10
$\begingroup$

Conventional helicopters have a tail rotor or equivalent to counteract rotor torque. The pilot's rudder pedals control the force generated by the tail rotor (e.g. by changing its pitch).

But the V-22 Osprey lacks a tail rotor: it has rudders on its twin vertical stabilisers. Rudders wouldn't seem to have any useful effect when in vertical flight, because there's no horizontal airflow for them to deflect. The AW609 appears to lack even a rudder, in the photographs I've seen: the vertical stabiliser appears to be one piece in a fixed shape.

Co-axial helicopters such as the Ka-50 can yaw by varying the torque of one rotor compared to the other, but it seems unlikely to me that the same mechanism would work well when the two rotors are at opposite ends of the wings. The effect of differential torque would be much smaller, and it would have huge secondary effects (such as adverse roll). For that reason I don't think the Osprey can work that way.

So what mechanism controls the yaw on a tiltrotor?

Improve this question
$\endgroup$
2
  • 2
    $\begingroup$ "The effect of differential torque would be much smaller, and it would have huge secondary effects" - You're right about the secondary effects, but the effect of the diffential torque would be the same as if the rotors were coaxial. A torque is a torque, no matter where it is "applied". $\endgroup$
    – pericynthion
    Commented Oct 1, 2016 at 18:40
  • $\begingroup$ How does a Chinook yaw? Same method... $\endgroup$
    – Zeiss Ikon
    Commented Feb 25, 2021 at 15:45

1 Answer 1

Reset to default
18
$\begingroup$

The V22 Osprey yaws by tilting one rotor backwards from the vertical and one forward by moving the swashplate up on one side and down on the other causing a cyclic change to the rotor blade angles of attack. This is accomplished using the pedals in just the same way as a helicopter.

Since the rotors are tilted from the vertical, this introduces a horizontal component to the thrust vector. The rearwards titled rotor produces a horizontal thrust component to the rear and the forwards tilted rotor produces a horizontal thrust component to the front. This produces a turning moment, using the wings as the lever, around the centre of gravity and therefore the aircraft yaws.

The secondary effects will be as expected. Since some of the thrust vector is no longer vertical, a little more power will be required to maintain height and I expect that there will be a pitch change although I'm not familiar enough with the aerodynamics of this type to figure out which way and how big.

Improve this answer
$\endgroup$
2
  • $\begingroup$ Tilting one rotor back while the other one forward makes sense to me, also, you mentioned correctly that this will result in loss of total lift, but tilting the engines has nothing to do with the swash plate, I don`t agree on that one. The swash plates will be used for cyclic and pitchcollective, tilting the entire aircraft back and foth, as well as increasing or decreasing total lift. $\endgroup$
    – John
    Commented Feb 25, 2021 at 15:33
  • $\begingroup$ I have question in here, I asked, how such this Bell V-280 Valor (look similar to V-22 Osprey), how does it make side move when it is being hover? $\endgroup$
    – AirCraft Lover
    Commented Sep 8, 2021 at 7:23

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .