Physics in Everyday Life

How do helicopters work?

By: Sai Piyush Pathak - Researcher

Helicopters are fascinating machines that defy gravity using the principles of aerodynamics and physics of motion. Unlike airplanes, they don’t need a runway to take off, they can lift straight into the air!

The secret lies in their rotors, the large spinning blades on top. These blades act like wings, but instead of moving through the air like an airplane, they rotate. As the blades spin, they create lift by changing the pressure of the air around them. According to Bernoulli’s principle, faster-moving air above the blades has lower pressure than the slower-moving air below. This difference in pressure pushes the helicopter upward, allowing it to hover.

To control direction, helicopters use a tail rotor. This smaller rotor counteracts the spinning force (called torque) created by the main blades. By adjusting the angle of the tail rotor, the pilot can steer the helicopter left or right.

Helicopters are also incredibly versatile because of their ability to hover and make sharp movements. By changing the angle of attack of the main rotor blades (known as collective and cyclic controls), pilots can make the helicopter move forward, backward, or even sideways.

In short, helicopters are an amazing combination of physics principles, including lift, torque, and air pressure.