Let's say an Osprey appears to be flying normally in forward flight. In preparation for landing, the pilot tries to command the engines to begin tilting to vertical, but nothing happens. What now?

If there's a manual way to crank the engines up, that's not working either.

  • $\begingroup$ I'm not an Osprey pilot, but I'm guessing the procedure is something like "land normally" (i.e. not vertically.) $\endgroup$ – reirab Oct 21 '15 at 21:06
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    $\begingroup$ @reirab Wouldn't the props hit the ground? $\endgroup$ – ryan1618 Oct 21 '15 at 21:10
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    $\begingroup$ I suspect "fasten your seatbelts" would feature strongly in the emergency landing procedure. $\endgroup$ – Greg Hewgill Oct 21 '15 at 21:14
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    $\begingroup$ @RyanBurnette Ah, looks like you're right. I didn't realize the blades were long enough to touch the ground, even with the prop mounted so high, but it looks like they are. This might be useful information to add to the question. $\endgroup$ – reirab Oct 21 '15 at 21:27
  • $\begingroup$ @reirab That was the purpose of the question. When an Osprey is in forward flight, the propeller disk's lowest point is significantly lower than the extended landing gear. That's why I was wondering what the procedure is if the Osprey can't get it up. I apologize for not being more specific about the V-22's design. $\endgroup$ – Howard Miller Oct 21 '15 at 21:58

The Bell Helicopter V-22 Guidebook covers survivability in Appendix 1.

Specifically it refers to

Redundant Fly-by-Wire Controls

Redundant Electrical Power

Redundant Hydraulics Swashplate

Actuator Armor

implying that this possibility has been engineered to a minimum.

Nevertheless, the premise of your question is that it's occurred, so further on in the same section we see

V-22 crashworthiness is a function of design. Heavy components, such as the engines and transmissions, are located away from the cabin and cockpit area. The proprotors are designed to fray or “broomstraw” rather than splinter on impact with the ground. The energy-absorbing landing gear system is designed to attenuate most of the energy for hard landings up to 24 fps. The wing is constructed to fail outboard of the wing/fuselage attachment in a manner that absorbs kinetic energy and ensures the cabin area will not be crushed, thereby protecting the occupants. An anti-plow bulkhead prevents the nose from digging in on impact, and the fuselage provides a reinforced shell that is designed to maintain 85% of its volume during a crash. Aircrew and embarked troops receive additional protection from crashworthy seats that stroke vertically to absorb energy

(my emphasis)

Since the aircraft is still flying, I'd head for the nearest decently equipped airfield, conduct a normal fixed wing approach and land, trusting that the rotors will sweep a nice clean path along the runway instead of peppering the fuselage with shrapnel. I'd probably take the precaution of cutting power early to reduce the kinetic energy in the rotors before they hit the ground.

  • $\begingroup$ I appreciate the information about crashworthiness of the Osprey. I'd like to ask if your description of making represents the response of an actual Osprey pilot? $\endgroup$ – Howard Miller Oct 21 '15 at 22:15
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    $\begingroup$ Yeah, I think you'd definitely want to kill the power either before or immediately after touchdown and hold the nose high as long as possible. I suppose you could also adjust prop pitch to try to slow the props as much as possible, but you'd want to be careful to do this evenly and not create any weird yawing moments. $\endgroup$ – reirab Oct 22 '15 at 5:30
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    $\begingroup$ The USAF experimented with tail-sitting VTOL aircraft in the Fifties (Convair XFY-1), but found them challenging to land. Attempting it in an aircraft not designed for it would be even more difficult. As a passenger I'd not be enthusiastic about climbing down the now vertical cargo hold only to have to fall the last twenty or thirty feet. $\endgroup$ – user11933 Oct 24 '15 at 3:35
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    $\begingroup$ @DanielGriscom A possible answer to why the 'proprotots' rotate the way they do is so that when in vertical mode, the outer blade will be advancing. As the rotors spin, for part of their cycle, a given blade is moving forward faster than the V-22 is moving, while another blade will be retreating, and moving slower than the aircraft. The retreating blade doesn't have as much lift as the advancing blade, and is passing over the wing where there will be more turbulent airflow. The advancing blade acts like an extension of the wing, generates more lift, and is moving through less turbulent air. $\endgroup$ – Howard Miller Oct 28 '15 at 7:32
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    $\begingroup$ This answers another question I was going to post... Given that they are used both vertically and horizontally, does the Osprey have propellers or rotors? Apparently they just smashed then together into "proprotors". 😎 $\endgroup$ – eidylon Jun 23 '16 at 2:32

A fixed nacelle landing is an emergency procedure practised routinely in a flight simulator, however actually getting this condition is very rare to date. In short, we reduce gross weight if able, calculate a touchdown speed, fly a shallow approach, and shut down engines after touchdown on rollout.

As for "hanging on the proprotors" in airplane mode, theoretically possible at low gross weights but highly unstable. Besides violating operating limits, the swash plates are locked out in airplane mode giving you no control, not to mention the a few other systems that rely on gravity to pull down instead of back.

  • $\begingroup$ Welcome to Aviation.se! Thanks for adding more information about these procedures. $\endgroup$ – fooot Feb 24 '17 at 4:44
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    $\begingroup$ @Creighton you answered another question I came up with later. Namely do the rotors have a collective when in hover mode. This makes it a true helicopter in that mode. I guess another question is whether the Osprey can go into autorotation. $\endgroup$ – Howard Miller Mar 3 '17 at 1:24
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    $\begingroup$ I've seen videos of more conventional aircraft landing with a dead engine, and unable to extend the landing gear. These are two bladed engines. Just before touchdown, the pilot tries to 'bump' the prop to a more horizontal position with the engine's starter motor. $\endgroup$ – Howard Miller Dec 14 '17 at 20:59

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