A.Andrews. The Flying Machine: Its Evolution through the Ages (Putnam)

The references to gunpowder already made may be expanded. In 1870 Gustave Trouve actually made a model ornithopter fly for 60m, after a mid-air launch, by the action of 12 blank cartridges automatically fired into a Bourdon tube [a coiled metallic tube which tends to straighten out when pressure is exerted within it, and to spring back into coil afterwards]. The straightening of the tube flapped down the wings and the relaxation of the tube at the end of the explosion brought the wings up, while the next cartridge slipped into place for another shot.