Can a V22 hover with only one propeller rotating under power? If yes, is the other prop feathered like in an airplane or still rotating sans power? Also, can the Osprey hover if one prop happens to fall off?
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12$\begingroup$ Key parts of this answer (which may make this question a duplicate): "It is possible to drive the two rotors of the V-22 Osprey from a single engine..." and "On aircraft with two distant rotors, it is vital to have both rotating, as if one slows or stops the aircraft is unbalanced to the extent {that} it crashes." $\endgroup$– Ralph J ♦Commented Sep 9 at 18:16
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2 Answers
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The V-22 Osprey has an elaborate gearbox, clutch, and cross-shaft system by which both rotors can be driven from one engine.
Both rotors must always be turning for flight, but there are multiple layers of redundancy to keep that the case.
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6$\begingroup$ @Jpe61 - sure, but that is like saying if one engine fails, and then the other engine fails, its a problem. Two critical failures is hard to overcome. $\endgroup$ Commented Sep 10 at 15:12
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3$\begingroup$ @Jpe61 - yes, and military aircraft don't have the same safety requirements as civilian aircraft. $\endgroup$ Commented Sep 10 at 19:41
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1$\begingroup$ @JonCuster your point being? V-22 Osprey is a military aircraft. $\endgroup$– Jpe61Commented Sep 10 at 20:21
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2$\begingroup$ @Jpe61 - survival of two major failures is not a large consideration for military equipment. Once one engine has failed, the cross-connection is the backup. If the cross-connection fails, well, people die and that is expected for military action. The decision on how-safe-is-safe stopped there at two critical failures. For a civilian aircraft a different decision, such as adding some additional safety factor, might be done. $\endgroup$ Commented Sep 10 at 20:24
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4$\begingroup$ @JonCuster: Indeed, in a civilian aircraft, if adding additional safety systems makes the aircraft slightly heavier and thus less maneuverable, that's considered a tolerable annoyance in exchange for reducing risk. Making a military aircraft less maneuverable increases the risk of failures induced by enemy ordnance, and that increase in risk may exceed any reduction in risk the systems might otherwise have provided. $\endgroup$– supercatCommented Sep 10 at 23:02
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Definitely not. The operating propeller applies huge rolling and yawing moments. In hovering flight there is nothing to counter these except the other propeller.
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$\begingroup$ I thought the Osprey could complete a flight while maintaining forward motion. Taking off and landing while rolling across a runway. There would be rudder and differential braking. I think the question is: would the rudder authority be sufficient for a high speed landing on a long runway? $\endgroup$ Commented Sep 11 at 1:31
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1$\begingroup$ @AnonymousPhysicist The question is about hovering flight. With sufficient airspeed it should be possible to maintain control. $\endgroup$– ChrisCommented Sep 11 at 1:35
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2$\begingroup$ @AnonymousPhysicist The Osprey's rotors are so large that they would strike the ground in the forward flight position if it tried to land. They will sometimes do a rolling takeoff/landing with the nacelles tilted 45deg, but not much lower than that. I do not think the Osprey rudders are sized to maintain controlled flight with one rotor inoperative or missing. They rely on the cross shafting, gearboxes, and clutches. $\endgroup$ Commented Sep 11 at 4:48