Explain why helicopters need 2 rotors to fly in a straight line. Talking about centripetal force.
Helicopters require two rotors, typically a main rotor and a tail rotor, to fly in a straight line because of the principle of centripetal force. Centripetal force is the force that pulls objects inward when they are in circular motion. In the case of a helicopter, it is necessary to counteract the torque, or rotational force, generated by the main rotor.
To understand why two rotors are needed, let's first consider the main rotor's role. The main rotor generates lift, which allows the helicopter to rise into the air and maintain altitude. As the main rotor spins, the blades create a pressure difference between the top and bottom surfaces of the rotor. This pressure difference generates lift, similar to the way airplane wings generate lift.
However, the main rotor's rotation also creates a torque that would cause the helicopter to spin in the opposite direction. To counteract this torque and keep the helicopter from rotating, a second rotor, known as the tail rotor, is used. The tail rotor generates a sideways force called "thrust" that opposes the torque produced by the main rotor. This opposing torque allows the helicopter to remain stable and fly in a straight line.
The direction of the tail rotor's thrust can be controlled by a pilot through the use of the helicopter's pedals. By adjusting the thrust of the tail rotor, the pilot can counteract the torque and keep the helicopter in balance. This balance is crucial for maintaining control and stability during flight.
In summary, helicopters need two rotors, a main rotor and a tail rotor, to fly in a straight line because the main rotor creates a torque that would cause the helicopter to rotate. The tail rotor, by generating an opposing thrust, counteracts this torque and keeps the helicopter stable. This configuration allows the helicopter to maneuver and maintain a desired flight path.