"The Osprey took 20 years and $19 Billion to develop. The program has been on serious probation most of its history. It can't autorotate (as a helicopter would) to a safe power off landing, has no defensive guns, lacks the ability to perform quick evasive combat maneuvers under fire and can't descend too quickly or it will go into a dangerous role. The program was nearly cancelled due to several fatal crashes during testing. These were due to a mysterious ""vortex ring state"" problem which some doubt has been fully resolved.  Hopefully they've got (or will get) the bugs worked out."
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