Aerofoil Pressure Distribution

Question 1

What does the magnitude and direction of the total reaction depend on

Answer 1

The pressure distribution created around the aerofoil.

Overall area of the aerofoil.

Question 2

What factors affect the magnitude and shape of the pressure distribution

Answer 2

Speed of flow.
Aerofoil’s angle of attack
The camber

Question 3

Relationship between Speed and Dynamic Pressure

Answer 3

Dynamic Press (q)=
0.5x rho xV*2
So if speed is double then dynamic pressure increases 4x. A corresponding drop will also occur in static pressure.

Question 4

Symmetrical aerofoil with 0% AOA

Answer 4

No lift is created only drag.

Question 5

Camber Aerofoil

with 0% AOA

Answer 5

Produces differential pressure and lift.

Question 6

Effect of small positive angle of attack cambered aerofoil

Answer 6

Increase the total reaction and move the CP forwards.

Question 7

Effect of small positive AOA symmetrical aerofoil

Answer 7

Increase in total reaction but CP remains the same.

Question 8

What the Pattern of Pressure Distribution determines

Answer 8

Determines the position of the centre of pressure. Affected by the angle of attack and camber but not flow speed.

Question 9

Increase in camber

Answer 9

Increase in pressure distribution between upper and lower surfaces of airfoil. Dynamic pressure increase on upper surface

Question 10

Aerodynamic force Coefficient

Answer 10

How much lift and drag a wing is likely to produce. Depends on AOA and camber

Question 11

Aerodynamic force coefficient

Answer 11

F=qxsxCf
F=AD.Force
Q=Dynamic Pressure
S=Surface Pressure
Cf= Force Coefficient 

Cf=Surface Pressure/Dynamic pressure