# Tilting a helicopter rotor, does it create torque?

• Moafak m
In summary, when the cyclic is pushed forward, it creates a torque that rotates the helicopter around its lateral axis. This torque is countered by a large aerodynamic damping force and can be stopped faster if the pilot overcorrects with the cyclic. In a rotor system with hinge offset, there is also a control moment generated from the difference in lift between one side of the rotor disc and the other. This allows helicopters with hinge offset, such as the Jolly Green Giant or Hughes 500, to perform rolls and loops, while helicopters with a teetering rotor, like the R22 or BHT-214ST, cannot.

#### Moafak m

Hello
I am making a helicopter flight simulation and I need an answer to this question:
when you push the cyclic forward, does this create a torque which will rotate the helicopter.
if the answer is yes, please tell me what counteracts this torque and stops the rotation when I return the cyclic stick to its original position.

if the answer is no, how can you explain that the lift force doesn't pass through the body's center of mass and yet doesn't have a torque.

(I assume lift force is represented as a vector which is always perpendicular to the rotor's plain of rotation)

Yes you are correct that forward cyclic input causes the lift force vector to be off set from the aircraft center of mass and thereby creates a moment or torque about the lateral axis of the aircraft which in turn causes the aircraft to rotate on that axis.

The moment goes away when you neutralize the cyclic because the thrust vector is now back in line with the aircraft center of mass again. The aircraft would, by Newtons 1st law, keep rotating except there is a large aerodynamic damping force generated by the change in the relative wind at the rotor blade from the tangential blade velocity of rotation on the lateral axis.

If the pilot however wanted to stop the rotation faster he would not just neutralize the cyclic but he would over correct to create the opposite moment until the aircraft stopped rotating then he would neutralize the cyclic.

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I should also add that the description above is more accurate for a teetering, semi-rigid type of rotor. However, in a rotor system which has hinge offset, whether it be an actual hinge or some kind of flexible member, or even a rigid rotor hub, there is also a control moment generated just from the difference in lift between one side of the disc and the other and is independent of the angle change of the total rotor thrust vector. Plus it still generates the moment from the thrust vector angle. Therefore a rotor with hinge offset can create a larger control moment than one without and the larger the hinge offset, the larger the the control moment such a rotor can produce.

This is why a helicopter with hinge offset, as large as the jolly green giant or as small as a hughes 500, can be seen performing rolls and loops. Where a helicopter with a teetering rotor whether it be an R22 or BHT-214ST will probably never be seen performing any such maneuver.

## 1. How does tilting a helicopter rotor create torque?

Tilting a helicopter rotor creates torque by changing the angle of attack of the rotor blades. As the blades tilt, they create a force that is perpendicular to the direction of rotation, resulting in torque.

## 2. What is the purpose of creating torque in a helicopter rotor?

The purpose of creating torque in a helicopter rotor is to counteract the torque created by the engine and keep the helicopter from spinning in the opposite direction. This allows the helicopter to maintain a stable and controlled flight.

## 3. How does the direction of the torque created by tilting a helicopter rotor affect the flight?

The direction of the torque created by tilting a helicopter rotor determines the direction in which the helicopter will turn. Tilting the rotor to the right will create a torque that will cause the helicopter to turn right, while tilting to the left will result in a left turn.

## 4. Can the amount of torque created by tilting a helicopter rotor be controlled?

Yes, the amount of torque created by tilting a helicopter rotor can be controlled by adjusting the angle of attack of the rotor blades. The greater the angle of attack, the more torque will be created.

## 5. Are there any other factors besides tilting the rotor that can affect the torque in a helicopter?

Yes, other factors such as the weight and balance of the helicopter, the air density, and the speed of the rotor blades can also affect the amount of torque created. Changes in these factors may require adjustments to the angle of attack to maintain a stable flight.