Chapter 12, Problem 38A

Why does a typical small helicopter with a single main rotor have a second small rotor on its tail? Describe the consequence if the small rotor fails in flight.

To determine

To Explain: The importance of the second small rotor on the tail of a typical small rotor and the consequence if the small rotor fails in flight.

Explanation of Solution

Introduction:

Helicopter rotor is connected by the engine through the rotating mast. The rotor has large diameter and designed to operate at fixed round per minute which generates the horizontal thrust.

The small rotor is held vertically near the tail of a helicopter which is also used to generate the horizontal thrust.

Main rotor of the helicopter provides the upward force perpendicular to the plane of main rotor which works against the force of gravity while the small rotor on the tail is designed to cancel out the torque of the main rotor.

In the case if small rotor fails, the helicopter would rotate in the opposite direction to that of the main rotor and would fall to the ground.

Conclusion:

Therefore, the main function of the small rotor on the tail of the helicopter is to cancel out the torque produced by main rotor otherwise helicopter would fall on the ground.