rkbsiti

03.04.2021 01:28

Английский язык

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Задание 2. Выпишите и переведите 10 терминов из задания.

The wing makes its «magic» by forcing the air down. Some people like to compare it to water skiing, where water skis and speed are used to force the water down and the skier up. But that analogy tells only part of the story. Most of the time, the top of the wing does the majority of the «pushing» on the air (actually, in this case, «pulling» the air down). The top and the bottom of the wing combine to produce a force, and the part of this force perpendicular to the relative wind is lift. Since the wing not only pushes the air down but slows it down as well, some drag (induced drag) is caused.

The chord line is an imaginary line drawn from the leading edge to the trailing edge of an airfoil. Secondly, the relative wind is the airflow which acts on the airfoil and is parallel to but opposite the direction of flight. The angle between the chord line and the relative wind is called the angle of attack, which is called «alpha». As the angle of attack increases, the change of vertical momentum increases. Additionally, as the angle of attack increases, the coefficient of lift (CL) increases. The result is an increase in lift. However, there are limits to how much the angle of attack can be increased. At some higher angle of attack, the lift coefficient begins to decrease. The angle of attack where the lift coefficient begins to decrease is called the critical angle of attack. Once the critical angle is exceeded, the wing can no longer produce enough lift to support the weight of the aircraft and the wing is said to be «stalled». In other words, the aircraft will stall when the critical angle of attack is exceeded.

Knowing what happens when the controls are operated is the most basic skill of piloting. It is also among the most misunderstood. When an airplane is flying, it has a good deal of forward speed and airflow over all of its surfaces. Control movements must be understood in terms of this airflow and its effects.

The elevator controls the Angle of Attack [AOA] of the wings, and subsequently the pitch. Pulling back on the stick results in a down force on the tail (the same thing is operating here that was operating on the wings, only in a different direction). If the controls are reversed, the opposite happens.

Backward stick movement forces the tail down and the nose up. This rotation occurs around the center of gravity of the airplane. Initially the airplane, even though its nose is up, is still headed in the same direction - the only thing that has changed is

the angle of attack. But an increase in the angle of attack results in an increase in lift, so now the airplane starts to go up. Then, like an arrow, it points into the wind, increasing its pitch. This process continues, viewed from the cockpit as an increase in pitch, until the pilot moves the stick forward to a neutral position and stabilizes the pitch.

The temptation to think that the stick directly raises or lowers the nose is very strong, and most of the time, roughly correct. But if the stick is moved back when the airplane is very close to the stall the aircraft will not pitch up much, if at all. This back stick movement and increase in AOA will stall the wing, causing a loss of lift and acceleration downward: now the pitch moves opposite the stick movement.

The ailerons are a much simpler control than the elevator. Located near the wing tips on the trailing edge of the wing, they are used in unison to change the amount of lift each wing is producing and roll the airplane.