the santos-dumont demoiselle ("damselfly") was an early aircraft built in france by brazilian aviation pioneer alberto santos-dumont. it was a light-weight monoplane with a wire-braced wing mounted atop an open-framework fuselage built around a reinforced bamboo boom. the pilot's seat was below the wing, and between the main wheels of the undercarriage. the rear end of the boom carried a tailwheel and a conventional empennage. as originally designed (as the santos-dumont no. 19) santos-dumont used a liquid-cooled dutheil & chalmers flat-twin engine rated at 15 kw (20 hp)