Why does the plane take so long to gain altitude? Let's lift the curtain. How do planes take off? “The turbines turned off a couple of times.”

It is very interesting to watch an airplane take off, when a heavy machine turns into a light-winged bird.

The lowest speed at which an aircraft can fly is, as we already know, the minimum speed of horizontal flight. But at this speed the plane is still not stable enough and is poorly controlled. Therefore, the pilot takes off the aircraft from the ground at a slightly higher speed. After liftoff, the pilot continues to accelerate the aircraft, as they say, “holding” the aircraft above the ground until the speed is sufficient for safe ascent.

Thus, the takeoff of an aircraft can be divided into three stages: takeoff, staying above the ground to increase speed, and ascent (Fig. 25, a).

These three stages make up the so-called take-off distance.

Let's see how the pilot takes off, what forces act on the plane during the takeoff, and how acceleration is created). For the sake of simplicity, we will again assume that all the main forces are applied at the center of gravity of the aircraft, that is, their moments are equal to zero (since now we are interested in the forces, not their moments).

Here the plane is standing at the start, ready to fly, and the engine is running at low throttle (Fig. 25, b). The propeller thrust is still insufficient to overcome the friction force of the wheels on the ground. But the pilot gave full throttle, the propeller thrust increased to maximum and the plane began to take off. Excess thrust creates acceleration, and speed increases. To increase speed faster, the pilot slightly deflects the elevator down, so the tail of the aircraft rises and the angle of attack of the wing decreases (Fig. 25, b). As the speed increases, the lifting force of the wing increases, and soon the plane's wheels barely touch the ground. Finally, the lifting force becomes equal to the weight of the aircraft, then a little more, and the machine lifts off the ground (Fig. 25, b). The takeoff run is over - the plane has taken off.

The car flies low for some time, picking up speed. Then the pilot turns the steering stick toward himself and switches the plane to the ascent mode (Fig. 25, a).

When climbing onto an airplane, the same forces act as during horizontal flight, but their interaction is somewhat different (Fig. 26).

The lift of a wing is always perpendicular to the direction of flight. Therefore, during lifting, it is no longer directed vertically and, therefore, cannot completely balance the force of the weight. If we decompose the weight force into two terms of force, as shown in Fig. 26, it becomes clear that the lifting force of the wing can balance only one of them - B. The other component of the weight force - B2 - together with the drag must obviously be balanced by the thrust force of the propeller.

When an airplane gains altitude, the lift on the wing is less than the weight of the airplane. Why, then, does the plane gain altitude? The fact is that the propeller thrust here not only overcomes the drag, but also takes on part of the weight of the aircraft, as shown in the figure. In other words, when an airplane rises, the thrust force partially plays the role of a lifting force.

And if the plane could rise vertically upward, then the fixed wing would become completely useless - the machine would be lifted upward solely by the thrust of the propeller. The plane would turn into a helicopter.

When ascending, the aircraft gains a certain altitude every second, which is called the vertical rate of ascent. For example, the vertical speed of a Yak-18 aircraft at the beginning of its ascent is 4 meters per second. But then it decreases.

Why does this happen and what does it lead to?

As you rise in altitude, the air density becomes less and less, so less oxygen is supplied to the engine cylinders needed for fuel combustion, and as a result, power power plant falls. Consequently, the excess power required for lifting is reduced. And finally, at some altitude there is no longer any excess power, and the plane cannot continue to climb. The altitude at which this occurs is called the "ceiling" of the aircraft.

IN passenger aviation The flight altitude is determined by the technical capabilities of the aircraft and established rules. The height can be maximum and ideal. The choice of altitude does not depend on the decision of the commander; he is limited in his actions by ground services.

Why 10 thousand?

The liner reaches the ideal ten kilometers in 20 minutes. If the flight does not exceed half an hour, such a need does not arise. The decision whether to maintain the corridor or go up another one to two thousand depends on the situation. The higher the aircraft rises, the thinner the atmosphere becomes. It creates less drag, which reduces the amount of fuel burned to overcome it. In the atmosphere at an altitude of 10 thousand, the amount of oxygen necessary to ensure the combustion process of kerosene is retained. Birds do not fly at this altitude; a collision with them will cause an accident.

The decision on flight altitude is made by ground control services.

They give commands to pilots based on objective factors:

weather;
wind speed at the surface of the earth;
vessel weight and technical characteristics Oh;
flight time and distance;
direction: west or east.

The selected altitude is defined in flight rules as flight level. Air law defines uniform flight levels for airspace all countries. If the ship is flying east, the dispatcher has the right to choose odd levels of 35, 37, 39 thousand pounds ( from 10 to 12 kilometers). For aircraft traveling to reverse direction, even echelons are offered. This is 30, 36, 40 thousand pounds above sea level ( from 9 to 11 kilometers). This tactic is aimed at avoiding collisions. The flight level is calculated before the vehicle takes off.

Affects height and range of flight, on small routes, gaining altitude is impractical. The ship's commander determines the altitude using a barometer installed on board.

This video explains why planes fly:

Maximum height

The maximum altitude is directly related to the maximum speed. At a speed of 950-1000 kilometers per hour, the altitude reaches 10 kilometers. For small private jets the ratio will be 300 km per hour and 2000 thousand meters.

It is not only the aircraft model that determines its maximum possible altitude, but also the physical characteristics of the atmosphere. Aircraft specifications are different for passenger and military air transport vehicles.

The maximum height is determined by:

technical characteristics are engine power and wing lift;
make and type of vessel;
aircraft weight.

The Russian TU-204 can reach an altitude of no more than 7200 meters. The IL-62 will rise 11 kilometers, the same amount as the Airbus A310. The newest Irkut MS-21, which first took to the skies on May 28, 2017, will be able to gain 11.5 kilometers due to its low mass. The leader among new products in the industry, the Sukhoi Superjet SSJ 100SV, already rises to 12,200 meters.

Before Sukhoi’s development entered the market, only Boeing managed to exceed the 12 thousand limit.

There are altitude limits related to the amount of oxygen in the atmosphere. They depend on the type of engine. An airplane with a turbojet engine can reach 32 thousand meters, for ramjet air jet plane the limit will be higher, it will be 45 thousand meters.

The maximum altitude of a turbojet military vessel can exceed 35 thousand meters; the Russian MIG-25 managed to reach it.

Watch a video about how Mig 25 rises into the stratosphere

Ideal height

The definition refers to the same altitude in the range of 10-12 thousand meters, where the ideal air flow density is observed. They are sufficiently discharged to reduce the friction of the sides with the air and fuel consumption. Their density remains sufficient to support the wings of the aircraft. When entering the stratosphere, the level of support drops and the aircraft begins to “collapse.”

Taking these parameters into account, the pilots developed a definition of the “ideal” corridor. Coming down from it increases fuel consumption, the economic efficiency of the flight decreases along with its altitude, so in any situation the pilot would rather increase the altitude than decrease it.

Within the allocated flight level, the pilot himself decides on the altitude, taking into account the current ratio of friction and support, taking into account the technical characteristics of the vessel. Often the change in altitude is associated with turbulence, but it is also coordinated with ground services. Clouds are more often overcome when rising above their level, and the closure of space over the region due to military operations or mountain peaks can also cause a change in height.

Remember. Changing flight levels is possible only when leaving the route at a distance of 20 kilometers and in agreement with ground services.

How tall are Boeing 747 and 737?

Models of the American corporation also fly on Russian flights. Among wide-body passenger aircraft it is most often used by airlines due to the cost-effectiveness of mass transportation. Five Boeing 747s belong to Rossiya Airlines. The maximum speed of the vessel is 988 km per hour for the 747-8 modification, the maximum altitude to which it can rise is 13,700 meters.

Boeing 737 gains a lower altitude, the ceiling is 12,500 meters for the 737-800 model and 11,300 meters for the Boeing 737-500. The ability to reach such an altitude ensures fuel efficiency of flights. The designers envision the release of the Boeing 737 MAX 8, which should further improve these characteristics.

In aviation, the optimal heights of air corridors for all types of aircraft have been calculated. Pilots must adhere to the instructions of air traffic control services, retaining freedom of maneuver and the right to make independent decisions in a critical situation. The safety of the airspace depends on the coordinated actions of the crew and ground controllers in choosing the maximum altitude.

Many people are interested in the speed of an airplane during takeoff. Some are interested because they are curious about the history of aircraft, while others are interested because they are about to begin their first flight. There are a large number of opinions on this topic, and many of them, as always, are wrong. Nevertheless, it is precisely this moment of lifting off the ground that is one of the most important and longest processes for any air transport. This topic will be discussed in more detail below.

The take-off phase takes all the time from the start of movement until complete separation from the surface of the canvas. However, there are several important nuances- the resulting lifting force must exceed the mass of the ascending aircraft, so that it can eventually gradually break away from. Moreover, each air transport model has its own ability to gain speed on the runway. For example, at passenger airliners the engines switch to a special mode that lasts a couple of minutes, which allows you to climb as quickly as possible. However, it is rarely used near settlements so as not to bother local residents with noise.

Takeoff types

There are a number of factors that pilots must constantly consider when beginning the takeoff phase. Mainly weather, direction and strength of the wind (if the wind blows directly “in your face”, the plane will have to gain much more speed to rise, in addition, sometimes a strong wind can deflect the aircraft to the side), limitations runway and engine power. And there is also great amount various little things that ultimately have a critical impact on the process. All this forced aircraft designers to work to improve models of flying machines.

Heavy transport airliners have two takeoff options, namely:

The aircraft is able to gain speed only after the engines have generated the necessary thrust. Until this moment, the plane simply stands on the brakes.
The classic takeoff occurs immediately after a short stop. In this case, no preliminary power generation of the engines is required. The plane simply accelerates and rises into the sky.

Other types of aviation, mainly military, use their own methods, for example:

Aircraft serving on aircraft carriers take off with the help of a whole system of auxiliary aids. Catapults and various springboards are also used; in special cases, additional engines are even installed on fighters.
Vertical take-off is used only for those aircraft that have a vertical thrust engine. A good example is the Yak-38. In this case, the aircraft gradually gains altitude from a standstill or immediately goes into horizontal flight from a slight acceleration.

The typical takeoff speed at which a jet like a Boeing 737 leaves the ground is 220 km/h. While another model under the symbol 747 already requires 270 km/h. Sometimes this may not be enough. This is especially pronounced in strong winds. In such cases, a longer takeoff distance is required.

Humanity has long been interested in the question of how it turns out that a multi-ton aircraft easily rises to heaven. How does take-off happen and how do planes fly? When an airliner moves at high speed along the runway, lift is generated at the wings and works from the bottom up.

When an aircraft moves, a pressure difference is generated on the lower and upper sides of the wing, resulting in a lifting force that keeps the aircraft in the air. Those. High air pressure from below pushes the wing upward, while low air pressure from above pulls the wing towards itself. As a result, the wing rises.

For an airliner to take off, it needs a sufficient runway. The lift of the wings increases as the speed increases, which must exceed the limit takeoff mode. Then pilot increases takeoff angle, taking the helm to himself. Bow The liner rises up and the car rises into the air.

Then landing gear and exhaust lights are retracted. In order to reduce the lifting force of the wing, the pilot gradually retracts the mechanization. When the airliner reaches the required level, the pilot sets standard pressure, and engines - nominal mode. To see how the plane takes off, we suggest watching the video at the end of the article.

The aircraft takes off at an angle. From a practical point of view, this can be explained as follows. The elevator is a movable surface, by controlling which you can cause the aircraft to deflect in pitch.

The elevator can control the pitch angle, i.e. change the rate of gain or loss of altitude. This occurs due to changes in the angle of attack and lift force. By increasing the engine speed, the propeller begins to spin faster and lifts the airliner upward. Conversely, by pointing the elevators down, the nose of the aircraft moves down, and the engine speed should be reduced.

Tail section of an airliner equipped with a rudder and brakes on both sides of the wheels.

How airliners fly

When answering the question why planes fly, we should remember the law of physics. The pressure difference affects the lift of the wing.

The flow rate will be greater if the air pressure is low and vice versa.

Therefore, if the speed of an airliner is high, then its wings acquire a lifting force that pushes the aircraft.

The lifting force of an airliner wing is also influenced by several circumstances: angle of attack, speed and density of air flow, area, profile and shape of the wing.

Modern airliners have minimum speed from 180 to 250 km/h, during which the takeoff takes place, plans in the skies and does not fall.

Flight altitude

What is the maximum and safe flight altitude for an aircraft?

Not all ships have the same altitude, the “air ceiling” can fluctuate at altitude from 5000 to 12100 meters. At high altitudes, air density is minimal, and the airliner achieves the lowest air resistance.

The airliner engine requires a fixed volume of air for combustion, because the engine will not create the required thrust. Also, when flying on high altitude, the aircraft saves fuel up to 80% compared to an altitude of up to a kilometer.

What keeps a plane in the air?

To answer why airplanes fly, it is necessary to examine one by one the principles of its movement in the air. A jet airliner with passengers on board reaches several tons, but at the same time, it easily takes off and carries out a thousand-kilometer flight.

The movement in the air is also influenced by the dynamic properties of the device and the design of the units that form the flight configuration.

Forces affecting the movement of an aircraft in the air

The operation of an airliner begins with the engine starting. Small ships run on piston engines that turn propellers, creating thrust that helps aircraft move in airspace.

Large airliners are powered by jet engines, which emit a lot of air as they operate, and the jet force propels the aircraft forward.

Why does the plane take off and stay in the air for a long time? Because the shape of the wings has a different configuration: round at the top and flat at the bottom, then the air flow on both sides is not the same. The air on top of the wings glides and becomes rarefied, and its pressure is less than the air below the wing. Therefore, through uneven air pressure and the shape of the wings, a force arises that leads to the plane taking off upward.

But in order for an airliner to easily take off from the ground, it needs to take off at high speed along the runway.

From this it follows that in order for an airliner to fly unhindered, it needs moving air, which the wings cut and creates lift.

Airplane takeoff and speed

Many passengers are interested in the question: what speed does the plane reach during takeoff? There is a misconception that the takeoff speed is the same for every aircraft. To answer the question, what is the speed of the aircraft during takeoff, you should pay attention to important factors.

An airliner does not have a strictly fixed speed. The lifting force of an airliner depends on its mass and the length of the wings. Takeoff occurs when a lifting force is created in the oncoming flow, which is much greater than the mass of the aircraft. Therefore, the takeoff and speed of the aircraft depends on the direction of the wind, atmospheric pressure, humidity, precipitation, length and condition of the runway.
To create lift and successfully lift off the ground, the aircraft needs reach maximum takeoff speed and sufficient takeoff run. This requires long runways. The larger the aircraft, the longer the runway is required.
Each aircraft has its own takeoff speed scale, because they all have their own purpose: passenger, sport, cargo. The lighter the aircraft, the significantly lower the takeoff speed and vice versa.

Boeing 737 passenger jet take off

The take-off run of an airliner on the runway begins when the engine will reach 800 rpm per minute, the pilot slowly releases the brakes and holds the control lever at a neutral level. The plane then continues on three wheels;
Before leaving the ground The speed of the airliner should reach 180 km per hour. The pilot then pulls the lever, which causes the flaps to deflect and raise the nose of the aircraft. Further acceleration is carried out on two wheels;
After, with the bow raised, the airliner accelerates on two wheels to 220 km per hour, and then lifts off the ground.

Therefore, if you want to learn more about how a plane takes off, to what altitude and at what speed, we offer you this information in our article. We hope that from air travel you will have great fun.

Does an airline passenger moving from one point on the planet to another wonder: what was the speed of the plane during takeoff? Or the sensations are enough for him: the beginning of movement; speed dial; separation Most likely the latter assumption. Details are a matter for specialists.
Long ago, more than a century ago, man overcame gravity and soared like a bird. What was more in this indomitable desire to rise into the air? Romantics of flight? Or naked rationalism? Or maybe someone tried to confirm their scientific calculations in this way? History is silent about this, and the facts dryly list the number of disasters and victims that mark the path to heaven.
Aircraft. They really look like birds. Big and small birds. Large and small aviation. Birds of prey. Military aviation. Migratory birds. Passenger Airbuses. There is an analogy everywhere.
In order to take to the air, many birds gain momentum on land or water. Airplanes scatter along the runway, and seaplanes across the water surface. What speed should be developed from the starting point to the take-off point? How much effort should you put into this? Birds are guided by innate instinct, and humans are guided by accumulated knowledge, experience and precise physical and mathematical calculations.
What do you need to be able to do to lift a multi-ton structure off the ground? What do you need to know to design and build an airplane? All the basic laws of physics are woven into a “Gordian knot”, which is cut by the sharpness and accuracy of calculations of power and aerodynamic characteristics.
It can be strange to see how a clumsy-looking “transporter”, having slightly run up, slowly but surely rises above the ground. And, on the contrary, a lean fighter rushes and rushes along the runway and only when it seems that he will not have enough space, he soars up.
What is more important during takeoff – speed, shape or weight? And where does the takeoff begin? At the moment of lifting off the ground? Or when reaching a certain altitude? And if you take off from the take-off pad - that means take off, then vertical take-off aircraft, in general, at this stage have a speed close to zero.
Technically, takeoff is considered to be the movement of an aircraft with acceleration from the start of the takeoff run to the rise to a 25-meter altitude.
At selected airports where traffic volumes aircraft very high, the plane takes off immediately after taxiing to the runway, without stopping. Take-off with brakes involves the engines gaining maximum power in a static state. After which the brakes are smoothly released, and the plane begins its takeoff run. Takeoff with a short stop is a kind of intermediate option.
At the moment of acceleration, lift-off and take-off, the aircraft engines operate under rated load, both mechanical and thermal. This mode can only be used for a short time.
There is one indispensable component in the acceleration of an aircraft - the speed of decision-making. That is, the speed at which, in the event of a malfunction of the engines or detection of any other malfunction, emergency braking is possible, without catastrophic consequences. If this speed is overcome, then there is only one way out - takeoff with a subsequent glide path. Fortunately, the technical equipment of modern aircraft allows the aircraft to be lifted into the air, even if one of the engines malfunctions.
Wing mechanization is of great importance during acceleration and takeoff of an aircraft. Flaps, fender liners, spoilers, spoilers and other elements collectively affect the load-bearing properties of the wing. For example, retractable flaps, increasing the wing area, make it possible to reduce takeoff speed. The flaps are extended immediately before acceleration.
While the aircraft is speeding along the runway with the front wheel centered and locked, adjustments to the aircraft's movement, if necessary, are made by braking the main wheels.
Upon reaching takeoff speed, the pilot smoothly takes the helm, thereby increasing the angle of attack. First, the nose of the aircraft rises, then the entire aircraft lifts off the ground. Having overcome the five-meter height, the crew retracts the landing gear.
Takeoff is considered complete when the aircraft reaches transition altitude. The transition altitude is a conventional unit, not tied to height relative to the runway or “sea level”. It is generally accepted by all international dispatch services and is determined by a preliminary “echelon”. In the transition altitude position, the crew has no right to continue horizontal flight. The plane climbs to altitude and takes up its “working” flight level, along which it continues its route.
For each type of aircraft there is a certain average takeoff speed. So, for a Boeing 747 it is approximately 270 km/h; for Airbus A300 - 300 km/h; for TU 154 M – 210 km/h; for IL 96 – 250 km/h; for Yak 40 – 180 km/h.
However, we should not forget that the lift-off speed directly depends on the specific load on the wing and air density. That is, the lower the air density (high altitude, summer heat), the lower the lift coefficient, and the higher the lift-off speed should be.
In some emergency cases (insufficient runway length), an explosive takeoff can be performed. In this case, the pilot, using the steering wheel, sharply changes the angle of attack, thereby significantly increasing the lift, but at the expense of speed. The maneuver itself is very dangerous, threatening loss of control.
On the contrary, when an aircraft takes off, there is such a moment as “holding.” The pilot does not immediately bring the car to the transition altitude, but directs it along a slight upward angle, continuing to gain speed.
Loss of speed during takeoff is especially dangerous because the plane, at this moment, is maximally loaded with fuel, which significantly increases the total weight. Large weight increases uncontrollable inertia, which can lead to an aircraft crash.
IN winter time, an increased coefficient is included in the take-off speed in case of temperature differences in altitude. The upper air layers can be much warmer than the aboveground layers. As a result, the air density drops sharply and the “failure” of the aircraft, followed by a fall, is inevitable.
Such “surprises” are provided for by the staff of ground and air meteorological services, which provide information to dispatchers, and dispatchers are always in touch with aircraft crews.
There is no need to worry if flight safety is handled by professionals.

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