Part 1

Transcriber’s Note

In the following transcription italic text is denoted by _underscores_. Small capitals in the original publication have been transcribed as ALL CAPITALS.

See end of this document for details of corrections and other changes.

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MODEL AEROPLANES AND THEIR ENGINES

_A Practical Book for Beginners_

BY GEORGE A. CAVANAGH MODEL EDITOR “AERIAL AGE”

DRAWINGS BY HARRY G. SCHULTZ PRESIDENT THE AERO-SCIENCE CLUB OF AMERICA

WITH AN INTRODUCTION BY HENRY WOODHOUSE Managing Editor “Flying” Governor of the Aero Club of America

NEW YORK MOFFAT, YARD & COMPANY 1917

COPYRIGHT, 1916, BY MOFFAT, YARD AND COMPANY NEW YORK ———— _All rights reserved_

Reprinted August, 1917

TO M. T. H.

INTRODUCTION

History tells us—what some of us luckier ones heard the Wright Brothers themselves tell—that the Wrights’ active work in aëronautics was a result of the interest aroused by a toy helicopter presented to them by the Reverend Bishop Milton Wright, their father.

Tremendous developments have taken place in aëronautics and aircraft are fast developing in size, speed, and range of action. They have revolutionized warfare, and seem to be destined to become a most important factor in the reconstruction that will follow the war.

The greater the development the truer the fact that model aëroplanes may be instrumental in bringing to aëronautics men who may make valuable contributions to aëronautics. As a matter of fact, there are already in active life, contributing their share to the development of aëronautics, young men who only a few years ago competed for prizes which the writer offered for model competition.

The young men who are now flying models will live in the new age—and they have much to give and much to receive from it.

Through the tremendous strides forward of aëronautics there are wonderful possibilities for the employment of ingenuity, genius and skill, and business opportunities, as great as have ever been created by progress in important lines of human endeavor. Problems of engineering as huge as were solved by master builders; juridical and legal questions to be decided as stupendously difficult as any Gladstone would wish them; possibilities for the development of international relations greater than were ever conceived; problems of transportation to be solved by the application of aircraft, as wonderful as any economist could wish; opportunities to gain distinction splendid enough to satisfy the most ambitious person.

HENRY WOODHOUSE.

New York, June 5th, 1916.

LIST OF CONTENTS

PAGE INTRODUCTION ix

HISTORY OF MODEL AVIATION 1

CONSTRUCTION 8 Propellers—Wings—Frame—Assembling—Launching— Chassis—Pontoons—Launching an R. O. G. or Model Hydroaëroplane.

WORLD RECORD MODELS 52 Lauder Distance and Duration Model—Hittle Tractor Hydro—La Tour Flying Boat—Cook No. 42 Model—Rudy Funk Duration Model—Alson H. Wheeler Twin Pusher Biplane.

A MODEL WARPLANE 83

A SIMPLE COMPRESSED AIR ENGINE 85–93

COMPRESSED AIR DRIVEN MODELS 94–102 The Dart Compressed Air Driven Model—The McMahon Compressed Air Driven Monoplane—The McMahon Compressed Air Driven Biplane.

COMPRESSED AIR ENGINES 103–109 Wise Compressed Air Engine—Schober-Funk Three Cylinder Engine—The Schober Four Cylinder Opposed Engine.

GASOLINE ENGINES 110–117 Jopson—Midget Aëro Gasoline Engine.

STEAM POWER PLANTS 118–122 H. H. Groves Steam Power Plants—G. Harris’s Steam Engine—Professor Langley’s Steam Engine—French Experiments with Steam Power Plants.

CARBONIC GAS ENGINE 123–124

THE FORMATION OF MODEL CLUBS 125–138

WORLD’S MODEL FLYING RECORDS 139–141

DICTIONARY OF AËRONAUTICAL TERMS 142–152

LIST OF ILLUSTRATIONS

PAGE Model Aëroplane in Flight _Frontispiece_

First Model Aëroplane Exhibition Opp. 4

Propellers (Diagram 1) 9

How to cut propellers (Diagram 2) 11

Designs for propellers (Diagram 3) 14

Designs for propellers (Diagram 4) 17

Wing construction (Diagram 5) 20

Members of the Aëro Science Club Opp. 22

Members of the Milwaukee and Illinois Model Aëro Clubs Opp. 22

Frame construction (Diagram 6) 25

Model Assembly (Diagram 7) 30

C. W. Meyer and Wm. Hodgins exhibiting early type models Opp. 32

Henry Criscouli with five foot model Opp. 32

Schultz hydroaëroplane Opp. 32

Rubber winder (Diagram 8) 35

Chassis construction (Diagram 9) 38

Pontoon construction (Diagram 10) 43

Obst flying boat Opp. 44

McLaughlin twin tractor hydroaëroplane Opp. 44

Louis Bamberger hydro about to leave water Opp. 44

E. B. Eiring and Kennith Sedgwick Milwaukee Club How to launch R. O. G. model Opp. 48

Waid Carl, Concord Model Club Launching R. O. G. model Opp. 48

Wallace A Lauder model (Diagram 11) 54

Lauder distance and duration model Opp. 56

Lauder R. O. G. model Opp. 56

Lindsay Hittle world record hydroaëroplane (Diagram 12) 61

La Tour Flying Boat (Diagram 13) 66

Ellis Cook R. O. G. model (Diagram 14) 73

Funk duration model (Diagram 15) 78

Rudy Funk speed model Opp. 80

McMahon and Schober compressed air driven models Opp. 80

Alson H. Wheeler twin pusher biplane Opp. 82

C. V. Obst tractor Opp. 82

Model Warplane 84

Simple compressed air engine (Diagram 16) 87

Schober compressed air driven monoplane Opp. 90

Schober compressed air driven biplane Opp. 90

Dart compressed air driven model 95

John McMahon and compressed air driven monoplane Opp. 98

Frank Schober preparing model for flight Opp. 98

John McMahon pusher biplane (Diagram 17) 102

Wise compressed air engine Opp. 104

Schober-Funk three-cylinder rotary engine Opp. 105

Schober four cylinder engine (Diagram 18) 107

Jopson gasoline engine Opp. 110

Sectional view of Jopson engine (Diagram 19) 112

Power curve of Jopson engine (Diagram 20) 115

Midget gasoline engine Opp. 116

English steam power plant Opp. 120

V. E. Johnson steam driven hydroaëroplane Opp. 120

English compressed air driven biplane Opp. 122

Tractor hydroaëroplane fitted with steam power plant Opp. 122

English compressed air engine fitted with simple speedometer Opp. 122

The Rompel six-cylinder carbonic gas engine Opp. 124

MODEL AËROPLANES

HISTORY OF MODEL AVIATION

Model aëroplaning, as a sport, was first introduced in America during the year of 1907. It was then that the first model aëroplane club in America was formed by Miss E. L. Todd, with the assistance of Mr. Edward Durant, now Director of the Aëro Science Club of America. Prior to this the model aëroplane was considered an instrument of experimentation or, when built to resemble a full sized machine, was used for exhibition purposes. Noted scientists, men such as Maxim, Langley, Eiffel and others, depended largely on models to bring about the desired results during their experiments. Before the Wright Brothers brought forth and launched the first heavier than air machine their experiments, to a great extent, were confined to model aëroplanes. There is little doubt but that a large majority of aviators engaged in flying machines in different parts of the world were at one time in their career interested in the construction and flying of model aircraft, and from which no doubt they obtained their initial knowledge of the aëroplane, in so far as the same principles and laws apply to any aëroplane, regardless of its size.

The first model aëroplane club went under the name of the New York Model Aëro Club and during its existence a great many of its contests were carried on in armories. The reason for this was because of the fact that the greater number of the models prevalent at that time were built along the lines of full sized machines, and their manner of construction was such as to interfere with the flying efficiency of the model. Streamline construction was something unknown to model constructors in those days and, in consequence, crudely constructed and heavy models were very often evidenced, and, as a result, flights of over one hundred feet were very seldom made. At about the same time model enthusiasts in both England and France were actively engaged in constructing and flying models, but the type of model used was of a different design from those flown by the American modelists and as a result of this innovation many of the early records were held abroad. The type of model flown by the English modelists resembled in appearance the letter “A”, hence the term “A” type.

It was not long after the introduction of this type of model in America that model aëroplaning as a sport began to assume an aspect of great interest. Models were constructed along simpler lines and with a greater tendency toward doing away with all unnecessary parts, thus increasing the flying qualities of the models. Flights of greater distance and duration were the objects sought and, in their efforts to achieve them new records were made at most every contest, until flights of from 500 to 1000 feet were common occurrences. By the use of the A type model and the single stick model which made its appearance shortly after the A type model, American modelists succeeded in breaking most of the world records for this type of model which is now termed by English modelists “flying sticks.”

One by one model aëroplane clubs were formed in different parts of the country until to-day there are in existence about twenty-five clubs and all with memberships of from two to eight times that of the first model aëro club. The work which was started by the New York Model Aëro Club is now being carried on by the Aëro Science Club of America and its affiliated clubs. The interest in model flying grew to such an extent that during the year of 1915 the Aëro Club of America decided to hold the First National Model Aëroplane Competition for the purpose of offering to the young men of America an opportunity of becoming acquainted with this new sport and its advantages. The results of this competition were beyond expectation. Models were made capable of flying distances and with durations that, to the early flyers, seemed impossible. In the hand launched contests models were flown for distances ranging from 2000 to 2500 feet, the winning flight being 3537 feet, and it might also be said that the contestant who flew this model, with a model of the same design established a duration record of 195 seconds. As this goes to press, information is received that the World’s Record for distance for hand launched models has been broken by Thomas Hall, of Chicago, Ill., an Illinois Model Aëro Club member, with a flight of 5337 feet. Another interesting result of the competition was the establishing of a world hydroaëroplane record by a member of the Illinois Model Aëro Club with a model of the tractor type, a four-bladed propeller being used in connection with the model. The flying boat which is a late advent to the field of model flying also proved a record breaker in this competition, having remained in the air after rising from the surface of the water, for a duration of 43 seconds. This model was flown by a member of the Pacific Northwest Model Aëro Club of Seattle, Washington. The establishing of these records clearly indicates the advantage of scientific designing and construction and careful handling.

So satisfactory have been the results of the First National Model Aëroplane Competition that the Aëro Club of America has made arrangements for holding the Second National Model Aëroplane Competition during the year 1916. But in the announcement of the Second National Competition the Aëro Club of America has made provision for the holding of contests for mechanically driven models, in view of the interest which is being shown by model flyers in the construction of models more closely resembling large machines to be driven by compressed air, steam and gasoline power plants. This is the outcome of a desire on the part of model constructors to substitute for what is now commonly known as the “flying stick,” models more closely resembling large machines, which models can be more satisfactorily flown by the use of compressed air, steam or gasoline power plants. As in the early days, the best flights made by models using compressed air and steam have been made by English flyers, the duration of the flights ranging anywhere from 25 to 50 seconds.

Whether or not the American flyers will repeat history and achieve greater results with this type of model motive power is something that can only be determined in the future. But in any event the scientific mechanically driven model will, without doubt, assume an important position in the field of model aviation.

CONSTRUCTION

PROPELLERS

Propellers may be cut from various kinds of wood, but the most suitable, from every standpoint, is white pine. The advantage of using this wood lies in the fact that the propellers may be cut more rapidly and when cut are lighter than those made from most other kinds of wood. When coated with the proper kind of varnish they are sufficiently strong for ordinary flying. Wood selected for propellers should be free from knots, holes and other imperfections and it is very desirable that it should be of perfectly straight grain.

A piece of such clear white pine 8″ long, 1″ wide and ³⁄₄″ thick should be selected and on one side marked TOP. A tracing of the propeller similar in design to Figure 1, should be laid on this piece of wood and an imprint of the propeller design drawn on the TOP side.

To find the center of the block two lines should be drawn from the opposite corners, their point of meeting being approximately in the center—near enough for all practical purposes to insure greater accuracy. Similar lines should be drawn from the corners on the BOTTOM side of the block of wood. A hole ³⁄₃₂ of an inch in diameter should be bored through the center thus obtained, through which the propeller shaft will be inserted when the propeller is finished. The two sections of the propeller blades drawn in diagrammatical form on the TOP of the block, should be marked respectively BLADE 1 and BLADE 2, as shown in diagram 1. The block is then ready for the commencement of the actual cutting. In cutting out the propeller, BLADE 1 should be held in the left hand and the knife in the other, with the blade of the knife on the straight edge of BLADE 1. The cutting should be carried out very carefully with attention constantly paid to Fig. 2, and should be stopped when the line shown in Fig. 2 has been reached. The semi-blade should then be sandpapered until a small curve is obtained by which the propeller will be enabled to grip the air.

To cut BLADE 2, BLADE 1 should be held in the left hand and BLADE 2 cut until the line shown in Fig. 3 is reached, after which the sandpapering process is carried out in the same manner as in the case of BLADE 1. During all of the foregoing operations it must be clearly borne in mind that the TOP of the blank propeller must always face upward, and the cutting should always be done on the STRAIGHT lines. Should the straight edge be cut on one edge of the blank propeller and the curved edge on the other, it would result in the blades of the finished propeller having a tendency to push in opposite directions and in consequence no propulsion of the model would be possible.

Attention should next be turned to the back of the propeller blank on which the manner of cutting is exactly like that suggested for the top side, with the exception that instead of cutting along the STRAIGHT lines, the cutting is done along the CURVED lines. In this part of the work great care is to be exercised for by the time the necessary cutting has been done on the back of the propeller the entire structure is very fragile and one excessive stroke of the knife may result in destroying the entire propeller blade. By constantly holding the wood to the light it is possible to determine with a reasonable degree of accuracy the evenness of thickness. To complete the BOTTOM side of the propeller the blade should be sandpapered as was the top.

The method of cutting the second propeller is exactly that used in cutting the first propeller, only that the diagram shown in Fig. 4 should be used. This will result in two propellers being made that will revolve in opposite directions in order to produce even and balanced propulsion. If both propellers revolved in the same direction the effect would be to overturn the model.

In diagram 1 the propellers are shown with the straight edge as the entering or cutting edge of the blade. Some of the model builders prefer the curved edge as the cutting edge (diagram 2). It is significant that Mr. Frank Schober, a well known model constructor, tested both designs on his compressed air driven model, and while both propellers were the same in weight, diameter and pitch, the one having the straight edge as the cutting edge was found one-third more efficient.

When the propellers have been given a light coat of shellac they should be laid aside until the assembling of the complete model.

By following the foregoing instructions a simple and effective set of propellers will be produced. But in order to vary the experimental practice of the constructor various other diagrams, Nos. 3 and 4, illustrating suitable designs, are provided and can be made by applying the above general theory and using the diagrams herewith.

WINGS

One of the most important considerations in the construction of a model is the making of the wings. To obtain the greatest efficiency the wings must be carefully designed, with due attention to whether the model is being constructed for speed, duration or climbing ability. Attention should be given to streamline construction; that is, the parts of the wing should be so assembled that the completed wing would offer the least possible resistance to the air, if the best results are to be obtained.

For the main wing three strips of spruce, each 30″ in length, two of them being ³⁄₁₆″ × ¹⁄₄″ and the third ³⁄₁₆″ × ¹⁄₁₆″ are required. To make them thoroughly streamline all edges should be carefully rounded off and all surfaces should be smooth. A strip of bamboo at least 20″ long, ¹⁄₂″ wide, ¹⁄₈″ thick, should be cut into pieces, each piece to be 5 in. long. To secure the necessary curve, ¹⁄₂″ depth, the pieces of bamboo should be held in steam and slowly bent in a manner closely resembling the skids of an ordinary bobsled. When the curvature has been obtained, care should be exercised in cutting each piece into four longitudinal strips, from which twelve should be selected to be used as ribs, each to be ¹⁄₈″ wide. The bending of the bamboo preliminary to making the ribs is done in order to secure uniformity of curvature.

When this has been done the ribs are ready for fastening to the sticks—entering and trailing edges—and each must be attached an equal distance apart. In order that the ribs may be evenly spaced it is necessary to put a mark every 3″ on the larger stick or entering edge of the wing, and also on the flat stick or trailing edge. The main beam which is of the same dimensions as the entering edge is afterwards fastened across the center of the wing, and does not necessarily need to be thus marked, as it is fastened to the ribs after the ribs have been attached to the entering and trailing edges of the wing frame. By holding the ribs one at a time so that the curved edge rests upon the entering edge where the mark indicates, as shown in diagram 5, they should be fastened thereon by means of thread and glue. The rear end of the rib must be fastened to the trailing edge where the mark indicates, also by thread and glue.

After all ribs have been thus securely fastened to both edges of the frame the third stick, or main beam, should be attached to the frame on the underside, the fastening being made at the highest point of the curve of each rib. This main beam prevents the wing covering from drawing in the end ribs and adds very materially to the strength of the entire wing structure. To cover the wings fiber paper may be used and is a suitable material, but the best results, from a standpoint of flying efficiency and long service, are obtained by the use of China silk.

The frame of the forward wing or elevator is made in the same manner as is the main wing, but it is only 12″ in span by 4″ in chord, and is constructed without the use of a main beam. This wing has only five ribs which are made in the same manner as those for the rear wing, and each is placed a distance of 3″ apart.