Question

Why do helicopters with two sets of lifting blades have them rotate in opposite directions?

a) It enhances maneuverability.
b) To counteract torque without needing a tail propeller.
c) It's a safety feature.
d) It's more aesthetically pleasing.

Answer 1

Helicopters with two sets of lifting blades have them rotate in opposite directions to counteract the effects of torque, maintaining stability without a tail propeller.

Step-by-step explanation:

Helicopters with two sets of lifting blades have them rotate in opposite directions to counteract the effects of torque. When a single set of blades rotates, it creates rotational kinetic energy which, due to conservation of angular momentum and Newton's third law, would cause the helicopter's body to rotate in the opposite direction of the blades. This is typically counteracted by a small propeller on the helicopter's tail.

However, with two sets of blades rotating in opposite directions, the torque produced by one set of blades is canceled out by the other, thus maintaining the helicopter's stability without the need for a tail propeller.

This method is not for enhancing maneuverability, safety, or aesthetics, but specifically to counteract torque and maintain stability during flight.