THE PETROL MOTOR.

Auckland Star, Volume LXVI, Issue 158, 6 July 1935, Page 3 (Supplement)

THE PETROL MOTOR.

DETAILED SPECIFICATIONS,

As promised in the recent article I am giving you the detailed specifications of the petrol motor for model aeroplanes. The sketch shown is accurate to scale. This will be a little on the technical side for some readers, but I think that there are plenty whe will welcome accurate information of this description.

Specifications, tile numbet of the part mentioned being given in parentheses: — Bare motor weighs Oioz, or complete with gas tank, coil and condenser lljoz. Ready to run with propeller, gas, batteries and developing 1-5 h.p. 20ioz. Bore Sin, stroke lin, revs. 1200 (with special flywheel) or 3000 to 6000 as shown and driving propeller. Crankcase (1) die cast aluminium, Cilicon alloy, main bearings (1A) high speed bronze, with pressure lubrication

through oil well and duct to oil grooves. Cover plate (2), cover plate gasket (2A), cylinder (3), alloy steel witli cooling tins machined from solid bar, manifold and bypass (3B) welded on. Intake manifold (3A) cylinder gasket (3C), piston (4), alloy steel, machined from the solid bar, ground and lapped to a perfect lit on crankshaft and wrist pin. There are no rings in the piston. Wrist pin (4B) is of tool steel tempered and lapped. Full floating in connecting I rod and bearing. Retaining washer (GA) to prevent scoring. Connecting i rod (5) drop forged special alloy steel,

hardened and lapped to perfect fit. Crankshaft (0) drop forged special alloy .steel, heat treated and finished all over, bearing surfaces lapped and ground, shaft milled to receive timer cam and propeller drive flange. Tinier is made of spring steel, tempered with Tungsten points and adjustable gap. Carburettor (7 to 7D) has micrometer adjustment of petrol and choke. Gas tank (9) directly coupled to motor, carries enough mixture of oil and petrol for 18 minutes' running, strained (9D) in bottom. Spark plug (10) to fit fin 24 S.A. Eathread, can be taken apart for cleaning. Ignition coil and condenser special light-weight design. I think you will gain sufficient idea from this that the modern petrol motor for model aeroplanes is not a toy, and there is scope here for the more skilful worker to go ahead and make one of these engines. There are a number under way, I know, and I can't see why some of the Technical boys, with ail their advantages of lathes, etc., should not get to work and produce even better designs.