An airplane is an aircraft that is many times heavier than air. In order for it to fly, a combination of several conditions is needed. It is important to combine the right angle of attack with many different factors.
Why does he fly
In fact, the flight of an aircraft is the result of the action of several forces on the aircraft. The forces acting on the aircraft arise when air currents move towards the wings. They are rotated at a certain angle. In addition, they always have a special streamlined shape. Thanks to this, they "get up in 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
Even 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 figure will be small.
If the angle turns out to be steeper, then the resistance will becomelarge, 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 the aerodynamic quality, and the larger it is, the less energy the aircraft will need to fly.
About lift
Lift force is a component of the aerodynamic force, it is perpendicular to the aircraft's motion vector in the flow and occurs due to the fact that the flow around the vehicle is asymmetrical. The lift formula looks like this.
How lift is generated
In today's aircraft, wings are a static structure. It will not create lift by itself. Lifting a heavy machine 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 gets smaller above the structure and increases below it.
And thanks to the difference in pressure, in fact, there is an aerodynamic force, the height is gained. What indicators are represented in the lift force formula? An asymmetrical wing profile is used. At the moment, the angle of attack does not exceed 3-5 degrees. And this is enough for modern aircraft to take off.
Since the creation of the first aircraft, their design has been largely changed. At the moment, the wings have an asymmetrical profile, their upper metal sheet is convex.
The bottom sheets of the structure are even. It's made forso that air flows through without any obstacles. In fact, the lift formula in practice is implemented in this way: the upper air flows travel a long way 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 is an area with lower pressure.
The difference in pressure above and below the wings, together with the operation of the engines, leads to the climb to the desired height. It is important that the angle of attack is normal. Otherwise, lift will drop.
The higher the speed of the vehicle, the higher the lift force, according to the lift formula. If the speed is equal to the mass, the aircraft goes into a horizontal direction. Speed is created by the operation of aircraft engines. And if the pressure over the wing has dropped, it can be seen immediately with the naked eye.
If the plane maneuvers suddenly, then a white jet appears above the wing. This is the condensate of water vapor, which is formed due to the fact that the pressure drops.
About odds
The lift coefficient is a dimensionless quantity. It directly depends on the shape of the wings. The angle of attack also matters. It is used when calculating the lifting force when the speed and air density are known. The dependence of the coefficient on the angle of attack is clearly displayed during flight tests.
About aerodynamic laws
When an aircraft is moving, its speed, other characteristicsmovements change, as do 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 understand this better, simplifications are needed. This will greatly simplify the output, and the engineering value will remain the same.
First, it is best to consider steady motion. This means that the air currents will not change over time.
Secondly, it is better to accept the hypothesis of the continuity of the medium. That is, the molecular motions of air are not taken into account. Air is considered as an inseparable medium with a constant density.
Third, 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, drag is not taken into account.
Knowledge of the main aerodynamic laws allows you to build mathematical models of how an aircraft is flown around by air currents. It also allows you to calculate the indicator of the main forces, which depend on how the pressure is distributed over the aircraft.
How an airplane is flown
Of course, in order for the flight process to be safe and comfortable, wings and an engine alone will not be enough. It is important to manage a multi-ton machine. And taxiing accuracy during takeoff 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 height. It is important that the speedwas selected as precisely as possible to ensure a smooth fall. This is what causes the chassis to touch the strip softly.
Controlling an aircraft is fundamentally different from driving a ground vehicle. The steering wheel is needed to tilt the car up and down, to create a roll. "Toward" means to climb, and "away" means to dive. To change course, you need to press the pedals, and then use the steering wheel to correct the slope. This maneuver in the language of pilots is called a "turn" or "turn".
To enable the machine to turn around and stabilize the flight, there is a vertical keel in the tail of the machine. Above it are "wings", which are horizontal stabilizers. It is thanks to them that the plane does not descend and does not gain altitude spontaneously.
Elevators are placed on the stabilizers. To make engine control possible, levers were placed at the pilots' seats. When the plane takes off, they are moved forward. Takeoff means maximum thrust. It is needed in order for the device to gain takeoff speed.
When a heavy machine sits down, the levers are retracted. This is the minimum thrust mode.
You can watch how before landing, the rear parts of the large wings fall down. They are called flaps and perform a number of tasks. As the plane descends, the extended flaps slow down the aircraft. This prevents her from accelerating.
If the plane is landing and the speed is not too high,flaps perform the task of creating additional lift. Then the height is lost quite smoothly. As the car takes off, the flaps help keep the plane in the air.
Conclusion
Thus, modern aircraft are real airships. They are automated and reliable. Their trajectories, the entire flight lends itself to a fairly detailed calculation.
