School Encyclopedia. How an airplane takes off and flies Due to what an airplane can take off

Do you want to overcome your fear of flying? The best way is to learn more about how the plane flies, how fast it moves, and how high it rises. People are afraid of the unknown, and when the issue is studied and considered, then everything becomes simple and understandable. So be sure to read about how an airplane flies this is the first step in the fight against aerophobia.

If you look at the wing, you will see that it is not flat. Its lower surface is smooth, while the upper one has a convex shape. Due to this, as the aircraft speed increases, the air pressure on the wing changes. At the bottom of the wing, the flow velocity is less, so the pressure is greater. From above, the flow velocity is greater, and the pressure is less. It is due to this pressure drop that the wing pulls the plane up. This difference between lower and upper pressure is called wing lift. In fact, during acceleration, the aircraft pushes up when a certain speed is reached(pressure difference).

Air flows around the wing at different speeds, pushing the plane up

This principle was discovered and formulated by the founder of aerodynamics Nikolai Zhukovsky back in 1904, and already 10 years later it was successfully applied during the first flights and tests. The area, wing shape and flight speed are calculated in such a way that multi-ton aircraft can be lifted into the air without problems. Most modern airliners fly at speeds from 180 to 260 kilometers per hour - this is quite enough for confident keeping in the air.

At what height do planes fly?

Do you understand why planes fly? Now we will tell you about the height at which they fly.Passenger aircraft "occupied" the corridor from 5 to 12 thousand meters. Large passenger liners usually fly at an altitude of 9-12 thousand meters, smaller ones - 5-8 thousand meters. This altitude is optimal for the movement of aircraft: at this altitude, air resistance decreases by 5-7 times, but there is still enough oxygen for the normal operation of the engines. Above 12,000, the plane begins to fail - rarefied air does not create normal lift, and there is also an acute shortage of oxygen for combustion (engine power drops). The ceiling for many liners is 12,200 meters.

Note:an airplane flying at an altitude of 10,000 meters saves about 80% of fuel compared to flying at an altitude of 1,000 meters.

What is the speed of the aircraft during takeoff

Let's consider, how does a plane take off . Gaining a certain speed, it breaks away from the ground. At this moment, the airliner is the most uncontrollable, so the runways are made with a significant margin in length. The take-off speed depends on the mass and shape of the aircraft, as well as on the configuration of its wings. For example, we will give tabular values ​​​​for the most popular types of aircraft:

1. Boeing 747 -270 km/h.
2. Airbus A 380 - 267 km / h.
3. IL 96 - 255 km / h.
4. Boeing 737 - 220 km / h.
5. Yak-40 -180 km/h.
6. Tu 154 - 215 km / h.

On average, the separation speed of most modern liners is 230-250 km/h. But it is not constant - it all depends on the wind acceleration, the mass of the aircraft, the runway, the weather and other factors (the values ​​\u200b\u200bmay differ by 10-15 km / h in one direction or another). But to the question: at what speed does the plane take off you can answer - 250 kilometers per hour, and you can't go wrong.

Different types of aircraft take off at different speeds.

At what speed does the plane land

Landing speed, as well as takeoff speed, can vary greatly depending on aircraft models, wing area, weight, wind and other factors. On average, it varies from 220 to 250 kilometers per hour.

Man has always dreamed of flying in the sky. Remember the story of Icarus and his son? This, of course, is just a myth and we will never know how it really happened, but this story fully reveals the thirst to soar in the sky. The first attempts to fly into the sky were made with the help of a huge one, which is now more of a means for romantic walks in the sky, then the airship appeared, and with it, planes and helicopters later appeared. Now it is almost no news or something unusual for anyone that you can fly in 3 hours by plane to another continent. But how does it happen? Why do planes fly and don't crash?

The explanation from a physical point of view is quite simple, but it is more difficult to implement it in practice.

For many years, various experiments were carried out to create a flying machine, many prototypes were created. But to understand why airplanes fly, it is enough to know Newton's second law and be able to reproduce it in practice. Now people, or rather engineers and scientists, are already trying to create a machine that would fly at colossal speeds, several times higher than the speed of sound. That is, the question is no longer how airplanes fly, but how to make them fly faster.

Two things for an airplane to take off are powerful engines and proper wing design.

The engines create tremendous thrust that pushes forward. But this is not enough, because you also need to go up, and in this situation it turns out that so far we can only accelerate along the surface to great speed. The next important point is the shape of the wings and the body of the aircraft itself. It is they who create the uplifting force. The wings are made in such a way that the air below them becomes slower than above them, and as a result, it turns out that the air from below pushes the body up, and the air above the wing is unable to resist this effect when the aircraft reaches a certain speed. This phenomenon is called lift in physics, and to understand this in more detail, you need to have a little knowledge of aerodynamics and other related laws. But to understand why airplanes fly, this knowledge is enough.

Landing and takeoff - what is needed for this car?

An airplane needs a huge runway, or rather, a long runway. This is due to the fact that he first needs to gain a certain speed for takeoff. In order for the lifting force to begin to act, it is necessary to accelerate the aircraft to such a speed that the air from below the wings begins to lift the structure up. The question of why planes fly low concerns precisely this part when the car is taking off or landing. A low start makes it possible for an airplane to rise very high into the sky, and we often see this in clear weather - scheduled planes, leaving a white trail behind them, move people from one point to another much faster than can be done using land transport or sea.

Aircraft fuel

Also interested in why planes fly on kerosene. Yes, basically it is, but the fact is that some types of equipment use the usual gasoline and even diesel fuel as fuel.

But what is the advantage of kerosene? There are several of them.

The first, perhaps, can be called its cost. It is much cheaper than gasoline. The second reason can be called its lightness, in comparison with the same gasoline. Also, kerosene tends to burn, so to speak, smoothly. In cars - cars or trucks - we need the ability to abruptly turn on and off the engine when the aircraft is designed to start it and constantly keep the turbines moving at a given speed for a long time, if we talk about passenger aircraft. Light-engine aircraft, which is not designed to transport huge cargo, but for the most part is associated with the military industry, agriculture, etc. (such a car can only accommodate up to two people), is small and maneuverable, and therefore gasoline is suitable for this area. Its explosive combustion is suitable for the type of turbines that are installed in light aircraft.

Helicopter - a competitor or a friend of the aircraft?

An interesting invention of mankind associated with movement in airspace is a helicopter. He has the main advantage over the aircraft - vertical takeoff and landing. It does not require a huge space for acceleration, and why do planes fly only from seats equipped for this purpose? That's right, you need a sufficiently long and smooth surface. Otherwise, the outcome of the landing somewhere in the field may become fraught with the destruction of the machine, and even worse - human casualties. A helicopter landing can be made on the roof of a building, which is adapted, in a stadium, etc. This function is not available for an aircraft, although designers are already working to combine power with vertical takeoff.

Why do birds fly?

The wing of a bird is designed in such a way that it creates a force that counteracts the force of gravity. After all, the bird's wing is not flat, like a board, but arched . This means that the jet of air enveloping the wing must travel a longer distance along the upper side than along the concave lower side. For both air streams to reach the wing tip at the same time, the air stream above the wing must move faster than under the wing. Therefore, the speed of air flow over the wing increases, and the pressure decreases.

The difference in pressure under the wing and above it creates a lifting force directed upward and counteracting the force of gravity.

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Airplanes are very complex devices, sometimes frightening with their complexity to ordinary people, people who are not familiar with aerodynamics.

The mass of modern air liners can reach 400 tons, but they calmly stay in the air, move quickly and can cross great distances.

Why is the plane flying?

Because he, like a bird, has a wing!

If the engine fails - it's okay, the plane will fly on the second. If both engines failed, history knows cases that in such circumstances they landed. Chassis? Nothing prevents the plane from landing on its belly; subject to certain fire safety measures, it will not even catch fire. But an airplane can never fly without a wing. Because that's what creates lift.

Airplanes continuously "run into" the air with their wings set at a slight angle to the airflow velocity vector. This angle in aerodynamics is called the "angle of attack". The "angle of attack" is the angle of the wing to the invisible and abstract "flow velocity vector". (see fig 1)

Science says that an airplane flies because a zone of increased pressure is created on the lower surface of the wing, due to which an aerodynamic force arises on the wing, directed upwards perpendicular to the wing. For the convenience of understanding the flight process, this force is decomposed according to the rules of vector algebra into two components: the aerodynamic drag force X

(it is directed along the air flow) and lift Y (perpendicular to the air velocity vector). (see fig 2)

When creating an aircraft, great attention is paid to the wing, because the safety of flight performance will depend on it. Looking out the window, the passenger notices that it is bent and is about to break. Do not be afraid, it can withstand just enormous loads.

In flight and on the ground, the aircraft's wing is "clean", it has minimal air resistance and sufficient lift to keep the aircraft flying at high speeds.

But when it comes time to take off or land, the plane needs to fly as slowly as possible so that lift on one side does not disappear, and on the other, the wheels can withstand touching the ground. For this, the wing area is increased: flaps(planes at the back) and slats(in front of the wing).

If you need to further reduce the speed, then in the upper part of the wing are issued spoilers, which act as an air brake and reduce lift.

The plane becomes like a bristling beast slowly approaching the ground.

Together: flaps, slats and spoilers- called mechanization of the wing. Mechanization is released by pilots manually from the cockpit before takeoff or landing.

As a rule, a hydraulic system (rarely an electric one) is involved in this process. The mechanism looks very interesting, and at the same time is very reliable.

On the wing there are rudders (according to aviation ailerons), similar to those of a ship (no wonder the plane is called an aircraft), which deviate, tilting the plane in the right direction. Usually they deflect synchronously on the left and right side.

Also on the wing are navigation lights , which are designed to ensure that from the side (from the ground or another aircraft) it is always visible in which direction the aircraft is flying. The fact is that the left is always red, and the right is green. Sometimes white "flashing lights" are placed next to them, which are very clearly visible at night.

Most of the characteristics of an aircraft directly depend on the wing, its aerodynamic quality and other parameters. Fuel tanks are located inside the wing (the maximum amount of refueling fuel depends very much on the size of the wing), electric heaters are placed on the leading edge so that ice does not grow there in the rain, landing gear is attached to the root part ...

Aircraft speed reached using a power plant or turbine. Due to the power plant, which creates traction force, the aircraft is able to overcome air resistance.

Planes fly according to the laws of physics.

Aerodynamics as a science is based on t theorem of Nikolai Egorovich Zhukovsky, outstanding Russian scientist, founder of aerodynamics, which was formulated in 1904. A year later, in November 1905, Zhukovsky presented his theory of creating the lift force of an aircraft wing at a meeting of the Mathematical Society.

Why do planes fly so high?

The flight altitude of modern jet aircraft is within from 5000 to 10000 meters above sea level. This is explained very simply: at such a height, the air density is much less, and, consequently, the air resistance is also less. Airplanes fly at high altitudes because when flying at an altitude of 10 kilometers, the aircraft consumes 80% less fuel than when flying at an altitude of one kilometer.

However, why then do they not fly even higher, in the upper layers of the atmosphere, where the air density is even less?

The fact is that in order to create the necessary thrust by an aircraft engine a certain minimum air supply is required. Therefore, each aircraft has a maximum safe flight altitude limit, also called the "service ceiling". For example, the practical ceiling of the Tu-154 aircraft is about 12,100 meters.

Planes can fly, since at high speed the wing of the aircraft creates a force pushing the aircraft up. This force is called the lift force of the aircraft wing. According to the laws of physics, air pressure in places where the flow rate is higher will be lower, and vice versa. This pressure difference creates the lift force of the wing.

The scientific basis of aerodynamics is the theorem of the great Russian scientist Nikolai Egorovich Zhukovsky, formulated by him in 1904. Zhukovsky presented the theory of the formation of aircraft lift at a meeting of the Mathematical Society in November 1905.

The wing of a modern aircraft has a sufficient area so that the lift force can lift the aircraft up, even if the aircraft weighs tens of tons. The lift force of a wing depends on many factors: profile, area, wing shape in plan, angle of attack, speed and air flow density. Each aircraft has a minimum speed at which the plane can take off, fly and don't fall. For modern passenger aircraft, it ranges from 180 to 250 km/h.

Why do planes fly so high?
Modern jet aircraft fly at altitudes between 5,000 and 11,000 meters above sea level for a very simple reason: at such altitudes, the air is much less dense, which allows the aircraft to achieve less air resistance. Fuel economy when flying at 10,000 meters can reach 80% of a flight at an altitude of 1000 meters. This is why airplanes fly at high altitudes. However, what prevents them from rising even higher, where the air is even more rarefied? - you ask. The fact is that aircraft engines need a certain minimum amount of air for combustion, otherwise the engine will not be able to create the necessary thrust. Therefore, each aircraft has a so-called "practical ceiling" - the highest altitude at which the aircraft can fly safely. For example, the Tu-154 has a practical ceiling of approximately 12,100 meters.

This short video demonstrates the principle of wing lift:

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We continue to uncover the secrets of civil aviation. Today we will dispel the fears of air passengers from the take-off of a modern airliner.

I was inspired to write an opus now by one of the readers, who sent links to a couple of takeoffs from Kurumoch Airport (Samara), filmed by curious passengers from the cabin.

These videos have attracted comments. Well, here they are:

Comments on it:

And comments

Both cases are united by one sign - the pilots "immediately went to take off!"

Nightmare, isn't it?!

Let's find out!

Experienced passengers probably remember the ritual that is repeated in almost every takeoff of a Soviet airliner - the plane stops at the beginning of the runway, then stops for a while - the pilots let the passengers pray .. but why hide - they themselves "prayed" at that time - that's what they jokingly call reading the checklist. After that, the engines abruptly begin to roar strongly, the plane trembles, the passengers cross themselves ... the pilot releases the brakes and an unknown force begins to press the hushed passengers into their seats. Everything is shaking, the shelves open, something falls on the conductors...

And suddenly, quite by accident, of course, the plane takes off. It gets a little quieter, you can take a breath ... But suddenly the plane starts to fall down!

At the last moment, the pilots, as a rule, "level the liner", after that the turbines "turn off" a couple of times in the climb, and then everything becomes normal. Stewardesses with stone faces carry juices, water, for those who prayed badly - an oxygen mask. And then the main thing begins, for the sake of which passengers fly - they deliver food.

Missed nothing? It seems that I read such reviews about flights more than once on non-core forums.

Let's figure it out.

Right away, let's dot the e about the stop of the liner on the runway before takeoff. What should pilots do anyway - stop or not?

The answer is - and so and so right. Modern takeoff technique recommends NOT stopping on the runway unless there is a good reason for doing so. Under such reasons may be hidden:

a) The dispatcher is still thinking whether to let you out or hold you a little longer
b) The strip has a limited length.

On point A, I think everything is clear.

Regarding point B, I will say the following - if the runway (strip) is really very short, and the plane is loaded so that only the mass passes for this length - in this case it makes sense to save a few tens of meters and bring the engine to an increased mode, keeping the plane on the brakes . Or the runway is just, well, very unusually short, even if the plane is light. In this case, the pilot will also do this "just in case".

For example, we use such a takeoff in Chambery. There, the runway is only two kilometers, and there are mountains ahead. I want to get off the ground as quickly as possible and rush higher. And usually the mass there is close to the maximum possible for take-off conditions.

In the overwhelming majority of cases, if the dispatcher allowed us to take off at the same time as the runway was taken, we will not stop. We will taxi to the center line (and, perhaps, with acceleration), we will make sure that the aircraft is in a stable rectilinear movement, and after that we will “let it go”.

Stop!

How about "pray"? After all, it is written above about a certain "map of control checks!"

On B737, it is customary to read it out before obtaining permission to occupy the lane. And certainly before obtaining permission to take off. So when I get clearance to take off at the same time as clearance to enter the runway, I am ready to take off and I am not in any hurry, as it may seem to the passenger in the cabin. I have everything ready.

So why do it anyway? Why not stand up?

Obvious pluses - increase in throughput of the airport. The less time each individual aircraft occupies the runway, the more takeoff and landing operations can be performed from it.

The second is fuel economy.

The third is safety. Strange as it sounds, it reduces the risk of foreign objects (into the engine) and engine surge (read "failure") when taking off with a strong tailwind.

Here is what Mr. Boeing writes about this:

Yes, the documents of foreign cars are written in English. Do you want to become a pilot? Learn English!

And also Chinese. Neighbor is developing too fast.

We fly further.

Why do pilots turn their nose up so sharply after takeoff? Here, on Soviet technology, they did it smoothly, slowly ... After all, the hour is not even, they will drop what for!

There is naked aerodynamics and a take-off technique. Foreign cars, as a rule, take off with a very small angle of deflection of the wing mechanization (those funny things that especially get out of the wing on landing, and a little on takeoff). This provides many benefits:

a) Increasing angle of set
b) consequence from point A: the noise on the ground is reduced,
c) and further - the chances of not flying into obstacles in the event of an engine failure increase

Yes, modern airliners have such powerful engines that all the normalized climb gradients are achieved even with reduced thrust (it will still be enough if the engine is lost), but in some situations Mr. Boeing strongly recommends taking off at the maximum possible thrust. If the plane is light - it turns out just a cool attraction "Rocket".

Yes, this creates some discomfort for passengers (who like to fly with their legs up) - but it is absolutely safe and will not last very long.

"Almost Fell After Takeoff"

Above, I wrote that the plane after takeoff suddenly "begins to fall down!" This was especially well felt on the Tu-154, which took off with a straining attitude with a rather large flap angle, and then gradually removed them to the zero position. When the flaps are retracted, the aircraft loses part of the increase in lift (if you remove it too quickly, you can actually lose altitude - this is true, but for this you need to be a completely inept pilot, and both pilots must be inept), so it seems in the cabin, that the plane began to fall.

In fact, he can continue to climb at this time. It's just that the angle becomes flatter and at this transitional moment it seems to a person that he is flying down. This is how man is already made.

"The turbines were turned off a couple of times"

Oh, this is the most frequent incident in the stories of passengers! Only "the pilot only got to the airfield on the fifth attempt" can compete with this. This was most typical for the Tu-154 and Tu-134, that is, on aircraft with engines located far in the tail - they are almost inaudible in the cabin, unless they are operating at an increased mode.

The noise is just the same and a snag. Everything is primitive to disgrace. In climb, the engines operate at a very high rate. The higher the engine operating mode, the louder it is heard. But sometimes we, the pilots, have to obey the dispatcher's commands and stop climbing - for example, in order to pass (at a safe distance, of course) with another aircraft. We smoothly transfer the aircraft to level flight, and in order not to turn into a supersonic airliner (after all, engines operating in the set mode create a very large thrust), we have to clean up the mode. The cabin is much quieter.

It seems to be everything.

Thank you for your attention!