What About Steam ?

From Scientific American ( September 1933 )

A Steam Driven Airplane

[dropcap cap="T"]wo brothers, William J and George Besler recently installed a reciprocating steam engine in a conventional Travelair biplane, and a number of successful flights have been made at the Oakland, CA airport. The power plant is illustrated in these columns by photographs and a diagram. As the engine was really an old automobile engine, the airplane came out 300 lbs overweight, but it is expected that savings in weight will be readily made later.[/dropcap]

The Besler brothers’ steam engine is a two-cylinder double-acting, compound 90-degree V engine, with a cut off at about 50% of the stroke.

The high pressure cylinder has a bore of 4.25 inches and a stroke of 3 inches. The low pressure cylinder has the same stroke, but a 5 inch bore. The ordinary working pressure is 950 psi, and the temperature of the steam is 750 degrees F. The engine not only drives the propeller but also drives a blower through an over-running clutch. The blower (an electric motor used when starting) supplies air to a Venturi in which the fuel lines terminate. The Venturi leads the mixture to a fire box, where an ignition plug sets the mixture aflame. Once ignition has been started, the process of combustion is continuous.

The steam generator is of a modified flash type. The tubing is continuous in length, about 500 ft in total length; the coils are covered with metallic wool insulation and sheet aluminum. A pop valve is set to give relief at 1500 psi. A thermostatic normalizer device injects water into the superheater whenever the temperature goes over 750 degrees F. From the boiler the steam passes through a throttle to the engine proper, and then to two condensers --- one mounted at the top of the fuselage and one below. From the two radiators or condensers, the steam passes into the water tank, which is provided with a steam dome.    From the water tank, a pump passes the water through a primary heater and then to a secondary heater. By preheating the water, some of the energy of the exhaust steam is put back into the system, ad thus the overall efficiency is improved. After passing through the heaters the water again goes back to the boiler, and the process is repeated over and over again.