Lift Flashcards

1
Q

What is an airfoil?

A

It is any surface that is designed to obtain lift

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2
Q

What is the most suitable shape for producing lift?

A

most suitable shape is a curved or cambered shape

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3
Q

Which surfaces in an airfoil section has a greater curve?

A

The upper surface has a greater curve than the lower surface

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4
Q

what is a DOWNWASH?

A

air passes OVER the wing towards the trailing edge, the air flows not only rearward but downward as well

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5
Q

What was Isaac third law?

A

For every action there is an opposite and equal reaction

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6
Q

What happens to the airflow that passes under the wing?

A

The airflow is bended downward by the bottom surface of the wing

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7
Q

What happens when you put a downward force into the air?

A

When you put a downward force into the air the wing will receive an upward counterforce creating lift (refer to newton’s third law)

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8
Q

What happens when more air is bended downward?

A

the more air that is bended downward the more lift that is created

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9
Q

What is the Bernoulli principle?

A

if one element of an energy system is increased, another decreases to counter balance it

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10
Q

How does the Bernoulli principle apply to lift?

A

the faster speed of air along the top of the wing leads to less air pressure therefore creating lift

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11
Q

What is relative airflow/relative wind?

A

Relative airflow is the direction of airflow to the wing

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12
Q

What is the relative airflow to the wing when the wing moves forward and downward?

A

the relative airflow is upward and backward

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13
Q

If the wing is moving forward horizontally what is the relative airflow?

A

the relative airflow moves backwards horizontally

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14
Q

What is the connection between the relative airflow to the wing?

A

the connection is that they are always parallel but opposite of each other

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15
Q

How is relative airflow created?

A

It is created by the motion of the airplane through the air or by the motion of air that passes a stationary body. Or it could be created by a combination of both

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16
Q

Does the direction and speed of the wind have an effect on relative airflow?

A

No, this is because only the motion and mass of air will produces relative airflow

17
Q

What is the angle of attack?

A

The angle of attack is when the airfoil meets the relative airflow

18
Q

What happens when the angle of attack increases?

A

when the angle of attack increases this changes the pressure over the upper and lower surfaces and amount of downwash which increases up to a point (angle of stalling) before it decreases.

19
Q

What is the centre of pressure?

A

If you add all the forces into one single force it will act as a straight line. The point where the line cuts the chord of an airfoil is the centre of pressure

20
Q

what happens when the angle of attack is increased up to the point of a stall?

A

The centre of pressure will move forward after this point it will move back

21
Q

How does the movement of the centre of pressure effects the airplane?

A

It will make the airplane unstable