High Speed

Question 1

Define Mach Number M

Answer 1

The speed of the aircraft divided by the local speed of sound

Question 2

Define Local Mach Number M L

Answer 2

The speed of the aircraft at a particular point divided by the speed of sound at that same particular point

Question 3

Define Critical Mach Number M CRIT

Answer 3

The free stream mach number at which the first local mach number becomes 1

Question 4

Define the Free Stream Mach Number M FS

Answer 4

The mach number aircraft measured at a point sufficiently far from the aircraft as to be unaffected by it

Question 5

What happens to the CP when an aerofoil accelerates in the transonic range?

Answer 5

The formation of the shock wave causes the CP to move rearward

Question 6

What occurs when an aircraft accelerates through the transonic range?

Answer 6

Tuck under (nose down pitch) occurs; this occurs because the aft movement of the CP and the subsequent shockwave causes increased turbulence on the tailplane. Usually overcome by an automatic Mach trim

Question 7

How could you achieve a higher M CRIT

Answer 7

Greater wing sweep and thinner wings