 "Pete" Knight reached in the modified X-15A-2 on 3 October 1967, a speed that remains the highest ever attained in an airplane.In addition to the X-15 Program, AFFTC and NASA also teamed up to explore a new concept called "lifting reentry" with a series of wingless lifting body aircraft.These rocket powered-vehicles – the M2-F2, M2-F3, HL-10, X-24A and X-24B – paved the way for the Space Shuttle and future spaceplane designs when they demonstrated that they could make precision landings after high-speed gliding descents from high altitude.