Originally Posted by
vikena
Thanks, but I'm no wiser.
Let me try to rephrase my question.
When Mach no increases how does that affect the speed and angle at which the wing will stall? And why.
Increasing flight Mach number into the transonic range eventually causes small shockwaves to form on the wing, which grow in size as the flight Mach number and/or AOA increase. Google "critical Mach number" for more info on this. These shockwaves disturb the airflow behind them, reducing the lift of the wing compared to subsonic flight conditions for the same AOA. Aerodynamicists deal with this by adjusting the relationship between CL and AOA to compensate. The effect is the stall EAS increases because the shockwaves cause CLmax to decrease. Another effect is that above sbout Mach 0.6, CAS and EAS diverge due to compressibility effects, with CAS over-reading compared to EAS. Most aircraft PFDs show CAS on the airspeed tape, so at higher Mach numbers the stall speeds shown in CAS must increase to compensate for the growing difference between EAS and CAS.
Finally, the shockwaves can also cause the wing to stall at a lower AOA, but this is all dealt with through reduced CLMax and thus higher stall speed.
Regards, WF