nearly so1 a very narrow surface1--one1 that is1 with a high aspect ratio1--will exert greater lifting power than a deeper plane of the same area4 ,an examination of the successful model aeroplanes of #aiaa will show that the depth of the planes has been cut away4 ,planes are used with an aspect ratio as high as ten4 ,the speed at which such a plane travels is a very important factor4 ,as the speed increases1 the efficiency of the plane surface increases1 so that a model aeroplane driven rapidly may be sustained by less wing area than in the case of one which flies slowly4 ,as the front edge of a plane is raised1 the center of pressure travels backward4 ,by the time the plane has reached an angle of about fifteen degrees1 its lifting power has diminished about one-half4 ,a very narrow plane1 or one with a high aspect ratio1 should1 therefore1 be set near the horizontal4 ,the model should1 moreover1 rest upon skids at as low an angle as possible4 ,in starting off1 the planes will thus exert their maximum lift1 or nearly so4 ,if the narrow planes be elevated too much1 the center of pressure will come nearer the rear than the front edge1 and tend to force the aeroplane downward1 or1 as the phrase is1 make it sit on its tail4 ,as long as a plane is traveling horizontally1 or at low angles1 its rear portion exerts very little sustaining power and may be cut away4 ,a plane with a high aspect ratio is much more stable in flight than a surface of greater depth4 ,the center of gravity of a flat plane would1 of course1 coincide with the center of the surface when the plane is in motion4 ,when the plane tilts1 the center of pressure1 as we have seen1 moves backward or forward4 ,if the plane has little depth or a high aspect ratio1 this center of pressure cannot move far4 ,it must oscillate back and forth within very narrow limits4 ,a very little tilt up or down will restore it to its normal position1 so that a plane with high aspect ratio is more stable than one with a deeper surface4 ,the efficiency of a curved surface over a flat plane was analyzed in a former volume4 ,such a curve1 when well drawn1 adds to the lifting power as well as the stability4 ,since a curved plane does more work than a flat surface1 its size may be reduced and its aspect ratio increased4 ,in other words1 the curved plane may be narrower than a flat surface1 and may be made thinner in proportion to its width4 ,the height of the curve1 or camber as it is called1 has been worked out by elaborate mathematical equations1 but we may take the general results without following the calculations4 ,for a plane six inches in depth1 the camber should be about one-half an inch1 or one in twelve1 or in this proportion4 ,the curve should be a parabolic with the highest point well forward1 one-third the way from the front edge4 ,the front1 or entering edge1 of the plane should be the thickest point4 ,it should be tapered off to a thin edge in the rear4 ,in theory1 it is possible to model a plane so delicately that it will fly against the wind by the pressure of the wind itself4 ,it is extremely important that both sides of the plane be brought to this curve as accurately as possible4 ,an efficient plane must1 therefore1 be covered smoothly on both sides4 ,such a plane again offers very little skin friction to the wind4 ,it is difficult to lay down any hard and fast rules for the relation of weight to wing surface1 since the types of aeroplanes differ so widely4 ,it has been found1 however1 that in large models one square foot of surface will support about one-half a pound of weight1 when traveling at a high rate of speed4 ,you will find that your model1 if its wings have a spread of thirty inches os thereabouts1 will approach one pound in weight4 ,the figuring will show you that two wings1 whose combined area is less than #aej square inches1 will be comparatively small and certainly well under those generally employed a year ago4 ,the planes used on this season's models are marvels of lightness and strength4 ,much has been learned by studying the methods employed by the builders of man-carrying aeroplanes4 ,it is a simple matter to build a three-foot plane which weighs complete less than one ounce1 and is strong enough to withstand many a violent shock4 ,illustration3 ,a geared model built by ,leslie ,v4 ,robinson ,illustration3 ,an ingenious biplane ,it will be found a good plan first to lay out the exact form of your plane on a smooth board4 ,make the depth of the plane one-fifth of its length4 ,it will be noticed that this plane is much more slender than those used last year4 ,next draw a line at the center the entire length of the board1 and mark off one-tenth of the length of the plane from either end4 ,from this center describe a quarter circle at either end1 on the same side of the line4 ,this will form your main or entering wedge4 ,the rear corners should be cut sharply away and only slightly rounded4 ,there is no better material for the main frame than a thin reed1 cane or bamboo4 ,the longer ribs may be made of any light lath and the cross ribs of a thin flat strip of the same material4 ,soak the reed overnight to make it as pliable as possible1 or heat it over a flame4 ,now lay the reed over the outline of the plane1 and hold it in this position by driving thin brads on both sides and bending them over the cane4 ,when the outer edge is complete1 mortise the ends slightly and tie and glue firmly together4 ,with the outer frame held rigidly in position1 it will be found a much easier matter to introduce the ribs4 ,if you are building a flexed plane first1 insert a stick of wood from end to end before placing your cross ribs in position4 ,the thickness of this temporary stick will1 of course1 determine the curve of your plane4 ,for a three-foot plane1 a height of one-half an inch will answer4 ,the ribs may now be bent over this obstacle and fastened securely to the outer rim by glueing1 tying1 or nailing4 ,the cross ribs may also be raised by inserting small wedges between them and the longitudinal ribs4 ,when your frame is complete1 loosen it from the board and you will find it regular and rigid4 ,cover it with a very thin cloth pulled tightly over the frame1 and glue or sew it in position4 ,a small plane may be covered only on the under side4 ,excellent results are being obtained in ,england with planes built up entirely of wire4 ,if aluminum wire is used1 the weight of the wings is considerably cut down1 but even ordinary wire will be found lighter than wood4 ,for a plane thirty inches in width1 or thereabouts1 the wire used should be at least one-sixteenth of an inch in diameter1 and should be soft enough to bend easily and hold its position4 ,it will be found a good plan to plot out the exact shape of your plane on a sheet of paper1 and then bend the wire over this outline4 ,the ends may be fastened together readily by binding tightly with fine wire1 such as florists use1 and touching the joint with solder4 ,be careful1 of course1 to keep the joint smooth4 ,the cross ribs of these metal frames may also be made of wire4 ,bend the ends at right angles and attach to the inner sides of the plane with fine wire1 and touch all the joints with solder4 ,there are several advantages in the metal planes4 ,it is a very simple matter to flex the plane by bending the cross ribs and the ends upward to the desired curve1 much easier than when working with wood4 ,such a frame will stand almost any amount of knocking about without injury4 ,a swift volplane to earth1 which would smash any ordinary wooden frame to smithereens1 would have little effect on a model plane4 ,such frames again are very easy to cover4 ,it will be found a good plan to sew the cloth to one edge1 draw tightly across and sew fast to the opposite side1 while a few stitches around the metal cross ribs will give it any curve you desire4 ,a metal frame makes it possible to experiment with various curves4 ,it is an easy matter to bend the ribs up or down and alter the line of the plane at will4 ,small stability or guiding planes may be made of a sheet of metal1 although such construction is not advisable for the main plane4 ,when your front or entering plane is the smaller one1 it is possible to turn it into a very efficient motor anchorage4 ,the plane should be cut from a sheet of aluminum1 preferably4 ,fasten this securely to the front of your motor base with nails1 or tying in position4 ,the wires of the hooks holding the ends of the motors may be passed through the holes cut to the back of the rear edge of the plane and bent over4 ,of course it is very simple to anchor double motors1 or even multiple motors1 in this way4 ,one of the novelties in plane construction is a narrow wing with ends brought well back4 ,it may be built either flat or flexed1 and promises to afford unusual stability4 ,the form is very popular among model builders in ,england1 where it is made very narrow1 its depth often equaling its width4 ,in many of the ,english models1 these planes are placed far forward and raised well above the main stability plane4 ,they are built with the entering edge either straight or slightly curved4 ,such front planes behave especially well in the open air and even against a considerable wind pressure4 ,there is still considerable difference of opinion as to the best material for covering planes4 ,several specially prepared aeroplane cloths have been placed upon the market which are guaranteed to be practically airproof4 ,the cloth is rather heavy1 however1 and better suited for large machines4 ,a thin silk answers the purpose perhaps as well as anything4 ,some model builders select the thinnest possible silk and then render it airproof by varnishing or covering with a thin solution of wax or paraffin4 ,when this is neatly done1 the planes are very taut and shipshape4 ,several preparations are offered for sale for coating planes1 which are excellent4 ,in the search for the lightest possible covering1 some builders have gone a little further and use a very thin paper known as bamboo paper4 ,even the thinnest paper will be found as impervious to air as a rather heavy cloth4 ,its weight is practically nothing1 even for a large plane4 ,it requires no varnishing or preparation1 although it is sometimes painted to render it more rigid4 ,there is1 of course1 a very obvious objection to paper that it is easily punctured1 but on the other hand1 such accidents are very easily repaired4 ,a bad rip may be patched up with a touch of paste1 or1 the plane may be re-covered very quickly4 ,with this paper care must be taken to fasten it to the frame of the plane as securely as possible1 as a loose sheet will flutter and increase the head resistance4 ,illustration3 ,a well-proportioned model built by ,reginald ,overton ,illustration3 ,a good model intended for long distance work built by ,a4 ,c4 ,odom ,in order to lighten the plane1 the outer frames at the ends and rear may be cut entirely away4 ,an appreciable saving of weight is thus obtained without weakening its structure4 ,this plan is especially to be advised in comparatively small planes4 ,design your plane and lay out its exact form on a board4 ,a thin strip of wood should be cut the width of the front or entering edge1 and similar straight lengths for the longer ribs4 ,it will be found a good plan to use a heavier piece back of the front edge or at the top of the curve4 ,in building your plane1 follow the former directions of laying a stick on the board to give you the height of the curve4 ,the shorter cross ribs may then be fastened by glueing to the longer ribs4 ,by using a light lath or strip for the cross ribs1 it will be possible to make them sufficiently rigid merely by glueing without the trouble of nailing4 ,a skeleton frame of this kind has the advantage of being very elastic4 ,in covering the frame1 draw the cloth tightly across the upper side of the frame and touch with glue at regular intervals along the ribs4 ,when dry1 trim away the cloth between the points of the ribs and the open ends4 ,the rear edge may be held in position merely by the shorter cross ribs4 ,trim the cloth along the edge4 ,in such a plane it is well to stiffen the cloth covering by painting with shellac or varnish4 ,this also lends a semi-transparent effect which improves the general appearance of the plane4 ,by cutting away the side and end pieces of the frame such a plane three feet in width may be made to weigh less than one ounce4 ,since it is very important that the covering of the planes may be perfectly smooth1 it will be well to experiment with several different methods of attaching the cloth or silk or paper4 ,by covering with paper1 a taut surface like a drumhead may be had4 ,use a rice or fiber paper and moisten the sheets by laying them between damp cloths1 as was explained in detail in a previous volume4 ,in drying1 the paper contracts and tightens4 ,in covering a frame with cloth1 the angle of the two sides may be altered by stretching the covering over the raised ribs on one side and drawing it tightly from edge to edge on the reverse side4 ,if you have difficulty in making your surface smooth1 try lacing it to the sides4 ,you will need a strong hem at the edge4 ,by using a thread1 you will be able to pull the cloth taut much the same as tent flaps are tightened4 ,the proper curve for a flexed plane is still a matter of dispute4 ,the highest part of the curve should come well forward1 while the rear surface is drawn straight4 ,a good camber may be plotted very simply4 ,draw a rectangle with a length sixteen times its height4 ,now mark off a point on the upper side one-fourth of the way from the left-hand corner and draw diagonal lines from this point to the two lower corners4 ,next round off the broad angle formed by the two lines and you will have a good curve to imitate in flexing your planes4 ,,chapter ,,vi ,,scientific ,,propeller ,,building ,ever since windmills were first set up1 men have been studying the merits of different propellers4 ,by the time steamships came to be driven through the water by rotary blades or screws1 their modeling had become a science4 ,the builders of rotary fans in turn contributed still further to our knowledge on the subject4 ,drawing largely upon all this experience1 the aviator has learned to build fairly efficient propellers1 although there is probably no department of aeronautics to-day so little understood4 ,in a windmill a current or cylinder of air flows1 of course1 against the propeller4 ,the blades must be shaped and spaced with this in view4 ,reverse the action of the windmill1 and the propeller proves inefficient4 ,the broad blades will stir up a current of air1 to be sure1 but a very weak one4 ,a revolving fan solves a very different problem in detaching a cylinder of air from the atmosphere and propelling it with the greatest possible momentum4 ,here1 again1 the propellers must be differently modeled and spaced4 ,neither the reversed windmill propeller nor the electric fan1 however1 would serve to drive an aeroplane4 ,illustration3 ,a beautiful monoplane built by ,r4 ,mungokee ,illustration3 ,detail of a model built by ,r4 ,mungokee ,illustration3 ,an ingenious application of the dihedral angle ,the propeller of an aeroplane must cut its way smoothly1 pressing the air backward without splashing4 ,it is only when an aeroplane is held fast that its propellers kick up such a fuss and blow your hat off4 ,the aeroplane propeller's work is much the same as that of a steamship1 although the air through which it travels has many tricks not yet understood4 ,the density of the air compares to that of water as one to eight hundred1 but the friction encountered by the air propellers is much greater than #a-hjjth that of water4 ,it may be laid down as a general rule1 however1 that the driving force of an aeroplane propeller varies as the square of the number of revolutions per minute4 ,there is at present no standard form of propeller for the man-carrying or model aeroplane4 ,one school of designers favors a small blade revolved at high speed1 while others claim that a larger propeller driven more slowly is more efficient4 ,as a general rule it may be laid down that a model with a span of thirty inches should be driven by twin propellers eight inches in length or diameter4 ,they should have a speed of about #a1bjj revolutions per minute1 or at the rate of some #bjj turns every ten seconds4 ,to test the strength of your motor1 give the propeller #bjj or #djj turns1 and watch in hand1 find how long it takes to run down4 ,illustration3 ,diagram ,showing ,how ,to ,make ,a ,propeller ,from ,a ,wooden ,blank ,there is much difference of opinion as to the proper modeling of the propeller4 ,it has been worked out by elaborate equations that the blade should be concave and yet in actual tests it has been found that some machines are driven faster by a flat blade propeller4 ,by a flat screw we mean a straight pitch propeller1 or one in which the angle does not vary from the hub to the tip4 ,when ,mr4 ,glenn ,h4 ,curtiss made his famous record flight at ,rheims1 he used a straight pitch propeller1 and when1 later1 his machine was equipped with propellers scientifically curved1 his aeroplane lost speed4 ,evidently the exact relation of propeller forms to the machine still remains much of a mystery4 ,illustration3 ,design of ,metal ,propeller ,a very simple test of the efficiency of propellers of various modeling may be made by running them in heavy smoke4 ,by burning a piece of oily cotton waste1 you may watch the action of the propellers on the smoke1 while1 at the same time1 this greasy smoke will leave its mark on the section of the propeller blade which does the most work4 ,the speed of the blades near the hub of the propeller is1 of course1 much less than at the tips1 and consequently the work they perform in sending the aeroplane forward is small4 ,at the extreme end of the propellers1 the air1 of course1 tends to slip off4 ,the most efficient part of the blade1 according to these tests1 is about one-third of the radius distant from the center4 ,less than two-thirds of the propeller seems to do effective driving work4 ,on the propellers driven against greasy smoke1 the blades near the hub remain comparatively clean while the portion most soiled extends outward from this point4 ,the test would seem to indicate that a broad blade narrowing to the hub would develop the maximum thrust4 ,it would also seem that it is unnecessary to carry the lines of the blade close to the axle1 thereby possibly weakening the propeller4 ,to understand the theory of the propeller1 bear in mind the principle of the action of the wings1 for the analogy between the two is very close4 ,the forward1 or entering1 edge of the propeller is curved so that it will cut its way smoothly and offer less resistance than a straight entering edge4 ,the blade of the propeller is made slightly concave for exactly the same reason that the plane is curved4 ,like the plane1 such a surface takes advantage of the resistance of the air4 ,the curve of the propeller blade near the hub is made much higher than further on because this part travels more slowly1 and it is important that the cylinder of air set in motion by the blade should have the same velocity throughout its diameter4 ,the blade is made widest at its outer end1 since this is the most effective surface and is expected to do the greatest amount of work4 ,the other end of the propeller blade is rounded off in order that the air may slip away1 thus avoiding skin friction1 which at this point is naturally high4 ,illustration3 ,a test of high aspect ratio planes ,illustration3 ,a modified ,bleriot built by ,cecil ,peoli ,the width of the propeller blade has been the subject of an immense amount of investigation and discussion4 ,the friends of both the wide and narrow blade back up their arguments with complicated equations1 which it would only be confusing to repeat4 ,it is argued by some authorities that since the narrow blade does not stir up the air as long a time as the wide blade1 therefore one blade does not stir up the air enough to interfere with the action of the second blade4 ,illustration3 ,langley ,propeller ,blade ,a small blade may be driven by a much lighter motor1 and is1 of course1 capable of much higher speed4 ,on the other hand1 the wide blade drives the model much further ahead per turn than the narrow blade1 while making a much greater demand upon the motor4 ,briefly a narrow propeller is best for speed and the wide blade propeller for power4 ,there is an immense amount of difference of opinion concerning the form and position of the propeller so that it is impossible to lay down any hard and fast rules4 ,it is argued by several well-known aviators that a propeller is more effective when driven with its straight edge forward and there is scarcely a point not in dispute4 ,one of the most novel propeller designs1 the ,cowley1 is a blade bent in the form of an arc of a circle1 the radius of the curve being equal to the diameter of the propeller4 ,the propeller is mounted with the convex surface forward4 ,the theory of this propeller is that it focuses the air1 as it were1 which it throws back forming a cylinder of air which travels at a higher speed than one set in motion by the horizontal blades4 ,the tendency for the air to slip off the ends of the propeller blades is probably reduced4 ,this form of propeller may be made by steaming the blades and bending them into position4 ,a mould may be prepared and the steamed blades forced to take their shape and held in position until they have dried4 ,a series of experiments have been made in ,england with boomerangs to discover the effect of curved surfaces on flight4 ,the ,langeley propeller1 which embodies the information gained in this way1 has a flat back while the face is concave1 following the general stream line form4 ,the ends of the propeller blades are practically square4 ,some of the new propellers are covered with a thin canvass glued smoothly over the greater part of the blade4 ,the covering guards somewhat against splitting and splintering4 ,in the latest ,percy ,pierce models1 for instance1 the blade is carried out in a semicircle at the end of the propeller1 thus practically doubling its surface4 ,the driving power of this blade is very high4 ,it is argued for this design that the blade being very thin is forced slightly backward at the beginning of the flight1 while the model is gathering motion1 but later1 when the tension is removed1 springs back thus increasing its effective surface and the thrust4 ,the propeller thus automatically adjusts itself for the work it has to perform4 ,since it is so difficult to fix upon the right pitch of a propeller1 the builder of model aeroplanes had best work out this problem for himself4 ,the propeller blank described later on1 with a depth of three-fourths of one inch to an eight inch diameter1 will give you a comparatively low-pitch propeller4 ,an eight-inch propeller cut from a block one inch in depth will give you as high a pitch as you are likely to need4 ,as you increase the pitch1 you1 of course1 increase the power of your aeroplane1 while at the same time you make a greater demand upon your motor4 ,try the propellers of different pitch until you find the one which gives you the greatest stability and the highest speed4 ,it is well to remember that in increasing the width of your propeller blade you add to the skin friction4 ,some designers carry the curve of the propeller blade to the center of the axle1 while others leave the center blank4 ,it is argued by the former that the longer the blade the greater is the thrust4 ,others believe that the blade exerts little or no thrust near the center and is weakened by being cut away too much4 ,the builder of model aeroplanes has one great advantage over the designer of passenger-carrying craft4 ,the model does not have to carry fuel4 ,after all1 the difference in the power required for the various models is so slight that an extra strand or two on the motor will probably solve the problem4 ,many successful builders of model aeroplanes now carve their propellers from solid blocks of wood4 ,this method1 to be sure1 allows the designer to shape the propeller blades with more freedom than with the ordinary or built-up propeller1 and of course does away with much of the preliminary work4 ,so great is the demand for the one piece propellers that the manufacturers of accessories now prepare propeller blanks or pieces of wood in a variety of sizes ready to be carved4 ,the one-piece propeller is likely to split1 but they are easy to make1 and this work is a very fascinating kind of whittling4 ,illustration3 ,a combination of several interesting features ,illustration3 ,a skilful adjustment of the front plane and skid built by ,percy ,pierce ,propeller blanks are easily prepared in case you find it inconvenient to buy them4 ,the following directions refer to a propeller eight inches in length1 but the same proportions hold good for any size4 ,select a piece of some straight-grained wood1 white pine is best1 which will not split readily1 and is easy to work4 ,the original block for an eight-inch propeller should be eight inches in length1 two inches in width1 and three-fourths of one inch thick4 ,now draw a line lengthwise1 exactly bisecting the block1 and mark off the middle of the line1 and two points one inch from either end4 ,with one of these outer points as a center1 describe a quadrant of a circle above the line1 and from the corresponding point1 draw a similar circle below the line4 ,from the center of the blocks draw a complete circle one-half of one inch in diameter4 ,draw straight lines from the ends of the arcs to the vertical diameters of the circle1 and saw away the wood to these lines4 ,in carving your propeller1 first cut away the wood from the longer straight lines of the block on opposite sides4 ,the blades should be slightly concave4 ,it will be found a good plan to finish one side of the blade before cutting away the opposite side4 ,cut away the wood until the blade is less than one-eighth of an inch thick1 and sandpaper away all marks of the knife or chisel4 ,the wood should then be oiled or covered with a light coat of varnish4 ,it is very important that the two ends of the propellers should be uniform both as to their modeling and weight4 ,to mount the axle1 drill a hole at the center just large enough to admit the wire4 ,the outer end may be bent over and inserted into the hole to keep it rigid4 ,if the axle does not fit tightly1 drive in small wedges of wood1 such as a toothpick1 at both sides4 ,the propeller used by the ,wright ,brothers on their machines is very simple to construct4 ,prepare a propeller blank eight inches in length1 two in width and three-fourths of an inch in depth4 ,draw two lines parallel with the longer sides1 the first seven-eighths of an inch and the second one and one-eighth inches back4 ,now at the upper right-hand corner mark off a point one and one-half inches from the end1 and from the opposite corner on the lower base the same dimension4 ,connect these two points4 ,illustration3 ,wright ,propeller ,blade ,the blank is completed by cutting away to these lines1 leaving the blades each one and one-eighth inches in width4 ,the axle should be left a little full1 say three-eighths of an inch across4 ,round off the outer corners4 ,in modeling your propeller cut away or bevel the sides formed by the two intersecting lines1 which will form the entering edge of the propeller4 ,the blade should be cut to a very slight concave1 although some prefer a flat blade4 ,the propeller is mounted by drilling a hole at the center and mounting in the usual way4 ,the propellers of a model aeroplane are subject to more wear and tear than those of a regular passenger-carrying machine4 ,at the end of every flight1 they face a possible catastrophe4 ,in the search for some durable form of screw1 a number of interesting discoveries have been made4 ,one builder has succeeded in coating a wooden propeller with bronze by subjecting it to an electroplating process1 but this is much too complicated for the amateur4 ,the lighter metals1 aluminum and magnalium1 naturally suggest themselves for the purpose4 ,such propellers weigh no more than wood and may be readily bent to the required shape4 ,procure a thin sheet of aluminum1 or1 if this cannot be had1 a smooth piece of tin will do4 ,it must1 however1 be heavy enough to hold its shape4 ,the design of the propeller may be laid out on the tin1 and the metal trimmed away4 ,to make an eight-inch propeller1 draw a rectangle eight inches in length and two inches broad1 and draw a line joining the middle of short sides4 ,at the center1 draw two vertical lines half an inch on either side of the center lines1 half an inch above and below the center1 forming a small inner rectangle4 ,now from a point on the bisecting line1 one inch from either end1 draw two semicircles4 ,next1 connect the top of one of these circles with the nearest point of the inner rectangle and draw another line from the point below to the corresponding corner of the large rectangle4 ,repeat the diagram on the other end of the rectangle1 reversing the curve as indicated in ,fig4 ,a4 ,in cutting out the design1 allow the straight sections running to the sides of the larger rectangle to remain4 ,they will be needed to hold the central piece in position4 ,this consists of a block of wood measuring one inch by one-half an inch and one-quarter of an inch in thickness4 ,the strips at the center should be bent tightly over the corners1 overlapped1 and nailed firmly down with brads4 ,next1 at the center1 punch a small hole and drill through the block a shaft large enough to hold the axle of the propeller which is then firmly imbedded in it4 ,one great advantage of the metal propeller is the fact that you may readily alter its pitch4 ,an efficient propeller may be made by mounting metal blades on a wooden shaft4 ,procure a stick one quarter of an inch square and three inches in length1 and saw through both ends for a distance of three quarters of an inch4 ,prepare your propeller blades by plotting them out on a sheet of aluminum1 as described above1 and cut away the middle section4 ,the blades may then be inserted in the open ends of the stock and nailed securely in position4 ,the edges of the wood may then be rounded off and the axle inserted firmly at the center4 ,the metal sheet should be bent into the proper pitch as in the case of other metal propellers4 ,,fabric ,,propellers ,the most nearly indestructible propellers are the fabric screws4 ,they are also doubtless the lightest form4 ,the blades will1 of course1 be perfectly flat1 making straight pitch propellers4 ,you will need a small cylindrical piece of wood one half an inch in diameter1 and one half an inch in height1 of some tough1 hard wood4 ,the blades may be made of reed or cane1 or1 still better1 of wire4 ,aluminum wire being very light is probably the best for the purpose4 ,bend the wire into the form of a triangle two inches in width and four inches in length4 ,determine at what angle you wish them to be set1 and bore holes in the hub and fix wires of each frame firmly in them4 ,cover the frames neatly with cloth and mount it in the usual way4 ,illustration3 ,an efficient model1 showing excellent construction1 designed by ,john ,caresi ,illustration3 ,one of the best minimum plane models of #aiaa ,,the ,,langeley ,,blank4 ,many model builders still retain the ,langeley propeller4 ,it is a very simple one to build4 ,to prepare a blank secure a block1 as before1 eight by two inches and three-fourths of an inch in depth4 ,connect the four corners with diagonal lines4 ,parallel to the longer side draw two lines1 one three-fourths of an inch inside and the second one-half inch below it4 ,cut away the block forming a double fan-shaped piece4 ,some prefer a wider center and the hub may be made a trifle broader if desired4 ,in shaping the propeller cut away from opposite sides of the blank4 ,the original ,langeley is a flat blade propeller so that the modeling is very simple4 ,you may use your own judgement as to the thickness of the blade1 although about one-eighth of an inch is suggested4 ,the ,langeley is mounted in the usual way4 ,to heighten the pitch of your propeller secure a thicker blank4 ,,chapter ,,vii ,,assembling ,,the ,,motors ,in the present stage of model aeroplane building1 rubber strand motors satisfy every demand4 ,models have been flown for more than #b1ejj feet by the force of these twisted strands1 and doubtless their efficiency will be still further increased4 ,such motive power is besides very easily obtained and applied4 ,careful tests have shown that more energy may be stored up in twisted rubber strands than in the same weight of springs of steel or any other metal4 ,in gauging the strength of your motor1 much depends upon whether your model is to rise from the ground or be launched from the hand4 ,in the model tournaments in ,england1 the flying machines are almost invariably thrown across the starting line1 while in ,america they are required to rise unaided4 ,it is obviously unfair1 therefore1 to compare the distance records of the two countries4 ,illustration3 ,a ,metal ,motor ,anchorage ,it requires a comparatively powerful motor to raise a model from the ground1 whereas a lighter motor would be sufficient to propel it through the air4 ,many models1 capable of flights of several hundred feet when thrown will refuse to rise1 while1 on the other hand1 some models which rise well enough have poor distance qualities4 ,it should be borne in mind that the length of the motor1 speaking broadly1 controls the distance qualities1 and its diameter the speed of the model aeroplane4 ,a long slender motor1 capable of from five hundred to one thousand turns which will revolve the propellers for thirty seconds or more1 should insure a flight of several hundred feet4 ,as you increase the number of strands of rubber1 building up the diameter of the motor1 you cut down the number of turns and therefore its duration1 although you increase its speed4 ,a motor capable of one thousand turns must be about forty inches in length and consist of but six1 or at most eight1 of these strands4 ,a model which may be driven by this motor1 it will be found1 must be very light4 ,a model aeroplane weighing upwards of one pound1 on the other hand1 will require motors composed of fourteen strands or more to raise it from the ground4 ,it is a very simple matter1 of course1 to add strands of rubber until your motor develops sufficient energy for the work it is expected to do4 ,the length and diameter of your motor1 again1 has a direct influence on the height of the flight4 ,too much power tends to raise the aeroplane higher than necessary above the ground4 ,since it requires more energy to drive a model aeroplane upward than along a horizontal direction1 this is obviously a waste of energy4 ,if it is desired to fly the model as far as possible1 it must be kept close to the ground4 ,in the case of weight-lifting contests1 the problem of altitude is1 of course1 entirely different4 ,overwinding is even worse than underwinding1 since it shortens the life of the motor4 ,try out your aeroplane with ten strands on each motor and increase them later4 ,the motor1 as previously explained1 is formed by looping the rubber strands loosely between the hooks1 just as zephyr is wound on a skein4 ,keep the strands very loose and fasten them to the hooks by tying with a strand of rubber4 ,in winding1 do not turn the propeller after the rubber has a double row of knots for its entire length4 ,such a motor should take up from three hundred to five hundred turns1 perhaps more4 ,do not keep the elastic wound up too long before starting your flight4 ,the strain is great and it quickly wears out4 ,illustration3 ,a ,metal ,motor ,anchorage ,the rubber strands should not be allowed to come in contact with any metal parts of the model4 ,the copper that is often used for wiring is especially injurious and tends to decompose the rubber4 ,the hooks of both the propeller and motor anchorage should be covered with a piece of rubber tubing4 ,this serves a double purpose4 ,with this protection1 the rubber when tightly twisted is in no danger of being cut by the wire or of taking up the oxides which quickly eat through it4 ,illustration3 ,a notable model possessing unusual stability4 ,built by ,w4,s4 ,howell1 ,jr4 ,illustration3 ,front view of model built by ,w4,s4 ,howell1 ,jr4 ,it requires an expert to pick out the best quality of rubber4 ,if the strands be examined under a magnifying glass1 it will be found that the edges of fresh rubber of the best quality are clean-cut1 whereas the cheaper rubber1 and that which is worn1 has commenced to granulate1 giving the edges a ragged appearance4 ,a simple test is to stretch the rubber over a ruler4 ,a good rubber1 in first-class condition1 will stretch about seven times its length1 and on being released instantly spring back to its original size4 ,the same rubber should stretch to ten times its length without breaking4 ,there is a great difference of opinion among the most successful model builders as to the best shape of rubber strands4 ,some prefer the flat1 band rubber1 while others are obtaining satisfactory results with rubber cut in square strands4 ,the strand used by the ,english model builders is seldom more than one-sixteenth of an inch square1 while in ,america one-eighth of an inch strand is commonly used4 ,experiments have been made with a single strand of rubber one-fourth of an inch square1 but the results have not been satisfactory4 ,one theory is that the corners of the square rubber tend to cut into one another and quickly wear out1 and that a perfectly round strand would be the more efficient4 ,at present there are no such strands on the market4 ,it is argued by some that the square strand in twisting must be turned on itself further than the flat strand1 and is therefore placed under an unnecessary strain4 ,after all1 the advantage of one form over another is fractional1 and an extra strand added to the motor will balance any possible defects4 ,figures have been prepared giving the exact relation of the size of rubber to the number of turns1 although such statistics are elastic4 ,the problem may be worked out with your own motor4 ,differences of temperature will be quickly noted4 ,the rules prepared by ,v4 ,e4 ,johnson1 ,m4,a41 an ,english authority on aviation1 are as follows3 ,the motive power is doubled by increasing the number of rubber strands one-half2 by doubling the number of strands1 the motive power is increased more than two times2 and the tripling of the strands increases the motive power seven times4 ,as regards the number of turns the same authority states that the doubling of the number of strands diminishes the number of turns by one-third to one-half4 ,illustration3 ,a ,metal ,skid ,it is also found that each strand will have doubled knots of #caj turns2 four strands1 #ddj2 sixteen strands at #bjj2 and eight at #baj4 ,this is working with strands one-sixteenth of an inch square4 ,as a rule1 rubber should not be turned after the second row of knots is formed4 ,and by the way1 you will find that the rubber1 after being tightly twisted1 tends to stick together1 and should be carefully separated after a flight so that the air can reach all surfaces4 ,according to the experiments made by ,mr4 ,johnson1 one pound of rubber may be made to store up #cbj foot pounds of energy1 while one pound of steel1 in the form of springs1 will only store up #fe pounds4 ,in the early model aeroplanes much valuable energy was lost through friction4 ,there has been a marked improvement in the construction of the propellers1 axles1 and bearings4 ,friction has been reduced to practically nothing4 ,it is possible1 of course1 to drive a propeller with the shaft turning in a hole drilled at random through a stick1 with a glass bead for a washer4 ,it is very important1 however1 that the axle should turn exactly at right angles1 and to hold it in position requires careful adjustment4 ,to meet the demands of model aeroplane builders1 several shaft mechanisms have been prepared1 even to a very complete arrangement of miniature ball bearings4 ,the model builder who cannot avail himself of these parts can1 nevertheless1 imitate their action with reasonable fidelity4 ,the axle attached to the propeller should be heavy enough to resist bending in ordinary wear and tear4 ,a bicycle spoke is just the thing4 ,when you have decided upon this axle1 procure a piece of metal tubing in which the axle will turn freely1 without binding or rattling about4 ,the tubing should then be passed through the frame supporting the propeller exactly at right angles1 and extend out at either side about half an inch4 ,to fasten it securely in position1 glue and if necessary drive small wedges1--a match or toothpick1--about it4 ,several metal washers should be strung on the axle between the upper edge of the shaft and the propeller4 ,these may be punched from a sheet of metal4 ,a section of this tube may also be inserted part way in the propeller1 and washers introduced where they meet4 ,the second tube will insure smooth action4 ,the projecting tube will serve also to remove the propeller far enough from the frame to prevent its striking4 ,by freely oiling these parts1 the propeller may be made to turn very freely4 ,illustration3 ,an ingenious adjustment of ailerons ,illustration3 ,tuning up the model for a flight4 ,in bending the axle into a hook for holding the rubber strands of the motor1 care must be taken to keep the ends of the strands on a line with the axle4 ,after turning the wire into a hook1 bend back the shank to the proper angle4 ,it will be seen that if the motor carries the axle about from side to side1 the friction will be considerably increased4 ,over this hook1 slip a piece of rubber tubing before attaching the strands of rubber1 since the metal is likely to cut and wear the motor4 ,it will be found a good plan to tie the strands together just below the hook to keep them from slipping off4 ,and1 by the way1 do not keep your motor wound up any longer than you can help before a flight1 since the strain on the rubber in this position is very great4 ,as motors have increased in power and distance qualities1 the process of winding up has become a serious problem4 ,the simple method of turning the propeller by hand takes too long1 and a slip with a powerful motor may give one an ugly cut4 ,an ordinary machine drill will do the work much more quickly4 ,some drills are geared so that a single turn of the wheel will give you ten revolutions of the propeller4 ,to arrange your motor for winding with a drill1 run the axle through the propellers and turn in the form of a closed hook4 ,a small hook should then be fixed to the end of the drill1 which may be inserted in this loop4 ,some boys use a double hook on the propeller1 detach the strands of rubber1 wind them up1 and then attach them to the propeller4 ,a very simple and ingenious method of winding up has been adopted in the remarkable model constructed by ,mr4 ,mungokee4 ,the motor is anchored by running the wire holding the strands through the supporting stick of the base1 and bending the end into a hook which1 as the rubber pulls1 is held securely in a second hole at the side4 ,illustration3 ,showing ,construction ,and ,mounting ,of ,propeller ,and ,axle4 ,to wind up1 it is only necessary to draw out this hook1 attach it to the winding drill and turn4 ,when wound up1 the pull of the motor will obviously hold the end of the hook firmly in the hole1 making it impossible for it to turn4 ,this does away with extra hooks and the trouble of hooking up the motor when once it has been wound4 ,the life of your rubber motor may be lengthened by careful winding4 ,as long as you wind up by turning the propeller by hand1 it is safe to turn it as fast as you can1 since the process is slow at best4 ,in case the turning is done with a machine drill or some similar geared wheel1 there is danger at some points of winding too fast4 ,it is safe to wind as quickly as you can until the first row of knots has formed in the rubber strands1 but at the moment the double strands begin to appear the winding should proceed very slowly4 ,you will find that if you wind very quickly the double knots will appear in tight groups or bunches1 and that only after considerable winding do these begin to spread out evenly4 ,this puts the rubber under a severe and unnecessary strain and shortens its life4 ,the simplest way of locking the propellers when once wound up is to thrust a piece of cane or reed through the hooks4 ,the twist of the motor will hold it tightly in position1 so that you can carry your model about1 even shake it vigorously without danger of dislodging it4 ,if you have twin propellers1 use a strip long enough to pass through both hooks4 ,remove the strip just before starting4 ,be careful1 of course1 that your axles have not been thrown out of plumb4 ,it will be found very convenient to equip your model with a single clasp for holding the propellers after they have been wound up1 which may be easily released4 ,it is awkward to keep them from slipping4 ,an effective break may be made by attaching two strips of reed or cane1 such as you use for skids1 to either side of the motor base1 so that the free ends will pass between the propeller blades and the frame1 thus locking them fast4 ,these bands should spring outward and be held in position by rubber bands running from one to the other4 ,to release the propellers1 simply pinch the two free ends together1 and the propellers will be freed at the same instant4 ,do not keep your motor wound up a moment longer than you can help4 ,it is very trying to the rubber to be held in this tightly-twisted position4 ,in mounting your propeller1 it is well to make the support for the bearing of the propeller axle as long as possible4 ,an axle turning in a shaft one inch in length will meet with much less resistance than in a half-inch shaft1 and with a good motor an inch-and-a-half shaft is still better4 ,the rear stick of your motor base1 which often holds the propeller axle1 is usually made as thin as possible and rarely gives you more than a half-inch support4 ,it is a good plan to lengthen the shaft by attaching a block of wood to the frame and passing the axle through it4 ,cut from a strip one-half an inch square a piece one inch in length1 or whatever seems necessary4 ,this may be mortised slightly into the stick and glued at right angles4 ,illustration3 ,an excellent monoplane capable of long flights4 ,illustration3 ,long-distance model built by ,percy ,pierce4 ,now drill a hole through the stick1 with the grain1 and the stick of your motor base and pass the tube holding the propeller shaft through both4 ,to make this look shipshape1 round off the edges4 ,a great advantage of this stick is that it enables you to mount the propeller as far as you like from the frame1 thus preventing it from striking4 ,illustration3 ,showing ,an ,excellent ,way ,of ,fastening ,the ,propellers ,to ,the ,framework4 ,in mounting the propellers above or below the frame1 you will need similar supports4 ,the blocks should measure half an inch in width by one and a half inches square and should be cut with the grain of the wood running lengthwise4 ,the hole for the propeller shaft is drilled near the top1 and the block is securely fastened to the frame4 ,it will be found a good plan to mortise the frame slightly in order to make the joint perfectly rigid1 even in the face of a bad smash-up4 ,many boys merely glue the stick in position and bind it securely to the motor base with fine strong thread1 and paint it with glue or shellac to hold it in position4 ,these blocks may be fastened either above or below the frame or at the sides4 ,in mounting the propellers1 bear in mind that a position above the planes tends to drive the aeroplane downward1 while the thrust exerted below tends to throw the aeroplane upward4 ,the builders of model aeroplanes differ as much as to the best position of the propellers as the designers of man-carrying machines4 ,excellent models have been built with the propellers in either position4 ,it is obviously impossible to lay down a rule for all models1 since the properties of the planes vary so widely4 ,a very simple and efficient support for the propeller shaft may be made of metal to correspond to the motor anchorage4 ,procure a sheet of heavy tin--a piece of sheet aluminum is still better--one-half inch in width and three inches in length4 ,now mark off a one-half inch1 one inch1 two inches1 and two and one-half inches1 and bend over the ends at right angles1 as shown in the accompanying drawing4 ,this support may be nailed or screwed rigidly to the end of the motor base1 and a hole for the shaft of the propeller drilled through the two uprights4 ,the propeller must be mounted so that the blades will1 of course1 be free of the base4 ,the size of the support may be altered to suit the frame4 ,in case you are using a heavy propeller1 say an inch blade1 the metal must be heavy enough to resist the pull of the propeller4 ,the forward ends of the motors may be held by a cross piece cut from a sheet of aluminum six inches in width and two inches in depth1 which is bound rigidly to the end of the motor base with shoemaker's thread4 ,aluminum suitable for this purpose costs about fifteen cents a square foot1 and is soft enough to be cut with heavy shears4 ,an ingenious motor anchorage of metal construction has been hit upon by the builders of model aeroplanes in ,france4 ,we are all familiar with the difficulty of raising the hook1 holding the rubber bands1 high enough above the main frame1 or fusilage1 to be perfectly free4 ,instead of attaching a wooden block1 the ,french boys bend a piece of tin1 or some such metal1 very simply into a support for the hook4 ,you will need a sheet of metal heavy enough to withstand the full force of the motor when wound up4 ,the tin used in cans1 as a rule1 is not heavy enough4 ,for each support you will need a rectangle of tin or metal measuring three by one and one-half inches4 ,parallel to the longer base1 draw a line one-quarter of an inch above4 ,from the center1 erect a long rectangle one-quarter of an inch wide1 extending to the opposite side4 ,now connect the ends of the line above the base with the points at which the upright rectangle intersects the top line1 round off the edges neatly and cut away this triangle4 ,four holes should be cut or punched in the tin1 as indicated in the drawing4 ,now bend the tin on the two upright lines until the two sides are parallel4 ,this support is fitted to the end of a motor base and secured by driving nails through the three holes at the base covering the wood4 ,the end of the hook which holds the rubber strands of the motor should be passed through the opening at the end1 bent over and fastened into position with a drop or two of solder4 ,such a support adds practically nothing to the weight of the frame1 and obviously anchors the motor rigidly4 ,illustration3 ,model built by ,rutledge ,barry1 winner of spectacular flight contest4 ,illustration3 ,a model by ,percy ,pierce1 winner of the indoor long-distance record4 ,the efficiency of a rubber-strand motor may be considerably increased by careful adjustment4 ,if the strands first be wound rather loosely1 as a rope is formed1 and strung between the propeller hook and the motor anchorage1 you will find that about thirty per cent4 more rubber may be added without increasing the length and that a five to ten per cent4 increase in the number of effective turns may be gained as well4 ,by increasing the amount of rubber1 you will1 of course1 add accordingly to the power of the motor4 ,it is safe to say that the efficiency of your motor is increased upwards of twenty-five per cent4 by this adjustment4 ,the credit of this ingenious arrangement is due to ,mr4 ,w4 ,howell1 ,jr4 ,it will be well to experiment with a short-strand motor1 using a single strand of rubber for the test4 ,let us assume that your motor is twelve inches in length1 thus making a double strand twenty-four inches long4 ,first knot this1 string it between the two hooks and turn it1 counting the revolutions until the first row of double knots begins to appear4 ,note the number of turns4 ,now untie the strand and1 holding one end1 twist it until the lines of the edges make a continuous loose spiral throughout its entire length4 ,the easiest way of twisting them is to lay them on a flat surface and rub with the palm of the hand4 ,now bring the two ends together and let the strands twist and wriggle until they come to rest4 ,fasten the ends and measure the double twisted strand4 ,you will find that it measures less than ten inches4 ,to prepare a strand for a twelve-inch motor1 you must therefore begin with a piece of rubber fully thirty inches in length4 ,it is clear1 therefore1 that the new plan enables you to gain considerably more rubber length for length4 ,now string your twisted rubber on the hooks of your motor so that to wind up you must turn against the twisted strand4 ,you will find that a number of turns are required before the rubber strands are untwisted and lie parallel1 which is pure gain4 ,count the number of turns up to the time the first line of the double knots appears1 and you will find that it is about five per cent4 greater than in the case of the single strands4 ,the power exerted by your motor is meanwhile increased in direct proportion to the amount of rubber added4 ,still another advantage of this adjustment lies in the fact that such a motor will unwind to the first turn4 ,in preparing a multiple-strand rubber1 each strand must1 of course1 be twisted in the same direction and exactly the same number of times before being installed4 ,the builders of model aeroplanes may profit from the experience of the automobile tire manufacturers in studying the properties of the rubber used for motors4 ,rubber is at best comparatively short-lived4 ,it suffers a surface deterioration on being exposed to the air1 which in time affects the entire mass4 ,this process of decay goes on fastest in very warm weather and in very bright sunlight4 ,it is believed that sea air and the rarified air of the mountains are bad for rubber4 ,on the other hand1 a very low temperature1 as you may perhaps have discovered1 robs the rubber of much of its elasticity4 ,it will pay you to take some trouble to protect the rubber strands as far as possible4 ,lay them away in a can or jar in some cool1 dry and dark place when they are not in use4 ,some boys cover the rubber with powdered chalk4 ,when the surface of the rubber begins to granulate1 its best days are over4 ,rubber is originally white in color1 while the refining process gives it the familiar gray tone4 ,the ,para rubber is generally considered the best of the many kinds now on the market4 ,as a rule1 any oil or grease tends to decay the rubber1 as any motorist can tell you4 ,this is particularly unfortunate for the aviator1 since the efficiency of the rubber motor is increased by slightly lubricating the strands4 ,many boys prefer to chance injuring their motors in order to gain the advantage of the oiled strands4 ,the strands thus prepared slide smoothly on one another and do not grip each other even when tightly wound4 ,the simplest preparation for greasing the strands is a solution of ordinary soap and water4 ,a few drops poured over the strands will suffice4 ,when your motor unwinds1 be careful to keep your face out of range1 since a few drops might be flung into your eyes4 ,several preparations for lubricating the motors have been placed upon the market4 ,the direction flights may be controlled very easily by winding the motor4 ,if you care to fly your model in circles or spirals1 the simplest plan for influencing its direction is to give different power to your propellers4 ,it often happens that a model must be in a restricted place1 perhaps a straight-away flight is out of the question4 ,the model may be deflected to the right or left by the use of vertical propellers1 but they require delicate adjustment1 and a gust of wind may destroy their effect4 ,by winding up one double the number of turns of the other1 a circular flight is assured4 ,to gauge the diameter of the circle merely alter the relation of the number of turns4 ,you will soon find that you can control the diameter of the circle with remarkable accuracy4 ,illustration3 ,a ,motor ,anchorage ,,chapter ,,viii ,,directional ,,control ,the unerring flight of birds is1 of course1 the model for the builders of heavier-than-air machines4 ,much of the birds' skill in directing their motive power remains a mystery to us1 but we are learning to analyze and1 in a measure1 imitate them4 ,the builder of model aeroplanes again must not alone imitate the methods of the birds2 he must make their system of maintaining stability automatic4 ,a study of a variety of successful models shows that there is great difference of opinion as to the best plan for stabilizing the aeroplane4 ,directional stability is gained by the use of horizontal elevators or tails for controlling vertical movement1 by vertical rudders or fins for steering to right or left1 and by flexible wing tips to guard against tipping4 ,in designing any system of rudders1 or ailerons1 for gaining stability1 one should always have in mind the general principles upon which such surfaces act4 ,the movement of the horizontal planes or ailerons has an important effect upon the direction of the flight1 because they change the angle of incidence4 ,in other words1 they alter the angle of the plane with the line along which the aeroplane is flying4 ,if you bend the rear edge of the plane1 or aileron1 downward1 the angle of incidence is increased4 ,what happens is this4 ,as the plane is lowered1 the air is compressed beneath it1 which tends to lift the plane1 throwing up the front edge and changing the course of the flight4 ,this method of securing stability1 which was invented and patented by the ,wright ,brothers1 has been widely imitated4 ,in their later machines1 the ,wrights have even abandoned the front elevating surfaces and depend upon the movement of the main plane and a small elevating plane placed just back of the rear rudder for their directional control4 ,they have thus done away with the friction encountered by the front planes1 which has resulted in giving the machine greatly increased speed4 ,now in the model aeroplane1 it is1 of course1 impossible to flex the planes up or down during flight4 ,some adjustment must be hit upon which will give the machine automatic stability4 ,the principle of the action of the stabilizer remains1 of course1 exactly the same4 ,in designing rudders for controlling horizontal flight1 it should be borne in mind that their stabilizing power varies largely in proportion to their distance from the center of gravity4 ,in most models the further they are removed1 either front or back1 the greater is their leverage1 and the smaller need be their surface4 ,by placing the rudder on an outrigger carried far out1 a very small plane will suffice4 ,illustration3 ,a serviceable model showing excellent workmanship built by ,cecil ,peoli ,illustration3 ,a serviceable model showing excellent workmanship built by ,cecil ,peoli ,the vertical rudders or fins1 as they are sometimes called1 are1 of course1 intended to control the movement to right or left and keep the model from sliding sideways4 ,they have no counterpart in the wings of birds1 and are believed by some aviators to have little effect4 ,at any rate1 they can do little harm since their head resistance is practically nothing4 ,unlike the horizontal forward planes1 these fins should not be carried too far forward4 ,in practice it is found that they often get in the way1 and a slight side gust of wind striking them1 with their great leverage1 will knock the aeroplane completely off its course1 perhaps upset it4 ,the best position for such rudders is either above or below the main plane1 or behind it1 where they are out of the way of cross currents4 ,in last year's models1 these vertical surfaces were often very large1 presenting as much surface as the planes themselves4 ,it has been found that they may be cut down in size1 thus saving weight without losing their efficiency4 ,a long vertical fin1 or keel1 has the disadvantage of presenting a dangerously broad surface to any cross current of wind4 ,the question of the position of the rudder was taken up in a previous volume4 ,a glance at the successful model aeroplanes of the year shows that the vertical rudders have been adopted very generally4 ,considerable ingenuity is displayed in adjusting them4 ,the use of wing tips of any form is intended to control both the horizontal and vertical movement4 ,the general theory or equilibrium1 of course1 applies in both cases4 ,the most perfectly adjusted model is subject to many forces which tend to tip it to one side or the other4 ,a gust of wind1--and the air is never perfectly quiet1--will tip one end of the plane up or down4 ,illustration3 ,various ,steering ,devices4 a and b1 simple aileron forms4 ,a novel fin on ,vinet plane4 ,b ,l-shaped aileron4 ,c vertical rudder 7,bleriot type74 ,d ,blinkers1 an effective rudder4 ,e stability planes not unlike the runners of a sleigh4 ,in the early models1 this tendency was met by fixing the plane at a dihedral angle4 ,an examination of last year's models will show how common was this design4 ,the dihedral angle lowers the center of gravity4 ,now1 after one side of the model is raised and the plane rights itself1 the center of gravity swings through a considerable arc1 like a pendulum1 before it can come to rest1 so that the center must swing back and forth several times4 ,this tendency to tipping is fatal to a steady flight4 ,it was first observed by the ,wright ,brothers while studying the early ,langeley type of machine4 ,the ,wrights abandoned the dihedral angle entirely1 as all the world knows1 and replaced it by the horizontal plane with a straight entering edge4 ,the keel will in a measure overcome this side motion4 ,much of the advantage of the dihedral angle may be borrowed1 however1 by turning up the extreme ends of the plane1 without materially lowering the center of gravity4 ,in several of the successful models of the year1 these tips have been made equal to about one-fifth the width of the plane1 and are raised as high as forty-five degrees4 ,the theory is that1 when the oscillation commences1 these surfaces damp out the swinging tendency1 and bring the model to an even keel4 ,sometimes the tips are rounded off1 although in some cases they are made triangular and brought to a point4 ,as a rule1 they are added to the rear plane1 although one notable exception is the case of the ,lester ,robinson model1 which carries these tips on both planes4 ,the tips1 or ailerons1 at the ends of the planes maybe made of the same material as the planes themselves4 ,in case you are using wire frames1 it is1 of course1 a very simple matter to bend up the tips to any desired angle4 ,when the frames of the planes are made of reed1 as is generally the case1 the tips should be made separately4 ,bend your reeds to the desired shape and cover them with the same material used for the planes4 ,it is quite as important that they be covered smoothly as in the case of the planes4 ,they may then be attached to the ends of the planes by wiring rigidly in position4 ,it will be found convenient to adjust them so that they may be bent up or down to suit conditions4 ,the same plan should be followed in building and attaching the ailerons to the rear of the main stability planes4 ,some interesting experiments have been made by placing several vertical surfaces above the main stability plane4 ,a series of four or six vertical rudders are sometimes spaced apart at equal distances1 extending from the front to the rear edge1 with a height of about half their length4 ,in some cases the corners are rounded off1 while others prefer to cut away the front edge sharply4 ,in the ,vinet monoplane1 the vertical fin appears in an entirely new form4 ,the fin is attached near the outer edge of the main plane and the upper edges curled inward1 forming an arc of a circle4 ,the theory of the curve is that it tends to keep the air from slipping off the ends1 after the manner of the curtains of the ,vaison biplane4 ,as a rule1 these curled fins are about three-fourths the depth of the plane and are attached with the front ends on a line with the entering edge of the plane4 ,these curled planes may be stretched on frames of light wire or thin reed4 ,as the model tilts to one side1 the air striking the curved surface of the outer side of the fin meets with little resistance1 while the fin at the opposite side1 acting with its concave surface against the wind1 offers considerably more resistance1 thus tending to check the side motion and bring the aeroplane to an even keel4 ,an effective form of aileron consists of an ,l shaped plane set closely against the rear corner of the main wing4 ,these ailerons are made in pairs and hinged to a rear edge4 ,the side should extend about half the width of the plane4 ,the action of the hinged plane at the rear is1 of course1 familiar4 ,the extension at the side1 which should be kept rather narrow1 not more than one-fourth the depth of the main plane1 is likely to prove very efficient4 ,if the aileron be turned too far either up or down it will offer considerable resistance4 ,in one of the new ,english models1 these ailerons are so connected that as one rises the opposite aileron is lowered4 ,here is a fascinating field for experiment in automatic control4 ,the vertical rudder used on the new ,bleriot1 the result of an immense amount of experiment1 suggests interesting possibilities for the model builder4 ,the rudder is built in the form of a long triangle and is mounted by hinging one of its shorter sides to the upper surface of the rear plane1 so that its corner will extend upward and outward4 ,in this position it suggests a fish's fin4 ,the receding angle of the front edge offers very trifling resistance4 ,the new ,baby ,wright racer depends for its lateral control largely upon a novel form of rudders known as blinkers4 ,these rudders are triangular in shape and extend out in front of and below the forward planes with their longer edges forward4 ,they act much the same as the jib of a sailing vessel1 and1 because of their position well in front of the center of gravity1 act with considerable leverage4 ,the design appeals especially to the builder of model aeroplanes1 since they can be added with very trifling weight by curving the front skids forward and stretching the cloth across their forward corners4 ,the ,valkyrie monoplane is equipped with similar rudders1 in the form of half circles carried in the same position4 ,in addition to the vertical and horizontal stability planes1 many aeroplanes are now equipped with stability planes extending diagonally from the vertical axis4 ,these are placed below the main planes1 extending outward not unlike the runners of a sleigh4 ,this box-like form tends to confine the air and affords increased support4 ,there is even an upward tendency from this pressure of air4 ,these planes are usually rectangular in shape1 the forward or entering edge being cut away sharply4 ,by mounting these planes on the skids1 their additional weight is practically nothing4 ,several interesting applications of this principle are shown in the accompanying illustrations of models4 ,,chapter ,,ix ,,model ,,aeroplane ,,designs ,whether one be designing the simplest paper glider1 a model or a passenger-carrying aeroplane1 the problem of stability is the same4 ,to keep afloat1 your air craft must be supported1 as a rule1 by at least two surfaces to provide longitudinal stability4 ,to understand the principle of longitudinal stability1 picture to yourself a very delicately-balanced board or seesaw4 ,the center of gravity naturally falls between these two planes at either end1 and the wings therefore tilt up or down1 or seesaw1 on this invisible fulcrum4 ,with this principle in mind1 the movement of your aeroplane1 which may seem so capricious1 will be seen to follow definite laws4 ,when a gust of wind forces the front plane upward1 the rear plane swings down4 ,this movement increases the angle of both planes to the horizontal2 they offer much greater resistance to the air1 and the speed of the machine is checked4 ,as the aeroplane slows down1 as a rule1 it tries to right itself1 that is1 to seesaw back to balance at a horizontal position4 ,this in turn reduces the resistance the planes offer to the wind1 and the flight is continued at its original speed4 ,illustration3 ,an excellent piece of workmanship4 ,model by ,r4 ,mungokee ,illustration3 ,model with minimum plane surface4 ,built by ,a4 ,c4 ,odom ,the trick1 therefore1 is to adjust your planes with regard to the center of gravity so that they will always seesaw back to a horizontal position2 in other words1 to secure automatic longitudinal stability4 ,in designing a motor base bear in mind that it must be made as long as possible for installing the motor1 and broad enough to afford stable support for the wings1 the whole being kept as light and as rigid as possible4 ,since the length of the flight depends directly upon the length of the motor1 the frame of your model should be at least two feet in length4 ,the width of the frame may vary widely1 as a glance at the successful model aeroplanes of the year will prove4 ,for racing model aeroplanes1 the base may be increased to four or even five feet in length4 ,,the ,,famous ,,one ,,ouncer4 ,the one-ounce models1 which have been brought to such perfection in ,england1 are among the simplest aeroplanes to build4 ,fig4 ,a models have a record of #a1ejj feet4 ,the adjustment is delicate1 however2 it is a very tricky affair to manage1 and whether you can get the remarkable flights made abroad is another matter4 ,for the stick1 select a piece of straight-grained ash or some light wood three feet in length and one-quarter of an inch square4 ,the planes should be cut from a thin board one-sixteenth of an inch thick4 ,the main plane should measure fifteen inches by three inches1 and the smaller plane eight by one and a half inches1 thus giving them a high aspect ratio4 ,they should taper slightly towards the ends4 ,round off the corners of both planes and sandpaper the edges down4 ,if the wood will stand it1 work it down1 using a sharp plane or sandpaper4 ,the planes should be bent by steaming slightly across the middle and set at a slight dihedral angle4 ,illustration3 ,a -- ,the ,famous one ,ouncer4 ,b -- ,a ,small ,experimental ,model4 ,c -- ,a ,modified ,burgess ,webb ,model4 ,the model is driven most efficiently by a six-inch propeller4 ,if it be a one-piece blade1 prepare a propeller blank six inches by one inch1 cut from a half-inch board4 ,cut away to the thinnest possible blade4 ,use a very simple support for your propeller shaft as well as for the motor anchorage at the extreme forward end4 ,the planes should be tied with rubber strands to the stick and glued in position when properly adjusted4 ,try out your model with a motor consisting of two strands of one-eighth-inch rubber1 and increase if necessary4 ,you will need all your ingenuity and skill and workmanship to construct a stable model even of so simple a design which will come within one ounce4 ,throw it with the wind4 ,a ,,modified ,,bleriot4 ,in improving the lines of the various self-raising models1 many of the designs have been greatly simplified4 ,with the number of members reduced1 the construction of a successful model becomes much easier and the chances of failure more remote4 ,a simple rectangular frame with two planes driven by twin propellers requires very little skill or experience to put together4 ,it is very easy to locate and correct the trouble in such a model1 and quickly adjust it to rise and fly for considerable distances4 ,there are many forms of such planes this year which are marvels of lightness and strength1 but the beginner should try the simplest4 ,begin by building a simple rectangular frame1 three feet in length and ten inches in width of half-inch or quarter-inch strips4 ,mortise the corners half way through each stick and glue them in position4 ,increase the steadiness of the frame by a cross piece at the center1 without mortising4 ,mount your motor above the frame1 selecting some simple1 strong support for the axle and the anchorage4 ,a model which rises unassisted requires considerable power and your propellers should have eight-inch blades and be carved from blanks one inch thick4 ,you may find it advisable later on to install propellers with very broad blades4 ,first install motors of considerable power1 each consisting of twelve or fourteen one-eighth-inch rubber strips4 ,you will not get more than two or three hundred turns out of them1 but with a high-pitch propeller this will give you an excellent flight1 say #bjj feet4 ,illustration3 ,model ,with ,minimum ,plane ,surface4 ,for the early trials use planes with a rather high aspect ratio4 ,make one of the planes four by sixteen inches with square corners1 and the second1 which will be carried forward1 about the same size with rounded corners4 ,both planes should have a slight camber4 ,attach the planes to the under side of the motor base4 ,the theory of this adjustment is that the planes thus rest upon undisturbed air and are more stable4 ,the planes above the frame come in contact with air which has been churned up more or less by the passage of the frame4 ,a small vertical rudder may be added below the rear frame and well back of the center of gravity4 ,the model should be supported at a slight elevation by a simple skid4 ,by adjusting the angle of the forward plane1 this model may be made to perform a number of spectacular flights4 ,a model very similar to this was the winner of a cup offered for the best spectacular flights at an important ,new ,york tournament4 ,a ,,simple ,,experimental ,,model4 ,a great deal of pleasure and profit may be had from a small experimental model aeroplane4 ,the beginner who is constructing his first model will find a small machine by far the most satisfactory4 ,the more experienced model builder1 on the other hand1 will find that so simple a model will enable him to try out new theories quickly and cheaply4 ,a simple ,bleriot form1 one foot in length1 driven tail foremost is recommended4 ,many successful model builders keep such a model constantly in their workshops4 ,a model aeroplane of this type and size can be made to fly from the very first4 ,many of the problems which appear so difficult in constructing a three-foot model1 such as balance1 head resistance1 and the proper adjustment of power1 practically are avoided in this miniature aeroplane4 ,there is a great advantage again in the fact that the small model may be flown indoors in the average room1 where the air problems are almost negligible4 ,fig4 ,b4 ,let the motor base consist of a single stick one-fourth or three-eighths of an inch square and one foot in length4 ,at one end of the base1 attach a block of wood one inch square and of a thickness equal to that of the stick4 ,glue this in position and bind it securely by wrapping with thread touched with glue4 ,at a point three-quarters of an inch above the stick1 drill a hole parallel to the frame for the axle of your propeller4 ,a hooked wire should be attached to the opposite end of the base4 ,one end may be run through the stick and fastened1 or it may be imbedded in a block fastened to the stick corresponding to the axle block4 ,a simple and effective motor anchorage may be made of metal 7described elsewhere74 ,your propeller should measure four inches in diameter4 ,a propeller cut from a blank one by four inches and one-half of an inch thick will give a good pitch4 ,either a propeller of wood or metal such as has already been described will answer4 ,the propeller should be mounted upon an axle and adjusted to the bearings1 and the hook after passing through the bearings in the support turned into a hook for the rubber strands4 ,select from the detailed instructions the method which appeals to you4 ,be sure that the propeller spins smoothly4 ,it should be so delicately adjusted that it will turn literally at a breath4 ,before stringing the rubber strands between the two hooks of your motor1 be sure that the hooks are bent back1 so that the strands will be in a line with the bands4 ,the bearings should be carefully oiled4 ,in flying out of doors1 there is danger of getting fine sand or dirt in the bearings which1 of course1 greatly increases the friction4 ,try out your motor with four strands of rubber one-eighth of an inch square4 ,the rubber sold for one-eighth inch is often a trifle under this measurement4 ,the propeller should1 of course1 be mounted with the shorter or curved edge forward4 ,in winding your motor1 never turn it after the second row of double knots begin to appear1 and do not keep your propeller wound a second more than is necessary before a flight4 ,illustration3 ,an ,american ,fleming ,williams built by ,c4 ,mc,queen ,illustration3 ,one of the earlier models built by ,cecil ,peoli ,for a model of this size1 wooden planes are entirely practical and very simple to construct4 ,much depends upon the modeling of the planes and the smoothness of both of their surfaces4 ,for the planes you will need two thin boards1 one eight by two inches and another four by two inches1 each one-eighth of an inch thick4 ,select a wood such as poplar or spruce1 which will not split easily4 ,the ends of the planes should be rounded in front and cut sharply away at the rear edge1 as described elsewhere4 ,if the wood will stand reduction without breaking1 plane or sandpaper away the surfaces until they are about one-sixteenth of an inch thick4 ,the planes may be flexed by steaming1 but there is a still simpler method4 ,paint your planes with a thin glue or varnish1 and while they are still wet and pliable1 bend them to the desired shape4 ,to shape them1 procure a strip of wood one-quarter of an inch square1 tack it to a board and bend the planes over it1 and fasten them in position with brads driven about the edges and bent over to hold it down4 ,the stick should be placed parallel to the entering edge and one-half an inch back of the line4 ,this will give you planes flexed with a dipping edge4 ,later you will probably want to experiment by changing this curve1 which is very easily done by bending over a stick of different size and altering its position4 ,the model is driven by the propeller with the small plane forward4 ,attach the planes to the stick with the curved or entering edge forward by tying them with a rubber band4 ,this will hold them in position and allow them to give when they fall4 ,slip the planes back and forth until the proper position has been found4 ,a small block of wood may be inserted between the planes and the stick to raise the wing to the desired elevation4 ,practise throwing the model as a glider until it sails across the room on an even keel1 when the motor may be installed4 ,directional stability may be gained by adding a vertical rudder4 ,it may be made from a thin board similar to that used in the planes4 ,cut a piece two inches square and round off the corners1 and shave to a knife edge4 ,attach this1 curved edge downward1 to the edge of the stick directly beneath the rear plane1 taking care that the motor does not touch it4 ,to complete the model1 attach skids to the under surface at the front and rear4 ,these should be of light reed1 cane or bamboo1 glued to the main frame and curved downward and backward like runners4 ,,model ,,with ,,minimum ,,plane ,,surface4 ,in the experiments in building models with very narrow planes1 some amazing results have been produced during the past year4 ,the limit in this reduction would seem to have been reached in the model with planes with a ratio of eight separated by a distance equal to ten times their width4 ,the forward part of this amazing model is a modified biplane1 and in this respect it resembles a successful model of last season4 ,the two models are reproduced side by side1 for the sake of comparison4 ,the economy of weight and resistance is instantly obvious to the most inexperienced eye4 ,the model rises quickly and flies for nearly three hundred feet in a perfectly straight line4 ,the motor base1 which has a length equal to six times its width1 or eight by forty inches1 is constructed of one-quarter inch strips4 ,a light cross piece at the center braces the two sides4 ,the supports for the propeller axles extend out horizontally from the sides4 ,this arrangement makes it possible to mount two ten-inch propellers on an eight-inch base4 ,the front ends of the frame are joined by a semicircular piece of reed which acts as a shock absorber and does away with the weight of the cross piece4 ,the workmanship in every detail of this frame must be exceedingly delicate4 ,the planes have an aspect ratio of eight and measure two inches in depth by sixteen in width4 ,the outer ends of the rear plane are three inches in their fore and aft dimensions1 thus making the outer rear edge a slight concave4 ,the front is cut sharply away at an angle of forty-five degrees4 ,the upper plane lies flat upon the motor base4 ,the lower plane is not set directly below it as in the ordinary biplane form1 but to the rear1 its front edge being on a line with the rear edge of the upper plane1 after the manner of the ,valkyrie machine4 ,the two planes are separated by a space slightly greater than their width4 ,two small rudders1 elliptical in shape1 are carried just behind and below the rear plane4 ,the model is mounted on very delicate skids built of reed1 and is inclined at a very slight angle4 ,six strands of one-eighth-inch rubber are used for each motor4 ,the unusual length of the motor makes it possible to give six hundred turns4 ,,the ,,burgess ,,webb ,,model4 ,an ingenious method of lightening the front end of the motor base and at the same time reducing the head resistance is employed in the ,burgess ,webb model4 ,a single stick frame is used with a base equal to one-fourth its length4 ,the cross piece is mortised to the central stick and braced by the diagonal sticks1 joining at the main frame4 ,this cross piece is carried out beyond the braces and pierced for the propeller shafts1 where two twin propellers are mounted4 ,fig4 ,c4 ,the front plane is elliptical in form1 with a width equal to two-thirds the width of the base4 ,it has an aspect ratio of two4 ,the propeller motors are strung on hooks attached to the outer sides of this frame4 ,the plane must be unusually strong to stand the pull of the motors1 which is naturally great4 ,it is fixed to the extreme outer end of the central stick4 ,the main plane1 which is mounted well forward in this model1 is an almost perfect semicircle4 ,one can1 of course1 carry out his own ideas in selecting the design of the planes4 ,a very light central stick is used which is strengthened by wires running to a vertical strut at the center4 ,it is claimed that the ingenious arrangement of the forward plane cuts away from one to two ounces in the weight of the model1 and the decreased head resistance adds both to its stability in flight and distance qualities4 ,the simplified form of front plane may be adopted on a variety of models4 ,a ,,model ,,with ,,adjustable ,,stabilizers4 ,a serviceable model may be built up with flat planes equipped with ailerons both at the rear and outer ends of the planes4 ,these tips make it possible to control both the horizontal and vertical movement1 and permit a great many adjustments impossible with other models4 ,the motor base may be borrowed from some earlier model4 ,it should be fairly heavy4 ,a rectangle measuring ten by forty inches built of one-half inch strips will be found sufficiently rigid4 ,the sides should be braced by a cross piece at the middle4 ,the ends and central strut may be made of some form of truss1 if desired4 ,one of the simplest means of providing supports for the axles of the propellers is to carry the stick at the rear1 one and a half inches beyond the side pieces1 and pass the axle through a hole drilled one-half an inch from the end4 ,illustration3 ,a ,model ,with ,adjustable ,stabilizer4 ,the pull of the motors when wound is thus well distributed and1 as has been pointed out1 permits of a larger propeller being used without danger of their striking in turning4 ,still another advantage is that it keeps the strands of the motor from interfering with the planes4 ,when the motors are strung above the planes1 they have a tendency to force the machine downward4 ,construct two serviceable planes the same size1 six by eighteen inches4 ,these should be flat and covered as smoothly as possible4 ,now attach to the rear edges of each plane a series of three ailerons each two by five inches1 fastening one at either end and the third at the middle4 ,make the frames of the ailerons of a very light lath strip and wire them to the rear edge in such a way that they may be swung up or down through a small arc4 ,at the outer ends of each of the planes1 attach semicircular tips1 each with a base of six inches and a radius of six inches4 ,these may be rounded off or cut away to sharp points as desired4 ,they should also be attached so that they may be bent up or down and will hold their position4 ,mount the model on some simple arrangement of reed skids1 so that it will be elevated at a very slight angle above the horizontal4 ,the model complete should weigh about eight ounces4 ,equipped with twin motors of fourteen strands of one-sixteenth-inch rubber each1 the propellers should be turned about four hundred times4 ,a medium-pitch propeller will best serve your purpose4 ,in flying this model1 bear in mind that the flight will be directed in an opposite direction from the angle of the ailerons1 or rudders1 just as a boat answers its helm4 ,the wing tips should be bent up or down until the flight is stable4 ,the complete equipment of ailerons enable one to correct any defects in proportion which are likely to be needed in models built by beginners4 ,,an ,,efficient ,,three-,,ounce ,,model4 7,record #ijj ,feet7 ,a surprising variety of designs may be carried out in models of the three-ounce class4 ,one of the easiest to control is a broad adaptation of the ,bleriot model1 flown with its small surface forward4 ,for a three-foot model1 first build two planes of very light material4 ,wire frames are especially suited for this model4 ,the main plane should measure two feet in length by four in width1 or with an aspect ratio of six4 ,the smaller plane1 carried forward1 should be one foot in length with the same aspect ratio4 ,it will be found a good plan to carry the outer edges of this plane back1 forming two inch squares at the rear edges4 ,a plane with a slight camber will prove the more stable4 ,for the frame secure two light sticks three-sixteenths of an inch square of some fairly strong wood2 a straight spruce is good4 ,attach the motors to these sticks before completing the frame4 ,select some rigid support for the propeller axle4 ,prepare two ten-inch propellers1 carving the blades from propeller blanks three-fourths of an inch thick4 ,the motor will probably work best when made up of six strands of rubber1 one-eighth of an inch square1 although this should be finally determined by actual test flights4 ,keep all parts of the motors extremely light4 ,to assemble the model1 connect the forward ends of the sticks carrying the motors by a piece of reed bent to a half circle1 by merely binding the ends firmly together4 ,the sticks should diverge so that the propellers will be about ten inches apart1 giving plenty of room for the propellers to turn without striking one another4 ,next fasten the larger plane in position across the top of the sticks1 and about two inches away from the propellers1 making the plane serve as a cross piece to hold them firmly in position4 ,the strands of the motor should preferably be carried above the plane4 ,this plan does away with the rear stick of the motor base1 thus saving this weight4 ,adjust the parts very carefully1 that the frame will be rigid enough to stand the strain of the motor4 ,illustration3 ,an ,efficient ,three-ounce ,model4 ,the model will require careful adjusting to be brought to an even keel4 ,the forward plane should be attached in such a way that it may be tilted up or down as desired4 ,with care1 the weight of the model may be brought within three ounces1 although a fraction over will not matter4 ,models built on these lines have flown in a perfectly straight line for #ijj feet4 ,,an ,,all-,,metal ,,model ,,frame4 ,in a previous paper1 it was suggested that the motor base be made of tubes of aluminum4 ,the idea has been carried further1 and attractive frames are now constructed in which not only the main frame is constructed of metal tubing1 but the cross piece supporting the propellers and the braces as well are of the same material4 ,the new metal1 magnalium1 has been used successfully for this purpose4 ,it is a trifle heavier than aluminum1 but much stronger1 and almost as easy to work4 ,in ,england1 the motor base is sometimes made of metal tubing one inch in diameter1 and the rubber motor is passed through the tube itself4 ,illustration3 ,an ,all-metal ,model ,frame4 ,such a frame may be made readily by one who has had no experience in tinsmithing or metal work4 ,the metal frames are sometimes constructed by driving wooden blocks into the ends of the tubes and letting them project one-half an inch or more4 ,the plug may be cut off flush1 and the cross piece fastened by wire and stout nails through the cross tube into the plug of the main tube4 ,a convenient brace may be constructed by cutting the tubes to the proper size1 fasten the ends and pass the rivet through both tubes at the point of intersection1 and screw the nut down firmly on the opposite side4 ,such a frame is practically indestructible4 ,there is one possible drawback1 however1 in the tendency of the metal to bend if the rubber motor pulls too strongly4 ,once bent1 it is difficult to get back into shape4 ,this tendency may be overcome when twin propellers are used1 by winding alternately1 giving one propeller one hundred turns and the other propeller one hundred turns1 then the first another hundred1 and so on until the motor is wound up4 ,the planes1 propellers and skids may be of any reliable design4 ,,an ,,efficient ,,single ,,sticker4 ,a very light single-stick model may be built of bamboo rods1 which will stand an immense amount of wear and tear4 ,it consists of a single longitudinal member with crossed pieces at either end1 braced against the central stick to withstand the pull of the motor4 ,select a bamboo stick about half an inch in diameter and three feet long4 ,an old fish pole will answer4 ,the cross pieces at the ends should be of some light1 strong wood1 such as poplar1 whitewood or ash1 since they must be mortised and drilled1 and the bamboo is likely to split under the operation4 ,use a three-eighth-inch strip1 cutting a piece ten inches long for the rear and another six inches in length for the front of the base4 ,fasten these rigidly in position at right angles by mortising1 glueing and tying in position4 ,run diagonal pieces cut from quarter-inch strips from the ends of both cross sticks to the central frame4 ,be careful not to cut away the wood in mortising it1 for a bad break is likely to occur at the weakened point4 ,build two serviceable planes4 ,the larger one1 which should be carried in the rear1 should measure about twenty-four inches by eight1 and the front plane twelve by four inches4 ,since your frame is very light and strong1 there is no need to economize weight4 ,by carrying the braces running from the cross sticks well out on the stick1 you can provide a broad support for the planes4 ,tie the wings on the motor base with strands of rubber4 ,in landing they will then give enough to save a bad smash4 ,illustration3 ,one of the best models of the year1 built by ,john ,caresi ,illustration3 ,an excellent model1 showing careful attention to details4 ,built by ,l4 ,v4 ,brooks ,the propellers are mounted by passing the axles through holes drilled through the center of the rear stick about one inch from the ends4 ,the rubber strands may be simply passed around the front stick and tied in position1 or may be looped about a hook inserted in the stick4 ,use a fairly high pitch propeller1 since the base will carry a powerful motor4 ,select some simple form of skid1 for the model will be comparatively light1 say within ten ounces4 ,a ,,one-,,plane ,,model4 ,interesting experiments have been made this season by altering the angle at which the main planes are set to the motor base4 ,the theory of these designs is1 of course1 that the resistance offered by an entering angle is less than that of a straight edge4 ,in some models1 the main planes are carried backward until the rear tips are on a line with the propellers4 ,the model is driven tail first by twin propellers4 ,the planes are besides set at a slight dihedral angle so that the angle of incidence is greater at the ends4 ,a rectangular base is suggested1 with a central stick4 ,the planes1 which may be either flat or cambered1 are attached to the central stick and slightly raised by inserting strips of wood above the outer edges of the motor base4 ,in this way1 it is possible to fix them rigidly4 ,wire braces running from the outer ends to the rear of the motor base will add to its strength4 ,the angle of the wings to the motor base may be altered to suit conditions4 ,a plane of high aspect ratio works best in this position4 ,,the ,,canning ,,model4 ,there is much to be said for the model with propellers placed near the centers of gravity and pressure4 ,many authorities believe that the successful aeroplane of the future will carry propellers somewhere near the center of the motor base4 ,since the thrust is exerted near the point where the aeroplane balances1 it is argued that its stability is greatly increased1 while with the propellers far removed1 either to the front or rear1 the torque gains a leverage from its position which it is difficult to control4 ,the main difficulty with this arrangement all along for rubber-strand motors has been that the length of the motor must be cut down to about half1 and their efficiency reduced4 ,in the ,canning model1 this difficulty has been overcome1 and a motor extending the entire length of the motor base is hitched up to twin propellers placed near the center of gravity4 ,a powerful motor extends along the center of the motor base1 attached to a gear wheel at the forward end4 ,this wheel turns two smaller gears at either side4 ,in this way1 a motor running the entire length of the frame may be used with an increased number of turns4 ,a third gear wheel should be introduced to make the propellers turn in opposite directions4 ,,the ,,flemming ,,williams ,,model4 ,an immense amount of curiosity has been aroused regarding the famous ,flemming ,williams model4 ,this machine has completely outdistanced all rivals1 and set a new and amazing distance record4 ,its builder frequently gets flights of eighteen hundred feet with his model1 and has made the astonishing record1 under favorable conditions1 of one-half a mile4 ,in order to study this model at first hand1 the writer has imported one of the machines1 built by ,ding1 ,sayles ,company1 one of the leading model builders of ,england4 ,the distance qualities of this model will be recognized at a glance4 ,it is a single sticker1 extremely light in all its members1 combining an extraordinarily long motor base with well-adjusted plane surfaces4 ,the arrangement of the wings is original4 ,the main stability plane is set forward in front of the center of pressure4 ,the rear plane is formed by filling in the space between the rear stick and the braces1 thus saving the weight of the frame usually carried in this position4 ,the model is driven by two seven and a half inch propellers of very high pitch4 ,the model is without skids and is launched from the hand4 ,the central member measures four feet two inches in length4 ,the stick is one-half by one-fourth of an inch1 with the forward part tapering gradually to one-fourth of an inch square4 ,the base stick is eight inches in length1 cut from a strip five-eighths by one-eighth of an inch4 ,the diagonal pieces forming the triangle are cut from the same material1 and meet at a point eight inches from the rear1 thus affording a surface of twenty-four square inches4 ,the wooden parts are glued and tied together1 no nails or brads being used4 ,the main plane is an exceedingly refined piece of workmanship4 ,a glance shows that it is very speedy4 ,the frame consists of steel wire one thirty-second of an inch in diameter4 ,the plane measures sixteen and one-half inches in width and four and one-half inches in depth at the narrowest point at the center1 and five and one-half inches in the widest part at the ends4 ,it has four cross ribs of the same wire4 ,the frame is covered1 on the upper side1 with oiled silk4 ,the camber is slightly higher at the sides than the middle4 ,the plan of fixing a rigid shaft for the propeller axle is very simple and effective4 ,a piece of aluminum tubing is forced over the ends of the rear stick and glued firmly in position4 ,a hole for the axle is then drilled through this tube1 and the wooden stick which forms its core4 ,the axle thus turns in what is really a metal shaft1 and the friction is reduced to a minimum4 ,a piece of tin tubing1 a putty blower1 for instance1 will serve as well4 ,in this particular machine1 the propellers are cut from a board one-sixteenth of an inch thick and bent by steaming to the desired curve4 ,the shafts of the propellers are formed of a very light steel wire1 less than one thirty-second of an inch in diameter4 ,this is passed through the hole in the rear stick and bent into a hook in the usual way4 ,the motor anchorage consists of a wire passed through the central stick and bent back1 and turned into two hooks4 ,the rubber-strand motor consists of twenty strands of strip rubber one-eighth of an inch broad4 ,a special preparation resembling cosmoline is used to lubricate the rubber1 thus increasing the number of turns4 ,the motor will take on one thousand turns without undue strain4 ,,chapter ,x ,,designing ,,the ,,skids ,much more attention is paid to designing the skids for model aeroplanes in ,america than abroad4 ,since the ,american model usually rises from the ground under its own power1 this detail of construction naturally has come to be of vital importance4 ,by attacking the problems faced by the designers of large aeroplanes1 our work is helpful in developing the science of aviation as a whole4 ,nothing has been found better for building skids than cane or bamboo4 ,a chassis may be made of these materials which will weigh but a fraction of an ounce1 so that even the most elaborate skids will add but little weight4 ,they are1 besides1 exceedingly elastic1 which makes them easy to work1 while this quality enables them to take up the shock of a violent landing4 ,the thinnest sizes are best for our purposes4 ,the reed one-eighth of an inch in diameter will answer for all ordinary models4 ,to prepare reed for working1 soak it for an hour4 ,another plan is to heat it slightly over a flame1 when it may be bent with little danger of breaking4 ,in case of a bad smash during a meet such skids may be readily pieced out and repairs made so quickly that the model need not be kept long out of the contest4 ,illustration3 ,a model with limited plane area built by ,r4 ,barry ,illustration3 ,an interesting experiment in metal frame building by ,r4 ,fisher ,the simplest skid is made by splitting a section of reed1 or splicing it1 to form a ,y1 and attaching the upper ends to the bottom of your motor base4 ,the lower end is then bent into a half circle4 ,wrap the reed tightly at the crotch to keep it from splitting1 and touch the wrapping with glue4 ,to make such a skid stable1 join the two pieces by a cross brace4 ,the skid should slant backward at a slight angle to reduce the friction on starting4 ,several methods of bracing such a skid are suggested in the accompanying photographs of models4 ,a stronger skid is formed by turning the reed to form ellipses and attaching them to the motor base4 ,the curved parts will require bracing4 ,two diagonal braces will keep them in position4 ,some model builders prefer to shape the skids at the bottom1 so that only a single point of the reed comes in contact with the floor4 ,this plan makes it possible to shape the skids into several graceful forms which help to make the model attractive4 ,still another plan1 followed by some of the most successful model builders1 is to shape the skids like the runners of a sleigh4 ,in some of the ,percy ,pierce models this year1 about six inches of the rear skids come in contact with the ground4 ,it might be supposed that the friction in this case would be considerable1 but this particular model is one of the quickest to rise4 ,this design has the great advantage of being extremely elastic and letting the rear of the model down gently after a considerable fall4 ,some model builders still retain the wheel skid in a much simpler and lighter form4 ,the miniature bicycle wheels do very well for scale models1 but since they are likely to add an ounce or two to the weight of the aeroplane1 they are prohibitive4 ,to avoid this weight1 the wheels may be made of simple disks of wood cut very small4 ,a wheel one-half an inch in diameter1 cut from a board one-eighth of an inch thick1 weighs practically nothing and affords sufficient support4 ,these may be mounted very simply on axles made of bent wire attached to the feet of the skids4 ,sandpaper the rims to an edge in order to reduce the surface presented to the air4 ,since their surface is edgewise to the line of flight1 they will offer very little resistance4 ,the wheels on some of this year's models are formed of wire disks covered with silk4 ,the weight of these wheels is practically nothing1 and they add much to the appearance of a well-finished model4 ,wire disks which may be covered in this way may be bought from the supply houses4 ,it requires rather a skilful hand to shape the wire into perfect circles which will run easily4 ,the covering again is a very nice operation4 ,the silk wheel is not recommended for the beginner2 but for one who is anxious to finish his model to the last detail as attractively as possible1 they form an interesting feature4 ,ping-pong balls make serviceable skids4 ,since they are carefully rounded1 they will turn easily4 ,to mount them1 drill a hole for the wire shaft or axle1 taking great care to have it pass through opposite points of the sphere4 ,the wire may then be bent above it and attached to the skid4 ,the celluloid turning on the wire axle produces practically no friction1 and the ball offers very little resistance to the air4 ,the balls are1 of course1 extremely light and add little to the weight of the model4 ,by combining the skid and wheel form of support1 your model will gain the advantage of both these devices4 ,the general form of the ,farman skid may be followed4 ,the skid in this case should be fairly heavy1 strong enough to hold its shape1 although elastic enough to take up a considerable shock4 ,the simplest plan is to connect the two skids by a cross piece1 and use this as the axle for two small wheels1 mounted on the outside of the skid4 ,this plan enables the aeroplane to rise with the minimum amount of resistance and land at the end of a flight with protection4 ,in the collapsible skid we find one of the most interesting novelties of the year4 ,this ingenious mechanism1 which is very easy to adjust1 and which is placed under the front of the model on rising from the ground1 is drawn into a horizontal position extending out before the machine and acts as a buffer1 an aerial cow-catcher4 ,any simple form of skid may be adjusted in this way4 ,the upper end or ends are merely fastened to the motor base so that they will swing easily back and forth4 ,from a point half way down the skid1 a rubber band is run to the front end of the motor base4 ,when the model is set on the ground1 after winding up1 the skid is pulled back to form the forward support4 ,it will be found necessary to adjust it to stand at a trifle less than the vertical4 ,the rubber bands must be just strong enough to permit the skid to stand in this position when held down by the weight of the machine4 ,as the machine rises1 the skid is1 of course1 released and instantly snaps up to a horizontal position4 ,a new interest is lent to model aeroplane building by mounting them on pontoons contrived to float them on the water4 ,several large men carrying machines have risen from the water1 notably the ,curtiss model4 ,it is believed by some aviators that since the water offers less friction than the earth or than a wooden runway1 it is easier to rise in this way4 ,the builders of modern aeroplanes have been quick to adopt this idea4 ,the models are mounted on miniature pontoons1 and after winding up the motors are released in the usual way4 ,an actual photograph of a model thus mounted in the very act of rising clear on the surface of the water is reproduced as a frontispiece of this volume4 ,the pontoons1 it will be noticed1 consist of two small pieces of board1 placed almost directly beneath the planes4 ,the model is mounted on these pontoons by ordinary skids of reed4 ,the angle of the planes with the surface of the water is the same as in the ordinary mounting4 ,the pontoons are kept as small and light as possible4 ,to start the machine1 the propellers are wound up in the usual way4 ,it has been found that a model would rise rather more quickly from the water than from the land or within a few feet4 ,as our photograph shows1 the pontoons leave a slight wake behind them in the water4 ,once started to rise1 however1 the machine rapidly gains its elevation4 ,one advantage of the pontoon skid flying over the water is the safety it insures on landing4 ,at the end of such a flight the model drops into the water1 but with little danger of breaking any of its parts4 ,it will be found interesting to experiment in mounting the model loosely on pontoons1 so that when it rises it will leave them behind1 thus doing away with the increased load4 ,,chapter ,,xi ,,geared ,,motors ,a ,,more accurate control may be gained over a strand motor by using gear wheels4 ,both their speed and duration may be increased indefinitely4 ,the gear will restrain a powerful motor from racing1 acting much the same as the governor of an ordinary engine4 ,still another advantage is the steadiness they insure to a machine in flight by cutting down the vibration4 ,the geared wheels and the frames for mounting them will be found to add very little weight1 and they make possible a saving of rubber in the motor which renders such equipment no heavier than the ordinary direct-drive motor4 ,gears may be installed upon any ordinary motor base4 ,here is a fascinating field for experiment4 ,the great advantage of the geared motor lies1 of course1 in the fact that it enables you to divide up your rubber motor into smaller groups of strands4 ,as you increase the power by adding more rubber1 you of course cut down the number of the turns it will take4 ,a motor forty inches in length1 comprising six strands of rubber1 one-eighth of an inch square1 may be twisted to about one thousand turns4 ,double the number of strands and you will find that you cannot get more than five hundred turns with safety4 ,double the diameter of your motor one more and it cannot be twisted more than to two hundred times4 ,now it is clear that if the motor consists of two groups of six strands each1 and the axles be geared together1 it may be wound up with one thousand turns while the power exerted will be that of the twelve strands4 ,a motor with three groups of strands in turn will give you one thousand turns with the propelling force of the combined number1 or eighteen strands1 and so on4 ,as a general rule1 it may be laid down1 that by dividing your motor you double the number of revolutions4 ,the heavier the motor the greater is the vibration in unwinding1 and as you have doubtless discovered1 a model which vibrates in flight offers a greatly increased resistance to the air4 ,the geared motor cuts the vibration in half1 or a third1 as the case may be4 ,incidentally1 this renders your motor practically noiseless4 ,the resistance offered by a set of smoothly-running geared wheels is slight1 and may be compensated by adding more strands to the motor4 ,in mounting them use the same care as used in the shafts of ordinary motors4 ,by mounting them on a simple metal frame the friction may be cut down still further4 ,this mechanism1 moreover1 is so slight that you can afford to select substantial material for the purpose4 ,the clock wheels used in most of our ,american clocks are too thin for the purpose and easily slip apart4 ,a wheel one-sixteenth of an inch thick will add little weight to your model and will run much more smoothly4 ,they may be bought very cheaply from clockmakers4 ,the ingenious miniature ball bearings constructed for model aeroplanes are excellent for mounting gears1 but they are not essential by any means1 and the ordinary arrangement of washers used for motor axles will be delicate enough for gear adjustments4 ,complete sets of gear wheels mounted on metal frames1 ready to be attached to the motor bases1 may be purchased from the supply houses1 but they are so simple that almost any bright boy can construct them for himself4 ,in experimenting with gears it will be well to begin with but two sets of strands with gears of the same number of teeth4 ,several models equipped in this way have been flown with success in ,america4 ,the best flights are those made by a model built by ,mr4 ,frank ,schoeber of ,new ,york1 a winner in several competitions4 ,mr4 ,schoeber's model is driven by two motors of three strands each4 ,he uses wheels of the same size and number of teeth4 ,the support on which the gear wheels are mounted must be perfectly rigid1 since any play will result in a serious loss of power through increased friction4 ,compressed-air motors have not yet been developed to a form practical for use in small model aeroplanes4 ,illustration3 ,an aeroplane of simple construction that flies remarkably well1 built by ,r4 ,s4 ,barnaby ,a number of inventors are at work on this problem and high hopes are entertained that a practical form of compressed-air engine will soon be invented4 ,an unlimited supply of compressed air may of course be carried without adding to the weight of the model4 ,it costs nothing again to get a supply4 ,anyone with a bicycle pump can get up enough energy for his model as easily as he can inflate a bicycle tire4 ,the best compressed-air engines at present weigh from one-third to one-half as much as the model they drive1 and will run only from ten to thirty seconds4 ,spring motors hold out a promise for the model aeroplane builder4 ,a number of fascinating experiments have been made to utilize the power of a coil spring4 ,one young aviator mounted the spring of an ordinary shade roller upon a model aeroplane4 ,the spring was connected up for a direct drive1 a single propeller being used4 ,it was found that such a spring could turn fifty times1 storing up a relatively large amount of energy4 ,once released1 however1 it unwound with startling rapidity4 ,the unwinding process was so rapid that the propeller spun through the air without taking hold or exerting any appreciable driving power4 ,a propeller of very high pitch was employed1 but with the same results4 ,evidently a spring of this nature is not practical4 ,experiments have been made in ,germany1 however1 with coil springs better suited for model aeroplanes1 with satisfactory results4 ,since trolley cars have been driven for considerable distances by energy wound up in coil springs1 the model aeroplane should be able to take advantage of this elasticity4 ,doubtless another year will find model aeroplanes flying by energy stored in this way4 ,the ,petrol motors are now offered for sale in sizes suitable for model aeroplanes by several firms4 ,a motor developing one-half of one horsepower weighs but little4 ,the principal difficulty of these little power plants is that they set up a more or less violent vibration which racks the entire machine and renders a stable flight difficult4 ,to set up one of these engines and adjust it to so delicate a task requires the highest engineering skill4 ,unless one has had such experience it will be well to avoid such experiments for the present at least4 ,as a rule the engines are used to equip scale models which are not intended to fly4 ,the beautiful model illustrated on the cover of this volume built by ,mr4 ,karl ,h4 ,de ,leon is equipped with a rotary ,knome engine especially imported4 ,,chapter ,,xii ,,lessons ,,of ,,the ,,man-,,carrying ,,aeroplanes ,,the builder of model aeroplanes will do well to keep in touch with the development of the passenger-carrying air craft4 ,the development of both types of machines will always be more or less parallel4 ,it is especially important that you watch the design and position of wings1 and the modeling of propellers1 since here the problem confronting both classes of builders is practically the same4 ,the use of ailerons and vertical surfaces and all improvement in steering the large machines again may have a direct application on model aeroplane buildings4 ,the photographs of the new models of the large machines published in the newspapers will often give valuable hints1 while the technical aeronautical papers will1 of course1 give more detailed information4 ,in a few years1 at the present rate of model aeroplane development1 the designers and pilots of large machines may be looking to the new designs of model aeroplanes with much the same interest4 ,there is at present but one passenger-carrying monoplane1 the ,valkyrie1 flown tail first4 ,it is built in two sizes1 the smaller1 fitted with high-powered engines1 being intended for racing4 ,the general lines of the ,valkyrie resemble those of many of the model aeroplanes1 but there are some features which deserve careful study4 ,the main plane of the ,valkyrie is set at a pronounced elevation1 and has a high aspect ratio4 ,the front and rear planes are separated by a distance equal to about five times their width4 ,both planes have a slight camber4 ,one of the most novel features of this model is that the forward plane is tilted upward at a positive angle1 while the rear plane is elevated considerably less1 thus giving the machine a longitudinal dihedral angle4 ,this arrangement makes for fore and aft stability much the same as the dihedral angle of the wings makes for lateral stability1 and suggests an interesting field of experiment4 ,the new type of ,bleriot ,,xi follows the general lines of the famous machine which first crossed the ,channel4 ,the fuselage of the new machine1 however1 is completely covered1 tapering to a broad flat surface at the rear4 ,this plan of gaining more surface by covering the frame is becoming general4 ,in model building1 it is unsafe to follow this plan1 unless the motor base be comparatively small4 ,the new ,bleriot carries a larger horizontal rudder than formerly1 placed aft1 while the vertical rudder above it has been increased in size4 ,the general design of the main plane1 which is placed forward1 remains unchanged4 ,a single tractor screw is carried in front as usual4 ,in the new ,blackburn aeroplane1 the fuselage is covered with wood as far back as the pilot's seat1 and with cloth to its extreme end4 ,the use of thin board for this purpose suggests interesting possibilities4 ,one of the most novel features of this model is the light skid attached to the outer ends of the main plane4 ,the skid is very light1 adding little to the weight or head resistance1 and prevents the end of the plane from digging into the ground on landing4 ,such an attachment may readily be added to model aeroplanes when they will save many a broken wing4 ,a novelty in plane-designing is shown in the ,handley ,page monoplane4 ,the main plane1 carried forward1 as in the ,bleriot1 is cambered just back of the entering edge1 flows back to a flat surface at the middle and then tilts upward toward the rear edge4 ,the two sides1 in turn1 are set at a slight dihedral angle to the horizontal4 ,this modeling is believed to secure automatic stability in two dimensions1 both longitudinal and transverse4 ,the planes are unusually broad in their fore and aft dimension1 extending back nearly one-half the length of the motor base4 ,the horizontal and vertical rudders are very small4 ,the design should work well in models4 ,builders of biplane models will find some interesting suggestions in the new ,bristol biplane4 ,the forward planes are of the biplane form1 the lower surface being much narrower than the superimposed plane1 the comparative width being one-third wider4 ,another original feature of this machine is that the planes are connected by only four struts instead of by rows of struts along both the front and rear edges4 ,the planes are held rigid by a series of braces4 ,it is believed that this arrangement decreases the head resistance1 at the same time insuring considerable lateral automatic stability4 ,the rear plane is of the monoplane type4 ,the friends of the ,dunn monoplane believe that the question of automatic stability has been practically solved in this ingenious machine4 ,the ,dunn machine has flown on an even keel for five miles without the pilot once touching the controlling levers4 ,the trick is in the design of the main wings4 ,the greater part of the wing1 extending out from the central stick1 has a slight camber and is slightly elevated1 besides being set at a dihedral angle4 ,near the outer edge the wings are bent sharply down1 much as the wings of a swallow are bent1 and are given a considerable negative angle both forward and outward4 ,the tips1 therefore1 form pockets at either end under the arched tips4 ,wings modeled in this way are remarkably stable even when traveling across the wind4 ,when a gust of wind strikes the outer edge of the plane1 it tends to thrust it down rather than up1 as is the case when a gust gets under a wing of the ordinary design4 ,the wing quickly rights itself1 however1 since the angle of the plane tends to lift it4 ,the pockets in turn by compressing the air tend to counteract this tipping tendency4 ,these pockets are besides closed to an extent by ailerons or flaps1 which may be pulled down1 thus confining the air still further4 ,an effective device for securing lateral control appears in the new ,grahame-,white machine4 ,narrow ailerons are placed on the forward edge of the front plane near the outer tips4 ,the tips at the opposite ends are hinged and so connected that as one is raised the corresponding tip is lowered1 or the other way about4 ,now as one of these tips is lowered1 tending to lift the machine1 the opposite aileron working in the other direction tends to depress it4 ,the increased resistance offered by the lowered flap again tends to keep the machine from swinging around in the direction of the side on which the other aileron is lowered4 ,the lateral control is thus much more quickly applied than in the case of the rear ailerons4 ,in applying this principle to model construction1 it must be borne in mind that the resistance of these forward tips is tending to retard the machine and must be used with care when the motive power is limited4 ,as far as general appearance is concerned1 the ,piggot monoplane is probably the greatest novelty of the year4 ,it is the first aeroplane to carry a cabin1 as it were1 in which the pilot sits completely enclosed4 ,in general appearance it suggests a great whale with exaggerated fins4 ,the pilot looks out through elliptical windows at the sides and bottom1 covered with mica1 to protect him from the wind4 ,the wings of the ,piggot aeroplane resemble the ,bleriot machine1 the propeller1 or rather tractor1 being carried forward4 ,it is extremely interesting1 however1 since it suggests for the first time what the appearance of a cabined1 passenger-carrying aeroplane of the future may be4 ,on the ,farman aeroplane1 the arrangement for providing stability is very interesting4 ,the ailerons in this case are attached to the rear of one of the main planes1 the lower one1 by hinges4 ,this general plan will be followed in the case of the model aeroplanes4 ,in a number of successful model aeroplanes1 the ,farman ailerons have been closely imitated4 ,the ,curtiss biplane depends for its stability upon ailerons mounted midway between the two main planes and partly within them4 ,this plan is scarcely practicable in the case of model aeroplanes1 since they increase air resistance and are difficult to control4 ,the ,baldwin biplane has introduced a new feature for obtaining stability which may be closely imitated4 ,a large plane is set vertically1 directly above the upper main plane which may be swung from side to side by the pilot4 ,the theory of this stabilizing surface is that it will restore equilibrium from side to side1 since it works in undisturbed air while meeting with very little head resistance4 ,many builders of model aeroplanes have introduced a similar vertical plane directly above the main plane1 or have placed it well forward at the extreme front of the motor base4 ,by removing this rudder as far as possible from the main supporting surface1 it exerts a greater leverage1 and a very small plane carried well forward will be more effective than a larger plane directly above the main supporting surface4 ,it has the disadvantage of catching any chance side current and thereby knocking the aeroplane off its course4 ,illustration3 ,percy ,pierce1 winner of the distance record ,illustration3 ,a well-proportioned model1 capable of long flights ,illustration3 ,a well designed aeroplane built by ,james ,mac,pherson ,the same principle has been carried somewhat further in the case of the new ,herring biplane1 which carries six triangular stabilizing fins set vertically above the upper plane4 ,it is believed that these fins offer considerable resistance to any tipping motion of the planes1 and if the machine slants to one side or the other1 for any cause1 there is a tendency1 of course1 to dart downward at an abrupt angle4 ,the fins retard this motion as far as the upper plane is concerned1 and the lower plane without such an equipment tends to swing back like a pendulum1 thus bringing the aeroplane to an even keel4 ,in the case of the ,antoinette aeroplane1 of a monoplane type1 a somewhat different device is depended upon for stability4 ,the ailerons in this case are attached to the outer edges of the rear wing and are hinged so that they may be raised or lowered at will4 ,one of these may be turned up while the other is turned down4 ,although these resemble the ,farman ailerons1 they are believed to be twice as effective since they may work in opposite directions1 while those of the ,farman aeroplane may only be inclined downward4 ,it will be noticed in the photographs of many successful model aeroplanes that the tips of the wings are flexed upward at an angle often as much as #de degrees4 ,these planes1 it is believed1 tend to lower the center of gravity1 and in the case of a turn tend to bring the aeroplane to an even keel4 ,their head resistance in a straight flight is1 of course1 rather great4 ,it is claimed that the ,antoinette aeroplane is the easiest of all aeroplanes for a beginner1 largely because of this adjustment of ailerons4 ,one of the most novel devices for gaining stability which has appeared during the year1 is that of the ,pfitzner monoplane1 which gains lateral stability by means of an ingenious sliding wing tip which may be pushed out or drawn back at will4 ,when the aeroplane begins to fall from its level1 one of these wing tips is shot out1 while the other is pulled in4 ,this increased surface tends to throw one plane upward while the shorter plane1 which for the time exerts less lifting power1 falls correspondingly4 ,the ,pfitzner monoplane makes many sharp turns with very little tipping4 ,a ,new ,york aviator has succeeded1 it is reported1 in building a practicable aeroplane1 which combines the best features of both the lighter and heavier than air machines4 ,in the earlier stages of the development of aeronautics many believed that the solution of the problem was to be found in some such combination4 ,the attempts usually consisted in adding large planes to dirigible balloons4 ,gradually1 however1 the combination was given up as impossible4 ,the great dirigibles of to-day carry considerable plane surface1 but this is intended to lend stability for guiding and not support4 ,the ,new ,york aviator1 however1 reverses matters and retaining the aeroplane form attempts to gain additional support from gas pockets4 ,he does this by building his plane after the general ,bleriot model but with a considerable space between the upper and lower surfaces1 which he fills with gas4 ,the machine has not yet been exhibited1 but it is understood that this space is upwards of one foot in thickness and as wide and long as the planes4 ,the front entering edge is kept sharp so that the wings1 for all their size1 meet as little resistance as possible4 ,whether the support gained from so small a body of gas is worth while1 and counteracts the increased resistance of the enlarged wing1 is of course an open question4 ,the dirigible aeroplane has been flown successfully several times1 however1 with a passenger and is reported to have behaved well4 ,the new ,paulhan biplane introduces an entirely new form of plane which is being watched with great interest4 ,the wings have the appearance of being fluted or corrugated4 ,the frames of the planes consist of a great number of ribs1 running from front to rear1 placed but a few inches apart4 ,these ribs are made very flexible4 ,the canvass covering of the planes is sewn with a series of pockets1 exactly corresponding to the ribs4 ,the wings are covered by merely pulling the canvass on the ribs and fastening it rigidly in place4 ,this gives the canvass a tendency to arch between the ribs so that the planes consist of a series of corrugations4 ,it is believed by some aviators that the supporting power of the aeroplane is increased in this way4 ,it has the advantage at least of being very easy to adjust4 ,a model aeroplane built on these lines should fly well and have a distinctive appearance4 ,another feature of the new ,paulhan which should appeal to the builder of model aeroplanes is its ingenious trussed girder4 ,it is known as the ,fabre girder4 ,it is interesting to note here that the built-up girder was used in the model aeroplanes even before it was adopted in the man-carrying machines4 ,the ,fabre girder consists of two long strips of light wood connected by crosspieces of steel running diagonally4 ,this form of construction gives unusual strength and is very light4 ,it has its parallel in the beautifully built-up trusses to be found for instance in the models built by ,mr4 ,mungokee4 ,in this case the girders are made entirely of wood4 ,the question is often asked whether the rear edge of the front plane should be straight or brought back and tipped at either end4 ,a study of the various models of the standard manufacturers shows that there is considerable difference of opinion among the experts4 ,the builders of model aeroplanes in ,america still retain the straight line1 while in ,england the tips are brought well back in a great many of the designs4 ,the theory of this form is1 obviously1 that this tip tends to damp out any lateral motion1 and makes for stability4 ,in the most successful ,american models the rear line of the plane is kept straight without apparent loss of stability4 ,turning now to the large machines1 we find a similar contrast4 ,in none of the ,bleriot models is the rear line broken4 ,the ,wright1 ,curtis and ,antoinette machines1 even in their latest form1 still retain the straight line4 ,the ,etrich monoplane has had good results with rear wing tips4 ,the model has been accepted by the ,austrian ,minister of ,war who has ordered a fleet of twenty of these craft for the army4 ,the rear tip was first suggested by ,lilienthal4 ,the friends of this form claim that it more nearly approaches the form of a bird's wing than any of the other planes now in use4 ,the depth of the main plane is nine and three-quarter feet and at the tips twelve feet4 ,the entire tip is so adjusted that it may be flexed at will from the pilot's seat4 ,it will be seen that this arrangement makes it possible to imitate the flight of a bird very closely4 ,in adopting this idea in model aeroplanes it will be well to attach the extension by a hinge so that it may be turned up or down at will4 ,since it is placed well out from the main axis of the machine its leverage is naturally great4 ,in the large machines as well as in the models there seems to be a general tendency to increase the aspect ratio of the main planes4 ,the ,bleriot ,,xi still retains its broad deep plane1 but in several of the models the depth of the model has been greatly reduced4 ,in the new ,voisin monoplane the main wing has a width of thirty-seven feet and a depth of but five feet1 thus giving it an aspect ratio of nearly one to eight4 ,the machine flies with great ease1 its resistance is very low and it answers well to its stabilizing devices4 ,the ,cody biplane again has supporting planes measuring fifty-two feet by only seven feet six inches4 ,the same tendency to reduce the size of the planes is noticeable in the recent ,wright models4 ,the ,wright machines 7model ,r71 are the smallest yet used on an aeroplane4 ,they have a spread of but twenty-six feet six inches and a chord of only three feet seven inches1 giving them an exceedingly high aspect ratio4 ,in the racing machines the spread has been cut down to twenty-one feet six inches4 ,attention has been called in an earlier chapter to this same tendency to reduce the wing area in model aeroplanes4 ,it is interesting to find our amateur aviators increasing the aspect ratio of their planes although working independently4 ,in many of the large machines the front and rear planes are brought much closer together in the more recent models4 ,it would seem that as the front and rear planes are brought closer together there would be a loss in fore and aft stability1 but on the other hand the reduction in weight made possible by shortening the frame is very important4 ,a careful report has been prepared in ,france recently of all the serious accidents to aeroplanes with the idea of classifying them4 ,the record of fatal accidents shows a total of thirty-one up to the beginning of the present year1 resulting in thirty-four deaths4 ,although these figures taken alone are appalling1 they are found on analysis to indicate that aviation is nevertheless growing safer and not more dangerous4 ,in #aiaj there were twice as many fatal accidents as in the previous year1 but on the other hand there were more than five times as many flights made1 so that the percentage of accidents1 as a matter of fact1 was but forty per cent4 as great as for the preceding year4 ,the commonest cause of accidents according to these tables has been faulty construction4 ,next in turn came the accidents due to the errors of the pilots4 ,atmospheric conditions rank third in the list and fourth the carelessness of the spectators4 ,there were in all some forty-seven accidents in #aiji1 and #aja in #aiaj4 ,an increase is to be noticed last year in the accidents due to atmospheric conditions4 ,this was caused in most cases by the unusual daring1 even foolhardiness of the pilots4 ,in their attempts to amaze their audience by performing hazardous dives and volplanes from great heights many machines were wrecked and several aviators met their death4 ,since the main cause of fatal accidents has not been structural weakness or the carelessness of the pilots1 it is clear that the science of aviation itself cannot be blamed4 ,it is of course a comparatively easy matter to build machines sufficiently strong to fly without breaking down4 ,the number of accidents1 especially fatal accidents1 due to the inherent danger of flying1 to dangers which cannot be overcome1 has been very trifling1 and is steadily diminishing4 ,,chapter ,,xiii ,,selected ,,questions ,,for ,,beginners ,how can ,i find the center of pressure of my model aeroplane8 ,the simplest plan is to adjust the planes so that the model flies on a perfectly even keel1 and then balance the machine4 ,since the center of pressure and the center of gravity must coincide to produce horizontal flight1 this point of balance will be the center of pressure4 ,as a rule1 the center of pressure will be found to be near the front edge of the main plane1 perhaps slightly back of this forward edge4 ,what is the best position for the propeller8 ,in the case of a model driven by a single motor1 the propeller shaft should pass through the center of gravity and center of pressure of the machine4 ,it is very important that the alignment should be perfect or you will have great difficulty in securing a horizontal flight4 ,in case of a double propeller machine1 the line midway between the two propeller shafts must pass between the center of gravity4 ,my aeroplane starts off all right but often begins to rock from side to side like a cradle and then flutters to the ground4 ,how can ,i prevent this8 ,illustration3 ,a beautiful model built by ,stewart ,easter ,illustration3 ,a successful model of #aiaj built by ,e4 ,g4 ,halpine4 ,note contrast in plane area ,this rocking motion is probably caused by a too low center of gravity in your machine4 ,if your planes are set at a dihedral angle1 they should be brought nearer to the horizontal4 ,another plan is to place them lower down4 ,a side gust of wind will start this rocking or vibration1 and in order to right itself the machine loses momentum and falls4 ,this difficulty is seldom experienced with horizontal wings1 especially if their aspect ratio is high4 ,i have no trouble in getting my model off the ground1 but it seems to rise too fast and fall backward or uses up the power before it really gets under way4 ,is the trouble with the propeller or the planes1 for my motor seems all right8 ,if your model rises quickly1 the planes are probably well designed and built1 the motor is effective1 and the propeller sufficient for all needs4 ,the trouble is likely to be with the angle of the planes4 ,perhaps your front plane is elevated too high4 ,the rear plane should be kept horizontal or very nearly so4 ,an aileron at the rear of the main plane will help you to properly adjust same4 ,as a rule1 the angle of ascent should be a little more than that of the front plane4 ,if it still acts badly1 strengthen your motor and bring your large plane back a trifle4 ,what is the best place to put the keel8 ,the greatest stability is usually gained by fixing the keel at the center of gravity4 ,there is great difference of opinion as to whether it should be above or below4 ,try both ways4 ,what is stability for one aeroplane may mean disaster for another4 ,why should an aeroplane pitch and roll when rising or even traveling horizontally1 but sail in a bee line when it begins to descend8 ,the stability of a model is greater when its course is downward than when in a horizontal flight4 ,in this position1 the center of pressure is much less likely to shift1 and the pole of gravity has rather a steadying effect4 ,for this reason a glider thrown from an elevation travels much more evenly than a power-driven machine4 ,try reversing your planes4 ,why is it that my aeroplane sails all right1 but when ,i increase the power of my motor it falls off and darts about until it reaches the ground8 ,it has been found in experiments of man-carrying machines that an increase in the speed of a flight would often render an ordinarily steady machine unstable4 ,it is argued by some authorities that the air is churned up1 as it were1 by the forward planes1 and that the rear wing1 therefore1 rocks just as will a boat in rough water4 ,if your model flies well at a certain speed1 you had better stick to the motor1 and try a larger plane4 ,how far apart shall ,i place the two wings of my monoplane8 ,there is no general rule possible4 ,some designers believe that the two planes should be separated by a distance equal to four times the width of the main plane4 ,an excellent model which makes long flights is illustrated herewith1 in which the distance is equal to nearly twenty times the width of the main plane1 while another successful model has an open space of only twice the width of the main plane4 ,much depends1 of course1 upon the speed at which the aeroplane flies4 ,the wings may be much further apart on a high-speed than on a slow-flying model4 ,are there any simple equations for working out the relation of the proportion of the size and weight of model aeroplanes8 ,there are many such equations1 but none of them are simple4 ,the formula which obliges one to solve a complicated problem in algebra or calculus to know where to cut off a stick is obviously absurd in the case of small models4 ,these formulas which may be found in technical books on aviation seem to savor too much of certain school books to be brought in for the builder of model aeroplanes4 ,a good rule to remember is that the thrust should equal the weight of the machine4 ,some of the large aeroplanes are driven by propellers made up of four blades4 ,would you try this arrangement on a model aeroplane8 ,by no means4 ,as explained in the chapter on propellers1 the work performed by your propeller blades is entirely different from that of an electric fan4 ,it is true that fairly efficient propellers made up of four blades have been used on some passenger-carrying aeroplanes4 ,this form might prove effective on a model aeroplane1 but increased weight is prohibitive4 ,by carefully designing your two blades1 you can get equally as much work out of them and at the same time reduce the weight by one-half4 ,it is argued by some authorities that the single blades act upon undisturbed air and are therefore more efficient than a four-blade propeller1 as the air is always churned up4 ,how can ,i calculate the speed of my machine from the size and pitch of my propeller8 ,it is practically impossible to do so4 ,if you multiply the pitch of a propeller by the number of turns at a given time1 you will arrive theoretically at the speed4 ,in practice1 however1 the slip of an aerial propeller is from twenty-five to forty per cent4 ,it is very difficult to determine just what the slip is4 ,your calculation is likely to be a matter of thirty per cent off and is of little value4 ,i am troubled with my machine trembling a great deal during flight4 ,what can ,i do to make it steady8 ,the framework of your model is probably too light for your motor4 ,strengthen your machine if it will stand it1 or take off some strands of your motor1 if it will stand it4 ,the frame may be strengthened by using wire braces4 ,this method so commonly used last year is being abandoned by the successful builders1 as it makes it necessary to attach struts at right angles to the frame1 which add to the weight and resistance4 ,the wire in vibrating also offers an appreciable amount of resistance to the air4 ,in a large passenger-carrying machine1 these wire braces are absolutely necessary1 but the model being so much smaller it is better to make the frame heavy enough to remain rigid4 ,a great deal of extra work and annoyance is saved by doing away with wires4 ,this trembling again may be caused by your propeller not being properly balanced4 ,what is the lightest metal ,i can use8 ,aluminum has less specific gravity than any metal now available4 ,its cheapness also makes it practicable4 ,magnalium is a trifle heavier than aluminum but considerably stronger1 and is preferred by many model builders4 ,there are still others who prefer steel to either of these4 ,steel is three times as heavy as aluminum and about five times as strong4 ,if you can get the metal in the proper size for model aeroplane building1 steel is probably the lightest after all4 ,some model builders have great success with umbrella ribs1 which is probably the most available form of steel for our purpose4 ,as most of us have discovered1 a steel bicycle spoke is by far the best axle for propellers4 ,should the propeller be in front or behind the machine8 ,it will require some years of experimenting to answer this question definitely4 ,on one hand it is argued that the forward propeller1 or tractor as it is called1 works in undisturbed air and is therefore more efficient4 ,most of the large passenger-carrying aeroplanes are driven by tractors4 ,others argue that the propeller churns up the air and that the planes would therefore balance themselves against the gusts thus set in motion1 which makes their flight unstable besides requiring additional power4 ,practically all of the successful model aeroplanes this year are driven by propellers4 ,what is the lightest practical model aeroplane8 ,the ,english aviators who excel in constructing very light models have had great success with what are termed one ouncers4 ,some of the models of this type weigh even less than one ounce4 ,the distance qualities of these machines are marvelous4 ,mr4 ,burge ,webb claims a record of #a1ejj feet in a straight-away flight by one of his one-ounce models4 ,can ,i make a model fly by turning the propellers in the same direction8 ,it is doubtful4 ,in using twin propellers the blades should1 of course1 revolve in opposite directions although they are wound up by turning them away from the center4 ,be careful1 of course1 to mount the right and left propeller in the proper position4 ,some aviators believe that the propellers should be turned at the same time1--there are machines to do this1--in order that the thrust may be exactly balanced4 ,what is the longest flight ever made by a model aeroplane8 ,mr4 ,flemming ,williams1 the ,english expert1 claims to have made a flight of almost exactly one-half a mile4 ,his machine1 which is illustrated in this volume1 weighs ten ounces4 ,it was launched by throwing it in the air1 and in making this record flight travelled with the wind4 ,what is the best weight for a model8 ,here is a very difficult question4 ,it depends entirely upon what you are trying to accomplish4 ,in ,england1 where everything is sacrificed to the distance qualities of the model aeroplane1 the best models vary from five to ten ounces in weight4 ,in ,america1 where much more is required of a model aeroplane1 since it must rise from the ground under its own power and possess considerable automatic stability1 the average weight is much more4 ,what is the average speed of a model aeroplane in flight8 ,about twelve miles an hour4 ,when sailing with the wind this speed may be increased indefinitely4 ,in sailing against the wind1 a model aeroplane may creep along while remaining almost stationary4 ,will tandem propellers make my model swifter or steadier8 ,little has been accomplished either in ,america or in ,england with the tandem propeller4 ,several small ,french models have been flown in this way1 but without striking results4 ,theoretically1 the torque of the propellers balance one another in this position2 the forward propeller creates a considerable backwash1 and the second propeller works at a disadvantage4 ,further experiments may discover an advantage in this arrangement ,how hard should ,i throw my machine when starting it8 ,it is not a good plan to launch the machine at a higher speed than that at which it travels under its own power4 ,by increasing its speed1 you are likely to set up violent oscillation1 and1 as explained elsewhere1 a model becomes unstable with increased speed4 ,it is better to start it too slowly than too rapidly4 ,in the case of a glider1 of course1 it is well to throw it with all your might4 ,this is a problem1 incidentally1 which does not occur when the models rise by their own power4 ,my machine flies very well indeed1 but ,i cannot make it start from the ground4 ,when ,i add more power it swerves to one side and will not fly off4 ,what would you advise8 ,illustration3 ,percy ,pierce launching a prize-winning model ,illustration3 ,launching the sling-shot gliders ,this is a common experience4 ,our advice is to return to the original motor and make the most of the successful flights4 ,your model may not be adapted to rising at all1 that is1 it is too light to carry the motor required to raise it from the ground4 ,if your frame is made strong enough1 it may be able to stand the increase in power1 if it vibrates violently1 as is probably the case with a heavier motor4 ,what is the best time to release the propellers1 just as it starts or before8 ,try both ways4 ,some model builders allow their propellers to get under way a second or so before the flight commences1 and release them and push the machine forward at the same instant4 ,one amateur secures his propellers by means of a thread which he breaks by touching it with a match1 but it is rather fanciful4 ,what is the best height for a model aeroplane to fly8 ,in the principal model tournaments held in ,new ,york the models were seldom more than twenty feet from the ground at any time4 ,most model builders have this altitude in mind in designing their machines4 ,it seems to be generally agreed that when a model rises higher than this too much power is used up in gaining altitude and there is a corresponding loss in the distance qualities4 ,on the other hand in the remarkable #a1fjj foot flight made by ,cecil ,peoli in ,july1 the model rose to a height1 it is believed1 of more than #ajj feet and gained considerable distance in gliding down4 ,after all it is a problem which must be decided by the individual4 ,incidentally it is estimated that a large man-carrying aeroplane on rising to an altitude of one mile can safely soar with all power shut off for twelve miles4 ,this means of course that an aviator has the choice of landing anywhere within a circle twenty-five miles in diameter1 which gives him a rather wide choice4 ,what is meant by critical soaring speed8 ,it is claimed by some aviators that every aeroplane has a certain speed at which it flies best and beyond which it is unsafe to push it4 ,if more power is put on1 they argue1 it will only tend to send the machine up in the air and will not increase its speed4 ,this is probably true in a measure of model aeroplanes as well4 ,when you have found the speed at which your aeroplane flies best do not change the number of rubber bands of your motor or the number of turns in winding4 ,do the tails of birds serve as rudders to guide them in flying8 ,it is an open question4 ,some aviators who have made very careful observations of birds in flight deny that the tails have anything to do with their direction4 ,the theory is advanced by some scientists that the birds used their heads to change their course1 operating them as a forward rudder1 much as do some types of aeroplanes4 ,they argue that since a rudder is much more effective when placed forward the smaller surface presented by the flat heads and necks of birds has more effect than a comparatively large tail4 ,what is the relation of the wing surface to the weight and horse-power of the biplane as compared with the monoplane8 ,the ,wright biplane carries a trifle more than two pounds of weight for each square foot of lifting surface4 ,the ,bleriot monoplane carries about five pounds weight to every square foot of lifting surface4 ,on the other hand the ,wright machine carries about forty pounds per horse-power1 whereas the ,bleriot will only carry about twenty-seven pounds4 ,these figures do not work out for all biplanes or monoplanes but they indicate broadly the relation between the two general types of aeroplanes4 ,what would be the effect of bending down the outer ends of the wings of an aeroplane as the wings of some birds droop8 ,the experiment is well worth trying4 ,it would seem that this angle would give increased stability1 although if the model were knocked off its course it might increase the resistance considerably4 ,an elaborate test of this form has been made by an aeronaut named ,weiss in ,england1 who believes he has gained automatic stability in this way4 ,mr4 ,weiss has built and flown a number of aeroplanes1 varying in size from one weighing five pounds to one which carried a weight of #adj pounds1 and the tests are reported to have been very satisfactory4 ,what is meant by the phugoid path of a model aeroplane8 ,the line described by the machine in flight4 ,every aeroplane left to itself flies in a series of waves swaying more or less up and down from the horizontal4 ,in a aeroplane under the control of an aviator this is largely overcome by manipulating the rudders controlling the vertical motion4 ,every model aeroplane or soaring machine has a phugoid path peculiar to itself which is affected by the power of its motor1 the form of the wings1 its ability to right itself1 etc4 ,it is obvious of course that if the path of your model aeroplane is irregular the machine must travel more slowly and its distance qualities are therefore reduced4 ,is a variable wing surface an advantage and can it be applied to model aeroplanes8 ,in theory at least there is a great advantage in the variable surface plane4 ,as yet but one aeroplane has been flown in which the pilot may increase or cut down the spread of his wings at will4 ,when such control is possible the aviator may employ the maximum spread of the wings for rising1 for instance where it is needed1 and then reduce their area when aloft1 thus gaining in speed qualities4 ,at the present stage of the development of the model aeroplane a variable wing does not seem practicable1 although it is reasonable to suppose that the improvement will come in time4 ,the control would of course have to be automatic1 which renders the problem rather complicated4 ,what is a vortex pack8 ,literally a small cyclone or eddy of the air4 ,the term is used by aviators to describe a turbulent section of the atmosphere4 ,it is very common in flying1 especially at low altitudes1 to run into a very turbulent eddy of air1 such as is set in motion by high buildings or deep valleys4 ,they are extremely dangerous since they cause the aeroplane to dip and roll about violently1 and call for quick and skilful handling of the aeroplane to keep it from being upset4 ,the term might be used to describe an eddy of air which brings a model aeroplane to grief4 ,what form of propeller will give the highest efficiency8 ,it is impossible to lay down a hard and fast rule4 ,much depends upon the form of the machine4 ,the ,voison propellers have been found in actual practice to give only about forty per cent efficiency4 ,this is said to be partially due to the fact that their parts are held together by bolts and projecting nuts which offer considerable skin friction4 ,the ,wright propellers are believed to be the most efficient propellers for large machines since their efficiency is about seventy per cent4 ,the accompanying photographs of the standard model aeroplane types in ,america will show that there is great difference of opinion as to the diameter and pitch of the screws4 ,what is meant by a variable speed machine8 ,merely an aeroplane whose speed may be increased or reduced by degrees at the will of the aviator4 ,this will enable the pilot to use a slow speed for rising1 for instance -- and on reaching a desired altitude increase his speed4 ,on encountering high winds1 for instance1 the speed might be increased so that the aeroplane would cut through them almost undisturbed4 ,the variable speed aeroplane will doubtless soon make its appearance4 ,many aviators expect that it will be the next great step in the advancement of the science of aviation4 ,has any model aeroplane been fitted with an automatic stability device and what is it like8 ,no such equipment has attracted public attention up to the present writing4 ,an interesting method of securing automatic control has been suggested by ,h4 ,l4 ,twining1 the well-known writer on aviation4 ,his plan is to attach a geared wheel to the propeller shaft in such a way that it will not begin to move until the propeller has made about #ajj revolutions4 ,a string is then run about this wheel which is pulled back as it turns4 ,the pull of this string in turn is made to raise or lower the horizontal rudder of the model1 but only after the machine propellers have made #ajj turns and the model is presumably well up in the air4 ,in this way the propeller may be set to send the model upwards at a sharp angle and then made to take the proper angle for a horizontal flight4 ,the attachment suggests very interesting possibilities4 ,it may be possible1 if the device works1 to alter the angle of the rudders either vertical or horizontal several times during a flight4 ,what is the record flight for a motor-driven model aeroplane8 ,a flight of upwards of one mile is reported to have been made by a motor driven model in ,india1 while in the ,united ,states the mile mark is claimed to have been passed4 ,neither of these flights are official4 ,the most advanced work with motor-driven models is at present being done in ,france4 ,at a recent model tournament at the ,velodrome du ,pare des ,princess1 ,paris1 a number of model aeroplanes equipped with engines of various types were flown4 ,one of these1 a biplane measuring nearly seven feet in length1 was fitted with a petroleum two-cylinder motor which developed one-third of a horse-power4 ,it rose beautifully1 cleared a high building and was flying well when it unfortunately collided with some telegraph wires and came to grief4 ,before the accident it had flown nearly three hundred feet in a perfectly straight line4 ,another model at the same meet equipped with a carbonic acid motor flew very well for a time but was injured in a collision4 ,how long has a model aeroplane remained in the air8 ,the ,american record for time aloft is held1 we believe1 by ,cecil ,peoli of ,new ,york1 whose model has remained in the air for sixty-five seconds4 ,several records of from thirty to forty seconds are reported from ,france4 ,it is probable that the best record has been made in the long distance flights in ,england when #bf1jjj feet was covered4 ,has the model aeroplane any practical commercial utility8 ,probably not1 unless we take seriously the suggestion of a writer on aerial warfare1 who believes they will some day be so perfected that they may be used to drop bombs or high explosives over forts or besieged cities4 ,his suggestion is that hundreds of model aeroplanes equipped with miniature engines might be released in a swarm1 each carrying a deadly explosive which would be dropped automatically at a certain time4 ,it would be impossible1 he argues1 for gunners to bring down an entire fleet of these swiftly moving machines1 and so while many of them might fall short enough would succeed in dropping their missiles to make them an exceedingly dangerous weapon4 ,the writer points out that the expense of such a mosquito fleet would be trifling compared with the cost of the ordinary engines of warfare and might be operated without risking any lives4 ,illustration3 ,a tractor with large plane forward built by ,f4 ,w4 ,curtis ,illustration3 ,model built by ,william ,robinson ,how large may a model aeroplane be made with good results8 ,none of the successful strand motor models at present exceed five feet in length4 ,this would seem to be the practical limit at which a model may be carried with this motive power4 ,flights of more than #a1ejj feet have been made with models but two feet in length4 ,when regular engines are installed there is of course no limit to the size of models4 ,when was the first model aeroplane constructed8 ,crude machines propelled through the air by twisted rubber strands were used as playthings more than a century ago4 ,the model built and flown by ,langeley in #ahhg1 was probably the first machine to appear on the lines now generally followed by aeronauts4 ,successful model aeroplanes have been used as toys for less than five years4 ,their development in this period has been remarkable4 ,are the equations for calculating the thrust of propeller in terms of wing area and skin friction and general proportions useful in designing model aeroplanes8 ,only in a general way4 ,when the dimensions are very small these complicated equations are misleading4 ,they are for the most part extremely complicated and for this reason we have avoided them entirely in the present volume4 ,much better results may be obtained by proceeding merely by the rule of thumb1 and testing out the proportions of your aeroplane by actual practice4 ,what is the ,american indoor record for model aeroplanes8 ,a flight of #bfe feet was made at a ,new ,york tournament by ,stewart ,easter1 the model rising from the ground under its own power4 ,this was made diagonally across the hall as far as it could go4 ,many flights have been made at the ,new ,york meets in which models have flown the entire length of the hall and struck the further wall with their motors far from run down4 ,in other words1 model aeroplanes have reached a state of development where they have outgrown the largest indoor enclosures available for flying4 ,,chapter ,,xiv ,,among ,,the ,,model ,,builders ,a number of model aeroplane builders in ,america have developed distinctive designs which have come to be accepted as standard types4 ,among thousands of boy amateurs these models are looked upon much as1 in the larger field of aeronautics1 the ,wrights1 ,curtiss1 or ,bleriot are accepted as authoritative4 ,like the famous designers and pilots of man-carrying craft this younger generation of designers give their names to their machines4 ,our young designers1 as a rule1 confine themselves to developing a particular type of machine4 ,a comparison of the models of the same builder for a year or more will usually show that the same general form and arrangement of the planes remain the same4 ,the ,percy ,pierce model1 which borrows the name of its designer1 is probably the best known of these model aeroplanes4 ,the designer is a ,new ,york schoolboy seventeen years of age1 who has won distance records both for indoor and outdoor flying4 ,his machines rise from the ground under their own power4 ,the ,pierce model of #aiaa is equipped with wings much narrower than those used last year1 spaced well apart on a four-foot frame4 ,the planes1 which are slightly flexed1 are covered with silk1 or bamboo paper drawn taut and varnished4 ,twin propellers of high pitch are used and the motors are carried above the planes4 ,they are wound more than five hundred times4 ,the planes are carried beneath the main frame4 ,directional stability is obtained by carrying back the edges of the rear plane and by a vertical rudder placed beneath4 ,the model is mounted on skids of bent reed and is elevated very slightly above the horizontal4 ,it starts off very fast1 often leaving the ground within five feet4 ,the model reaches its maximum altitude1 traveling at an angle equivalent to its position at starting1 and maintains its height throughout its flights4 ,the later ,pierce machines1 while preserving the same general lines1 are considerably lighter and have developed surprising distance qualities4 ,the planes are made of light lath or bamboo covered with specially prepared paper1 while the pitch of the propellers has been increased as has the power4 ,the latest models have flown for #a1fjj feet4 ,another prize-winning model which has attracted considerable attention of late is the aeroplane designed and built by ,cecil ,peoli4 ,it shows an intelligent appreciation of the principles involved and excellent workmanship4 ,it is a monoplane1 flying with the smaller plane forward1 and has recently flown for nearly #agjj feet4 ,planes are used with both silk or paper covering4 ,the success of the model is largely due1 no doubt1 to the careful workmanship and finish of the planes4 ,the models are usually high powered and are driven by twin propellers of high pitch1 carved from especially designed blanks4 ,the aeroplane rises very quickly and will successfully combat a high wind4 ,it is doubtless due to this fact that the model has won in a contest for altitude4 ,it has repeatedly flown over a thousand feet4 ,it does not follow1 of course1 that the beginner can equal these records since much depends upon the skilful adjustment of the model which comes only with experience4 ,another prize-winning aeroplane which has been much admired is the ,leslie ,robinson model4 ,this model1 which is of an original design1 makes long and remarkably stable flights4 ,in no other model has metal been used so extensively in construction4 ,the propellers are made of aluminum as is the framework of the planes4 ,both planes are built in the proportion of about one to five1 the smaller wing being carried forward4 ,a novel feature of this model is the turned wing tips of both planes1 which are slightly tapered and bent upward and outward at a slight angle4 ,the model is beautifully finished in every detail4 ,skids of reed are used and the model is tilted upward sharply at an angle of nearly forty-five degrees4 ,the motors1 three feet in length1 are composed of ten strands of square rubber1 which will take about #djj turns4 ,the model rises quickly at a sharp angle but soon comes to a horizontal position and flies with great steadiness4 ,it weighs complete1 ready for flight1 nine ounces4 ,its metal construction makes it very durable and proof against many of the smaller accidents4 ,the later machines have been equipped with geared motors1 which work well in practice4 ,the models built and flown by ,h4 ,l4 ,watkins always give a good account of themselves4 ,a comparison of the ,watkins models of #aiaj and #aiaa shows that their inventor has kept closely to his original design and has made remarkable progress in lightening his machine while keeping it sufficiently strong to support two powerful motors4 ,the wings have been cut down in size and made extremely light1 the smaller wing being set well forward4 ,directional stability is gained by a small vertical and horizontal rudder1 carried far in the rear of the rear main plane4 ,every part of the frame is kept extremely light4 ,the model complete weighs but four ounces4 ,the ,watkins model stands on very light skids so arranged that a single point comes in contact with the floor1 thus reducing the friction on rising4 ,in many of his models ,watkins covers his planes with thin red paper4 ,the machine rests almost horizontally but rises very quickly on being released4 ,its extreme lightness often gives its flights a slightly waving form4 ,twin propellers1 with unusually broad surfaces are used for driving1 although1 in some models1 a single propeller is carried just back of the rear plane4 ,it is an extremely graceful model in flight4 ,in the models built by ,stewart ,easter the wing surface has been reduced still further4 ,the surfaces are no more than knife blades and are mounted surprisingly far apart on a rectangular frame4 ,every part of the frame has been cut away where possible to economize weight and resistance4 ,although four feet in length the model weighs less than three ounces4 ,the front planes are flat with straight entering edges and the sides are cut slightly away4 ,the rear edge of the rear plane is slightly concave4 ,in some of his models two thin blades are carried forward1 the upper one being placed slightly in front1 thus ingeniously varying the biplane form4 ,two slight vertical rudders1 elliptical in form1 are carried back of the rear plane4 ,the frame stands in a practically horizontal position4 ,the skids used are very light1 touching the ground at a single point4 ,with a six-strand motor the twin propellers are wound about six hundred times4 ,the propellers are broad and of a high pitch4 ,the ,easter model clears the ground instantly1 rises rather high and makes a beautiful flight4 ,the model shows extremely fine workmanship in every detail4 ,the model built by ,john ,caresi contrasts strikingly with these extremely light frames4 ,they are of excellent workmanship and illustrate many new ideas in construction4 ,the ,caresi model flies well and has acquitted itself specially in the weight-lifting contests4 ,it is safe to say that no other ,american model aeroplane shows a more comprehensive knowledge of the scientific principles involved in model building or a higher standard of workmanship in every detail of their construction4 ,the planes are large1 thus affording unusual stability4 ,the frames are marvels of delicate and ingenious construction4 ,in contests in which the workmanship and design are considered as well as the distance qualities1 the ,caresi model stands in a class apart4 ,no list of the successful model aeroplane models of the year would be complete which did not include the prize-winning machine built by ,j4 ,ragot4 ,the aeroplane carries two planes of about equal size and shape mounted on a simple frame4 ,it is driven by twin propellers of rather low pitch and a high-powered motor4 ,by skilful adjustment of the planes and weights the model performs the most amazing spectacular flights4 ,the model is well made4 ,the unexpected course of the machine is controlled by flexing the ends of the planes4 ,the ,ragot model loops the loop and performs other amazing feats4 ,in point of workmanship few of the model aeroplanes which have appeared at the meets this year compare with those built by ,r4 ,mungokee4 ,the genius of the ,japanese for delicate construction finds an admirable opportunity in such work4 ,these models are unusually large1 and their wing area considerable1 yet so delicate are all the parts that they weigh less than one pound4 ,the sticks used for the motor base are hollow1 being built up of a light veneer one-sixteenth of an inch thick4 ,the joints are so cleverly arranged that they would deceive the average eye4 ,the main sticks of the frame are joined by a series of trusses of the same delicate construction which form an exceptionally rigid base of amazing lightness4 ,every detail of the model shows the same delicacy of construction4 ,the planes are built up of thin strips of bamboo covered with ,japanese silk on both surfaces1 the curve being drawn perfectly4 ,the models are driven by two very wide propellers of high pitch1 placed back of the rear plane4 ,the smaller plane is carried forward4 ,the model rises to considerable height1 often fifty feet or more1 and flies horizontally with unusual stability4 ,the frame is braced by fine wires running through struts placed midway above and below the main sticks4 ,the finest scale model aeroplane in ,america to-day is doubtless the biplane built by ,mr4 ,karl ,h4 ,de ,leon1 illustrated on the cover of this volume4 ,its great size is indicated by comparison with the boys standing about it4 ,the most delicate workmanship is to be found in every detail4 ,the planes are controlled by a complete system of wires and levers centered at the driver's seat1 exactly as in the large man-carrying machines44 ,the wings may be flexed and the guiding rudders turned from side to side or their angle elevated or depressed by the slightest movement of the controlling devices4 ,the model is equipped with a miniature ,gnome engine especially imported for the purpose4 ,the materials employed in constructing this model alone cost upwards of #ejj4 ,the model embodies several original features1 the inventions of the builder4 ,illustration3 ,front view of the ,de ,lion model ,several of the most interesting models of the year have been designed and built by ,mr4 ,w4 ,s4 ,howell1 ,jr41 a very painstaking and intelligent student of aeronautics4 ,mr4 ,howell has done much valuable original work in building scientific gliders4 ,one of his gliders weighing nearly two pounds1 has been thrown for more than #fjj feet measured in a straight line1 while the actual distance traversed was probably two or three times this distance4 ,the model is of exquisite workmanship in every part4 ,mr4 ,howell is the inventor of several devices for increasing the efficiency of rubber-strand motors by reverse winding4 ,,chapter ,,xv ,,curiosities ,,of ,,the ,,air ,until the summer of #aiaa1 the longest model aeroplane flights officially recorded in ,america remained under #cjj feet4 ,from ,england meanwhile came disquieting reports of #a1jjj foot flights and better1 made by a number of aeroplanes4 ,a comparison of the best ,american and ,english models showed that1 both as regards form and workmanship1 ,american boys were holding their own against their ,english cousins1 and utterly failed to account for the much greater distance qualities of the foreign models4 ,in ,july1 #aiaa1 the ,american distance record was suddenly jumped to #a1fia feet1 #f inches1 by ,cecil ,peoli of ,new ,york4 ,the model used had been flown in the regular indoor meets for very much shorter distances4 ,this sensational advance in the distance record was made at an outdoor tournament at ,van ,courtland ,park1 ,new ,york ,city4 ,of the thirty-four models entered for the contest1 including the familiar models built by ,percy ,pierce1 ,h4 ,watkins and others1 several showed a similar increase in distance qualities4 ,the model aeroplanes were the same as had flown but #bjj feet indoors1 their rubber motors exerted no more power than before1 the pitch of the propellers remained unchanged4 ,what then is the secret of the suddenly acquired distance qualities8 ,evidently the difference lies in the quality of the air the little ships navigate4 ,it is commonly said that the air indoors is dead as contrasted to the live air found out-of-doors4 ,the variation in the quality and movement of the air forms a very interesting study which no aviator can afford to neglect4 ,to the actual navigator of the air this study is just as important as life and death1 while to the designer even of model aeroplanes it is of course of vital importance4 ,although the composition of the air and its behavior under various conditions has been the subject of scientific examination for centuries1 it is only within the past few years that it has been studied with the idea of bringing it under control4 ,the long painstaking experiments of ,langeley and ,lilienthal1 referred to in the previous volume1 for determining the resistance of the air and its effect on the surface of the aeroplane1 opened a new field of scientific research4 ,within the past few years1 even months1 the advancement in our knowledge of the air has been greater1 it is safe to say1 than in the previous century4 ,it is not generally realized by the laymen how rapid has been the development of aerology1 nor how practical are the results obtained4 ,there have already been established in ,germany three scientifically equipped stations for observing air conditions for the benefit of aeronauts1 just as the weather bureau observes weather conditions and informs ships at sea of approaching storms4 ,one of these1 established by ,dr4 ,polis at ,aachen1 is now in operation4 ,in addition to this the ,public ,weather ,service ,stations of ,germany have been equipped recently with the necessary apparatus for making daily observations of the upper air for the special benefit for aerial navigators4 ,the resistance offered by the air to the passage of an air ship of any type depends upon its density4 ,the air is obviously an exceedingly variable medium1 as capricious as quicksilver1 as both the sky pilot and the flyer of model aeroplanes have learned4 ,the density and therefore the resistance depends upon the temperature1 the pressure and the state of equilibrium4 ,we are in the habit of thinking of density and pressure as affecting enormous volumes or areas miles in extent1 such as are reported in the weather forecasts from day to day4 ,to an extent these same conditions are found changing within a few feet4 ,it is this tendency to rapid change of conditions which makes the problem of stability in aeronautics so baffling4 ,the pressure upon an aeroplane1 whether a man-carrying machine or a model1 varies considerably between the level of the seashore and the top of a mountain4 ,an aeroplane in rising from the level of the sea for several thousand feet therefore meets new and unexpected conditions4 ,the density is reduced fully one-half at an altitude of #ah1jjj feet1 and since aeroplanes have risen more than #aj1jjj feet this must be taken into consideration4 ,even at a height of #cjj feet1 which is often reached by aeroplanes in flight1 the difference in the pressure calls for skilful manipulation on the part of the sky pilot4 ,the density varies again according to the temperature4 ,let an aviator suddenly run into a hot or a cold strait of air and the pressure upon his planes will instantly change4 ,the effect of temperature must be taken into consideration by any one flying model aeroplanes4 ,it may happen that a draft of cool or of hot air1 by changing the pressure on the planes1 will throw a model aeroplane out of balance and mar an otherwise promising flight4 ,a difference of a few degrees of temperature will often affect a very sensitive model4 ,the only way to combat this is of course to build your model with the greatest possible stability4 ,the presence of high buildings or other violent inequalities will also affect the density of the air and in turn the pressure exerted on the wings of an aeroplane4 ,among aviators it is generally believed that a great city is one of the most dangerous possible objects to fly above4 ,in the case of ,new ,york with its many sky-scrapers1 for instance1 the danger is vastly increased4 ,even in the open country the presence of a deep valley or other depression will so affect the density of the atmosphere that an aeroplane is likely to be drawn down from its course4 ,these areas are known among aviators as pockets1 and are often large enough to swallow up a large man-carrying craft1 at times with disastrous effects4 ,the chance of your model aeroplane running into such a pocket is of course considerable4 ,a striking illustration of the effects of these chance currents was afforded during a recent model aero tournament in ,new ,york4 ,a model aeroplane which had flown with remarkable steadiness for more than #aej feet chanced to pass over the head of a boy who was walking slowly across the course4 ,this moving object served to set up a small whirlpool of air4 ,the model on striking it was instantly checked1 when it turned1 skirted the column of air and passed on4 ,in an indoor flying1 an open window1 merely by changing the temperature slightly in its vicinity1 will often cause a model to be seriously deflected1 perhaps to be thrown completely off its course4 ,it will often be noticed in outdoor flying that a model1 in passing over a stream or body of water or a mass of dense foliage1 will encounter a change of temperature which will appreciably affect its course4 ,in flying model aeroplanes the performance of a machine will often vary unaccountably from day to day4 ,with the same motor and winding1 the model will fly much higher and more freely at different seasons of the year4 ,it is well to bear in mind that in the summer months the heat causes a low density4 ,the pressure exerted by the atmosphere is therefore correspondingly small2 the model1 or for that matter a large machine1 travels much faster4 ,a dry day also tends to cause low density4 ,this will account for the excellent flights on warm1 dry days and the crankiness of the machine when the weather is damp4 ,cold weather on the other hand tends to increase the density of the air4 ,the speed of an aeroplane is materially reduced but on the other hand the air will be found more buoyant4 ,such weather is better for heavy models1 although they fly much more slowly4 ,it will be seen that at high altitudes1 where the density is least1 models should fly both faster and higher than they will nearer the sea level4 ,one of the curiosities of the air is the effect of eddies created by the passage of aeroplanes4 ,let an aeroplane move fast enough through the air and it will create high density above its course1 and low density below its line of flight4 ,this condition may also be found in the wake of model aeroplanes4 ,it will often be noticed when two models are flying near together that the disturbance caused by one will seriously interfere with the second machine4 ,the contrast between the air above and below the models in flight in especially noticeable when the planes are flexed4 ,illustration3 ,two of the earlier ,peoli models ,a great deal has been learned of the action of the air upon aeroplanes by photographing the air currents4 ,the smallest eddies of the air have been made visible by taking instantaneous photographs of thin smoke as it passes obstacles of various size and form4 ,it has been found that a square object causes a great deal of disturbance when in an air current4 ,the air is compressed in front of it and eddies for some distance in its wake before finally coming to rest4 ,an elliptical object causes less disturbance1 but the air continues to splash in its wake for some distance4 ,even a perfectly spherical object offers a surprising amount of resistance to the air4 ,in the case of a long narrow ellipse the disturbance is considerably reduced4 ,a curved surface however1 such as is used for the planes of an aeroplane1 cuts the air with practically no resistance1 and the air flows smoothly about and joins behind it with very little wake or splashing4 ,a form which suits the air in this way or a stream line body as it is called is obviously just the right design for the wings of an aeroplane4 ,even the experts in aeronautics differ so widely1 however1 that it is impossible to lay down any definite rules4 ,one of the greatest authorities on the science of aviation1 ,mr4 ,horatio ,philips1 of ,england1 believes that aeroplanes gain more support from the entering edges of their planes than from the rest of their surface4 ,he argues that it is this edge1 meeting the air currents1 which serves to hold the aeroplane suspended4 ,this theory is founded on the experiments made with a machine of original design flown by ,mr4 ,philips as far back as #ahij4 ,it consisted of a series of planes mounted one above the other at regular intervals1 much the same as the strips of a ,venetian blind4 ,the lifting power of this model in proportion to its surface and the power exerted was enormous4 ,this theory is borne out in part by the success of the model aeroplanes with very narrow wings which have been flown with great success during the year4 ,the beautiful model built by ,stewart ,easter1 for instance1 which is illustrated on another page1 depends for its support on planes which are no wider than ordinary window blinds4 ,there is an immense difference of opinion again as regards skin friction4 ,some writers believe the air has a tendency to stick to certain materials more than to others1 and that this difference is so great as to materially retard some machines in their passage through the air4 ,a complicate series of tables has been worked out in great detail to show the exact amount of this friction on various bodies4 ,some aviators go to great pains to make every part of their aeroplanes as slippery as possible4 ,this is done by polishing the surfaces exposed to the air and in some cases enclosing the foreward part of the aeroplane1 like a ship's prow1 to diminish friction4 ,on the other hand we find some of the greatest authorities on aviation disregarding this question almost entirely4 ,in the ,wright machines1 for instance1 the surface of the wings is usually left comparatively rough1 and the sticks and wires are placed without any attention to diminishing friction4 ,this is true as well of the ,delegrange1 ,voison and ,farman machines4 ,still other aviators design every detail of their machines to cut down this so-called skin friction4 ,the uprights1 for instance1 are made elliptical in shape1 with the sharp edges turned forward so that they will cut their way the more smoothly through the air4 ,several interesting attempts have been made to design a prow for an aeroplane which will cut the air with the least possible amount of friction4 ,it is noticeable in these designs that the prows are very blunt1 like the prow of a canal boat1 and not as might be expected1 sharp and narrow like that of a racing craft4 ,the blunt-nosed prow is considered best for the air ship1 because the air being one eight hundredth as dense as water offers very little resistance to its entrance4 ,it is so much easier1 in other words1 to push an air ship through the air than a boat through water that there is no object in sharpening its nose4 ,the air1 however1 in flowing along the sides of a rapidly moving body sticks to it1 and retards its progress relatively more than water retards a boat4 ,it is important1 therefore1 that the body of the aeroplane be made very short1 so that the sides will offer as little friction as possible4 ,this reverses the proportions of a water-borne ship4 ,we are so accustomed to see fast boats with long1 narrow hulls1 that it comes as a surprise to find that a fast air ship must have a very broad beam and as short a hull as possible4 ,it is probable that1 as air ships develop1 this general characteristic will become more marked4 ,as aeroplanes become larger and faster they will therefore depart further and further from the conventional ideas concerning water-borne craft4 ,it is impossible to prophesy at present what form the great passenger-carrying air ships of the future will take1 but it is certain that their hulls or the closed-in portion carrying the machinery and passengers will be very short1 snubbed-nose affairs4 ,the world will be obliged to change its mind as to what constitutes a speedy-looking craft4 ,man has learned to fly4 ,more than #a1jjj aeroplanes have been built which have successfully risen above the earth4 ,it is estimated that these aeroplanes have flown in all more than #bej1jjj miles1 or a distance equal to ten times the circumference of the earth4 ,but no machine has yet been made which will fly alone1 without the skilful manipulation of planes and rudders4 ,the model aeroplane which soars gracefully aloft1 suiting itself to the varying air conditions1 perhaps comes nearest to the automatic flying machine4 ,a great advance will be made in aviation with the appearance of some practical contrivance for securing automatic stability4 ,the aeroplane as it stands to-day shows a wonderful advance in the improvement of its general lines1 and the mechanical perfection of its parts1 but the question of stability remains practically the same as it was when the ,wright ,brothers made their first flights4 ,the machine has been brought under a remarkable control1 but only as it is directed by the practised hand of the sky pilot4 ,let him take his hand even for a moment from the levers1 which control the planes and rudders1 and there is danger of a bad spill1 perhaps a fatal accident4 ,practically nothing has been accomplished in building machines which will fly unaided4 ,it has been pointed out1 elsewhere in this volume1 that the experiments with the model aeroplanes are certain to have an important influence upon the development of aeronautics as a whole1 because they address themselves particularly to this problem of stability4 ,it is believed by many aviators that the problem of automatic stability will be solved by some form of the gyroscope4 ,a great many experiments are being made with various forms of the gyroscope1 although no machine has as yet been actually fitted and flown with such a device4 ,the general principle of the gyroscope is very simple4 ,it consists of a wheel which is made to revolve at very high speed4 ,when such a wheel turns fast enough it will remain in a fixed position4 ,every one is familiar for instance with the gyroscope top4 ,you wind it up and place it at any angle1 and it will support itself and retain the position until it has run down4 ,the gyroscope has been applied for instance to railroad trains and has worked1 experimentally at least1 with remarkable success4 ,by installing a gyroscope on a car running on a single track the car may be kept upright by the stabilizing force exerted by the revolving wheel4 ,the same principle has been applied to steamships to prevent their rolling in heavy seas4 ,the tipping of a car running on a single track1 or of a ship at sea1 is of course very much like the rolling of an aeroplane in flight2 and it would seem that such a stabilizing device might solve the problem4 ,the gyroscope has a serious disadvantage1 however4 ,since it revolves at enormous speed any breakage would tend to throw the detached part to one side with dangerous force4 ,in the case of the gyroscope used to steady ships at sea this force would be sufficient to send a piece of metal through the hull4 ,on so delicate a craft as an aeroplane such an accident might readily prove disastrous4 ,it has been found again in experiments with gyroscopes on steamers that the frames have been seriously strained1 even when the gyroscope worked smoothly4 ,when a ship rolls and pitches to the motion of the waves1 it is of course under a great strain but this balances itself4 ,when it is held in a rigid horizontal position the pitching and rolling exert an exaggerated strain on the hull4 ,in one instance a vessel actually broke its back under such a strain and was lost4 ,an air ship1 being at best a very frail structure1 could scarcely be expected to stand the strain which has wrecked a steel ship4 ,at the recent ,paris ,aeronautical show several extremely ingenious combinations of the pendulum and gyroscope principles were illustrated4 ,it is of course possible that some modified form of the gyroscope may solve the problem4 ,a remarkable series of tests has been made this year in ,france with an automatic stability device based upon an entirely new principle4 ,the rudders are operated automatically1 in this case by a vertical fin opposed to the wind4 ,as the pressure of the air varies1 the rudder is forced up or down1 thus bringing the aeroplane to an even keel without the assistance of the aviator4 ,it is reported that model aeroplanes equipped with this device have been flown in three hundred experiments without a single accident4 ,the day is approaching when the air conditions will be observed and announced for the benefit of aviators exactly as the weather is foretold to-day4 ,an aviator who is about to start on a cross-country flight will thus be able to study the conditions of the air lanes and lay out his route just as an automobilist looks up good-roads maps4 ,in crossing a particular piece of country he will therefore know whether to take a low or a high air lane1 that is1 one of few hundred feet above the earth or the one several thousand feet aloft4 ,the pressure of the air on the regular air lines will be announced as well4 ,in this way aviation will be made much safer than it is to-day1 when the aviator must venture without any knowledge of conditions aloft except those he may gain from the ground surface weather maps4 ,during the year #aiaj1 fully a score of lives might have been saved had aviators had such information4 ,the first of these observation stations is actually in operation in ,germany to-day4 ,each of these stations is supplied with a number of rubber balloons equipped with automatic apparatus for recording atmospheric conditions in the upper air lanes4 ,the stations also contain the proper apparatus for measuring the ascensional force of the balloons1 with the gas generators used for inflating the balloons4 ,when the balloons are sent up for great heights their altitude will be measured by means of the theodolite4 ,the soundings of the air are taken twice daily at eight o'clock in the morning and two in the afternoon whenever the weather permits4 ,in the summer the morning observations are made much earlier4 ,the movements of the balloons are then carefully observed at various altitudes until they are lost4 ,these observations are then telegraphed to the central station at ,lindenberg and sent out much the same as the regular weather forecast4 ,,chapter ,,xvi ,,rules ,,for ,,conducting ,,model ,,aeroplane ,,contests ,,prepared ,,by ,,the ,,west ,,side ,,young ,,men',s ,,christian ,,association1 ,,new ,,york4 ,,general ,,rules ,,and ,,conditions ,,for #aiaa4 #a4 ,these ,general ,rules and ,conditions shall apply to the events conducted by the ,west ,side ,y4 ,m4 ,c4 ,a4 #b4 ,each and every contestant for a prize shall accept without reservation the conditions laid down by the ,west ,side ,y4 ,m4 ,c4 ,a4 and shall abide by the decision of the referee4 ,each contestant must register his name1 age and address before the event4 7a7 ,all contestants in ,class ,a must be #ah years of age or over4 7b7 ,all contestant in ,class ,b must be under #ah years4 #c4 ,every machine competing must be made by the operator 7no toys admitted71 and it must be built along practical lines1 that is1 a model from which a practical man-carrying machine can be built4 #d4 ,the ,committee shall have the right to reject any entry1 the rejection of which they deem advisable4 #e4 ,the flights shall be accounted level flights and no allowance will be made for variation of height4 #f4 ,a trial shall be considered to have ended whenever the machine touches the ground4 #g4 ,competitors shall decide by drawing lots the order in which they shall take their turns4 #h4 ,any entrant not ready to commence his trial when called upon will forfeit his turn to him who is next ready1 and will fall back to the end of the list4 #i4 ,the commencement of the distance flown shall in the case of machines on wheels be counted not from the starting line1 but from the point which is determined by the judges as that at which such machines actually leave the ground4 ,in the case of machines using the catapult1 there shall be deducted from the total distance flown the equivalent of the initial impulse of the catapult4 #aj4 ,there shall be no restrictions as to the design1 size1 weight1 form or amount of power1 but the power must be self-contained in the model4 #aa4 ,all models must start from the ground4 #ab4 ,each contestant shall have three trials4 #ac4 ,the longest flight in the three trials will be counted for the prize4 #ad4 ,all awards shall be made to the owner of the model and not to the operator1 unless by special agreement between owner and operator4 #ae4 ,the contests shall cover a period of two hours1 unless otherwise designated by the judges4 ,,rules ,,for ,,conducting ,,model ,,aeroplane ,,contests ,,prepared ,,by ,,the ,,new ,,york ,,model ,,aero ,,club4 ,the officials at the distance contest will be3 ,one entry clerk1 one starter1 one judge4 ,the officials at the spectacular flight contest will be3 ,one announcer and starter1 a jury composed of three persons selected from spectators1 not members of the ,club4 ,the officials at the demonstration of a lifting-power contest will be3 ,one entry clerk1 one measurer and calculator1 and one judge4 ,there will be a director in the center of the armory room to order the flights4 ,the director will have a whistle4 ,each starter will have a flag4 ,starters will ask for the floor by showing flag4 ,the director will order the flights as follows3 ,three whistles for a spectacular flight4 ,two whistles for a distance flight4 ,one whistle for a lifting-power flight4 ,contestants must keep off the floor unless following their own machine in flight4 ,after they have picked up their machine1 they must leave the floor in the most expeditious manner4 ,contestants will apply to entry clerks for directions4 ,,rules ,,for ,,model ,,aeroplane ,,contests ,,prepared ,,by ,,the ,,new ,,york ,,model ,,aero ,,club4 ,the contests shall be open to all4 ,the entries are free1 and shall be received at the ,new ,york ,model ,aero ,club1 #ada ,lexington ,avenue1 either by letter until ,march #ah1 #aiaa1 or verbally on ,march #d #aa1 #aiaa1 from #h3ae ,p4 ,m4 to #aj p4 ,m41 and at the #acth ,reg4 ,armory on ,march #ah from #h to #i p4 ,m4 ,models must be built by the contestants4 ,there shall be two contests3 ,a distance contest and a spectacular flight contest4 ,,distance ,,contest ,two prizes3 ,i4 ,the first prize shall be awarded to the contestant making the longest flight1 and the second prize to the contestant making the next longest4 ,,ii4 ,each contestant shall have only his longest flight recorded4 ,,iii4 ,models must start from the ground under their own power4 ,,iv4 ,contestants are not allowed to push their models4 ,two special officers of the ,club shall be appointed to watch this particular point4 ,v4 ,all models must start from the same starting line1 which will be marked on the floor2 they must be off the ground at a distance of twenty feet from the starting line4 ,in case a model is not off the ground at said distance1 it shall be disqualified for that flight4 ,,vi4 ,flights shall be measured from the starting line to the point of landing4 ,,vii4 ,a one-quarter-inch rope shall be laid on the ground without being fastened at either end1 at a distance of #bj feet from the starting line4 ,,viii4 ,models must measure at least two feet in length and two feet in spread4 ,,spectacular ,,flight ,,contest ,one prize3 ,i4 ,the cup shall be awarded to the contestant making the most spectacular flight as previously announced4 ,,ii4 ,a jury of five persons1 selected from the spectators1 shall decide upon the most spectacular flight4 ,,iii4 ,power shall be optional4 ,,iv4 ,models must measure at least two feet in length and two feet in spread4 ,v4 ,models must be fitted with a landing device by which1 if proper speed was obtained1 the machine would leave the ground4 ,,vi4 ,each contestant1 before launching his model1 must announce the object of his flight4 ,the announcement will be made to the public4 ,,vii4 ,contestants are at liberty to fly their models from the ground or from the hand1 and start wherever they wish4 ,non observance of any of the above rules shall disqualify any flight4 ,,constitution ,,and ,,by-,,laws ,,of ,a ,,model ,,aeroplane ,,club ,,courtesy ,,of ,,new ,,york ,,model ,,aero ,,club ,,constitution ,,art4 ,i ,this association shall be called the 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 ,the object of this ,club shall be to popularize and study the ,science and ,art of ,aviation through models4 ,,art4 ,,ii ,membership4 ,there shall be two classes of members3 #ast4--,senior ,members1 who have been elected as such by the ,admission and ,membership ,committee2 who are qualified to represent the ,club at all competitions1 and shall have a vote at all meetings in the conduct of the affairs of the ,club2 #bnd4--,junior ,members1 comprising all such that have not qualified as seniors1 and who shall have no vote4 ,any person may become a member of this ,club who is passed upon by a majority of the ,admission and ,membership ,committee1 to whom all applications1 either made directly or through a member of the ,club1 must be submitted4 ,all applicants accepted shall at once become ,junior ,members1 and shall remain so until elected ,senior ,members by the ,admission and ,membership ,committee4 ,,art4 ,,iii ,officers4 ,the ,officers of this ,club shall be a ,president1 two ,vice-,presidents1 a ,secretary-,treasurer1 and a ,board of ,governors1 to consist of said officers and the ,chairman of the ,patent ,bureau and ,contest ,committee4 ,the ,president and ,second ,vice-,president shall constitute an ,executive ,committee of the ,board of ,governors1 with full power to act for them in the affairs of the ,club4 ,,art4 ,,iv ,dues and ,assessments4 ,the dues shall be #be;c 7twenty-five cents7 per month for ,junior and ,senior ,members alike1 to be collected at the first business meeting of each month4 ,,art4 ,v ,standing ,committees4 ,there shall be the following ,standing ,committees1 to consist of four members each3 #ast4--,patent ,bureau4 ,the ,patent ,bureau shall investigate and pass upon claims for any feature of a member's own contrivance1 and register and insure to members the exclusive use thereof in the ,club4 #bnd4--,contest ,committee4 ,the ,contest ,committee shall arrange details of1 attend and record all competitions held by the ,club4 ,they shall also attend and report on any other competition at the request of the ,board of ,governors4 #crd4-- ,admission and ,membership ,committee4 ,the ,admission and ,membership ,committee shall examine all applicants for membership1 with full power to accept or reject them1 and shall further examine the ,junior ,members who wish to qualify as ,senior ,members4 ,the ,committees shall convene regularly at every business meeting and besides1 as often as their duties may require4 ,,art4 ,,vi ,special ,committees4 ,special ,committees may be appointed at any time1 by motion or resolution1 to take into consideration and report upon special matters4 ,unless otherwise provided for1 they shall be appointed by the presiding officer4 ,art4 ,,vii ,meetings4 ,regular meetings shall be held every ,saturday4 ,the first ,saturday in ,october and the first ,saturday in ,april shall be semi-annual election and business meetings4 ,following these1 every first and third ,saturday of each month shall be a business meeting4 ,all other meeting nights shall be called ,social meetings4 ,at the social meetings no regular order of business shall be observed4 ,,art4 ,,viii ,elections4 ,the officers and members of the standing committees shall be elected by written ballot4 ,the ,president and ,first ,vice-,president shall be elected at the first business meeting in ,october1 to serve for one year2 the ,second ,vice-,president and the ,secretary-,treasurer shall be elected at the first business meeting in ,april1 to serve for one year4 ,two members of each of the standing committees shall be elected at the first business meeting in ,october1 to serve for one year2 the two other members of each of the standing committees shall be elected at the first business meeting in ,april1 to serve for one year4 ,,art4 ,,ix ,amendment4 ,this ,constitution may be amended by a two-thirds vote at any regular business meeting2 but1 no amendment shall be entertained unless it shall have been proposed in writing at the previous business meeting4 ,by-laws may be altered1 suspended1 annulled or amended by the majority action of the members present at any meeting4 ,,by-,,laws ,,art4 ,i ,duties of ,president and ,vice-,presidents4 ,the ,president shall preside at all meetings of the ,club and of the ,board of ,governors1 and perform such other duties as usually pertain to that office4 ,the ,vice-,president1 in the absence of the ,president1 shall in his stead perform such duties4 ,,art4 ,,ii ,duties of ,secretary-,treasurer4 ,the ,secretary-,treasurer shall keep a record of all meetings of the ,club and of the ,board of ,governors2 issue notices to members of all special meetings1 and perform such other duties as may be assigned him by the ,constitution1 by the ,club1 or by the ,board of ,governors4 ,the ,secretary-,treasurer shall keep the accounts of the ,club2 receive all moneys1 fees1 dues1 etc42 pay all bills approved by the ,board of ,governors1 and preserve all proper vouchers for such disbursements4 ,he shall1 at each regular meeting of the ,board of ,governors1 make a statement of the financial condition of the ,club2 and shall1 at the semi-annual meetings1 submit a report1 approved by the ,board of ,governors1 of the financial transactions of the preceding fiscal half year4 ,,art4 ,,iii ,enforcement of ,rules by the ,board of ,governors4 ,the ,board of ,governors shall have full power to expel or suspend any member whose conduct shall be pronounced1 by a two-third vote of the members present at a meeting1 to have endangered the welfare1 interests or character of the ,club4 ,,art4 ,,iv ,liabilities4 ,the ,board of ,governors shall have no power to make the ,club liable for any debts exceeding in total the amount of five dollars1 unless authorized to do so by a recorded vote of a meeting of the ,club4 ,,art4 ,v ,meetings of the ,board of ,governors4 ,the ,board of ,governors shall hold regular meetings on the last ,saturday of each month4 ,,art4 ,,vi ,non-,attendance at ,governors' ,meetings4 ,a member of the ,board of ,governors who1 without satisfactory explanation1 shall fail to attend two consecutive meetings of that body1 shall be deemed to have resigned4 ,,art4 ,,vii ,colors4 ,the ,club colors are ,sky ,blue and ,red4 ,,art4 ,,viii ,arrears4 ,a member one month in arrears shall not have a vote at the meetings1 nor hold office in the ,club4 ,,art4 ,,ix ,order of ,business4 #a4 ,reading of ,business4 #b4 ,reports of ,officers and ,committees4 #c4 ,unfinished ,business4 #d4 ,election of ,officers4 #e4 ,new ,business4 ,,dictionary ,,of ,,aeronautical ,,terms ,a ,aerodrome4 ,a tract of land selected for flying purposes4 ,aerodynamics4 ,the science of aviation1 literally the study of the influence of air in motion4 ,aerofoil4 ,a flat or flexed plane which lends support to an aeroplane4 ,aeronaut4 ,one engaged in navigating the air4 ,aeronautics4 ,the science of navigating the air4 ,aeroplane4 ,a heavier than air machine supported by one or more fixed planes4 ,aerostatics4 ,the science of aerostation1 or of buoyancy caused by displacement1 ballooning4 ,aerostation4 ,the science of lighter than air or gas-born machines4 ,aileron4 ,the outer edge or tip of a plane1 usually adjustable1 used to balance or stabilize4 ,airship4 ,commonly used to denote both heavier and lighter than air machines2 correctly a dirigible balloon4 ,angle ,of ,incidence4 ,the angle of the plane with the line of travel4 ,area4 ,in the case of planes1 the extent of surface measured on both the upper and lower sides4 ,an area of one square foot comprises the actual surface of two square feet4 ,aspect ,ratio4 ,the relation of a surface crossing the direction of flight with that paralleling the line of flight4 ,automatic ,stability4 ,stability secured by fins1 the angle of the planes and similar devices4 ,aviator4 ,one engaged in aviation4 ,aviation4 ,the science of heavier than air machines4 ,b ,balancer4 ,a plane or other part intended for lateral equilibrium4 ,biplane4 ,an aeroplane with two supporting surfaces one above the other4 ,body4 ,the main framework supporting the plane and the machinery4 ,c ,camber4 ,the curve measured from the cord to the highest point of the plane4 ,carriage4 ,the part on which the main body is supported on land or water4 ,center ,of ,gravity4 ,the point at which the aeroplane balances4 ,center ,of ,pressure4 ,the imaginary line beneath the plane at which the pressure balances4 ,d ,deck4 ,the main surface of a biplane or multiplane4 ,directional ,control4 ,the ability to determine the direction of the flight of an aeroplane4 ,dirigible4 ,a balloon driven by power4 ,down ,wind4 ,with the wind4 ,drift4 ,the resistance of the plane to the forward movement4 ,e ,elevator4 ,the plane or wing intended to control the vertical flight of the machine4 ,engineer4 ,one who controls the power1 driving the machinery4 ,entering ,edge4 ,front edge of the forward plane of an aeroplane4 ,equilibrator4 ,a plane or other contrivance which makes for stability4 ,f ,flexed4 ,a plane is said to be flexed when it curves upward forming an arc of a circle4 ,fin4 ,a fixed vertical plane4 ,flying ,machine4 ,literally a form of lighter than air craft2 a gas-born airship4 ,following ,edge4 ,the rear edge of the plane or wing of an aeroplane4 ,fusilage4 ,the body or framework of an aeroplane4 ,g ,glider4 ,an aeroplane without motor power4 ,guy4 ,a brace1 usually a wire or cord used for tuning up the aeroplane4 ,gross ,weight4 ,the weight of the aircraft comprising fuel1 lubricating oils1 and the pilot4 ,gyroscope4 ,a rotating mechanism for maintaining equilibrium4 ,h ,hanger4 ,a shed for housing an aeroplane4 ,harbor4 ,a shelter for aircrafts4 ,heavier ,than ,air4 ,a machine weighing more than the air it displaces4 ,helicopter4 ,a flying machine driven upward by rotary screws on vertical shafts4 ,helmsman4 ,one in charge of the steering device4 ,l ,lateral ,stability4 ,stability which prevents side motion4 ,loading4 ,the gross weight divided by the supporting area measured in square feet4 ,longitudinal ,stability4 ,stability which prevents fore and after motion or pitching4 ,m ,mast4 ,a perpendicular stick holding the stays or struts which keep the planes rigid4 ,model ,aeroplane4 ,a toy aeroplane1 reproducing a man-carrying machine4 ,monoplane4 ,an aeroplane or heavier than air machine supported by a single main plane which may be formed of two wings extending from a central body4 ,motor4 ,a contrivance for generating driving power4 ,multiplane4 ,an aeroplane with more than three main planes one above another4 ,n ,nacelle4 ,the car of a dirigible balloon1 literally a cradle4 ,net ,weight4 ,complete weight of the machine without pilot1 fuel or oil4 ,o ,ornithopter4 ,a machine supported and propelled by planes moving in imitation of birds2 a flapping wing machine4 ,orthogonal4 ,a flight maintained by flapping wings4 ,p ,plane4 ,a surface or wing1 either plain or flexed1 employed to support or control an aeroplane4 ,pilot4 ,one directing an aeroplane in flight4 ,pitch4 ,theoretical distance covered by a propeller in making one revolution4 ,pylon4 ,correctly1 a structure housing a falling weight used for starting an aeroplane1 commonly a turning point in aeroplane flights4 ,propeller4 ,the screw used for driving an aeroplane1 plane4 ,r ,rudder4 ,a plane or group of planes used to steer an aeroplane4 ,runner4 ,strip beneath an aeroplane used for a skid4 ,s ,scale ,model4 ,a miniature aeroplane exactly reproducing the proportions of an original4 ,spar4 ,a mast1 strut1 or brace4 ,stability4 ,the power to maintain an even keel in flight4 ,starting ,platform4 ,a runway to enable an aeroplane to leave the ground4 ,skin ,friction4 ,resistance offered by planes or wings4 ,slip4 ,the difference between the distance actually travelled by a propeller and that measured by the pitch4 ,soaring ,flight4 ,a gliding movement without apparent effort4 ,surface4 ,the extent of planes measured on one side only4 ,sustaining ,surface4 ,extent of wings or planes which lend support to an aeroplane4 ,t ,tail4 ,the plane or planes1 both horizontal and vertical1 carried behind the main planes4 ,tandem4 ,an arrangement of two planes one behind the other4 ,thrust4 ,the power exerted by the propeller of an aeroplane4 ,tension4 ,the power exerted by twisted strands of rubber in unwinding4 ,tractor4 ,a propeller placed before the main plane4 ,triplane4 ,an aeroplane with three main planes one above another4 ,u ,up ,wind4 ,against the wind4 ,w ,wake4 ,the churned or disturbed air in the track of a moving aeroplane4 ,wash4 ,the movement of the air radiating from the sides of an aeroplane in flight4 ,wings4 ,planes or supporting surfaces1 commonly a pair of planes extending out from the central body4