How It Works!

Planes fly because they are lifted off the ground by "lift force". The lift force is caused because there is more pressure below the wing than above it. Just like when you arm wrestle, the one who exerts more pressure causes movement toward the one with less pressure.  

The difference in pressure is usually caused by the shape of the wing. Flat on the bottom and curved on the top means the air on top has farther to go. Since the same amount of air goes above the wing as below it, the air on the top is spread out more, causing the lower pressure above the wing.  

The faster the plane moves, the more air passes above and below the wing, so the greater the difference in pressure. Once the lift force is more than the weight of the airplane, the plane takes off.

Wings are specially designed to allow a lot of lift force, with the least amount of air resistance, or drag. This allows the air flow to be stable and allows the pilot to control the plane easily. 

Actually, the lift force can be caused by the tilt of the wing as well as its shape. If you hold your hand outside the window of a car so that it is flat to the ground, it will not rise or fall. But, if you tilt your hand up a little, it takes off just like an airplane. Only do this with your parents! You have to be very careful whenever you put your hands outside.  

Even though the wing is curved more on top than on the bottom, if the pilot controls the angle, or tilt, of the wing, she can actually fly upside down.