LONDON - The maiden flight of a revolutionary US-made drone aircraft that can stay in the air for up to four days at 65,000 feet, prying at terror safe havens in countries like Pakistan, is just days away. The 'Phantom Eye', made by Boeing's secretive Phantom Works division, is a high-altitude long endurance unmanned airborne system which is powered by hydrogen. The inaugural flight of the new drone will take place at Edwards Air Force Base in California and is expected to last between four and eight hours, the Daily Mail reported Monday. 'Phantom Eye is the first of its kind and could open up a whole new market in collecting data and communications,' Darryl Davis, president of Boeing Phantom Works, said. The unmanned aircraft will produce only water as a by-product. "It is a perfect example of turning an idea into a reality. It defines our rapid prototyping efforts and will demonstrate the art-of-the-possible when it comes to persistent intelligence, surveillance and reconnaissance," the paper quoted Boeing officials as saying. The Phantom Eye had completed 12 days of ground vibration and structural mode interaction tests in June this year at NASA's Dryden Flight Research Centre at Edwards Air Force Base, California. "It's exciting to be part of such a unique aircraft," said Drew Mallow, Phantom Eye programme manager for Boeing. "The hydrogen propulsion system will be the key to Phantom Eye's success. It is very efficient and offers great fuel economy, and its only byproduct is water, so it's also a "green" aircraft," Mallow said. Phantom Eye is powered by two 2.3-litre, four-cylinder engines that provide 150 horsepower each. It has a 150-foot wingspan, will cruise at approximately 150 knots and can carry up to a 450-pound payload. Boeing is also developing a larger unmanned plane that will stay aloft for more than 10 days and 'Phantom Ray,' a fighter-sized Unmanned Aerial Vehicle that will be a test bed for more advanced technologies, which made its inaugural flight in April, the report said. The US regularly uses two types of unmanned armed drones, the Predator and Reaper, to attack militant hideouts in Pakistan and Afghanistan.