Trampoline

A trampoline is a recreational or competitive device designed for users to bounce on. It normally consists of a metal frame (rectangular or circular in shape) supporting a flat jumping surface connected to the frame by springs. The jumping surface may be of a strong synthetic fabric material or, mostly, of a mesh design. Trampolines allow users to bounce higher by storing energy in the springs as they land on the surface which then accelerates the user back away from the jumping surface as the springs contract.
The first modern trampoline was invented by George Nissen in 1920-1922 as a kind of equipment for gymnastics.
During World War II, the United States Navy Flight School developed the use of the trampoline in its training of pilots and navigators, giving them concentrated practice in spatial orientation that had not been possible before. After the war, the development of the space flight program again brought the trampoline into use to help train both American and Soviet astronauts, giving them experience of variable body positions in flight.