Helicopter Flight Information

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Left or Right Pedal Turns?

Lets not forget what we are flying. If it is an American built helicopter, the rotor turns to the left in most cases, there are some exceptions such as the experimental Rotorway, or so I have been told (I have no personal knowledge of that).  If it is European built, then it turns to the right in most cases.

If the rotor turns to the left as mentioned above, then the torque will be to the right, which will result in the need for left pedal to counter this torque. Conversely if the rotor turns to the right, right pedal will be necessary to counter torque. In the text throughout this web site, we will talk only about left turning rotors for simplicity. For those who will be flying right turning rotors, the directions would obviously be reversed.

Torque Turns

Remember that we apply left pedal to counter torque. Any time we want to maintain a stable hover on a given heading, or make a left pedal turn, we must apply left pedal to a varying degree. The helicopter tail rotor is thrusting the tail to the right (nose left). Remember this, Thrust to the left and torque to the right. Pedal turns are only accomplished at airspeeds below 45 knots, above that speed the turns are only cyclic in most circumstances.

Left Pedal Turns Only

During training I teach and we practice both left and right pedal turns so that students learn what is possible, and how to handle different situations. However, when a student is solo, he or she is permitted to make only left pedal turns in most cases. This is for two reasons.

The number one reason is the fact that a pilot can easily lose control of the helicopter if a right turn begins to accelerate, which it usually will. A right turn can quickly accelerate because it does not require power to make the turn, just the torque that is already there. Pilots will always notice that a pedal turn to the right is much faster than a pedal turn to the left for a given amount of input.

The second reason is that if you cannot complete a left pedal turn, that is if you do not have the tail rotor authority available, then you must not fly. Remember that LTE is an issue that we must deal with, and this is the test for whether we would be able to overcome it or not.

Right Pedal Turns

The above facts often confuse a pilot when they begin conducting commercial operations, and they believe that less power is required to make right pedal turns. Although this is true while in a hover, one must remember how a pedal turn is stopped.

If you are in slow flight (less than 45 knots), and you will be making a turn, this will be conducted with significant pedal. If you make this turn to the right because of the myth of the right-pedal-turn = less power demand, you will find that you cause a decrease in rotor rpm when you apply the left pedal needed to stop that turn.

The pedal authority needed to stop a turn is greater than that which is needed to enter a turn. In slow speed flight it is safer, and will require less altitude to make a pedal turn to the left than it will to the right. This is because when you stop the left turn you will be decreasing the load on the main rotor (where all kinetic energy is stored) and rotor rpm will not decay.

We do not always have the option of the direction of the turn. In commercial operations, perhaps while spraying a field, we must make every other turn to the right. This is ok. You must increase the altitude, and perhaps even lead with throttle even in helicopters like the Robinson with excellent governors (this is not true with turbine helicopters as they are always governor controlled, and the throttle is always fully opened).

One may ask why the altitude change? You must learn and keep in mind that you can recover most situations with altitude, that is you will trade some of your altitude during the recovery. If for example you made a right pedal turn during a low altitude air taxi (Ag spraying operations are basically low altitude air taxi), and when you applied left pedal to stop that turn, your rotor rpm will begin to decay. This is due to the engine load which is greater than power available. There is only one recovery, the collective must be lowered. If you did not have sufficient altitude, you will do what? Yes, that is right, you will crash. The helicopter will be in more than one piece, and helicopters in more than one piece do not fly well.

Milk the collective?

This is a term that you will hear sooner or later. This technique is in reference to a pumping action on the collective in an effort to regain rotor rpm during a decaying situation. Remember that the collective does not give milk, so don't try to milk it. It is physically impossible to gain more rotor rpm through a milking technique rather than just lowering the collective for an rpm gain. Think about it, at the very best, you will have collective down only 50% of the time. It will take more altitude to regain rpm milking the collective than it will with the collective just down, and altitude is precious and limited, or otherwise it wouldn't be important would it?

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Last modified: 01/19/08