garymortimer writes: "Phantom Eye’s innovative and environmentally responsible liquid-hydrogen propulsion system will allow the aircraft to stay on station for up to four days while providing persistent monitoring over large areas at a ceiling of up to 65,000 feet, creating only water as a byproduct. The demonstrator, with its 150-foot wingspan, is capable of carrying a 450-pound payload." Link to Original Source
The most difficult thing in the world is to know how to do a thing and to
watch someone else doing it wrong, without commenting.
-- T.H. White