The JVX aircraft was designated V-22 Osprey on 15 January 1985; by that March, the first six prototypes were being produced, and Boeing Vertol was expanded to deal with the project workload. Work has been split evenly between Bell and Boeing. Bell Helicopter manufactures and integrates the wing, nacelles, rotors, drive system, tail surfaces, and aft ramp, as well as integrates the Rolls-Royce engines and performs final assembly. Boeing Helicopters manufactures and integrates the fuselage, cockpit, avionics, and flight controls. The USMC variant of the Osprey received the MV-22 designation and the U. S. Air Force variant received CV-22; this was reversed from normal procedure to prevent Marine Corps Ospreys from having a conflicting designation with aircraft carriers (CV). Full-scale development of the V-22 tilt-rotor aircraft began in 1986. On 3 May 1986, the Bell Boeing partnership was awarded a $1. 714 billion contract for V-22 aircraft by the U. S. Navy. At this point, all four U. S. military services had acquisition plans for V-22 versions.