PPRuNe Forums - View Single Post - V-22 can't autorotate. Say what?
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Old 6th Oct 2007, 03:07
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US Herk
 
Join Date: Feb 2005
Location: NW FL
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You need sinkrates in excess of 1600-1800fpm to enter VRS in V-22. Most aproaches end up with no more than 400fpm sink/flare. At roughly 1000fpm, bitching betty comes on & yells, "sink rate" - should you choose to ignore it, & find yourself entering VRS, a 3-second application of Forward Nacelle & add power to fly out of it results in virtually no altitude loss.

One of the early V-22 crashes resulted because the test pilot kept resetting his master reset & eventually bled all his hydraulics away. The computer analyzes & contains hydraulic leaks through a protocal, but when master reset is iniated, it assumes all is well & must run through the protocal again.
Many of the small problems that are supposed to crop up during DT&E and OT&E have done - the overwhelming majority of them have been fixed.

My understanding of the autorotate deal was compromise. Original design for rotors was actually much larger diameter & sufficient energy was stored in them. In order to accomodate shipborne ops & folding blades, the size was reduced to the point autorotation was ineffective.

Current single engine safe speed is roughly 40-50kts, so you're going to "roll on" (shattering your rotors when you do) with 25-30+ knots of forward airspeed. That's emminently survivable on a hard surface - not so much on an unprepared surface - particularly with a top-heavy beast like the Osprey (probably a lot of tumbling).

Single engine failure in most helos results in arriving at the scene of landing - it merely cushions the autorotation. The same is true of the Osprey. Dual engine failure requires that forward airspeed mentioned in paragraph above.

The Osprey is not, nor was it ever, a helo replacement. It is a different animal entirely. Many USAF brass view it as a Pave Low replacement - it isn't. But those are political problems, not aircraft problems...
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