Chapter 7

Question 1

After the peak suction point what happens to the static pressure along the chord?

Answer 1

The static pressure should increase.

Question 2

How does a turbulent boundary layer affect the separation of the airflow?

Answer 2

A turbulent boundary layer delays the separation.

Question 3

What is the drag formula

Answer 3

D = 1/2 p v² s Cd

Question 4

What increases with Angle of Attack

Answer 4

Form Drag

Question 5

In 2 dimensional flow what are the 2 types of drag?

Answer 5

Skin friction drag: caused by surface roughness of the aircraft’s skin which traps
and slows air molecules in the boundary layer.
Form (pressure) drag: caused by the pressure of the aircraft acting on the frontal
cross-sectional profile of the aircraft as it moves.

Question 6

What is the definition of the boundary layer?

Answer 6

The boundary layer is defined as the area extending from the aircraft’s surface out
to the point where the speed of the airflow is 99% of the free-stream flow.

Question 7

What is the laminar boundary layer?

Answer 7

A laminar boundary layer is thin, slippery and low energy with relatively little drag.
Early separation because of the low energy in the layer. The laminar flow eventually
transitions to turbulent flow.

Question 8

What is a turbulent boundary layer?

Answer 8

A turbulent boundary layer is thick, draggy and high energy. Separation is delayed
because of the higher energy in the flow.

Question 9

What is the transition point

Answer 9

Transition point: the point on the surface of the aerofoil where the boundary layer
changes from laminar to turbulent flow.