Model Aeroplanes and Their Engines: A Practical Book for Beginners

by George Anthony Cavanagh

LAUNCHING

In the preliminary trials of a model close attention must be paid to the few structural adjustments that will be found to be necessary and which if not properly and quickly remedied will result in the prevention of good flights or even in possible wrecking of the model. Careful designing and construction are necessary but it is equally as important that the model should be properly handled when it is complete and ready for flying.

Charles W. Meyers and William Hodgins exhibiting models of early design.

Henry Criscouli and his five foot model. This model may be disassembled and packed conveniently in small package.

Harry G. Schultz hydroaëroplane.

The approximate idea of the balance of a model can be secured by launching it gently into the air. If the model dives down point first it indicates that the main wing should be moved a little toward the front. If it rises abruptly the main wing should be moved slightly toward the rear. In this way by moving the wing forward or rearward until the model glides away gracefully and lands flat upon the ground, proper adjustment of the balance can be effected. If when launching from the hand the model should curve to the left the main wing should be moved slightly to the left of the frame members. And if the curve is to the right the main wing should be moved in that direction. This process can be continued until the model flies in the course desired.

The winding of the rubber strands to get the necessary propelling power is an important detail. The model should be firmly held by some one at the rear with the thumb on either side member, pressing down on the jointure and with the four fingers of each hand gripping the under side of the frame members, and in this way holding the model steady and until the rubber strands have been sufficiently wound. With the hands in this position the propellers, of course, cannot and should not revolve. The hooks attached to the rubber strands at the point or front of the model should be detached from the side members and affixed to the hooks of the winder. A winder may be made from an ordinary egg beater as is shown in [diagram 8]. When the hooks attached to the rubber strands at the point of the model have been affixed to the winder the rubbers should be stretched four times their ordinary length (good rubber being capable of being stretched seven times its length) and the winding commenced, the person winding slowly moving in towards the model as the strands are wound. If the ratio of the winder is 5 to 1, that is if the rubber is twisted five times to every revolution of the main wheel of the winder, 100 turns of the winder will be sufficient for the first trial. This propelling power can be increased as the trials proceed. When the winding has been accomplished the rubber hooks should be detached from the winder hooks and attached to the hooks at the front of the side members as shown in the [diagram].

Diagram 8

In preparation for launching, the model should be held above the head, one hand holding it at the center of the frame, the other in the center of the propeller brace in such a way as to prevent the propellers from revolving. When the model is cast into the air if it is properly adjusted it will fly straight ahead.

A precaution which is sometimes worthy of attention before the launching of the model under its full power is to test out the propellers to find out whether or not they are properly mounted and whether they revolve evenly and easily. To do this the rubber strands may be given a few turns, enough to revolve the propellers for a brief period, while the machine is held stationary. If the shafts have been properly inserted in the hubs of the propellers and have not been bent during the winding of the rubbers, the propellers will revolve evenly and readily. If the propellers revolve unsteadily it indicates that there is a bend in the propeller shafts or the propellers have not been properly balanced. If the trouble is a bend in the shaft, it must be removed before the model is launched on actual flight. If the propeller does not revolve freely the application of some lubrication (such as vaseline) to the shaft will eliminate this trouble. With these adjustments made satisfactorily, the model can be launched with the anticipation of good flying.