ability to operate either from grass or damaged runways), as well as being reliable and easy to maintain. The resulting design was of a conventional twin-engine monoplane, featuring a high-mounted wing complete with all-swept flight surfaces. According to Fredriksen, the design emphasised simplicity as well as modernity. Due to political sensitivities and a strong desire to avoid one nation upstaging the other, the aircraft featured two separate names; in Romania, it was known as the IAR-93 Vultur while in Yugoslavia it was referred to as the J-22 Orao. The design team had originally planned to develop a single-engined aircraft capable of supersonic speeds, but the United Kingdom would not authorize the license to produce the British engine that the designers had selected; the rejection was reportedly due to Romania being a member of the Soviet-aligned Warsaw Pact. In its place, the less-powerful Rolls-Royce Viper was chosen as the powerplant, as Soko already possessed experience with license-building this engine. It was originally intended that an afterburner would be developed for the Viper engine, but there were prolonged difficulties with this project. Due to these complications, none of the pre-production aircraft or any early production examples would be equipped with afterburners; these would be largely restricted to conducting reconnaissance missions. During the 1980s, both countries developed slightly different versions of the aircraft to take advantage of the afterburning engines that had since become available. Into flight During 31 October 1974, the Yugoslav prototype 25002 conducted its first flight from Batajnica Air Base near Belgrade, with Major Vladislav Slavujević at the controls. For political reasons, this flight was timed to deliberately coincide with the first flight of the IAR-93 Vultur prototype. The third aircraft, numbered 25003, which was a pre-production two-seater version, performed its first flight on 4 July 1977. This aircraft was lost almost a year later, the cause of the accident was attributed to the occurrence of tail flutter. Construction of further pre-production aircraft was unimpacted by the loss; during 1978, the first batches of pre-production machines were delivered to the Air Force Aircraft Testing Facility in Belgrade. Subsequent serial production was established at a facility outside Mostar, (now in Bosnia and Herzegovina); this facility would be abandoned in 1992 and heavily damaged during the Yugoslav Wars. Production would never be resumed either in Yugoslavia or in its successor states. During October 1983, the first afterburner-equipped J-22 Orao was flown in