The tilt-rotor Bell Boeing V-22 Osprey combines the versatility of a helicopter with the performance of a fixed-wing turboprop aircraft. Having made a vertical or short take-off, the wingtip-mounted nacelles containing the two Rolls-Royce Allison AE1107C turboshaft engines tilt forwards to allow the transition into conventional flight. The maiden flight of the V-22 prototype took place in March 1989. It is now in service in MV-22B form with the US Marine Corps as a cargo and troop transport, and in US Air Force Special Operations Command as the CV-22B for long-range infiltration, exfiltration and re-supply tasks. Three wings fly the CV-22B, the 7th Special Operations Squadron of the 352nd Special Operations Wing at RAF Mildenhall, Suffolk, having received its initial examples - the first to be stationed outside the USA - in June 2013. A total of 49 CV-22Bs are on order for the US Air Force.