how do planes stay in the air?

Question

How does something as heavy and as big as a plane, then it gets heavier with the people and the luggage stay in the air for such a long amount of time. why doesn't all the weight make it fall?

Answer 1

I’d just like to point out that Bouncer Bobtail’s answer above is complete rubbish for two reasons:

Firstly, any aircraft with no propulsion (engines switched off) would not “drop like a dart” but glide just like any other. In complete contradiction to his/her answer, a modern jet aircraft would actually have a better glide ratio (i.e. glide further) than an “older propeller aircraft”, this is as the glide ratio of an aircraft, the distance it can glide for a given height, is given by the ratio’s of L/D (lift divided by drag) and therefore is not a function of weight at all. Modern jet aircraft have greater coefficients of lift (due to improved wing shapes/technology) and reduced coefficients of drag (due to improved airframe/fuselage design). Therefore simple mathematical deduction proves that modern jet aircraft have better glide ratios than older propeller aircraft. Also logic dictates that newer aircraft have better performance than older aircraft and lift and drag (the determinants of glide ratio) are the key performance criteria of any flying object. See the wikipedia link below to prove that Airliners have a better glide ratio (17:1) than propeller aircraft e.g Cessna 150(7:1)

Secondly, if Bouncer Bobtail knew anything at all about aircraft, he/she would know that although aircraft engines are immensely powerful, during cruise they are hardly used at all (usually no more than 20-30%). This is because the full power of the engines is only used during the take – off and climb stages of a flight. Also, referring back to my first point, the fact that modern aircraft are designed to be “low drag”, to conserve fuel, means that the air resistance needed to be overcome by the engines is reduced ( even bearing in mind the large speeds involved) and therefore doesn’t need the full power of the engines.

To answer your original question, what keeps an aircraft in the air is the design of the wings, and certainly not the engines (this is how gliders fly). As has been discussed before, the wings produce lift, which balances the weight of the aircraft. The lift produced is a function of the cambered design of the wing and the forward velocity of the aircraft.

I apologise to Bouncer bobtail, as this was not meant as a personal attack, but as both a qualified Aerospace engineer and a keen Glider pilot I feel the need to inform people about the true facts about flight and pass on some of the knowledge I have gained, as well as stopping some of the myths and untruths that surround aircraft. I hope this has been some help in answering your curiosity but if I can be of any more help then please contact me.

Answer 2

My turn! Take a piece of your printing paper, 81/2" x 11" and cut a strip about 3" wide by 11" long. Hold the narrow end between your thumb and forefinger. Hold the fingers close to your lips and blow across the top of the paper. The paper will rise more and more, the harder you blow.

The reason this happens is that an increase in wind velocity (speed) over the top of the paper causes a decrease in pressure, in relation to the nonexistant wind velosity on the bottom of the paper.

The wings of an airplane are shaped so that the top of the wings are longer, (due to it's curvature) than the bottom of the wings. Therefore, the air must move faster on top of the wings than the bottom and the same thing happens to the wings as happened to your piece of paper. It's called lift.

I know, it's amazing that so much lift could be made with such seemingly small wings, but, apparently it works. There's an awful lot of airplanes flying!

Answer 3

The simplest answer is that the wings create lift because of their shape. The way they do this is by having a curve on top(although the bottoms arent exactly straight lol). because of the curve, the air travelling over the wing has to speed up, this causes lower pressure. And anything will have a tendancy to go from high pressure to low pressure, such as toothpaste, or balloons, or winds etc i.e. the wing will lift, but it wont always be straight up, as it depends on the angle of the wings into the airflow, and for the plane to stay in the air the lift should overcome the gravity effect, and the thrust of the engines should overcome drag ( both form and surface drag etc). This is a bit oversimplified, but its the basic idea.

Answer 4

There are four main things of which you need to know about flight, the forces of: Lift, Thrust, Weight, and Drag. The wings and thrust of the engine (propellor or jet) need to overcome the forces of drag and weight. Drag is air resistance which slows the plane down (so generally the faster the plane, the more streamlined it is to overcome drag). Weight is obviously gravity's effect on the plane which needs to be overcome by lift just enough so the plane can fly with stability in a straight path.

The rudder, elevators, and ailerons control the movements of yaw (side to side), roll, and pitch (up and down).

A plane stays in the air because of the unique shape of its wing. The wing is curved in such a way that the air on top of it travels faster than the air below it, creating low pressure above, and high pressure below. The opposite effect is incorperated on to racecars, whose wings or spoilers are basically upside down wings, which cause the opposite effect of making the car stick to the ground.

If you will notice, most large planes, such as cargo jets and airliners, have straighter longer wings to maximize lift. Although their weight may seem impossibly heavy to fly, they are following all the aerodynamics laws. This is why smaller, faster aircraft (such as fighters), can have smaller wings. They are lighter and faster, and require less lift, but more thrust (in relation to their size). They also have broad wings to increase wing surface area to maximize turning ability.

Answer 5

get a bit of paper and blow on top not below notice how the paper lifts?

well first of all the engines are powerful... next is the more technical stuff I learned this a year ago

the planes wings are at an angle 15 degrees i think it is this is called the angle of attack as you have done with the paper the air lifts the plane up.

newtons 3rd law: every action has an equal and oposite effect so blowing the paper you thought the paper would go down... but if newtons 3rd law is correct the paper goes up. its the same with a plane

thts really the basics of how a plane stays in the air... :)

Answer 6

A simple demonstration may help; Turn on your cold tap and imagine this is the stream of air running over the planes wing ( except it is vertical instead of horizontal) now, hold a teaspoon by the handle loosely and slowly "dip" it into the stream of running water so that the bottom of the sppon hits the water. You should notice that the water "pulls" the spoon into the stream. This is the effect that a planes wing creates in the air as the shape of the wing creates less drag on the top than the bottom. This causes the wing to lift.
Hope this helps.

Answer 7

It's alot of magic spells and fairy dust !

no sorry it's to do with the shape of the wings and thrust from the engines. The wings are shaped to give the plane lift when air passes over the top of them. Coupled with enormous amounts of thrust from the engines enables it to take off. Whilst in the air the the rear of the wings have flaps on them that move up and down to stabilise the plane in flight. The bigger the plane, the longer the wings, the more engines you need to lift the weight.

Hope that helped, didn't want to make it too complicated.

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Answer 8

Most of the answers are correct about the shape of the wing which reduces the air pressure above the wing. When I flew gliders people use to say I wouldn't go up in a glider because there is no engine. In fact gliding is the safest form of flying because they rely on just there wings and in fact they fly downhill all the time. I can explain how if you want me to. Have you ever thought how do birds stay in the air. there wings are similar to the shape of aeroplane wings that was where the design of wings came from

Answer 9

It's called the Venturi Effect. It works simply because, the faster a fluid like air travels, the lower it's pressure.

The wing is so shaped that when air travels over the wing, or the wing travels through the air, the air above the wing has to travel further than the air below.
This means that the air above has to travel faster and so it's pressure drops.
Imagine you blow on a piece of paper - it moves away from you, right? That's because, Nature likes everything to be balanced and the paper is moving away from the higher pressure (your blowing) towards the lower pressure (where you're not blowing).
The wing does the same thing - it moves towards the lower pressure to even the pressures out, and so moves upwards, towards the faster moving air.
It's hard to visualise, but there are plenty of websites with diagrams.
The engines themselves are purely to give forward thrust (and also work on this principle!) in order to keep the air moving over the wing, and reach your destination.
Again, in fluids, higher speed equals lower pressure.
Good luck!

Answer 10

The top of a plane's wing is longer than the bottom. Because of this the air moving over the wing is at a lower pressure. As the palne is pushed forward by the engines the pressure below the wing increases as the pressure above decreases. The plane is the sucked into the lower pressure.

Answer 11

If you look at a wing side on it is flat at the bottom and curved at the top so air passing over it has further to travel than air under it.As it moves forward this causes the wings to lift.This is about the most simple basic principle of aircraft lift as it is explained in basic science.As long as the lift remains greater than the weight of the aircraft then it stays up when it starts to come down and land you will see the flaps move reversing surface areas on the wing so there is less lift and the plane heads downwards.