Thanks to GAN’s fuel expert Ben Visser for sending this link to a video of the Besler Steam Powered Airplane. Demonstrated by the Besler brothers April 12, 1933, over Oakland California, the plane was powered by a steam boiler that was so quiet that spectators on the ground could hear the pilot calling to them. Developers said 10 gallons of water were sufficient for a flight of 400 miles.
Check it out here.
Playback issue. Can’t get it started.