The Besler Steam Plane

On 12 April 1933 a Travel Air 2000 biplane made the world's first piloted flight under steam power over Oakland, California, powered by a two-cylinder V-twin steam engine developing 150 hp.

The aircraft, piloted by William Besler, raced down the runway and climbed into the air without a sound except the low whine of the propeller and the hum of wind through the rigging wires. The aircraft took off, landed, and circled three times, remaining aloft for 5 minutes at a time. Each time, as the machine descended to land and the wheels touched the runway, the pilot pulled back a small lever at the side of the cockpit and the steam engine instantly reversed, reducing the landing run to a minimum. The Beslers were quoted as saying that the aircraft, landing at 50 miles an hour, could come to a stop in a field only 100 feet square. The strangest feature of the flight was said to be the relative silence of the power plant; spectators on the ground could hear the pilot when he called to them from mid-air.

The aircraft's steam engine weighed 180 pounds, using steam generated by a barrel-shaped boiler behind the engine. Using vaporized fuel oil, the burner released as much as 3 million BTU per cubic foot of firebox space, an electric blower driving the heat down among the flat spirals of a single 500-foot pipe coiled within the boiler. Under the aircraft's nose was the condenser which looked like an ordinary car radiator, and which was said to recover more than 90 percent of the water from the used steam. Tests had shown that 10 gallons of water was enough for a 400 mile flight.

At the start of a flight, the pilot operated a small switch which activated the electric blower, to drive a mixture of air and fuel spray through the burner. An electric spark ignited the mixture, and a few minutes later steam pressure was high enough to take off. All the pilot had to do from then on was to operate the throttle and reverse lever.

The design had been assisted by former Doble Steam Motors engineer Nathan C. Price, who was working on high pressure compact engines for rail and road transport; the purpose of the flight was to obtain publicity for this work. Following its favourable reception Price went to Boeing and worked on various aviation projects, but Boeing dropped the idea of a steam aircraft engine in 1936. Price later went on to work for Lockheed, where his experience developing compact burners helped in the design of Lockheed's first jet engine.

The advantages of the "Besler System" listed at the time included the elimination of audible noise and destructive vibration; greater efficiency at low engine speeds and also at high altitudes where lower air temperatures assisted condensation; reduced likelihood of engine failure; reduced maintenance costs; reduced fuel costs (since kerosene was used instead of petrol); reduced fire hazard since the fuel was less volatile and operating temperatures were lower; and a lack of need for radio shielding.

However, the steam reciprocating engine turned out to be unsuitable for scaling up to the needs of large aircraft, as above 1000 hp a turbine captures the energy of the steam more efficiently than a piston.