How the plane flies, how the plane flies

Airplanes are heavier-than-air aircraft, so they need to expend their own power to gain lift. And the ** of lift is the effect of air on the wing in flight. The upper surface of the wing is curved and the lower surface is flat, so when the wing is in relative motion to the air, the air flowing through the upper surface travels a distance (s1) in the same time (t) than the air flowing through the lower surface (s2), so the relative velocity of the air on the upper surface is faster than the air on the lower surface (v1 = s1 t> v2 = s2 t1).

According to Panulli's theorem – "The pressure exerted by a fluid on the surrounding matter is inversely proportional to the relative velocity of the fluid." ", so the pressure exerted by the air on the upper surface on the wing f1 is less than that on the lower surface f2 . The resultant force of f1, f2 must be upward, which creates a lift force.

From the principle of the wing, we can also understand how the propeller works. The propeller is like a vertical wing, with the bump facing forward and the smooth facing backward. The resultant force of the pressure as it rotates forward, pushing the propeller forward, thus driving the aircraft forward.

Of course, the propeller is not simply raised and smooth, but has a complex curved surface structure. Older propellers were fixed shapes, while later designs were designed with relative angles that could be changed to improve propeller performance. Flying requires power to move the aircraft forward, and more importantly, for the aircraft to gain lift.

Early airplanes were usually powered by piston engines, and four-stroke piston engines were the mainstay. The principle of this type of engine is shown in the figure, which is mainly to inhale air, mix with fuel and ignite and expand, drive the piston to reciprocate, and then convert it into the rotary output of the drive shaft: The power emitted by a single piston engine is very limited, so people connect multiple piston engines in parallel to form a star or V-piston engine.

The picture below shows a typical radial piston engine. Most modern high-speed aircraft use jet engines, the principle is to draw air, mix it with fuel, ignite, ** the expanded air is sprayed backwards, and its reaction force pushes the aircraft forward. In the engine profile below, compressor fans draw in air from the air intake, and compressed air is compressed one by one to make the air better participate in combustion.

The orange-red cavity behind the fan is the combustion chamber, where a mixture of air and oil is ignited, and the combustion expansion is ejected backwards, pushing the last two fans to rotate and finally vent out of the engine. The last two fans are mounted on the same central shaft as the front compressor fan, so they drive the compressor fan to continue to draw in air, thus completing a working cycle.

Fart and fly.!! Oh.

Airliners flew along the course, and fighters flew in the designated area.

How to sit on the plane:

1. When you arrive at the airport, since it is your first time taking a plane, it is best to arrive at the airport two hours in advance for the sake of insurance.

2. Check-in, when you arrive at the airport, you can directly see the flight check-in counter on the display screen. After finding the corresponding counter, go and submit your ID card and ticket to the staff for processing. If you have baggage that needs to be checked, you can also check it here, and if you buy an economy class ticket, you can check it for free up to 20 kg.

Once the check-in process is complete, the ID card and boarding pass will be returned to the passenger.

3. After passing through the security check and finding the security channel, you need to submit the boarding pass, ID card, etc. to the security officer, and the boarding pass will be stamped after the review is not missed. After that, you need to go through the security gate, and you can enter the waiting hall if there is no problem.

4. Waiting for the flight, usually the waiting hall will be clearly marked on the boarding pass, if you do not find the waiting hall, you can ask the staff.

5. When boarding the aircraft, when you hear the announcement of boarding, you need to submit the boarding pass to the staff. After passing through the staff's inspection, they will tear off a small piece and return the boarding pass to the passenger, who will then board the plane with the other people.

6. Find a seat, when the boarding is successful, you need to find a specific position according to the seat on the boarding pass. Once you've found a place to sit down, you'll need to buckle up and wait for the plane to take off.

The wings provide lift, the engines provide power, and there is enough speed to fly. There are movable fins on the wings that can control the flight attitude.

It is mainly the lift generated by the wings and fuselage that "lifts" the aircraft into the air, and the thrust of the engines makes the aircraft fly forward.

The principle of lift:

The wing is designed to be suitable for flight, with a fixed "airfoil". From the leading edge to the trailing edge of the wing, the upper surface of the wing is protruding and the lower surface is relatively flat.

As the air flows through the wing, it is divided into upper and lower strands by the wing, and rejoins at the trailing edge of the wing to flow backwards. Because the upper surface of the wing is designed with protrusions, the upper surface of the airflow tube is relatively thin, so the speed is fast and the pressure is small; The lower surface airflow tube is thick, slow, and the pressure is high, which creates a pressure difference between the upper and lower surfaces of the wing. (It can also be popularly understood that the air flows through the upper surface of the wing for a long distance, but at the rear of the wing it has to meet with the air flow through the lower surface, that is, the upper and lower surface air flow through the wing for the same time, then the air flow velocity on the upper surface is naturally large and the pressure is small).

This pressure difference provides lift to the aircraft. Lift makes it possible for aircraft to fly in the air.

When the speed of the aircraft is fast enough that the relative airflow of the wings is large enough to create a sufficient pressure difference on the surface of the aircraft, no less than the gravitational force of the aircraft, the aircraft can take off.

The principle that an airplane can fly is actually the same as a kite can fly, and the specific theory can be learned from "Aerodynamics", which is a professional basic course for aviation majors.

Most of the aircraft's propellers and jet boosters are auxiliary, and the take-off of the aircraft mainly depends on its own structure. Aerodynamics, that is, the thrust caused by the propulsion device and the drag of the air itself are processed by the structure of the aircraft itself to evolve into its upward lift.

Civil airliners have standard routes, and the pilot enters all the data into the CDU before takeoff, and switches to automatic driving (AP) when cruising after takeoff.

The aircraft takes into account the weather conditions at the destination before take-off, and the passenger aircraft is equipped with radar and is in contact with the ground air traffic control during the flight. If there is a thunderstorm during the flight, the aircraft will also make a detour to avoid it, and if the weather at the destination becomes bad, the aircraft will be diverted to other airports.

When the planes meet in the air, they are relatively far away and can be seen with the naked eye. For flight safety, the vertical height and horizontal distance of the plane rendezvous are required, and it is impossible to be as close as the train rendezvous.

Why do airplanes fly? Despite the fit of the individual components, the main thing is that the aircraft has a pair of wings with a special cross-sectional shape.

Wing profiles are also known as airfoils. A typical airfoil is convex at the top and flat at the bottom, and is often referred to as streamlined. According to the continuity of the fluid and Bernoulli's theorem, the air flow through the upper surface is squeezed compared to the air far ahead, and the flow velocity accelerates and the pressure decreases, and even suction (negative pressure) is formed, and the flow velocity of the air flowing through the lower surface slows down.

As a result, a pressure difference is formed between the upper and lower wing surfaces. This pressure difference is aerodynamic. According to the law of force decomposition, it is broken down along the direction of flight into upward lift and backward resistance.

The drag is overcome by the thrust provided by the engine. The lift is just enough to overcome its own gravity and lift the aircraft into the air. That's why airplanes fly.

To understand the principle of aircraft take-off, we must first know a basic principle in fluid mechanics: flow velocity is inversely proportional to pressure. That is, the faster the air moves, the less pressure the air will be, and vice versa.

We can do a famous simple experiment: take a piece of paper in each hand, hold it at a certain distance in front of your mouth, and blow gently in front of the two pieces of paper, and you will find that the two pieces of paper are not blown open by you, but by you. Because the air between the two papers flows, the pressure becomes smaller, and the air on the outer side of the two papers does not flow, and the pressure increases relatively, and the paper is "pressed" by the air.

Well, knowing this principle of fluid mechanics, it is easy to understand the take-off of an airplane.

Let's take a look at the wing structure of an airplane. It turns out that the shape of the upper and lower sides of the wings of the aircraft is different, the upper side is more convex, and the lower side is flatter. When an airplane taxi, the wings move in the air, which is equivalent to the air flowing along the wings in terms of relative motion.

Because the shape of the upper and lower sides of the wing is different, the air on the upper side of the wing flows more distance than the air on the lower side (the curve is longer than the straight line) in the same amount of time, that is, the air on the upper side of the wing flows faster than the air on the lower side. According to the principle of hydrodynamics, when the aircraft slides, the air pressure on the upper side of the wing is less than that on the lower side, which causes the aircraft to produce an upward buoyant force. When the plane taxith to a certain speed, this buoyancy reaches a force strong enough to make the plane fly.

So, the plane went into the sky.

This is how airplanes take off.

Fly when it's time to fly!