FAA Private Pilot Helicopter (PRH)Helicopter Aerodynamics and SystemsMedium
A pilot smoothly raises the collective to climb out of a hover in a single main rotor helicopter with a counterclockwise-turning rotor (as viewed from above). To maintain heading, what pedal input is required, and why?
- ANo pedal input is required because tail rotor thrust automatically compensates
- BLeft pedal, because increased torque requires more anti-torque thrust from the tail rotor
- CLeft pedal, because decreased torque requires less anti-torque thrust from the tail rotor
- DRight pedal, because increased torque requires more anti-torque thrust from the tail rotor
Show answer & explanationAnswer & explanation
Correct answer: B. Left pedal, because increased torque requires more anti-torque thrust from the tail rotor
Raising the collective increases main rotor blade pitch and drag, which increases the torque reaction trying to yaw the fuselage clockwise (right); the pilot must apply left pedal to increase tail rotor thrust and counteract this increased torque.
Why the other options are wrong
- A. Tail rotor thrust is manually controlled via pedals, not automatic.
- C. Raising collective increases, not decreases, torque.
- D. Right pedal would reduce tail rotor thrust, allowing an uncommanded yaw.
Tail Rotor Anti-Torque Response
Changes in collective pitch change main rotor torque, requiring corresponding pedal adjustments to maintain heading.
- Raising collective increases torque, requiring more anti-torque thrust
- Lowering collective decreases torque, requiring less anti-torque thrust
- For CCW main rotors, more anti-torque thrust is achieved with left pedal
Memory trick: Power up, push left, to keep the nose still