14.84 Anti-torque Tail Rotor

14.84.2 Describe the torque couple (origin, direction, and strength).

Torque Couple

Origin:

• Caused by the engine driving the main rotor
• Newton’s Third Law → the fuselage experiences an equal and opposite reaction

Direction:

• Fuselage tends to rotate in the opposite direction to the main rotor

Strength:

• Varies with engine power / rotor thrust
• More power → greater torque effect

Summary:
The torque couple is the reaction force from driving the rotor, causing the fuselage to yaw opposite to rotor rotation, increasing with power.

14.84.4 State the purpose of the anti-torque (tail) rotor.

Purpose of the Anti-Torque (Tail) Rotor

• To counteract the torque reaction from the main rotor
• To provide directional (yaw) control about the vertical axis

Summary:
The tail rotor balances main rotor torque and controls yaw.

14.84.6 Describe the demand of anti-torque for power.

Demand of Anti-Torque for Power

• The tail rotor requires engine power to produce thrust and counter main rotor torque
• Power demand increases with:
  • Increased engine power / main rotor thrust
  • Higher collective settings
  • High gross weight or density altitude