Part 5

The cylinders are secured to the side plates of the crank case so that when those side plates are removed, the cylinders are removed with them. The pipes are detachable at their centers; small pipes running to the heads of the cylinders extending into the larger pipes which run to the valve chamber. This arrangement is shown in the end view of the engine. A 17″ propeller is used in connection with this engine.

GASOLINE ENGINES

THE JOPSON 1 H. P. GASOLINE ENGINE FOR MODEL AËROPLANES

During the past few years several attempts have been made, both in this country and abroad, to produce a reliable gasoline engine for model aëroplane work, but mostly without any degree of success. The reason for this inability, no doubt, is due to the scarcity of small working parts sufficiently light and at the same time reliable. The engine described herewith, designed by Mr. W. G. Jopson, a member of the Manchester Aëro Club, England, is one of the few that have been made to work satisfactorily.

As the accompanying diagrams 19 and 20 and photograph show, the engine is of the four-cycle, horizontal opposed type, having two cast-iron cylinders of 1¹⁄₄″ bore and 1³⁄₈″ stroke. Each cylinder is cast in one piece, and as the engine is air cooled, they are cast with radiating fins. One h.p. is developed at 1500 r.p.m. The total weight of the engine, gasoline tank and propeller is 7¹⁄₂ lbs. In preparing the design of this engine, the designs of similar full-sized aëro engines were followed as far as possible. The pistons are similar to those used on large aëro engines and are fitted with two rings; the crankshaft is turned out of two inch special bar steel, and is carried in two phosphor-bronze bearings. There is no special feature about the connecting rods, these being of the standard type, but very strong and light. To enable the two cylinders to be exactly opposite one another, the connecting-rods are offset in the pistons and are connected to the latter by gudgeonpins. The aluminum crank case is extremely simple, being cylindrical and vertically divided. The inlet valves are automatic, the exhaust valves being mechanically operated; the camshaft is driven from the main shaft by two-to-one gearing.

To assist the exhaust, and also the cooling, small holes are drilled round the cylinder in such a position that when the piston is at the inner end of its stroke, these holes are uncovered, thus permitting the hot exhaust to escape, and so relieve the amount passing through the exhaust valves. The commutator is also driven off the camshaft, as shown in the drawing. No distributor is fitted to the commutator, as small ones are somewhat troublesome and very light coils are obtainable at a reasonable price.

The gasoline tank is made of copper in streamline form, and is usually fitted to the back of the crankcase, thus reducing the head resistance, but if desired it can be fitted in any other position. The action of the carburetor can be easily seen from the drawings; it is of the surface type and much simpler, lighter and quite as efficient as the spray type. Specially light and simple spark plugs are used, that give very little trouble. The propeller used in connection with this engine is somewhat out of the ordinary, having been specially designed for this engine, and patented. The propeller is made entirely of aluminum and has a variable pitch, this being easily obtainable, as the blades are graduated so that any desired pitch, within certain limits, may be given at once. The results of a series of tests on a 30 inch propeller are shown on the accompanying chart, and from it the thrust as certain speeds with a certain pitch can be obtained. Taking the engine running at 1540 r.p.m. with a pitch of 15″, the thrust comes out at 9¹⁄₂ lbs., or more than the weight of the engine and accessories.

THE MIDGET AËRO GASOLINE ENGINE

Although numerous model constructors in America are experimenting with model gasoline engines, the Midget Gasoline Engine, the product of the Aëro Engine Company, Boston, Massachusetts, is perhaps the most satisfactory up to the present time. An engine of this type was used by Mr. P. C. McCutchen of Philadelphia, Pennsylvania, in his 8 foot Voisin Type Biplane Model, for which he claims a number of satisfactory flights.

The engine is made from the best iron, steel, aluminum and bronze and the complete weight including a special carburetor, spark plug and spark coil is 2¹⁄₂ lbs. From the top of the cylinder head to the bottom of the crank case the engine measures 7″. It is possible to obtain from this engine various speeds from 400 to 2700 r.p.m., at which speed it develops ¹⁄₂ h.p. The propeller used in connection with this engine measures 18″ in diameter and has a 13″ pitch.

It might be of interest to know that one of the parties responsible for the development of this engine is Mr. H. W. Aitken, a former model maker and who is now connected with one of the largest aëro engine manufacturing companies in America.

STEAM POWER PLANTS

Aside from the compressed air engine there is the steam driven engine which has been used abroad to considerable degree of success. Owing to the difficulty in constructing and operating a steam driven engine, very few model flyers in America have devoted any attention to the development of this engine as a means of propulsion for model aëroplanes. But irrespective of the limitations of the steam engine a great deal of experimentation has been carried on in England, and without doubt it will soon be experimented with in America.

H. H. GROVES STEAM POWER PLANTS

Perhaps one of the most successful steam power plants to have been designed since the development of the Langley steam driven model, is the Groves type of steam power plant, designed by Mr. H. H. Groves, of England. On one occasion several flights were made with a model driven by a small steam engine of the Groves type weighing 3 lbs. The model proved itself capable of rising from the ground under its own power and when launched it flew a distance of 450 feet. This is not a long flight when compared with the flight made by Prof. Langley’s steam driven model on November 28, 1896, of three-quarters of a mile in 1 minute and 45 seconds, but the size of the models and also that Mr. Groves’ model only made a duration of 30 seconds, must be considered. The model was loaded 12 ounces to the square foot and had a soaring velocity of some 20 m.p.h. The total weight of the power plant was 1¹⁄₂ lbs. Propeller thrust 10 to 12 ounces. The total weight of the model was 48 ounces. The type of steam plant used in connection with this model was of the flash boiler, pressure fed type, with benzoline for fuel.

Mr. Groves has done considerable experimenting with the steam driven type power plant. Many of the designs used in the construction of steam plants for models are taken from his designs. A Groves steam power plant is employed in one of Mr. V. E. Johnson’s (Model Editor of _Flight_) model hydroaëroplanes, the first power-driven, or “mechanically driven” model hydroaëroplane (so far as can be learned) to rise from the surface of the water under its own power. This model has a total weight of 3 lbs. 4 ounces.

G. HARRIS’S STEAM ENGINE

Another advocate of the steam driven type model is Mr. G. Harris, also of England. Several good flights were made by Mr. Harris with his pusher type monoplane equipped with a steam driven engine. As a result of his experiments he concluded that mushroom valves with a lift of ¹⁄₆₄ part of an inch were best, used in connection with the pump, and at least 12 feet of steel tubing should be used for boiler coils. The first power plant constructed by Mr. Harris contained a boiler coil 8 feet long, but after he had replaced this coil with one 12 feet long, irrespective of the fact that the extra length of tube weighed a couple of ounces, the thrust was increased by nearly a half pound.

The principal parts used in Mr. Harris’s steam power plant was an engine of the H. H. Groves type, twin cylinder, ⁷⁄₈″ bore with a piston stroke of ¹⁄₂″. The boiler was made from 12″ of ³⁄₁₆″ × 20″ G. steel tubing, weighing 10.5 ounces. The blow lamp consisted of a steel tube, ⁵⁄₃₂″ × 22″ G. wound round a carbide carrier for a nozzle. The tank was made of brass ⁵⁄₁₀₀₀″ thick. The pump, ⁷⁄₃₂″ bore, stroke variable to ¹⁄₂″, fitted with two non-return valves (mushroom type) and was geared down from the engine 4.5 to 1.

PROFESSOR LANGLEY’S STEAM ENGINE

The Langley steam driven model, of which so much has been said, and which on one occasion flew a distance of one-half mile in 90 seconds, had a total weight of 30 lbs., the engine and generating plant constituting one-quarter of this weight. The weight of the complete plant worked out to 7 lbs. per h.p. The engine developed from 1 to 1¹⁄₂ h.p. A flash type boiler was used, with a steam pressure of from 150 to 200 lbs., the coils having been made of copper. A modified naphtha blow-torch, such as is used by plumbers, was used to eject a blast or flame about 2000 Fahrenheit through the center of this coil. A pump was used for circulation purposes. With the best mechanical assistance that could be obtained at that date, it took Professor Langley one year to construct the model.

FRENCH EXPERIMENTS WITH STEAM POWER PLANTS

About ten months after Langley’s results, some experiments were carried out by the French at Carquenez, near Toulon. The model used for the experiments weighed in total 70 lbs., the engine developing more than 1 h.p. As in the Langley case, twin propellers were used, but instead of being mounted side by side, they were mounted one in front and the other behind. The result of these experiments compared very poorly with Langley’s. A flight of only 462 feet was made, with a duration of a few seconds. The maximum velocity is stated to have been 40 m.p.h. The span of this model was a little more than 6 meters, or about 19 feet, with a surface of more than 8 square meters, or about 80 square feet.

CARBONIC GAS ENGINE

The six-cylinder carbonic gas engine described herewith is the product of Mr. Henry Rompel, Kansas City, Missouri.

This is perhaps one of the most interesting of its kind to have been developed during 1916, and its appearance in the model aëroplane field adds weight to the claim that mechanical engines will soon replace the rubber strand as motive power for model aëroplanes.

Mr. Rompel’s engine is of rotary, carbonic gas type, having six cylinders, a bore of ⁵⁄₈″ and a stroke of ³⁄₄″.

The intake is derived through a rotary valve which also acts as a crank shaft bearing, thereby saving weight.

The exhaust is accomplished by mechanically operated valves situated in the heads of the cylinders being opened by the aid of rocker arms and push rods, which gain their timing from a cam placed on the crankshaft.

To save weight in construction the crankshaft, connecting rods, pistons and cylinders were made of telescopic tubing with a side wall of one thirty-second of an inch or less in thickness.

The engine has a swing of 5¹⁄₂″ over all, weighs a little less than 8 ounces complete, and is operated on 1,500 pounds pressure (carbonic gas) and at a speed of 3,500 to 3,700 r.p.m. will develop about 1 horse power. While spinning a 17″ propeller with a pitch of 20 inches it will deliver a thrust of 21 ounces, and has a duration of 40 seconds. Two hundred and fifty-six pieces were embodied in its construction.

THE FORMATION OF MODEL CLUBS

To form a model aëroplane club at least six interested persons are necessary. As soon as a place in which to hold meetings has been decided upon the club should proceed to elect a director whose duty should be to manage the affairs of the club. One of the first things to be considered is the name under which the club will operate; the custom is usually to adopt the name of the town or city in which the club is located, viz.: Concord Model Aëro Club, Concord, Massachusetts, although it is the privilege of the majority of the members to choose a name such as they might feel will best benefit the purpose for which the club was organized. As in the case of the Aëro Science Club of America, this club was formed for the purpose of stimulating interest in model aëronautics and to help those who might become interested therein, not only in New York City but throughout the entire United States.

When the matter of name and place has been settled the club should decide upon the course it is to follow, first by electing OFFICERS and second by preparing a CONSTITUTION AND BY-LAWS. In the case of clubs whose membership does not comprise more than six members, it does not seem desirable to have more than one officer, namely, a DIRECTOR, who might perform the duties of a president, treasurer and secretary until the club has reached a larger membership. In this way the members are enabled to concentrate upon the construction and flying of models and to engage in such other activities as to carry out the purpose for which the club was organized. However, the foregoing is merely a suggestion on the part of the writer, who by the way is a member of the Aëro Science Club of America and formerly acted in the capacity of secretary to that club.

Clubs whose membership totals more than twelve, however, should proceed to elect a President, Treasurer and Secretary, all of whom must receive a vote of at least two-thirds of the membership. With clubs of this size a director is not needed as the affairs of the club are usually entrusted with the governing officers, the President, Treasurer and Secretary. In as much as the constitution and by-laws are an important factor in the affairs of any model club, the governing officers, before mentioned, should hold a private meeting at the earliest moment whereat to frame a constitution and set of by-laws embodying the purposes and policy of the club. When the proposed constitution and by-laws are completed they should be presented to the members for approval after which a copy should be given to every member.

The following is a specimen of constitution and by-laws that might be used by any person or persons desiring to form a Model Aëro Club:

CONSTITUTION AND BY-LAWS OF A MODEL AËROPLANE CLUB

ARTICLE 1. NAME. The name of this club will be known as The .......... Model Aëro Club.

PURPOSE. The object of this club shall be to study and increase the interest in the science of aëronautics in every way possible and to realize this object, shall construct and fly model aëroplanes, gliders and man carrying machines.

FURTHER, Contests shall be held for model aëroplanes and prizes awarded to the winners thereof. And as a further step in the advancement of this art, meetings, lectures, discussions, debates and exhibitions will be held.

ARTICLE 2. MEMBERSHIP. Any person may become a member of this club provided his application receives the unanimous approval of the majority of members, or is passed upon by the membership committee. A member may resign his membership by written communication to the secretary who shall present it to the membership committee to be passed upon.

ARTICLE 3. OFFICERS. The officers of this organization shall be a President, Vice-president, Secretary and Treasurer and a board of governors to consist of said officers. The president and vice-president shall constitute the executive committee of the board of governors, with full powers to act for them in the affairs of the club. The election of officers shall take place at the first meeting held during the month of .......... of each year and shall hold office for one year. In the event of a vacancy in the office of the President the Vice-president or next highest officer present shall preside. Any other vacancy shall be filled by an officer temporarily appointed by the President. The President shall preside at all meetings of the club and of the board of governors, and shall perform such other duties as usually pertain to that office. The President shall have full authority to appoint committees or boards as may be necessary to further the interests of the club.

The Secretary shall keep a record of all meetings of the club, board of governors and committees and shall use the seal of the club as may be directed by the executive committee. Further, he shall issue notices to officers and members of all special meetings and perform such other duties as may be assigned him by the constitution, by the club or by the board of governors.

The Treasurer shall have charge of the funds of the club, receive all moneys, fees, dues, etc.; pay all bills approved by the board of governors, and preserve all proper vouchers for such disbursements.

RULES FOR CONTESTS

We now come to the matter of contests. As there are many different types of models so must there be rules to correspond to avoid misunderstandings, and until the club has reached the stage where it may decide upon a particular set of rules under which its members should participate perhaps the following set of rules, applicable to contests for hand launched models, can be adopted. In so far as there are different rules for different contests, namely, hand launched, R. O. G. and R. O. W. and mechanical driven, the following rules are used only in connection with contests for hand launched models; rules for other contests follow:

RULES

A contest to be official must have at least five contestants.

Each contestant must abide by the rules of the contest and decision of the judges.

Each contestant must register his name, age, and address before the event.

Each contestant must enter and fly models made by himself only.

Trials to start from a given point indicated by the starter of the trials, and distance to be measured in a straight line from the starting point to where the model first touches the ground, regardless of the curves or circles it may have made. Each contestant must have his models marked with his name and number of his models (1, 2, 3, etc.), and each model will be entitled to three official trials. Contestant has the privilege of changing the planes and propellers as he may see fit, everything to be of his own construction, but only three frames can be used in any contest. If in the opinion of the board of judges there are too many entries to give each one nine flights in the length of time fixed, the judges have the power to change that part of rule No. 6 to the following:

“Six flights or less, as circumstances may require, will be allowed to each contestant, which can be made with one model or any one of three entered; all of his own construction; due notice must be given to each contestant of the change.”

No trial is considered as official unless the model flies over 100 feet from the starting point. (The qualifying distance can be changed by agreement between the club and the starter provided the entrants are notified.) Should the rubber become detached from the model, or the propeller drop off during the trial, the trial is counted as official, provided the model has covered the qualifying distance. No matter what may happen to the model after it has covered the qualifying distance the flight is official. Contests should cover a period of three hours, unless otherwise agreed.

No contestant shall use the model of another contestant, although the former may have made it himself.

The officials should be: a starter, measurer, judge and scorer; also three or four guards to keep starting point and course clear. The first three officials shall, as board of judges, decide all questions and disputes. A space 25 feet square (with stakes and ropes) should be measured off for officials and contestants, together with an assistant for each contestant. All others must be kept out by the guards and a space kept clear (at least 25 feet) in front of the starting point, so a contestant will not be impeded in making his trial.

Each official should wear a badge, ribbon or arm band designating his office, and must be upheld in his duties.

HANDICAPS

At the discretion of the club there may be imposed a handicap for club events as follows: A contestant in order to win must exceed his last record with which he won a prize.

COMBINATION AND DURATION EVENTS

First, second and third records to count. Lowest number of points to win. For example:

A may have 1st in distance and 2nd in duration, 3 total points.

B may have 3rd in distance and 1st in duration, 4 total points.

C may have 2nd in distance and 3rd in duration, 5 total points.

Accordingly A wins.

R. O. G. CONTESTS

(Rising from the Ground)

Models to be set on the ground and allowed to start off without any effort on the part of the contestant. Models should rise from the ground before reaching a predetermined mark, no flight to be considered unless it does so. Contestant may start at any length back from the mark, but the distance is to be measured only from the mark.

MECHANICALLY DRIVEN MODEL CONTESTS

For duration, or distance, contests for mechanically driven models might be held under the same ruling that applies to R. O. G. models. But owing to the many types of engines used in mechanically driven models, definite rules for the holding of such a contest must be left to the discretion of the club or contestants.

EVENTS OPEN TO ALL

These events are open to all, with no handicaps to be imposed on either club members or others.

INTER-CLUB MODEL AËROPLANE TOURNAMENTS

(Prizes to be determined by contesting clubs)

The tournament to consist of five events as follows:

Duration: Models launched from hand.

Distance: Models launched from hand.

Duration: Models launched from ground. R. O. G.

Distance: Models launched from ground. R. O. G.

Duration: Models launched from water. R. O. W.

Dates for inter-club contest should be arranged for at least three weeks prior to date of first contest, to allow ample time for the construction of special models and elimination trials.

In event of inclement weather the contest to take place the week following (each contest following to be set one week ahead), or at any time that may be determined by a committee appointed by the contesting clubs.