G. HARRIS’S STEAM ENGINE
Another advocate of the steam driven type model is Mr. G. Harris, also of England. Several good flights were made by Mr. Harris with his pusher type monoplane equipped with a steam driven engine. As a result of his experiments he concluded that mushroom valves with a lift of ¹⁄₆₄ part of an inch were best, used in connection with the pump, and at least 12 feet of steel tubing should be used for boiler coils. The first power plant constructed by Mr. Harris contained a boiler coil 8 feet long, but after he had replaced this coil with one 12 feet long, irrespective of the fact that the extra length of tube weighed a couple of ounces, the thrust was increased by nearly a half pound.
An English steam power plant for model aëroplanes. Courtesy Flight.
Model hydroaëroplane owned by V. E. Johnson, Model Editor of Flight, England, equipped with an H. H. Groves steam power plant. This model is the first power driven—as far as can be learned—to rise from the surface of the water under its own power. Courtesy Flight.
The principal parts used in Mr. Harris’s steam power plant was an engine of the H. H. Groves type, twin cylinder, ⁷⁄₈″ bore with a piston stroke of ¹⁄₂″. The boiler was made from 12″ of ³⁄₁₆″ × 20″ G. steel tubing, weighing 10.5 ounces. The blow lamp consisted of a steel tube, ⁵⁄₃₂″ × 22″ G. wound round a carbide carrier for a nozzle. The tank was made of brass ⁵⁄₁₀₀₀″ thick. The pump, ⁷⁄₃₂″ bore, stroke variable to ¹⁄₂″, fitted with two non-return valves (mushroom type) and was geared down from the engine 4.5 to 1.