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How do helicopters fly?

How do helicopters fly?
Gary from Kent (Age 5-14)


One Response

  1. Helicopters (from the Greek helix-spiral and pteron-wing) have a set of blades, which act very much like wings, but they also rotate enabling the aircraft to lift vertically whilst also providing thrust. So to understand how helicopters fly first you must understand how aeroplanes fly. There is debate about this but I favour something called the Coanda Effect named after Henri Coanda. You might have noticed the Coanda Effect when you pour something from a rounded jug and the liquid follows the shape if the jug and drips on the floor! Fluids such as water or air follow the shape of a surface when they flow close to the surface so when the air flows over the curved surface of a wing it follows that shape. The useful thing is that the air carries on curving after it leaves the wing and moves down. This is a downward action and the reaction is that the wing lifts. As Issac Newton explained in one of his laws of motion; to every action there is an equal and opposite reaction. So the blades of the helicopter are like rotating wings and as they rotate the air goes down and the helicopter lifts up. It means that the helicopter can lift up without moving forward. The blades are attatched to a mechanism called a swash plate which allows the angle to be changed so that the helicopter can fly forward and even backward and sideways. The special curved shape of a wing is called an aerofoil and it can also be seen on an airscrew propeller.
    Peter Halford, Science and Technology Teacher, Imperial War Museum Duxford.

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