How does an airplane fly?

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concerned neighbor

Lift is the aerodynamic force that counteracts gravity and holds an airplane in the air. Most of the lift required by an airplane is created by its wings, but a certain portion is also generated by other parts of the aircraft, such as the fuselage. But what actually causes the lift to be created?

First, understand that air is a fluid, just like water, and that all fluids adhere to the same physical and mathematical principles. Next, realize that lift can only be generated when a fluid is in motion. For example, a wing must be passing through the air or the air must be moving around a stationary wing, one or the other. (The way it usually happens is that the wing is doing most of the moving, although the air may be moving too, at the same time.)

Most airplane wings have a special, basic shape as viewed edge-on: their upper surfaces are curved and their lower surfaces are flatter. This shape is what works with the fluid motion of the air to create lift. As air moves around a wing, some goes over the top and some goes underneath. The air that goes over the curved upper surface undergoes two important changes: it is reduced in pressure (by the centrifugal force of flowing across the curved surface) and it is accelerated downward (as it leaves the trailing edge of the wing). The wing is forced into the region of reduced air pressure above the upper surface of the wing by the higher air pressure beneath the wing. Also, the downward acceleration of the air (downwash) at the trailing edge forces the wing upward.

Since lift is dependant on the motion of the air, it increases as the speed of the air increases. Lift also increases (to a point) as the angle that the wing makes with the airflow (known as the angle of attack) increases. Past a certain point, however, increased angle of attack will cause the wing to suddenly lose its lifting ability, or stall.

confused

This a great site with lots of explanations, examples and pictures. Lift is complex taking pieces at a time will be more beneficial to learn how it all works.

http://quest.nasa.gov/aero/background/

FDH

It has to do with the shape of the wings. They are shaped in such a way that as air passes over them at high speed, it creates an imperfect vacuum above the wing. The air pressure beneath the wing is higher than the pressure above the wing so the wings are lifted up.

C.J I

engine or propeller sucks in the air, the air in return pushes the aircraft. once the aircraft gains enough speed, the wings come into effect. The air flows much faster over the top of the wing then airflow below the wing, causing the airplane to lift.

Exrotic_illusion

in simple terms the shape of the wing creates a vaccum and sucks it up

Help~me~Please

Lift, weight, thrust, and drag are the four forces that act on a plane the first three are responsible for keeping the plane up.

Ian M

Provide that lift exceeds weight anything will fly. If thrust exceeds drag it goes forwards and accelerates. If not it decelerates and/or goes backwards. If Lift equals weight and thrust equals drag it hovers.

Ian M

Techwing

Looks like you've received only partially incorrect answers so far.

Airplanes fly thanks to their wings. The wings produce an aerodynamic effect called lift, which raises the wings and the airplane to which they are attached and maintains both in the air.

A wing is typically a long, flat object, and when a plane is flying the wing is presented edgewise to the oncoming wind. It is also tilted very slightly upwards, so that the front edge of the wing (facing the wind) is slightly higher than the rear edge of the wing. This tilt causes air passing above the wing to speed up as it moves, and it causes air below the wing to slow down. Because of this, the air tends to twist downwards as it slides off the rear edge of the wing. And this in turn means that, as the wing moves forward through the air, it pulls the air above it downwards, creating a thick, invisible swath of downward-moving air behind the airplane as it goes forwards. This large mass of downward-moving air is called the downwash. In a big airliner like a 747, the mass of air pulled into the downwash can be hugeâ€”as high as a twenty-story building.

The wings exert tremendous force in order to create the downwash, because large masses of air are actually quite heavy. The air, in turn, resists this force, and tries to push the wings upward instead. This upward force is lift, and that's what keeps the airplane flying. As long as the wings are moving forward and maintain that slight upward tilt (often so slight that it's hard to see), lift is generated and the airplane continues to fly.

Because the downwash from the wings is invisible, it's hard to appreciate how huge it is. But if you look around on the Net, you can find some photos of airplanes flying just above cloud layers, where you can see the "ditch" that the downwash makes in the clouds behind the aircraft. Sometimes also, when the airplane is taking off or landing in misty conditions, you might be able to see part of the downwash racing down off the trailing edge of the wings.

Other stories about pressure and vacuum and so on are misleading. Pressure and such do play a part in allowing the wings to twist the air above them, but the actual lift comes from the resistance to the downwash, in accordance with Newton's laws of motion. The wings pull air down, and the air tries to push the wings up. It's as simple as that.