The MartinX-23APRIME (Precision Reentry Including Maneuvering reEntry) (SV-5D) is a small lifting-body re-entry vehicle tested by the United States Air
to provision for future addition in 1989. Formally designated as the YF-23A, the first aircraft (serial number 87-0800), Prototype Air Vehicle 1 (PAV-1)
fitted. The two aircraft, which replaced two 727-100QCs, have carried the Prime Minister of New Zealand, and flown to the ice-covered Pegasus Field near
his own aircraft. The Mk.VII and late Mk.X Lancasters used the heavier, electrically controlled Martin 250 CE 23A turret equipped with two .50 in (13 mm)