The unpowered X-25 'Discretionary Descent Vehicle' was intended as an escape means that could be stowed in an aircraft, ejected with the pilot and deployed during descent should the aircraft receive battle damage rendering it unflyable. The X-25A gyroglider on display here has a small engine giving limited fly-away ability. However with the air war in Vietnam winding down and doubts about feasibility, the program did not proceed. Behind is the McDonnell XH-20 Little Henry 46-0689, constructed to test the concept of using small ramjets at the tips of the rotor blades between 1947 and 1951

On display in the Research & Development Gallery at NMUSAF. The gyrocopter was an experimental concept to allow flyers downed over Vietnam to use one of these to escape on the ground to a safer area. It was to be stowed in the aircraft and integrated with the aircraft ejection seat. A 90 hp McCullough 4318G four-cylinder horizontally-opposed air-cooled engine powered the X-25A, which would give the pilot limited fly-away capability. First flown on 05 June 1968, it went to the museum in 1969.

A humble X-plane. The USAF acquired one powered X-25A and one unpowered X-25B to research ejection seats in rotor kite form to improve chances of survival. Photo from: Wright State University