An airplane is an aircraft that is many times heavier than air. In order for it to fly, you need a combination of several conditions. It is important that the correct angle of attack is combined with many different factors.
Why is he flying
In fact, the flight of an aircraft is the result of several forces acting on an airplane. The forces acting on the aircraft arise when air flows toward the wings. They are rotated at a certain angle. In addition, they always have a special streamlined shape. Thanks to this, they "get into the air."
The process is affected by the altitude of the aircraft, and its engines accelerate. Burning, kerosene provokes the release of gas, which breaks out with great force. Screw engines lift the aircraft up.
About coal
Back in the 19th century, researchers proved that a suitable angle of attack is an indicator of 2-9 degrees. If it turns out to be less, then there will be little resistance. At the same time, lift calculations show that the rate will be small.
If the angle is steeper, then the resistance will become large, and this will turn the wings into sails.
One of the most important criteria in an airplane is the ratio of lift to drag. This is an aerodynamic quality, and the more it is, the less energy the airplane will need when flying.
About lift
The lifting force is a component of the aerodynamic force, it is perpendicular to the vector of the aircraft in the flow and arises due to the fact that the flow flows around the apparatus asymmetrically. The lift formula looks like this.
How does lifting force arise?
In current aircraft, wings are a static design. She herself will not create lift. Raising a heavy vehicle up is possible due to the gradual acceleration to climb the aircraft. In this case, the wings, which are placed at an acute angle to the flow, form a different pressure. It becomes smaller above the structure and increases under it.
And thanks to the difference in pressure, in fact, there is an aerodynamic force, gaining height. What indicators are presented in the lift formula? An asymmetrical wing profile is used. At the moment, the angle of attack does not exceed 3-5 degrees. And this is enough to make modern aircraft take off.
Since the creation of the first aircraft, their design has been significantly changed. At the moment, the wings have an asymmetric profile, their upper metal sheet is convex.
The bottom sheets of the construction are even. This is done so that the air flows pass without any special obstacles. In fact, the lifting force formula is implemented in practice in this way: the upper air flows pass a long road due to the bulge of the wings compared to the lower ones. And the air behind the plate remains in the same amount. As a result, the upper air flow moves faster, and there forms an area with lower pressure.
The difference in pressure indicators above and below the wings, together with the operation of the engines, leads to a set of the desired height. It is important that the angle of attack is normal. Otherwise, the lifting force will fall.
The greater the speed of the device, the more, according to the formula of lifting force, the latter is greater. If the speed is equal to the mass, the aircraft goes into the horizontal direction. Speed is created by the operation of aircraft engines. And if the pressure over the wing has dropped, this can be seen immediately with the naked eye.
If the plane maneuvers suddenly, a white stream appears above the wing. This is condensation of water vapor, which is formed due to the fact that the pressure drops.
About coefficient
The lift coefficient is a dimensionless quantity. It directly depends on the shape of the wings. The angle of attack also affects. Apply it, calculating the lifting force, when the speed, air density, is known. The dependence of the coefficient on the angle of attack is displayed graphically during flight tests.
On aerodynamic laws
When the aircraft moves, its speed, other characteristics of movement change, as well as the characteristics of the air currents that flow around it. At the same time, the flow spectra also change. This is an unsteady motion.
To better understand this, simplifications are needed. This will greatly simplify the conclusion, and the engineering value will remain the same.
First, consider the best-established movement. This means that the air flow will not change with time.
Secondly, it is better to accept the hypothesis of continuity of the medium. That is, the molecular movements of air are not taken into account. Air is considered as a continuous medium with a constant density.
Thirdly, it is better to accept that the air is not viscous. In fact, its viscosity is zero, and there are no internal friction forces. That is, the boundary layer is removed from the flow spectrum and the drag is not taken into account.
Possession of the main aerodynamic laws allows you to build mathematical models of how an aircraft flows around air currents. It also allows you to calculate the index of the main forces, which depend on how the pressure is distributed across the plane.
How to fly a plane
Of course, in order for the flight process to be safe and comfortable, there will be few wings and an engine. It is important to control a multi-ton machine. And taxiing accuracy during take-off and landing is very important.
For pilots, landing is considered a controlled fall. In its process, there is a significant decrease in speed, and as a result, the car loses altitude. It is important that the speed be selected as accurately as possible to ensure a smooth fall. This is what causes the chassis to touch the strip gently.
The control of the aircraft is fundamentally different from the control of a ground vehicle. The helm is needed to tilt the car up and down, to create a roll. “On yourself” means to climb, and “on your own” means to dive. To change course, you need to press the pedals, and then use the steering wheel to adjust the tilt. This maneuver in the language of pilots is called a “U-turn” or “turn”.
In order for the machine to turn around and stabilize flight, there is a vertical keel in the tail of the device. Above it are "wings", which are horizontal stabilizers. It is thanks to them that the plane does not decrease and does not gain altitude spontaneously.
On the stabilizers are placed elevators. To control the engine was possible, levers were placed at the pilot seats. When the plane takes off, they are moved forward. Takeoff mode means maximum thrust. It is needed in order for the device to gain takeoff speed.
If the heavy machine sits down, the levers are pulled back. This is the minimum traction mode.
You can observe how, before landing, the backs of large wings descend. They are called flaps and perform a number of tasks. When the plane goes down, flaps released slow down the car. This does not allow her to accelerate.
If the plane lands, and the speed is not too high, the flaps perform the task of creating additional lifting force. Then the height is lost quite smoothly. When the car takes off, the flaps help keep the aircraft in the air.
Conclusion
Thus, modern aircraft are real airships. They are automated, reliable. Their trajectories, the entire flight lends itself to a fairly detailed calculation.