Question: How does a plane takeoff and fly?

Samantha Weaver answered on 6 Jul 2012:

This always amases me whenever I go on a plane – it’s a very clever bit of science!

Airspeed – Takeoff in an airplane requires airspeed. The airspeed is a measure of how fast the air is flowing over the airplane, not a measure of how fast the airplane is traveling. If the airplane is flying into a headwind, its airspeed is increased, which is why airplanes generally take off into the wind.

Bernoulli Effect – Airspeed creates lift across the wings. The wings have a curvature, or camber, that increases the distance the air has to travel over the top of wing. This creates the Bernoulli effect. The Bernoulli Principle states that pressure in air decreases as the speed of the air increases. Faster air over the top of the wing lowers the pressure, and the difference created between the top and the bottom of the wing creates lift.

Configuration – An airplane is lined up on a runway that will give it the best headwind. Flaps, which are movable surfaces on the trailing edge of the wing near the fuselage, are lowered. This increases the camber, which amplifies the Bernoulli effect, helping create more lift at lower airspeeds.

Acceleration – The engines of the airplane are revved up to a certain percentage of full power. This percentage depends on the size, weight and type of airplane, but once that value is reached, the brakes are released. The airplane then starts building up speed rapidly and the throttles are steadily pushed to full power for takeoff.

Roll Out – When the takeoff airspeed is reached for the particular airplane, the nose of the airplane will begin to lift off the ground. The nose is then raised to a certain angle, sometimes called the roll-out angle. This changes the angle of attack, or the angle at which the wings are cutting into the wind. This once again changes the airspeed over the top of the wings. When the airspeed over the wings is high enough, the plane will lift off the ground.

Flight – Once the airplane is off the ground, the flaps must be retracted. On the ground they were needed to get the plane in the air, but at flight speed, they create too much drag. Landing gear, if possible, also needs to be retracted. In most cases, once a safe altitude is reached, the airplane must also be turned to clear the traffic pattern for the next airplane in line for takeoff.