What forces act on a rotor blade hovering in still air?

In a hovering helicopter, the primary forces acting on a rotor blade are lift and drag. Lift is the upward force that enables the helicopter to rise and maintain its position in the air, generated by the rotor blades as they move through the air. This lift must counteract the weight of the helicopter in order to achieve a hover.

Drag, on the other hand, is the resistance force that opposes the motion of the rotor blades as they slice through the air. This aerodynamic drag arises due to the friction and turbulence created by the rotor blades' movement.

In a state of hover, the lift is equal to the weight of the helicopter, allowing it to remain stationary in the air. The rotor blades are designed to produce maximum lift while minimizing drag to ensure efficient flight performance. This balance and interaction between lift and drag forces are essential for a helicopter's ability to hover effectively in still air.

Other options may reference forces that are indeed relevant to helicopter dynamics, such as thrust or torque, but they don't accurately fit the scenario of a rotor blade in a hover. In this specific context, lift and drag are the fundamental forces at play.