MODEL AEROPLANE NOTES.

Dominion, Volume 30, Issue 113, 6 February 1937, Page 26

MODEL AEROPLANE NOTES.

BY

'AILERON'

A Petrol-driven Model. As a matter of interest, and to give some idea of what New Zealand modelbuilders arc doing in this field, I give iu these notes the plans and specifications of a recent Wellington petrol-driven model. It is of handy size (6ft. lin. span) and’is sturdily constructed. The wing area is four square feet and the weight tour pounds. , Fuselage: Of box construction. 1-oin. sq. spruce skeleton covered with 3-6-1 ■_>- play on the front portion and 1-l Gin. balsa on the rear portion, behind the sloping dotted lino. The nose section is reinforced witli 3-ply and the whole is covered with silk. The fittings for the attachment of wilig struts and undercarriage legs are bent of 20 gauge steel plate, bolted to the fuselage, having large aluminium washers on the inside. One such fitting is sketched. Engine: 5 c.c capacity, locally built, used inverted, adjustable timer, A.Q. 7 m.m. plug. "Baby Cyclone” coil, float carburettor witli adjustable mixture and throttle control. Propeller from a block 12in. by 2in. by 7-1 Bin. Undercarriage: 3-Jin. wheels, of three thicknesses of 1-1 Bin. 3-ply, brass tube hubs reinforced with washers and nuts on tlie outside. Structure of 12-gauge spring steel wire, all struts being streamlined with spruce, bound to the wire. Spring-

ing by 18-gauge coil springs in compres6'ion. . . Wings: Composite construction, clnrK Y wing section, balsa ribs, leading edge covered with baksa sheet, trailing edge of l-Bin. by fin. spruce, front spar box section, spruce and balsa, rear spar I section, spruce and balsa. Note that the total wing length ie not indicated on the plan. Wing struts' of jin. diameter aluminium tubing, flattened slightly. Wing halves are plug-in to fuselage, and are laced together underneath with soft iron wire. Wing is faired into fuselage. Elevator and rudder are of similar construction to wing, all covered with silk, doped and lacquered. Rudder has a trimming tab and is held Io fuselage by threaded rods passing through to the underside. Bolted to these is the tailskid, of thin strip steel. Details: Elevator adjusted slightly negative, wing slightly positive incidence, balance by sliding battery box on its conducting brass- runners, the diagonal shaded section on top of fuselage removes to allow of access to interior. A clockwork timer, with slowly rotating disc of brass, controls time of flight. An external switch is provided. Model uses slight sideways thrust to counteract torque. The chief problem in the construction of the model was the construction of the undercarriage to ensure that its fittings would uot pull out; 3-32 diameter steel bolts were used throughout, and proved j,1....i t'nr the purpose.