what KEEPS an aircraft in the air ? is it thrust or the wings ?

Question

a disscussion started at work one day when a aircraft flew over and i happend to comment that i thougt thrust was keeping it up. The others argued that it was the wings.I dissagreed saying that the wing was only helping to reduce the amount of thrust needed and gave a example of throwing a stone saying it would stay in the air indefinitly if the thrust was great enough and a stone has not got wings . can someone please help us all become friends again and settle this

Answer 1

The answer is neither. It is air pressure that keeps an aircraft from falling to Earth. This is why planes can't fly beyond a certain altitude where the air becomes too thin. If a plane weighs 50 tons, then there has to be more than 50 tons of total upward force to move that plane upwards..

Pressure is measured in force per unit of area. If that 50 ton plane has a wing area of say 1,000 square feet, then there has to be a pressure differential of more than 0.05 tons per square foot of the wing to lift the plane up. By pressure differential I mean the difference between the air pressure above the wing and that below it.

Where the wing is stationary, there is no pressure differential, but when the plane moves forward the way the air moves over the wing causes the pressure differential to increase.

If you watch a plane take off, you will see that there is firstly a period of acceleration, but when and only when a specific air speed is reached, the pilot operates the flaps to push the tail down so that the wing angle is increased to about 20 degrees to the air flow direction. This, at that critical speed, the take-off speed of the aircraft, generates the necessary pressure differential on the wings to lift the plane off the ground. As the plane continues to accelerate, and reaches its' cruising speed of about 600 miles per hour, the pressure differential is maintained with the wing angle almost level. This, as others have mentioned, is achieved by the wing being curved on the top and flat underneath. At high speeds, the curve creates a vacuum above it, so giving you the necessary pressure differential.

If you watch planes landing at the airport, again, at that much slower landing speed the nose has to be kept up at about 20 degrees to maximise the pressure differential on the wings. Landing is a controlled fall, so the landing speed is therefore slower than the take-off speed for the same aircraft..

Answer 2

What lifts the airplane is a force created by wind rushing past the wings. You could argue that the plane could fly without the thrusters because if the right wind came, it would lift the plane without using the thrusters. The physics behind it is that the shape of the wing causes the air coming at it to deviate over and under the wing; the shape of the wing is such that the air going over the wing takes longer to get to the tail end of the wing than the air going under the wing does. This difference lowers the pressure on the top side of the wing, making the pressure underneath the wing greater. These pressures are forces. When two forces push on an object, the object moves in the direction of the greater forces push. Since the upward force is greater, the plane lifts. The thrusters simply move the plane forward.

Answer 3

The short answer is both. Wings don't work unless there is an airflow, which can only be provided by thrust from an engine.

The wings generates uplift because of the different speeds at which air passes over and under the wing, leading to different air pressure.

Your friends are confusing aeroplanes with birds, whose wings a more directly responsible for keeping them in the air because they provide the thrust as well.

Go back to your friends and give them this analogy: If a Formula 1 car is sitting in a garage with the engine off, what are its wings on the front and back doing? Absolutely nothing at all. They only begin to work once there is airflow provided by the thrust of its engine and wheels.

An object can fly without wings (missiles and rockets), but it can't fly without thrust.

Answer 4

So think about a rocket going into space - it's all thrust and no wings! On the other hand, a glider stays aloft for quite a while with no thrust. But that glider initially had some thrust applied as it was towed up to be released. So I think you are right - you need some thrust in order to develop the lift on the wings that keeps the aircraft up. But if those aircraft had no wings, they would be so inefficient that it would not be economically feasible to fly around in them!

Answer 5

The forward thrust of the aircraft coupled with the shape of the wing causes a positive difference in air pressure above and below the wing. The result is lift.

Hold a piece of writing pad size paper between your thumb and forefinger so that the paper curves over the back of your hand. Then holding it up to your face blow gently across the top of the paper. You'll see the back of the paper rise. It's the same principle with a wing.

Answer 6

Aircraft are held up by blowing air down this can be done directly by pointing engines down or more practically by rapidly moving the wings through the air. Wings work exactly like a fan blade and they push air down as they move through it. Planes can fly upside down by tipping the nose up so the wings are still angled to force air down as the plane moves forward.

The stone staying in the air is a seperate issue and has nothing to do with thrust. On the moon you could theoretically throw a stone up so fast that it would never come down because gravity fades away faster than the stone slows down. You could not do this from the Earth because air resistance would cause the stone to burn up before it has time to clear the atmosphere.

Answer 7

Yeah I would say it's got to be both. You need the engines to give that trust so that the plane can defy gravity and take off then once in the air it's the wings design that keeps in the air, with forward motion wind passes over the wings the air passing over the wing is negative pressure and the air underneath is positive thus creating lift, to help the aircraft it has to have the propulsion which is supplied by the engines.

Answer 8

It's both. If you apply the same thrust to a car it won't fly but if you take the thrust from a flying plane it will also not fly for long. Thrust supplies the necessary air speed for the aerodynamically shaped wings to create the necessary uplifting forces that keep the aircraft in the air.

Answer 9

Four things govern aircraft flight , lift (wings ), thrust from what ever propulsion unit , drag (from shape of aircraft and aircraft movement through the air),weight there for lift must be greater than the weight , and thrust must be greater than the drag for forward movement , all this for level flight, can you have lift without thrust in directly yes but then gravity takes over so forward motion becomes thrust aided by weight . as for a rock it wont fly with gravity acting on it no matter what thrust , it becomes a trajectory like a shell

Answer 10

It's a combination of both, the wings need the forward thrust in order to generate the lift required to lift the plane in the air. Both elements are required, one is useless without the other.