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# How do airplanes fly?

Wiki User

2017-08-14 06:42:41

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Two primary principles contribute to the creation of lift, which is what makes flight possible. Those two principles are Bernoulli's Principle and Newton's Third Law. Let's break it down and look at each principle individually.

Bernoulli's Principle By definition, Bernoulli's Principle states:

or an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure.

From a practical standpoint, this basically means that as a fluid (air, water, etc) moves faster, it's internal pressure decreases.

But how does this help an airplane create lift?

Well, let's think about this. Picture an airplane's wing - but cut in half so we can see the shape of it (referred to as an airfoil). The top of the wing is more curved than that of the bottom of the wing. The reasoning behind this is that the increased curvature on top of the wing will take advantage of something called magnus effect.

Magnus effect? What the heck is that? Well - before we continue let's define magnus effect in a nutshell. I'll do this through an example. Close your eyes and envision a Baseball game. How does the pitcher get the ball to move in a desired direction? He or she can curve the direction of the ball's flight left, right, down, or even up if desired. But how?

Well, magnus effect states that a rotating ball or cylinder moving through a fluid (air, water, etc) will create faster moving fluid in the direction of rotation, thus lowering pressure and "pulling" the ball or cylinder in that direction. This force is not created when the object is stationary, which is why a baseball pitcher puts a "spin" on the ball when he or she wants a curveball.

Phew - okay, so back to our discussion on the wing. So we know the top of the wing is more curved than the bottom. But how does that have anything to do with magnus effect? Basically, the shaping of the wing "fools" the air around it into thinking it is a long rotation cylinder, and forces the air to travel faster over the top of the wing than that of the bottom. And according to Bernoulli's Principle, faster moving air = lower pressure. If we have lower pressure on top of the wing than we do on the bottom of the wing, we now have an inequality of pressures acting on the wing. There is more pressure pushing up on the bottom of the wing than there is on the top pushing down, which means we now have a total net force pushing UP. And voila.. we have LIFT.

With real airplanes and airplane models, Bernoulli's Principle (related to the curvature of the wing) and the magnus effect have very little to do with "flying". If what the author says were true - real airplanes could not fly upside down. But if you have ever seen an air show -- you know real, powered planes regularly fly upside down in air shows.

Almost all of the lift created on the underside of a wing is created as (A) the underside of the wing is blasted by the air rushing past the wing -- because the airplane engine is pulling the airplane very fast through the air and (B) the plane's geometrical configuration is holding the wing at an angle such that the front edge of the wing is a little higher in the direction of flight than the back edge of the wing. A & B, together mean the air pressure on the bottom of the wing is higher than the pressure on the top of the wing. Thus the wing is forced upward. You can get the same effect by holding your flat hand out the window of a moving car and tilting the front edge of your hand up or down.

Large gliders, in general, can't fly upside down because they do not have engines. They get lift from surrounding air currents which force the plane upward by either (a) rising warm air -- called "thermals" or (b) air that is being directed upward by a hill. Gliders can take off at one height and land at a higher elevation if they are near thermals and air moving over hills or mountains.

Clouds fly because they are lighter than the air around them.

Newton's 3rd Law This one is much less complicated than Bernoulli's Principle.

Newton's 3rd Law is defined as: To every action there is always an equal and opposite reaction.

Airplane wings are fixed onto the airframe of the plane at a slight angle. It may not be easy to see for the untrained eye, but upon a close examination of an wing's attachment point to the body of a plane, one will see a slight angle.

This angle creates a deflection of air downward. As air hits the underside of the wing, even in straight-and-level cruise flight, it is forced downward. And according to Newton's 3rd Law, the forcing of the air downward causes an equal and opposite upward force on the wing, thus contributing to the creation of lift.

Now, one thing worth mentioning about Newton's 3rd Law is that its contribution to lift is highly debated within the industry. Some say it only has a tiny effect, while others argue it has barely any effect.

I will say this much; without Newton's 3rd Law the creation of lift would be MUCH more difficult. It contributes greatly to the creation of lift. To make an example out of this, picture an aerobatic airplane in knife-edge flight (flying on its side). Bernoulli's Principle doesn't properly work in this configuration because the wing is at an unusual attitude. So I ask you this: how does the plane stay aloft? Newton's 3rd Law is the only explanation for such a flight scenario. As air is hitting the airframe and control surfaces of the plane, it is being forced downward at a great rate, creating an opposing force - LIFT - in the opposite direction.

Airplanes fly by airfoil. If you notice, an airplane's wings are curved on top, which reduces downward air pressure, while increasing upward air pressure, thus pushing the plane of the ground

Airplanes fly due to the special shape of their wings. This shape is more or less called the airfoil. The airfoil is designed to make the air the plane is flying through travel past the wing faster above the wing than below it. This causes a difference in pressure between the top and bottom of the wing, with the greater pressure under the wing. Since there is a difference, the greater pressure pushes the wing up to try to balance the force. This upward force is called lift and it is the reason airplanes are able to stay in the air.

The easy answer is based on the Four Forces of Flight: LIFT, DRAG, WEIGHT, and THRUST.

WEIGHT is basically gravity--the force that keepings things falling toward the ground.

LIFT is the opposing force generated by the design of an aeroplane's shape and surfaces to counteract gravity, get it in the air and keep it there.

THRUST is best understood as a sort of 'push', usually generated by an engine of some kind like a jet or a turbo-propellor. It is the force that moves the plane forward.

DRAG is the force working against thrust. The air resists the aeroplane moving through the air. This resistance is called DRAG.

Although there are many factors that affect an aeroplane's flight: weight, shape of craft, temperature, altitude, air density, engine size or power, etc., a very simple experiment can be done to help with understanding the basic science of flight.

Go outside on a very windy day, the more wind the better. Face into the wind and hold your arm out in front of you straight, with your hand flat. Keep your fingers together and your palm down. You will feel the wind flow over the back of your hand, and you will feel a little pressure underneath your hand, trying to lift it UP. If your hand is not perfectly flat--if your fingers point even a little bit up or down, it affects how the wind tries to move your hand. Next, lift your hand up as though you are telling the wind to STOP, holding your palm against the wind. You feel pressure against your hand, and if you try to push, the wind pushes back. That pressure you feel as you 'push' against the wind is a kind of DRAG. When your hand was flat, the wind flows over it with little trouble and even tries to lift your hand a little. Those are examples of LIFT. We already know that when there is very little wind, you have to use your muscles to keep your arm up. But when the wind is very high, it actually helps you a little.

The shape of an aeroplane wing is designed to put the wind moving across the top--which creates pressure underneath it. The harder and faster the air moves across the wing, the more pressure underneath trying to even it out. The shape causes the air to always be applying so much weight to the top, that the pressure underneath forces it to LIFT. The way we get more and more pressure is THRUST--the engines on a plane moving it faster and faster through the air. By making adjustments to CONTROL SURFACES (rudder, flaps, etc.) we slightly change the way a plane's fusilage (body) meets the rushing air--it is in this way we control how much DRAG the aeroplane experiences...less DRAG means more efficient flying.

We don't want DRAG in the air, it will slow us down. But on the ground, we use DRAG when we land. When the pilot(s) apply brakes and flaps (those things on the wings that stick up right after landing) it disrupts the flow of air across the wing, causing DRAG through friction. DRAG is GOOD on the ground.

There is much more to flight than this elementary explanation covers, but it is this basic concept that will cause anything from a massive jumbo jet...to a large passenger plane...to a child's balsawood glider...to a simple paper aeroplane...to take to the air in flight.

============================================ the force of the engine helps the aircraft push up so the power that is generates from the engine makes it push up

I think what your askings means, that a aircraft has two or more wings, or fixed surfaces that provide lift, or upward force. This is changed by certain control surfaces such as alileron or flaps. The propulsion on aircraft differs, from jets to propellers, to nothing at all! They all have one purpose, forward movement. All combined, you get an airplane!!

Airplane wings are rounded on the top and flat on the bottom. So the same amount of air traveling across the wing on top as the bottom has to travel faster creating, LIFT. Lift, is how airplanes can stay up in the air. The wing has a certain peculiar shape (called an aerofoil) which, when moving through the air, creates a pressure differential. It does this by speeding up the air on top relative to the air on the bottom. Pressure = force/area so that means there is an upward force on the wings (called lift). Above a certain pressure difference (meaning above a certain air speed) the lift is greater than the force of gravity pulling the plane down. Hence the plane accelerates upwards. So the plane is actually held up by the air itself. When the airplane is pushed or pulled through the air, the air moving over the winds must move faster than air moving under the wings (shape of wing makes the air move a greater distance going over the wing) This lowers the air pressure above the wing. Air below the wing pushes up, giving the airplane lift- and it flies.

Four forces push and pull an airplane in flight.

An airplane uses a propeller or jet engine to produce a forward force called thrust, which fights drag, which is caused by air resistance and slows an airplane down.

The wings act as an airfoil and produce an upward force called lift. The opposite of lift is the force of gravity, which pulls the aircraft downward. Aerodynamics

What makes a paper airplane fly? Air - the stuff that's all around you. Hold your hand in front of your body with your palm facing sideways so that your thumb is on top and your pinkie is facing the floor. Swing your hand back and forth. Do you feel the air? Now turn your palm so it is parallel to the ground and swing it back and forth again, like you're slicing it through the air. You can still feel the air, but your hand is able to move through it more smoothly than when your hand was turned up at a right angle. How easily an airplane moves through the air, or its aerodynamics, is the first consideration in making an airplane fly for a long distance.

Drag & Gravity

Planes that push a lot of air, like your hand did when it was facing the side, are said to have a lot of "drag," or resistance, to moving through the air. If you want your plane to fly as far as possible, you want a plane with as little drag as possible. A second force that planes need to overcome is "gravity." You need to keep your plane's weight to a minimum to help fight against gravity's pull to the ground.

Thrust & Lift

"Thrust" and "lift" are two other forces that help your plane make a long flight. Thrust is the forward movement of the plane. The initial thrust comes from the muscles of the "pilot" as the paper airplane is launched. After this, paper airplanes are really gliders, converting altitude to forward motion.

Lift comes when the air below the airplane wing is pushing up harder than the air above it is pushing down. It is this difference in pressure that enables the plane to fly. Pressure can be reduced on a wing's surface by making the air move over it more quickly. The wings of a plane are curved so that the air moves more quickly over the top of the wing, resulting in an upward push, or lift, on the wing.

The Four Forces in Balance

Long flights come when these four forces - drag, gravity, thrust, and lift - are balanced. Some planes (like darts) are meant to be thrown with a lot of force. Because darts don't have a lot of drag and lift, they depend on extra thrust to overcome gravity. Long distance fliers are often built with this same design. Planes that are built to spend a long time in the air usually have a lot of lift but little thrust. These planes fly a slow and gentle flight.

Thrust, drag, weight, and lift keep the plane from falling from the sky.

An airplane flies by using it's wings and tail. The speed of the aircraft through the air causes the air to move faster across the top of the wing, the faster moving air has lower pressure and lifts the wing.

An airplane flies by the result lift over the airfoils (wings). Moving the airfoil through the air creates 'lift'. Notice that on the wing, more surface area is on top of the wing. The bottom is flat and the top is rounded- this results in a pressure difference when cutting through the air. Because of the high and low pressure differences, it creates a suction, or lifting action, lifting the mass, or airplane, off of the ground.

the upper part of the wing is curved, and while the air flows, the air that goes above the wing has to go faster, so this creates low pressure, which creates lift. (remember high to low)

Also, in fighter aircraft, mostly the air just pushes on the relatively flat wing (like when you put your hand out of the window of a car)

Airplanes are able to fly because of Bernoulli's principle. The wings are shaped so that when they are moving fast enough they create a low pressure area above the wing and a high pressure below, causing lift.

The wing itself is shaped so that when air flows over it, pressure changes are made. Because the top of the wing is longer than the bottom side, the air has to travel faster over the top to meet with the air on the bottom. Because of this, it creates a low pressure underneath the wing pushing it upwards. The larger the plane, the bigger the wing Surface Area must be to allow flight.

Airplanes fly on the the principle of Newton's Third law. When the engine pushes the air, the air pushes the plane forward. Fast moving air causes the plane to produce lift which makes the airplane fly.

Airplane engines drive propellers or fan blades that push air backwards, causing the airplane to move forward. The forward motion forces air over the wings. Because of the unique shape of wings, air goes over the top of the wings faster than the bottom. Bernoulli's principle says faster moving air has less pressure than slow moving air. Thus, the high pressure below the wings pushes the wings (and the airplane) upwards.

Have you ever watched a big jetliner lumber into position on the runway for takeoff and wonder: "how does that thing ever get off the ground?" You know it's because of the wing that it stays up in the air, but how does it really work? Man has always watched birds as they take flight and wondered how these creatures can take to the sky while the rest of us remain earthbound. The key has always been figuring out how the wing works in lifting and propelling birds in flight. After centuries of trial and error, the Wright Brothers took their first powered, heavier than air flight in 1903. What they figured out, and what has since become a major aspect of modern civilization, is the "airfoil". The wing on an airplane is an airfoil. When air flows around the wing, it creates lift. They way it creates lift is based on the wing's movement through the air and the air pressure created around the wing. An airplane's wing, in varying degrees depending on the type and design of the airplane, is curved over the top of the wing and straighter underneath the wing. This shape is key in how lift is created as the wing moves through the air. As air hits the wing, it is "split in two", with air moving both over and under the wing. Since the top of the wing has more curve than the the bottom of the wing, the air moving over the top of the wing has further to travel, and thus must move faster than the air moving underneath the wing. The air moving over the top of the wing now has decreased air pressure than the slower moving air under the wing. Lift is created. This difference in air pressure is the primary force creating lift on a wing, but one other force exerted on the airfoil helps to produce lift. This is the force of deflection. Air moving along the underside of the wing is deflected downward. We remember that Isaac newton tells us that for "every action, there is an equal and opposite reaction". Thus, the air that is deflected downward (action), helps to push the wing upward (reaction), producing more lift. These two natural forces on the wing, pressure and deflection, produce lift. The faster the wing moves through the air and the greater the forces become, the greater the lift. The physics and math get a little more complicated when figuring just how to build a wing to produce the required lift for a particular airframe, and other components are needed to control and stabilize the airplane in flight. The components include the vertical fin, rudder, horizontal stabilizer, and elevator (which can be collectively termed the "tail" of the airplane). But all these elements, like the wing, are airfoils and operate in accordance with these basic principals of pressure and deflection as they move through the air. A propeller is also an airfoil, and it produces "horizontal" lift, pulling the airplane forward. Depending on choice of viewpoint, it can be said the airplane is drawn forward into the vacuum of a low pressure area created by the spinning airfoil we know as a propeller.(The reaction being thrust.)The wing of an airplane can also be said to induce a draw of the airplane upward into this airfoil created vacuum depending on how you care to view the pressure difference. The key to understanding more completely what an airfoil is doing is the knowledge that air it's self has a degree of mass. The more condensed the air, the more the airfoil (the wing, the prop, or the jet engine), has to work with. This is what restricts airplanes to altitudes that have air mass. So although airplanes are lifted and held up by pressure difference they ride on air mass. (jet engines are beyond the scope of this article, but they push air through their internal components at very high pressure, creating the required forward motion) As that giant jetliner rumbles down the runway, faster and faster, until it finally lifts of the ground and into the sky, you'll be secure in the knowledge that what is lifting the craft into the air are basic laws of physics. The same laws of physics that have lifted our feathered friends into the air for millions of years!

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Airplanes are able to fly because of bernoulli's principle. The wings are shaped so that when they are moving fast enough they create a low pressure area above the wing and a high pressure below, causing lift.

Aircraft engine produces thrust which pulls the aircraft forward. The Aircraft wing is designed in a shape called 'aerofoil' which has curve on top and almost flat surface at bottom. When the aircraft is moving forward through air due to thrust produced by engine, the air flows with more speed over wing and with less speed below the wing (as air has to travel more distance above the wing within the same time) which produces a low pressure above the wing.

This low pressure produces 'lift' which make aircraft fly.
Bernoulli's Principle:

For an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in Pressure.

An Aircraft makes use of this principle to fly. The flaps and the shape of the wings create a speed differential between air flowing past the top and bottom of the wings. This leads to a pressure difference between the top and bottom, resulting in the requisite lift.

The wing is shaped like an aerofoil (check related link). This controls how efficient the whole operation is. Air traveling over and under the wing of an airplane is deflected downwards and causes it to be lifted. This is known as aerodynamics. Air traveling over the curved upper surface of the wing moves fast. This air becomes low pressure. The air traveling under the wing moves slower and maintains a higher pressure. As the speed of the airplane increases, the pressure over the wing becomes far less then the pressure under the wing, and the airplane is lifted up.

When the air moves fast enough over the top of the wing, due to centrifugal force, it is lifted up off of the top hump of the wing, creating an area of low pressure below that. Again, that low pressure is created because the centrifugal force of the air flowing over the top of the wing causes it to lift up for a second over the top hump of the wing, creating low pressure below it.

Newton's Third Law:

For every action, there is an equal and opposite reaction.

There is a large amount of air being forced down by the wings. After the air flows over the top of the wing, due to the shape of the wing, that air also flows downwards, creating an upward force on the wing. Thus, the opposite force would be the air keeping the airplane up.

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A plane flies because of the shape of its wings. The tops of the wings have a larger surface area, a greater curve than the bottoms. The same is true for a bird.

When the plane develops forward motion through the air, from the thrust of its engines, air molecules are forced above and below the wings. Because the top of the wing has a larger surface area than the bottom, the air molecules become more rarefied there, and of a lower pressure than they were before they encountered the wing. The air molecules that go just below the wings do the opposite, and are compressed to a high pressure.

The difference in pressures causes a net force to be applied to the wings of the airplane, in the opposite direction of gravity, namely up. Gasses and other fluids are compelled to move from a place of higher pressure to a place of lower pressure, or at least to try. Planes fly because differences in pressure create forces that push them upward.

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Four forces keep an airplane in the sky. They are lift, weight, thrust and drag.

Lift pushes the airplane up. The way air moves around the wings gives the airplane lift. The shape of the wings helps with lift, too.

Weight is the force that pulls the airplane toward Earth. Airplanes are built so that their weight is spread from front to back. This keeps the airplane balanced.

Thrust is the force that moves the airplane forward. Engines give thrust to airplanes. Sometimes an engine turns a propeller. Sometimes it is a jet engine. It doesn't matter as long as air keeps going over the wings.

Drag slows the airplane. You can feel drag when you walk against a strong wind. Airplanes are designed to let air pass around them with less drag.

An airplane flies when all four forces work together. But, most airplanes need one more thing: They need a pilot to fly them!

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A airplane flies by balancing the force of gravity against the lift generated by its wings while at the same time balancing thrust of its engines against drag caused by the air stream going by it.
by creating a low pressure ontop of the wing creates lift for the plane
The engines give thrust to move plane though the air at high velocity. The uneven design of the wing makes it possible to lift the plane up. By making sure that more air moves below the wing than above it is possible to create an air pressure gradient. This means that air below the wing will actually lift the plane up (air pushes stronger below the wing than above), while engines provide necessary horizontal speed.

air> `````````````` <- lower pressure

wing> --------- ``````

air> ``````````````<- higher pressure

^

^

lift
by newtonslaw There is a large amount of air being forced down by the wings. After the air flows over the top of the wing, it makes this shape like aierfoil.

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2017-08-14 06:42:41
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Wiki User

2013-04-03 23:52:45

The way an airplane flies is based on 'Bernoullie's

Principle'. This principle explains that fast moving air creates low pressure, and slow moving air creates high pressure. When an airplane flies, some of the air flows over the top of the curved part of the wings, and some go underneath the flat part of the wings. The air that flows over top of the wing is fast moving air, which is low pressure, and the air that flows underneath the wing is high pressure. Since the slow moving air that is high pressure is flowing under the wing, it pushes it up, and there is less pressure from the top, not pushing it down, thus causing lift.

sail plans have specially designed wings that enable them to fly for hours at a time this is possible because of the raising air created from thermals ,slope

and wave just like soaring birds like hawks, falcons and buzzer that sustains its flight. But the most important is the wing. The wings a very long and thin so that there is reduced drag. the air foil is thin also the shape is semi symmetrical and the bottom tail end is pitched up so its stable and creates more lift

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Anonymous

Lvl 1
2020-07-07 23:20:43

Buoyancy like a boat to put it in simple terms. A boat floats because of pressure displacement differential. Same with an airplane. If there is not enough air to displace the aircraft it will never leave the ground. Same with a boat. If a boat weighs 10 tons and there is only 8 tons of water the boat won’t float.

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