# Bernoulli's Principle

Bernoulli's Principle is the principle that allows wings to produce lift and planes and helicopters to fly. There are many factors that can effect the lift produced under this principle, but in order to fully understand how and why things can effect flight one must understand how Bernoulli's principle works.

Bernoulli's principle works on the idea that as a wing passes through the air the its shape make the air travel more over the top of the wing than beneath it. This creates a higher pressure are beneath the wing than above it. The pressure difference cause the wing to push upwards and lift is created.

There are several things that effect the amount of lift created. The first is speed, the faster the wing moves through the air the more air is forced over and under the wing, therefore the more lift is created. Another thing that effects the amount of lift created is the density of the air. The denser the air is the more lift is produced. This is why planes climb better in the winter, the colder air is denser. The final thing that can change the amount of lift created by the wing is the shape of the wing. Certain wings produce more lift.

Lift

To maintain equilibrium in a straight and level flight, pilots must monitor the aircraft's speed and pitch angle. Those variables along with other factors are used in a formula to determine an aircraft's lift.

Lift=(1/2)(air density)(velocity expressed in feet squared)(aircraft's wing area)(coefficent of lift)

Air density changes with altitude. Such densities can be found in the I.C.A.O. standard atmosphere table.

The coefficent of lift which varies with the aircraft's type of airfoil and pitch angle uses the pitch angle velocity relationship curve to determine the aircraft's coefficient of lift.

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