On page 251 of Snip, Burn, Solder, Shred I make brief mention of flash boilers used in steam-powered airplanes, basically just to poo-poo them as dangerously whack–which, as it turns out, was pretty closed-minded of me. Here’s one in action:
I don’t usually advise clicking through to the pit of vitriol and distraction that is YouTube, but the original poster’s comments are pretty informative. A snippet:
The strangest feature of the flight was its relative silence; spectators on the ground could hear the pilot when he called to them from mid-air.
It goes on with some neat technical details; as it turns out, the flash-boiler design Besler used was arguably an optimal solution at the time for small planes like his. There’s a pretty fascinating contemporary article on Besler’s steam-powered flight in the June 1934 issue of Steam Car Developments and Steam Aviation. Besler’s steam engine was reversible at the flip of a switch, making it possible to slow the plane after landing without risk of doing an endo and flipping the bird. I.e., In a slightly different timeline, steam-powered planes would have been a perfect fit for aircraft carriers.