The first practical steam powered aircraft was demonstrated by the Besler Brothers on April 12, 1933 over Oakland California. It was powered by a steam boiler that was so quiet that spectators on the ground could hear the pilot calling to them. 10 gallons of water were sufficient for a flight of 400 miles.

 

  The advantages of the “Besler System” that were claimed at the time included the elimination of noise and vibration, greater efficiency at low engine speeds, more power at high altitudes (where lower air temperatures assisted condensation), reduced likelihood of engine failure, reduced maintenance costs, reduced fuel costs (fuel oil was used in place of petrol), reduced fire hazard (oil is less volatile and operating temperatures were lower) and a lack of need for radio shielding.