There are four primary forces acting on an aircraft that is airborne. They are namely its own weight(W), the lift(L), the thrust(T) from the engine, and the drag(D), a horizontal force component that opposes motion. For the plane to fly at constant velocity, L=W (vertical components) and T=D (horizontal components).
The wing of an aeroplane is shaped like an aerofoil. By virtue of its shape, as the aerofoil moves through air, a partial vacuum is created at the top trailing edge of the aerofoil. According to Bernoulli's principle, the pressure at the top of the aerofoil is lesser than at the bottom. This creates the precious lift. The angle of attack affects the lift and the drag. The ratio of lift versus drag maximises at an angle of attack of around 15 degrees.
Took these pictures during my trip to Europe.
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The wing of an airplane at rest position |
| Taking off... | |
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Lowering flaps to increase wing's curvature, increase the angle of attack and hence increasing lift. You may notice that the engine is especially loud when its running on the runway before taking off. This is to compensate the larger drag component (due to turbulence at the trailing edge of the wing) and of course to increase speed. |
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When the plane attains its required speed, a small angle of attack is required for cruising. Hence, it keeps its flaps back. By cruising at a small angle of attack, drag is lowered. |
| Landing... | |
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The aircraft gradually decreases its speed and altitude an hour (this depends on its altitude and speed) before you know it's going to land. When it is close to landing, the speed is slow and hence lift decreases. Flaps are lowered to increase lift for smooth landing, but because of the lowered flaps, drag increases. Therefore, to compensate for the increased drag, thrust has to be increased. You may also notice that the engine is louder when it's about to land, to increase the thrust. |
| Successully landed... | |
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When the plane has landed successfully, speed is effectively decreased further by raising the spoilers, applying reverse thrust at the jet engine and applying mechanical brakes. The engine gets very noisy here due to the reverse thrust applied. |
Some pictures taken from the airplane...
Does this look familiar?
Desert at the middle east
Reaching Frankfurt airport
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