Chapter 11

Question 1

True or False

Linearized theory does not apply to the transonic flow regime.

Answer 1

True

Question 2

Why does linearized theory break down when transonic flow is considered?

Answer 2

Transonic aerodynamics are highly non-linear and cannot be easily approximated to a linear form with any semblance of accuracy.

Question 3

For flow over an airfoil at low subsonic speeds (M<0.8), the point of maximum Mach number over the upper surface corresponds to the minimum _____ point.

Answer 3

Pressure point

Question 4

Define the critical Mach number.

Answer 4

The critical Mach number is the free-stream Mach such that the Mach number at the point of minimum pressure on the airfoil is equal to one.

Question 5

Why is the critical Mach number important?

Answer 5

At free stream Mach numbers just slightly above Mcr the drag on the airfoil increases drastically.

Question 6

What is the drag divergence number?

Answer 6

The value of the free-stream Mach number at which the drag curve begins to sharply increase.