As the Vietnam War escalated and the USAF saw more air crews shot down, thoughts turned toward something better than a parachute:
The USAF began to discuss with aircraft manufacturers and designers if there wasn’t a way to package an ultralight aircraft or glider into part of the ejection seat and cockpit that would give shot-down air crew more options on bail out. Proposals were issued to the industry in 1967 and Bensen Aircraft Corporation, a well-known builder of homebuilt autogyro aircraft, submitted an unpowered version of one of their autogyros to be used as an autogyro glider. Bensen’s proposals easily won the USAF over and contracts were issued in 1968 and the program received the X-plane designation of X-25A (a powered version) and X-25B (unpowered glider version). A third version called the DDV (Discretionary Descent Vehicle) was an even lighter and simpler version of the X-25B designed for one time use with automatic blade deployment to become a rotor chute even from a supersonic ejection.
The USAF took delivery of the X-25A and X-25B on 16 February 1968 and immediately embarked on a series of flights to determine the length of a pilot training cycle necessary to master the autogyro controls. [...] All 20 pilots were able to master the X-25B within 30 minutes.
The winding down of the Vietnam War ended interest in the autogyro solution.