Popular Mechanics/Volume 14/Issue 1/How to Build the Famous "Demoiselle" Santos-Dumont Monoplane

by Arthur E. Joerin, A. Cross, A. M.

HOW TO BUILD THE FAMOUS "DEMOISELLE"
SANTOS-DUMONT'S MONOPLANE

By ARTHUR E. JOERIN and A. CROSS, A. M.

(Paris)

(Continued from the June number of Popular Mechanics)

Having finished the steering arrangement it would be wise to take up the construction of the wings. The wings of the "Demoiselle" are made entirely of bamboo rods with bamboo or ash lateral beams as shown in Plate V. However, Clement Bayard, at whose factory in France these monoplanes are being manufactured, makes them of poplar or ash. Aluminum tubes have also been used. It would be advisable, however, to stick to the bamboo rods which served Santos-Dumont so well.

 

Building Santos-Dumont Monoplanes at the Clement Bayard Factory in France

In order to secure the curves as shown at the top of Plate V, on the left, it would be sufficient to bend the rods over a form by force. They may also be bent by means of a string tied to the ends, drawing them together, and then plunging them into boiling water for about 15 minutes. The rods should be given plenty of time to dry before the strings are removed and they are placed in position. They will retain their shape if given time to dry, so no attempt should be made to hasten matters. If the builder desires to use wood he may proceed in like manner. The curve is almost the true arc of a circle.

It is not necessary to bend the rear lateral rod. It suffices to bend the one in front. The whole plane structure is kept rigid by guide wires running from the rods to the frame as shown in Plate I.

In order to attach the cloth to the extremities of the rods, it is not necessary to employ any other method than that shown at C, Plate III. This is the best method known. As with the steering device the front ends of the rods have to be covered by means of cloth hemmed over. This diminishes the friction of the air against the rods. Santos-Dumont has not always used the same method of attaching the cloth, but the method shown here is the one he used on the machine with which he made the famous flight, and is the method which the builder is advised to follow.

In the original flyer there was a rod just above the head of the pilot. It has been thought advisable, however, to leave this rod out. Santos-Dumont is quite short, and when he was in the pilot's seat, his head did not reach the rod. In the machines now being manufactured in France, the rod is omitted. The wings completed, it would be well to next undertake the construction of the frame. The wheels are easily made, for, save that they have a longer hub, they are very similar in construction to the

 

View of the "Demoiselle" Showing Position of Motor and Propeller

ordinary bicycle wheel. In the construction of these wheels it would be well to use strong wire spokes, for at times, when the machine strikes the ground suddenly, great stress is put upon them. Santos-Dumont experimented a long time with the wheels before he finally settled on a hub length of 6 in. This he found was strong enough to support the machine when he used a 35-hp. motor. If a lighter motor is used, the size of the wheel hubs may be modified. These hubs are, as may be seen in the drawings, simply put on over the tubes and fastened by a cotter pin. The tubes should be allowed to extend out several inches beyond the end of the hub. Great care should be taken in the selection of this lower tube, for almost the entire weight of the machine comes upon it. It is not necessary to provide any special bearings for the wheels, as it is intended they should work with a slight friction. It may readily be seen that the wheels are inclined toward one another at the top. The angle of inclination of that part of the tubing, which forms the axle, is 1 to 9. This manner of placing the wheels prevents them from being broken when subjected to a slight jar if the machine takes to the ground unexpectedly.

The connection of the tubing with the framework of bamboo is somewhat difficult, but the details of assembling are always the same in principle, and are shown on Plate VII. The pieces, which are to hold the tubes, are prepared beforehand, and when the tubes are introduced, the whole is firmly bolted. (See Detail of Assembly "A" on Plate VII.) If the builder does not care to prepare these special pieces, the flattened end of the tube may be affixed to a square piece of metal by means of an additional bolt. It is considered better, however, to prepare these special pieces as receptacles for the ends of the tubes.

It would be imprudent and dangerous to make a hole in any of the three main bamboo rods which constitute the frame of the machine, for this would detract from their strength. When we are ready to attach the tubing to the frame, it would be well to follow the method shown on Plate VII. (Detail of Assembly of a Post with the Bamboo.) Out of a piece of sheet metal a joint may be formed so as to make a receptacle for the end of the tube. Provision should be made by a small piece of metal so that the bamboo will be protected if the end of the tube should strike it. Pieces of sheet metal can be wound around the bamboo rod as indicated on the drawing.

Let us now call your attention to the joint at the junction of the lower bamboo rods with the two upright tubes at the inside bearing of each wheel. This fork-like joint should be brazed in the manner of a bicycle frame. It may also be forged or made of a piece of sheet metal forced into shape. There may be some play at the joint, but this does not matter, as the wire stretchers, to be put on afterward, will give the necessary strength, and prevent the pieces from gliding one upon the other.

The machine thus far completed, we may proceed to attach the piano wire stretchers, and then the wires controlling the horizontal and vertical rudders and governing the warping of the planes. The rudder controls may be installed in accordance with the builder's ideas, and the motor controls will vary, of course, with the type of motor used. In the "Demoiselle" the wire regulating the horizontal rudder is attached to a lever within easy reach of the pilot's right hand. The vertical rudder is governed by a wheel at the pilot's left hand. The lever which controls the warping of the planes is placed behind the pilot's seat. Santos-Dumont operated this by bending his body to the right or left, the lever fitting into a tube fastened to his coat in the rear. A side movement pulls the rear end of the wing opposite to the side to which the pilot leans. The balancing of the whole apparatus, is, therefore, in a manner, automatic. The pilot has but to bend over to one side in order to balance the machine. Springs are introduced on the wires which control the rudders of some of the machines so as to bring the rudder back to its normal position without effort on the part of the operator. The seat is a piece of canvas or leather stretched across the two lower bamboo rods just behind the wheels.

 

This View Gives a Good Idea of the Location of the Gasoline Tank and the Radiator

Santos-Dumont had his motor control so arranged that he could regulate the supply of gasoline by his foot. The spark switch may be placed on the steering lever. These controls may be arranged differently, however, with other motors.

It is of prime importance that the motor should be perfectly balanced. It should be direct connected to the axle holding the propeller. The gasoline reservoir is located behind the pilot's seat, the fuel being forced up into a smaller one just above the motor. In his remarkable flight from St. Cyr to Buc, the inventor of the monoplane used a two-cylinder Darraeq motor of 20 hp., which gave the propeller 1000 r.p.m. It weighed a little over 99 Ib. The entire machine weighed 260 Ib. without the pilot. At the end of the crankshaft, opposite the propeller, is a pinion and eccentric working the oil pumps. This pinion also meshes with the gear which operates the water pumps. The cams which raise the valves at the same time operate the magneto. The radiator, which is composed of a great many small copper tubes connected up to a larger tube at the front and rear, is placed under the main surface of the wings and extends from the front to the rear of the planes.

 

How Santos-Dumont Conveyed His Aeroplane to the Aviation Field

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