How does an airplane lift off? How does an airplane take off?

The principle of aircraft lift-off is Bernoulli's principle, that is, the greater the flow velocity of a fluid (including air flow and water flow), the lower its pressure; The lower the velocity, the greater the pressure, and as the air flows through the wing (which is low and flat), the upper and lower sides of the wing generate different pressures. And the lower surface pressure is high, and the upper surface pressure is small. The pressure difference creates an upward lifting force that moves the aircraft upwards.

The airplane lifts off according to Bernoulli's principle, when the pressure under the wing is strong and the pressure above the wing is small, an upward thrust will be formed.

It should be the flow of air, and it's the wings of the plane, and then it's streamlined, so it's going to take off, and it's because of the power of the plane.

Summary. Hello, dear <>

We'll be happy to answer for you. The principle of airplane lift-off is aerodynamics. Powered by air!

If the aircraft is propelled in the air, it can fly off the ground when it reaches a certain speed and other conditions, and the aircraft is powered by the power plant to generate forward momentum, and the fixed wings are used to generate lift, and after reaching a certain lift, it can be lifted into the air. <>

How does an airplane lift off?

Hello, dear <>

We'll be happy to answer for you. The principle of airplane lift-off is aerodynamics. Powered by air!

If the aircraft is propelled in the air, it can fly off the ground when it reaches a certain speed and other conditions, and the aircraft is powered by the power plant to generate forward momentum, and the fixed wings are used to generate lift, and after reaching a certain lift, it can be lifted into the air. <>

Most aircraft consist of five main parts: wings, fuselage, tail, landing gear, and power plant. The flight of an airplane has two problems to solve:

One is the rise; The second is to move forward, which depends on the forward traction generated by the power of the engine to drive the propeller to rotate or the forward thrust generated by the jet. The ascent is based on Bernoulli's principle, which states that the greater the velocity of a fluid (including air and water), the less its pressure; The smaller the flow velocity, the greater the pressure. Also, lift and angle of attack have a lot to do with it.

First, inertia converts kinetic energy into potential energy until the potential energy and kinetic energy are balanced; Second, the air convection produces a lifting force that breaks the balance, making the lifting force bigger and bigger, that is, the potential energy is getting bigger and bigger, until the plane takes off. For example, the process of an airplane taxiing and taking off on the runway is a process of potential energy equal to kinetic energy plus lifting force and balance.

Junior high school physics has a detailed explanation of fluid pressure! When the airplane is fast enough, the air velocity difference will form between the upper and lower wings, and the pressure difference between the upper and lower wings will act on the wings to produce a lift! The lift is large enough and the plane takes off!

There is a difference in air velocity between the upper and lower wings, which causes the aircraft to generate lift, hydrodynamics, go and see!

It's very complex, to be precise, some aerodynamics, generating an upward force.

The airplane mainly uses the upper and lower surface areas of the wings to flow air at different speeds, resulting in pressure differences. The use of pressure difference to make the aircraft float in the air is the principle of fixed-wing aircraft take-off.

The take-off principle of the aircraft relies on the engine backjet take-off.

The take-off of an airplane depends on the lift generated by the relative motion with the air, and the magnitude of the lift depends on the relative speed of the aircraft with the air, not the relative speed of the aircraft with the ground. If taking off against a headwind, the aircraft taxiing speed is opposite to the direction of the wind speed, and the relative velocity of the aircraft and the air is equal to the sum of the two.

At this point, the aircraft only needs a small glide speed to get the lift it needs to get off the ground. As a result, the distance required to take off against the wind will be shorter than if it were to take off without wind. Conversely, if taking off downwind, the aircraft needs to reach a higher taxiing speed to get the lift required from the ground, and the glide distance is relatively longer.

Categories: Education Science >> Science & Technology >> Engineering Technology Science.

Problem description: Does an airplane generate a lot of heat when it is in the air?

Analysis: The side profile of the wing is a shape in which the upper edge is arched upwards and the lower edge is basically straight. As a result, the liquid is blown through the upper and lower surfaces of the wing and from the front to the rear at the same time, and the air flow from the upper edge is faster than that of the lower edge (because the upper edge has a large arc and a longer arc length, which means that the distance is longer).

According to the Bernoulli equation of physics, the same fluid flowing through a certain surface has less pressure on the surface at a faster speed. Therefore, it is concluded that the atmospheric pressure on the upper surface of the wing is smaller than that on the lower surface, so that the lift force is generated, and the lift force reaches a certain level, and the aircraft can lift off the ground.

There's a formula that I don't know if you've ever seen: l cl*1 2* *v*v*s.

Its significance is that the lift of an aircraft is the product of the following five quantities:

1.The lift coefficient cl (that c represents the coefficient, l is the corner code, I don't have a character tool can not type), its value is related to many fine variables such as the windward angle of the aircraft, generally in a few tenths, the details are not very affectionate: (

2.One in two is.

3.Atmospheric density (the environment in which the aircraft is located, which can be high or low altitude).

4.The square v*v of the airplane relative to the velocity of the surrounding atmosphere (it can only be expressed as this without a corner code).

5.Wing area s

This formula is only suitable for relatively slow flights, just like the common large and small passenger planes with orange flights, other aircraft (as long as the wings) speed does not exceed Mach 1 can basically be used, but like the fighter that of two or three Mach high-speed flight is not good, if the speed is too large, the air on the surface of the wing of Xiaowuwu will become viscous, to take into account the Reynolds number, at that time there is another formula, very complicated, I don't understand. ：）

I work in a civil aviation company, so the answer should be relatively correct. Hope it helps. ：）

The plane is flown by the principles of aerodynamics, the specific principle is:

The cross-section of the wing of an aircraft is generally rounded and blunt at the front and sharp at the rear, with an arched upper surface and a flat lower surface. When equal mass air passes through both the upper and lower surfaces of the wing, different flow velocities are formed above and below the wing.

The velocity of air passing through the upper surface of the wing is high and the pressure is small; When passing through the lower surface, the flow velocity is small and the pressure is strong, so the aircraft will have an upward resultant force, that is, the upward lift, due to the existence of lift, so that the aircraft can leave the ground and fly in the air. The faster the aircraft flies and the larger the wing area, the greater the lift generated.

The direction of gravity is the opposite of lift, it is a downward force caused by the gravitational pull of the earth, and the magnitude of gravity is affected by the weight of the aircraft itself and the amount of fuel it carries. The pulling force causes the aircraft to fly forward in the air, and the power of the engine determines the amount of pulling force.

In general, the greater the engine output, the greater the thrust generated and the faster the aircraft can fly. When the aircraft is in the air, it is hindered by atmospheric molecules in the air, and this obstacle forms a drag force that is opposite to the direction of the pulling force, limiting the flight speed of the aircraft.

The study of aerodynamics can be traced back to early human speculations about the forces experienced by birds or projectiles in flight and the way they act. In the late 17th century, Huygens, a Dutch physicist, was the first to estimate the resistance of an object to move in the air;

In 1726, Newton applied the principles of mechanics and deductive methods to conclude that the force on an object moving in air is proportional to the square of the speed of the object's motion and the characteristic area of the object and the density of the air. This work can be seen as the beginning of the classical theory of aerodynamics.

When the flight speed or flow speed is close to the speed of sound, the aerodynamic performance of the aircraft changes sharply, the drag increases suddenly, and the lift drops sharply. The extreme deterioration of the maneuverability and stability of the aircraft is the famous sound barrier in the history of aviation.

The advent of high-thrust engines broke through the sound barrier, but did not solve the complex problem of transonic flow very well. Until the 60s of the 20th century, due to the requirements of transonic cruise flight, maneuvering flight, and the development of high-efficiency jet engines, the study of transonic flow has received more attention and has developed greatly.

The overall design of the aircraft is based on aerodynamics, why the aircraft can fly, how to take off, land, and maneuver in the air, all relying on the aerodynamic design of the aircraft.

The principle of aircraft take-off: take-off, accompanied by the thrust brought by the engine, gives the aircraft a speed of rapid forward movement, so that the air and the aircraft produce relative motion, the air flows through the wing, due to the streamlined design of the wing, resulting in the pressure difference between the upper and lower surfaces, so as to produce upward lift, so that it is balanced with the aircraft's own gravity, and climb, of course, when taking off, the pilot will have a lever action, which is used to control the horizontal elevator located in the tail of the aircraft. In simple terms, it is to increase the attitude of the aircraft to raise its head, so that the aircraft can leave the ground in a short distance.

The principle of aircraft landing: landing, is to reduce the thrust of the engine, so that the speed of the aircraft is reduced, thereby reducing the speed of air flow through the wings, thereby reducing the lift, so that the aircraft falls, the process of landing is relatively complicated, because you have to control the aircraft at a relatively slow speed, while flying forward, while descending, but also to avoid stalling. Also strive to ground at the head of the runway.

During this period, it is necessary to adjust the wind direction and speed, and also put flaps, decelerate, increase lift, and adjust the angle of descent. Overall, it is a complex and important process.

Why can airplanes take off and land, and what principles are used? Today I know it.

It depends on the principle that the air velocity is large and the local pressure is small.

The process of generating the principle of aircraft lift.

In a real wing that generates lift, the airflow always converges at the trailing edge, otherwise there would be a point at which the airflow velocity is infinity at the trailing edge of the wing. This condition is known as the Kuta condition, and only when this condition is met can the wing generate lift. In an ideal gas or at the beginning of the wing's movement, this condition is not satisfied, and a viscous boundary layer is not formed.

Usually the airfoil (wing cross-section) is longer than the lower distance, at the beginning of the absence of circulation, the upper and lower surface airflow velocity is the same, resulting in the lower airflow to the trailing edge when the upper airflow has not reached the trailing edge, the rear station is located at a point above the airfoil, the lower airflow must bypass the sharp trailing edge and meet the upper airflow.

Due to the viscosity of the fluid (i.e., the Conda effect), a low-pressure vortex is formed as the lower airflow wraps around the trailing edge, resulting in a large backpressure gradient at the trailing edge. Immediately, this vortex will be washed away by the incoming current, and this vortex is called the starting vortex. According to Heimholtz's law of conservation of vortices, for an ideal incompressible fluid, there will also be an eddy around the airfoil in the opposite direction to the strength of the starting vortex under the action of force, which is called circulation, or circumferential circumference.

The circulation flows from the leading edge of the upper surface of the wing to the leading edge of the lower surface, so the addition of the circulation and the incoming flow causes the rear station to eventually move back to the trailing edge of the wing, thus satisfying the Kuta condition. The circumference generated by satisfying the Kuta condition causes the airflow on the upper surface of the wing to accelerate backwards, and the pressure difference can be deduced from Bernoulli's theorem and the lift force can be calculated.

The magnitude of the lift resulting from this ring can also be calculated by the Kuta-Zhukovsky equation: l (lift) = v (gas density, flow velocity, ring value), and the equation also calculates the aerodynamic force of the Magnus effect. According to Bernoulli's theorem – "The faster the velocity of a fluid, the smaller its static pressure (static pressure is the pressure generated by the fluid as it flows perpendicular to the direction of fluid motion).

Therefore, the pressure exerted by the air on the upper surface of the wing f1 is less than the net force of the lower surface must be upward, which produces lift. The principle of lift is that the presence of the ring around the wing (attachment vortex) causes different flow velocities and different pressures on the upper and lower surfaces of the wings.

Hello, I am happy to answer your questions, the flight principle of the aircraft is Bernoulli's principle, the greater the flow velocity of the fluid (including air flow and water flow), the smaller its pressure; The smaller the flow velocity, the greater the pressure. Most airplanes are composed of five main parts: wings, fuselage, tail, landing gear and power plant, the wing provides most of the lift force of the aircraft through the pressure difference between the upper and lower levels, the greater the speed of the aircraft, the greater the pressure difference between the upper and lower pressures of the wings, and the greater the lift force. The forward force of an aircraft is provided by the forward traction generated by the rotation of its propellers or the forward thrust generated by the jet.

Written by a co-pilot.

Let's start by looking at how airplanes fly.

Among them, the most important thing is, of course, speed, only when the speed is enough, the plane can leave the ground. So what does adequate speed mean? Means that there is enough airflow through the wings of the aircraft.

The design of the wings of the aircraft is very complex, and if you look at it from the side, most of the wing profiles resemble the appearance of a Don. If you place the two wings opposite each other (top surface to top surface), you will see that the two wings form a shape that resembles a horn.

According to Bernoulli's law, we know that when a fluid flows through a relatively narrow space, the velocity of the fluid increases, and at the same time, the kinetic energy increases (the wind blowing in through the cracks in the door or window usually has a high velocity, which is the reason). And because of the conservation of energy, while the kinetic energy of this part of the fluid increases, its potential energy decreases, resulting in a decrease in the pressure on the surroundings. In short, when air flows through a horn, the speed of the flow increases and the pressure (pressure) on the horn wall decreases as it flows through the thinner section of the horn.

As we said earlier, when two wings are placed together, you can form a flar, so when only one wing is placed there, the air flow from the upper surface of the wing can actually have the same effect, that is, the pressure of the air flow on the upper surface of the wing is less than the atmospheric pressure of the external environment.

As for the lower surface of the wing, we assume that it has no effect on the pressure of the airflow. In this way, the pressure on the upper surface becomes smaller, and the pressure on the lower surface remains the same, forming a pressure difference between the upper and lower surfaces, and it is this pressure difference that holds the wing up. The wings are attached to the plane, and the whole plane is held up.

Above we explained why an airplane has speed to have lift.

Then, according to Newton's third law, the airplane accelerates forward on its own, so that a sufficient amount of air flow through its wings, and the effect is the same as when the airplane stops there and allows a strong enough wind to blow in its face. If our plane needs a speed of 100 knots to get off the ground, then park the plane on the ground and let the wind blow at 100 knots, and the plane can get off the ground. In fact, many years ago, on the day of a typhoon, there was a case of a plane parked at the airport that was not reinforced, and began to run around on its own due to strong winds.

Therefore, we know that when the plane enters the runway and is in the right direction, if it is blowing headwind, it is equivalent to helping the aircraft to accelerate. For example, let's say that the plane needs to get off the ground at a speed of 100 knots, but now there is a headwind of 5 knots, then the plane itself only needs to accelerate to 95 knots, and that's fine. (At this time, the airspeed gauge of the aircraft still shows 100 knots, remember, it is the airspeed, and only the airspeed is meaningful to the maneuvering of the aircraft, whether this airspeed is run out of the plane by itself or blown out by the wind of nature.)

And if it is a tailwind of 5 knots, then the plane will have to accelerate to 105 knots before it can get off the ground, which is naturally not what we want.

Well, everyone knows why planes take off and land against the wind.