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Helicopter torque

Asked by: 2909 views ,
Aerodynamics, Helicopter

In terms of a hover auto why do we need to apply right pedal when rolling off throttle? I understand torque effect but if we remove it by rolling off throttle why would we begin to spin in the direction of the rotor? What force is this demonstrating? Thanks from r the insight

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3 Answers

  1. Best Answer


    Kris Kortokrax on Apr 24, 2017

    There is a balance between the torque and the thrust produced by the tail rotor. When you close the throttle to initiate the hovering auto, you reduce the torque. This leaves too much tail rotor thrust, which causes the helicopter to rotate in the direction of the main rotor rotation. I’m sure you have noticed that you don’t apply full right pedal, otherwise you would begin to rotate to the right instead of the left.

    It’s all a balancing act. Also, note that the pedal application will be reversed if the main rotor rotates the opposite direction, such as Astar.

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  2. wes eads on Apr 24, 2017

    That makes perfect sense, well said! Thanks Kris

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  3. R. Anderson on May 06, 2017

    Kris’ answer is well written and explains the aerodynamics clearly.

    I would like to add that in my experience it’s helpful to minimize the mechanical anticipation regarding which pedal will need to be pushed during torque changes. (hovering auto, liftoff, situations requiring significant power changes, etc.). For me, it’s most effective, since both feet are always on the pedals, to focus on keeping the nose of the helicopter straight. Whether you are pushing on the right pedal or releasing pressure on the left pedal, keeping the nose straight is often easier to accomplish than overthinking the aerodynamics. (for me anyway)

    Same thing with an engine failure on a multi-engine airplane. There are so many variables that, during stressful circumstances, if you mechanically move the rudder pedals in response to which engine you believe may be inoperative, you may wind up rolling the airplane upside down. (it has happened!) Flying the aircraft based on the visual cues, VMC (horizon or other outside reference point) or IMC (using the heading indicator, attitude indicator, etc.) allows your natural flying skills to overcome any potential shortcomings based on overthinking mechanical requirements based on your knowledge of aerodynamics. This is especially true during rapid changes in power during critical situations.

    Perhaps I’m a bit off topic, but your question made me reflect on a variety experiences I’ve had in flying myself or teaching others.

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