How does a helicopter rise up?

Question

An aeroplane goes up after taking a long way in the runway;Why even birds gradually increase their height...But how can a helicopter just go up from its place?

Answer 1

A helicopter is able to twist it's blades in order to increase the angle of pitch.  With a higher angle of attack, the blades move more air and produce more lift.  By keeping the rotor rpms at a certain fixed amount the flight of the helicopter is achieved simply by rotating the blades around their lateral axis.

Answer 2

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Answer 3

The rotor beats the air into submission!

Actually you can think of the rotor blades just like a wing on a plane.  Same principles involved.  only instead of roaring down the runway to get air moving past the wing fast enough to create lift, you are rotating the wing (rotor) to make that same speed.

Answer 4

The shape of the rotors on a helicopter is called "aerofoil" and are the same shape as an aeroplane wing. It is flat underneath and curved on top. The bernoulli principle states that air passing over the rotor blade as it spins would all reach the same point after the blade at the same time, but because of the aerofoil shape the air above the blade has to move faster. This means the air just above the blade is less dense than the air below, which creates lift. It is the exact same principle to create lift for an aeroplane.

Answer 5

A helicopter creates lift by moving its rotor blades through the air under torque power from the engine. A combination of Bernoulli principle lift (from the airfoil shaped rotor blades) and thrust lift (from the rotor's variable pitch) creates a lifting force equal to, or greater than the helicopter's weight, in order for it to fly.

If the lift force is exactly equal to the weight of the helicopter, it hovers or maintains altitude in flight, neither rising or descending. If the lift force is greater than the weight of the machine plus its load, it will climb, gaining altitude. To descend, the helicopter pilot can reduce power from the engine (thus slowing the rotor blades), or flatten out the pitch of the rotor blades, to reduce the lift force to less than the weight of the machine and its load.

Answer 6

Here is a more simple explanation.  An airplane has to have air going over and under its wings for it to lift up in the air. In order for this to happen it has to be moving forward at a high rate of speed.  That's why it has to roll down the run way to a speed that will cause it to rise in to the air. A helicopter has rotor blades that are shaped like a wing on an airplane.  If you spin these blade fast enough they to will create lift and cause the Helicopter to rise up.

Answer 7

Helicopters are so ugly, the Earth repels them. :P

Actually, the rotors are wings. As they rotate, they generate lift like an aircraft wing. Altering the angle at which they do this forces the helicopter in different directions.