The Army's first aviator, Thomas Selfridge, died in the crash of a wright biplane in 1908, the first man killed in a powered heavier than air flying machine, and also the first casualty in military aviation.
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Hap Arnold, one of the Army's first aviators almost gave up flying after his first major crash flying a wright machine. He was taught how to fly by the wrights, and eventually they helped ease him back into flying. Dozens of army pilots died in the abortive air mail fiasco of the 30's Dick Bong, america's WWII ace of aces died testing a YP-80 Boeing test pilot Eddie Allen died testing early B-29's and Glen Edwards died flying the YB-49 flying wing.
Military aviation by it's nature is hazardous. Military test aviation even more so.
Osprey is unlikly to replace too many helicopters because of the cost/benefit ratio. It will replace some but since its new technologies allow for new operational capabilities, it will be used in a different role than most helicopters.
MV-22 40.1M unit cost H-60 5.9M unit cost