High-Speed and High-Altitude Flight

Question 1

What is Mach Number (M)?

Answer 1

Ratio of TAS over the local speed of sound

Question 2

What is Free Stream Mach Number (MFS)?

Answer 2

Mach number of the airflow past an aircraft that is unaffected by its passage

Question 3

What is Local Mach Number (ML)?

Answer 3

Mach number of the airflow over the aircraft as measured by a localised point

Question 4

What is Critical Mach Number (MCRIT)?

Answer 4

MFS at which the ML of flow about an aircraft first reaches Mach 1.0. Shockwaves begin to form at this speed

Question 5

What is Critical Drag Rise Mach Number (MCDR)?

Answer 5

MFS at which an aircraft’s drag coefficient (CD) starts to increase significantly due to shockwave formation

Question 6

Detachment Mach Number (MDET)?

Answer 6

MFS at which the bow shockwave, first formed at MFS Mach 1.0 just ahead of the leading edge, attaches to the leading edge and varies with a further increase in speed. MDET marks end of transonic flight and beginning of true supersonic flight