High Speed Flashcards
What is the term used for the speed of sound?
Mach 1
What does the speed of sound vary with?
Temperature
How do you calculate Mach no. ?
Velocity of object(v)/local speed of sound(a)
M=v/a
What is the subsonic speed range?
0-0.8 Mach
What is the transonic speed range?
0.8-1.2 Mach
What is the transonic speed range?
0.8-1.2 Mach
What is the supersonic speed range?
1.2-5 Mach
What flow is measured for speed ranges?
Compressible flow
Where is subsonic flight used?
For most commercial and general aviation flights
Is air compressible or incompressible in subsonic flight?
Incompressible
How significant is air density change due to pressure at subsonic flight?
Negligible
Is air truly incompressible in subsonic flight?
No it’s just negligible so ignored
What is transonic flight?
Subsonic and supersonic airflow
What type of shockwave occurs in transonic flight?
Normal shcokwaves
What do shockwaves cause in transonic flight?
Stability challenges & causes airflow separation from wing
Causes nose down pitch tendency
Define supersonic flight?
All speeds on aircraft are greater than the speed of sound
What speed is hypersonic?
Above Mach 5
Where is the shockwaves during supersonic flight?
Shockwaves moves to rear and is affixed to trailing edge
What happens to pressure and air density during supersonic flight?
Slight change in pressure and almost no change in air density observed
Can air pressure change without air density changing?
Yes
Is air compressible in supersonic flight?
Yes
What compression effects develop during supersonic flight?
Reduction in coefficient of lift and an increase in coefficient of drag in the supersonic range
How do you calculate Mach no. ?
Velocity(true airspeed) / local speed of sound
What is critical Mach no. ?
Lowest mach no. at which airflow at some point reaches the speed of sound but does not exceed it
