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:

enter image description here
A large weight in the back would surely cause it to lean; original image source

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    $\begingroup$ 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, 2016 at 1:46
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    $\begingroup$ Why do you think your question is specific to the Osprey? Any aircraft would behave in the same way. $\endgroup$ Feb 29, 2016 at 4:57
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    $\begingroup$ Most airplanes use the (inverse) lift generated by the tailplane to balance, but this isn't applicable during VTOL. $\endgroup$
    – Dan Hulme
    Feb 29, 2016 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. $\endgroup$ Feb 29, 2016 at 13:05
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    $\begingroup$ 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"? $\endgroup$ Feb 29, 2016 at 23:39

3 Answers 3


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.

  • $\begingroup$ 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. $\endgroup$ Dec 1, 2018 at 13:20

According to various bits of online documentation, the rotors have cyclic pitch control like a helicopter as well as collective pitch control like a helicopter and most high-performance propeller airplanes (often referred to as having a "variable pitch" propeller). The cyclic on the Osprey is controlled with a swashplate that apparently has only front-to-back cyclic control since side-to-side is not needed. To move sideways, the Osprey would simply increase the collective pitch of one rotor while reducing the collective of the other. Here's a passage from one document I found:

Specifically by axis, pitch is controlled through longitudinal cyclic, lateral control is obtained through differential collective combined with lateral cyclic, and height control is via symmetric collective commands.

So it works like a typical helicopter and the lift can be adjusted as needed to deal with a variable center of gravity.


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.

  • $\begingroup$ The weight and balance envelope is a specification and prevents nothing. It is simply a chart on a piece of paper that tells the pilot the acceptable range of center of gravity such that the actual controls of the airplane can keep it flying. The question was about how the actual flight controls work so that there is an envelope and not just a single point for the center of gravity. For instance, the elevators on a conventional airplane control the center of lift to account for a variable center of gravity. What does the V-22 have to accomplish that when it is hovering? That was the question. $\endgroup$ Sep 17, 2021 at 23:28
  • $\begingroup$ No, the weight and balance envelope is a design criteria for range in which the aircraft center of mass must lie within to ensure controllability and stability as designed. $\endgroup$ Sep 18, 2021 at 9:17
  • $\begingroup$ And still, the question was about how the pilot controls the aircraft, and the weight and balance specification, design criteria, or whatever you want to call it, is not something that controls the aircraft in flight. The cyclic pitch control on the prop-rotors controls the lift such that the center of lift is made to align with the center of gravity to keep the aircraft from tipping. I'm sure that we can both present our pilot's licenses as a statement of authority but I'd rather just try to understand the original question which was about how the pilot can control the aircraft in flight. $\endgroup$ Sep 21, 2021 at 3:33

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