Aerofoil & Lift

Question 1

What is an aerofoil?

Answer 1

A device which gets a useful reaction from air moving over its surface.

Any part of an aircraft designed to produce lift.

Question 2

Describe the Leading Edge

Answer 2

The rounded forward part of an aerofoil

Question 3

Describe the Trailing Edge

Answer 3

The rear of the aerofoil

Question 4

Describe the Chord Line

Answer 4

The line joining the leading and trailing edges

Question 5

Describe the Longitudinal Axis

Answer 5

The line through the fuselage of the aircraft from nose to tail.

Question 6

Describe the Angle of Incidence

Answer 6

The angle between the Chord Line and the aircraft’s longitudinal axis.

Question 7

Is Angle of Incidence fixed?

Answer 7

Yes

Question 8

Describe Angle of Attack

Answer 8

The angle between the Chord Line and the Relative Airflow.

The difference between where the wing is pointing and where it is going.

Question 9

Is Angle of Attack fixed?

Answer 9

No

Question 10

Describe the application of Bernoullis Principle on an Aerofoil

Answer 10

The aerofoil is designed to increase the velocity of the airflow over its top surface.

Bernoulli’s principle tells us that this acceleration causes a reduction in pressure.

The reduction of pressure on the top surface produces LIFT.

Question 11

Describe the Boundary Layer

Answer 11

The air directly in contact with the surface of the aerofoil is described as the Boundary Layer.

Question 12

Describe Laminar Flow

Answer 12

If the boundary layer remains in contact with the surface, the flow is said to be Laminar.

Question 13

Describe a Laminar Aerofoil

Answer 13

An aerofoil designed for minimum drag and a smooth flow of the boundary layer is called a laminar aerofoil.

Question 14

Describe the Transition Point

Answer 14

The point at which flow becomes turbulent is called the Transition Point.

Question 15

Describe the Separation Point

Answer 15

The point at which flow separates is called the Separation Point.

Question 16

Describe what happens as the boundary layer separates from the surface?

Answer 16

The flow becomes turbulent, at the Transition Point and eventually separates from the wing, at the Separation Point.

Question 17

How is an aerofoil described when lift is lost?

Answer 17

Stalled

Question 18

When does stalling occur?

Answer 18

When the critical angle of attack is exceeded.

Question 19

Is the critical angle of attack fixed?

Answer 19

Yes. The critical angle of attack of a given aerofoil remains the same regardless of any external forces or characteristics placed on the wing.

Question 20

What is the critical angle of attack?

Answer 20

The angle of attack at which the wing begins to stall.