This is the fuselage, or ‘gondola’, of the rather extraordinary French WW1 Voisin X bomber and gunship.

The Voisin X was a two-seat pusher biplane produced either as a night bomber or a gunship armed with a 37 mm (1½”) Hotchkiss cannon and a defensive 7.7mm machine gun.

As it turned out, the canon was pretty useless as an aerial weapon. So in time, all the gunships were converted to bombers.

This example lives at the Air & Space Museum at Le Bourget, Paris.