Do helicopters need to use yaw pedals to fly a coordinated turn?

Question

I recall years ago, when I took a helicopter tour, I noted the pilot simply moved the cyclic left or right to bank the helicopter and initiate a turn. No pedal input was made whatsoever, and the ride seems completely fine.

In many fixed wing aircrafts, if rudder is not applied during the entry of a turn, the airplane will have a tendency to yaw to the opposite direction due to the drag induced by the ailerons.

Is pedal (rudder pedal? what are they called in a helicopter?) input necessary for turns in a helicopter?

Answer 1

Many helicopters have different flight characteristics, but for general information you can always look in the FAA Helicopter Flying Handbook, this is from Chapter 9:

This is from a section on the four fundamentals of flight (straight-and-level, turns, climbs, and descents):

Anticipate the following characteristics during aggressive maneuvering flight, and adjust or lead with collective as necessary to maintain trim and torque:

• Left turns, torque increases (more antitorque). This applies to most helicopters, but not all.
• Right turns, torque decreases (less antitorque). This applies to most helicopters, but not all.

So some (most) helicopters do require some torque pedal movement for aggressive maneuvering, but the pilot may have anticipated this and added the correction prior to beginning the turn. You may not have noticed as much pedal movement as you would in a coordinated turn for an airplane, or the helicopter you were riding in had different flight characteristics and was not maneuvering aggressively enough to need it.

Many helicopters "wind vane" pretty well, that is that they stay aligned with the relative wind at high speed. It could be that the helicopter you were in was travelling at a high enough rate of speed that a large (or any) correction was not needed to maintain proper alignment.

For an example of how speed cancels out the need for anti-torque control, see this article about a helicopter pilot that lost the tail rotor and continued to fly for half an hour to a proper landing site.

Answer 2

Coordinated flight means that the airflow over the fuselage flows along the longitudinal axis of the aircraft.

The main risk of uncoordinated flight in an airplane is the possibility of entering a spin.

But helicopters don't spin, and uncoordinated flight is not dangerous in them in the same way as in fixed-wings. This means that helis can fly at any angle to the direction of flight, which is one of the main benefits of flying them.

That being said, helis are equipped with a flight instrument invented by the Wright Brothers -- the yaw string. They are taped to the bubble, and in forward flight the pilot keeps the yaw string aligned with the fuselage by using the pedals.

The main benefits of coordinated flight in a heli are fuel efficiency and passenger comfort.

Answer 3

Fixed wing aircraft that deflect their ailerons experience adverse yaw: the aileron deflecting downwards experiences more drag than the one deflecting upwards, and this creates a yawing moment in the wrong direction. The magnitude of the effect depends on variables like aspect ratio, wing span, airspeed etc. It is this yawing affect that would be compensated by pedal input.

Helicopters effectively tilt the lift vector to the side where they need to go to, there is no adverse yaw effect that requires compensation from the pedals.

Both fixed wing and rotary wing aircraft experience side slip when only stick and no pedals are applied in a turn - to a limited extent due to directional stability in forward flight. The vertical fin provides this stability, and in helicopters the tail rotor as well: increase in side slip angle causes a change in angle of attack at the tail rotor, which results in a stabilising thrust change. But self stabilisation needs a slip angle to create force. Like Simon says, a true coordinated turn always requires pedal input.

Answer 4

Short version: Yes, helicopters require anti-torque correction to achieve co-ordinated flight. However, co-ordinated flight is usually not necessary/desirable