MODEL AVIATION

New Zealand Herald, Volume LXXI, Issue 21758, 24 March 1934, Page 4 (Supplement)

MODEL AVIATION

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Notes on General Construction

No. .VII

The model 1 am giving you next week is a single puuher spar model capable of a, good performance. Although this model is quite simplo to build, it requires careful construction and embodies several fittings that are new to the beginner. . Such fittings as thrust bearings, propeller shafts, cans, wing clips, and rubber " S " hooks are practically standard on nil flying models and are described here so that you will have no delays in construction next week. Illustration A shows i?he end of the motor-stick with the thrust bearing 1 lashed in position; also the propeller shaft with washers, or " collets," in place and rubber attached. Note how the shaft is bent back and pushed into the boss to grip the propeller firmly. Aluminium is the best material for thrust bearings. Besides being light it is easy to bend and pierce. 1 Illustration 15 shows how to attach a bamboo nose skid and wire hook for the motor. Apply a little balsa cement and bind in place with strong thread, i

work with the, pliers but has tho advantage of being strong and supple. Various gauges are used for model avil ation, ranging from 18 to 27 s.w.g. and any gauge can be secured from your local dealer. You will probably find he also stocks such standard fittings as rubber " S hooks, propeller spindles, collets, etc. Tho wings, stabiliser, and rudder on the single pusher are covered on one side only. When each surface is completed and wing clips attached, cut the tissue to shape, allowing at least a iin. overlap all round. Brush the centre rib, spa?B and wing-tips with banana oil, doing one side at a time. Fiiice the tissue m place on the centre rib, pull slightly endwise and press into place with the fingers, outward ail tho time. The banana oil hardens quickly and is best applied with a nit.;), :;:m?!rr to those used in gasket cement HrM'es-. Any brush will do but it must bo immersed in the bottle when not in use. The bamboo strips i:setl for wing ribs arid wing tips are bent to the necessary

Illustration 0 is a standard form of wire " can." These cans are forced into the balsa motor stick between, the propeller and the hook and cemented. They act as a guide for the rubber and prevent the motor-stick from warping when the motor is fully wound. The wing clips shown in D and E are used in practially all spar models to clip the wing and stabiliser to the motor-stick. Their use enables prompt assembly on the flying ground and easy adjustment for securing balance, Be careful to make the wing clips just wide enough to firmly grip the motor-stick. The points of the. arms are turned up slightly to pierce the balsa when attaching to the leading and trailing edges. Make sure they are dead centre and lying true before binding- with thread and cement. By varying the length of the wing clip arms any desired angle of incidence can be obtained. All these wire fittings can be made from 21 s.w.g. spring steel wire. This wire is stiff to.

shape by heating over a candle flame. To bend the ribs uniformly,, cut to length and heat them all together. The following materials are required for your next model:— Motor-Stick 3-16 in. x Jin. x 20in. balsa. Leading Edge & Trailing Edge Jin. x iin. x 10Jin. balsa. Stabiliser l-16in x l-16in. x 12in. balsa. Ribs l-32in. x l-16in. x 30in. bamboo. Wing Tips l-32in. x l-16in. x 24in. bamboo. Rudder 132 in. x l-16in. x llin. bamboo. Steel Wire, about 3ft. 21 s.w.g. Japanese Tissue. Rubber.' Balsa cement. . J' ■' Banana Oil. Two Collets. Thrust Bearing. The carving of the Sin. propeller was described last week. Now you know all the fittings and will be ready for a prompt start on your first spar model next Saturday.