Fig. 19.—Twining Hand-launched Biplane
It should be pointed out, in passing, that this machine is the subject of a patent for stability, it being claimed that greater lateral stability is obtainable from the curved lower mainplane. A sketch is also given in [Fig. 17] of a tractor hydro-biplane. This should weigh about 12 ozs. finished. The tandem monoplane shown by [Fig. 18] is another machine which has scored many successes in the early days of model aeroplaning at the Crystal Palace. Figs. [19], [20], [21], [22] show the Twining hand-launched biplane, a tractor biplane built by the writer, a fuselage biplane (canard or screw behind), and a Blériot type tractor monoplane.
A tractor machine is one having the screw in front, and a “canard” or “pusher” machine has its screw behind. It is best to designate the machine by the type formula. Thus, a pusher monoplane with twin screws would be a 1-1-P²-0 type. If it had a tail it would be 1-1-P²-1. A twin-screw “pusher” biplane with or without tail would be 1-2-P²-1 and 1-2-P²-0 respectively. A pusher monoplane with only one screw is a 1-1-P¹ type. A tractor monoplane with single screw is P¹-1-1; a tractor biplane with single screw is P¹-2-1. If a biplane tail is also used it becomes P¹-2-2. If twin screws are used it would then become P²-2-2, and so on.
CHAPTER III
Practical Construction:
Model Aeroplane Fuselages
In no other portion of a model aeroplane has standardisation become more marked than in the design and construction of the fuselage or main frame, both with regard to general details, methods, and materials. This fact is singular, because in other components contributing in a greater degree to the success of the model great diversity of opinion exists. It is difficult to ascribe this lack of uniformity to any particular reason, unless it is the failure on the part of zealous amateurs to appreciate the meaning of the term “efficiency.” Very few, it is thought, endeavour to extract the maximum amount of work for a minimum expenditure of power from the propellers, surfaces, and so forth, and the writer, in judging and tabulating some of the model aeroplane competitions held in different parts of the country, has found models giving excellent spectacular results which, judged on an efficiency basis, such as
| (distance flown × duration of flight) |
| (weight of rubber) |
show a very poor result. The model should be made to fly the longest possible distance, and to remain in the air the longest possible time with the smallest possible amount of elastic.
This chapter is devoted to the various types of fuselage for flying models (as distinct from “scale” models of full-size prototypes) and methods of constructing them, and the list is as representative of best practice as it has been possible for the writer, in his extensive connection with this subject, to make it.
The first shown is the A frame ([Fig. 23]), brought into prominence by Mr. R. F. Mann. It should have birch longitudinals and spruce cross members. Quite the best section wood to employ is that shown at B, which forms a convenient seating for the cross members, the latter being pinned and glued into position. The middle bay of such a frame requires to be braced, to counteract the torque or distortion caused by the elastic skein when the latter is in torsion. Diagram A shows the joint at the juncture of the longerons or longitudinals. The hooks which embrace the elastic skeins are formed from one continuous length of wire following round the nose of the machine. The bearings may be of brass, with a lug to follow round the end of the longeron to which it is bound.