THE SCHOBER-FUNK COMPRESSED AIR ENGINE
Two of the most enthusiastic advocates of the compressed air engine for use in model aëroplanes are Messrs. Frank Schober and Rudolph Funk, both members of the Aëro Science Club. For a number of months both these gentlemen have experimented with compressed air engines of various designs, until they finally produced what is perhaps one of the most satisfactory rotary engines now in use, from a standpoint of simplicity and results.
Schober-Funk three cylinder rotary engine
As can be seen from the accompanying [illustration], this little engine is remarkably simple in appearance. The engine complete, with equipment, weighs at the most but 14 ounces. The cylinders, three in all, are stamped from brass shells for strength and lightness. The pistons are made from ebony fiber. The cylinders have a bore of ⁵⁄₈″, with a piston stroke of ¹⁄₂″. The crank case is built up from a small piece of brass tubing and is drilled out for lightness. The crankshaft is hollow, and is supported at the rear by a special bearing which acts as a rotary valve, admitting the intake through the crankshaft and permitting the exhaust to escape through a specially constructed bearing.
The tank is constructed of 30 gauge sheet bronze, wire wound, and fitted at the ends with spun brass caps. The actual weight of the engine alone is 2¹⁄₂ ounces, the tank and fittings weighing 11¹⁄₂ ounces, making the total weight of the complete power plant 14 ounces.