미국이 비밀리에 고고도 스텔스 무인기(UAS)를 개발하고 있고, 자금은 Joint Unmanned Combat Air System (J-UCAS)에서 전용했다고 합니다. J-UCAS는 X-45/X-47를 개발하여 JSF와 같은 통합 무인공격기를 선정하는 계획으로 진행되었는데, 얼마전 X-45C의 롤-아웃 시점에 X-45C 개발이 폐기되었습니다. 따라서 2007년 예산에는 X-47B 예산만 남아있어야 하는데, 공군용의 비밀 계획과 해군용 UCAV(X-47B) 예산이 책정됨으로서 비밀이 공개되었다고 합니다. 새로운 UAV는 U-2가 운용되는 70,000~80,000 FT 고도에서 운용할 수 있다고 믿어지고, 70년대에 개발되었다가 보관되던 General Electric J97-GE-3 engine을 사용했다고 합니다. 보잉의 X-45가 상당히 앞서가는 느낌이었는데 항공모함에서 운용할 수 없다는 이유로 폐기되어 의아했는데, X-45라는 연막뒤에 록히드의 비밀병기가 있었네요. 역시 스컹크웍스 다운 사건을 만들었네요. " http://www.janes.com/defence/air_forces/news/idr/idr060321_1_n.shtml " Budget document discloses existence of secret US Air Force UAV programme Lockheed Martin's Skunk Works is believed to be developing a high-altitude, stealthy unmanned aircraft system (UAS) for the US Air Force (USAF) under a secret programme, funded with money taken from the terminated Joint Unmanned Combat Air System (J-UCAS) project. The existence of a classified air force UAS project was disclosed in a navy Fiscal Year 2007 budget document, which stated that the Pentagon "directed the J-UCAS programme to split into two separate programmes: one air force classified programme and a navy UCAV [unmanned combat aerial vehicle] programme". The new UAV, sometimes known as the Penetrating High Altitude Endurance (PHAE), is believed to be capable of operating at the 70,000-80,000 ft altitudes used by the U-2. One report refers to the aircraft using engines from an inventory that has been in storage since the 1970s. This almost certainly refers to the General Electric J97-GE-3 engine for the Teledyne Ryan AQM-91 Compass Arrow UAV (a project terminated in 1971). In 1998, a NASA paper reported that 24 J97 engines were in storage at the agency's Ames research centre. The Compass Arrow exceeded 80,000 ft during tests, the highest unclassified altitude ever recorded for a subsonic jet-powered aircraft. The J97 was rated at around 25 kN and the new UAV is probably a twin-engine design. The new UAV is much larger than the small stealth UAV that has been evaluated operationally in Iraq. That aircraft - believed to be powered by one or two Williams FJ33 engines - has only eight hours' endurance, like DarkStar, and that is currently seen as inadequate.