4
$\begingroup$

How do aircraft like the V-22 not tilt under an unbalanced load? if they are only supported by 2 forces on either side a large weight in the back should cause it to lean backward when stationary, should it not? its hard to put this into an image but here goes nothing:

-insert poor illustration here-

$\endgroup$
  • 12
    $\begingroup$ Weight and Balance is a consideration for all aircraft, not just the Osprey. If the weight is distributed out-of-bounds, this would be a problem. So, they distribute the load appropriately. $\endgroup$ – abelenky Feb 29 '16 at 1:46
  • $\begingroup$ Why do you think your question is specific to the Osprey? Any aircraft would behave in the same way. $\endgroup$ – David Richerby Feb 29 '16 at 4:57
  • 1
    $\begingroup$ Most airplanes use the (inverse) lift generated by the tailplane to balance, but this isn't applicable during VTOL. $\endgroup$ – Dan Hulme Feb 29 '16 at 13:03
  • $\begingroup$ It happens that there is something known as a Centre of Gravity which also serves as the centre of rotation and that is located in line with the wings. $\endgroup$ – SMS von der Tann Feb 29 '16 at 13:05
  • 4
    $\begingroup$ Is it possible the question that was meant to be asked is "how is pitch controlled for a tilt rotor aircraft in hovering and slow flight"? $\endgroup$ – Cpt Reynolds Feb 29 '16 at 23:39
9
$\begingroup$

If you think about it, your question applies in exactly the same way to a conventional helicopter. You might expect that it would pitch nose-down if the weight is forward, and nose-up if the weight is aft. In fact, it's even worse for a conventional helicopter, because with only one rotor it would roll (tilt left-right) as well as pitch.

The answer is the same for the Osprey as for a conventional helicopter: the pitch is controlled by cyclic control of the rotor. As the rotor spins, a mechanism inside it changes the angle of attack of the blade (the pitch of the blade) as it rotates. This change can cause it to generate more lift when it's at the rear than at the front (or vice-versa, or left-to-right). This creates a turning moment about the centre of the rotor disk, which counteracts the moment of the unbalanced weight.

You only get so much of a moment with it, though. The aircraft needs that moment in order to change its pitch to manoeuvre. If you had to use the full range of blade pitch (the maximum cyclic control) just to counteract the unbalanced weight, you wouldn't be able to pitch the aircraft any further in that direction. For this reason, the maximum moment of rotorcraft (how far the centre of mass can be away from the centre of lift) is typically smaller than for airplanes.

$\endgroup$
  • $\begingroup$ Elevator on aircraft has same issue when aircraft slows down! The olde Chinook twin rotor (front and back) helicopter can add or subtract power to compensate for a wide range of cargo CG points, but the V-22 Osprey is much faster. $\endgroup$ – Robert DiGiovanni Dec 1 '18 at 13:20
0
$\begingroup$

I suppose it could, if improperly loaded. But V-22s, like any other aircraft, have weight and balance envelopes to prevent this from happening. And any competent loadmaster and flight crew would load the aircraft accordingly and double check it prior to flight.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.