Old Smokey,
Thanks, It is nice to get a definitive answer from somebody who really understands this stuff.
Originally Posted by Old Smokey
Vc = SQR((Y/(Y-1)) X Po/Qc X ((Qc/Po + 1)^((Y-1)/Y) - 1) X SQR (2 X Qc/Rho0)
Since you give a formula for CAS, I'll give another CAS formula for comparison.
Vc = Ao X SQRT (5 X (Qc/Po + 1)^((Y-1)/Y) - 1)
Where:
Ao = Standard speed of sound at sea level (661.5 kts)
All other terms as defined by Old Smokey
I like this one because it is simpler and it works in any units: i.e if you want CAS in knots, enter Ao in knots, if you want it in m/s enter Ao in m/s etc. Also note the formula is very similar to the formula for Mach number (spot the differnces)
(NOTE - do NOT substitute the Po term for flight at altitude. CAS is a function of Qc and all other terms are constants. CAS is not a function of Ps)
I leave it up to more mathematically inclined readers to prove that this CAS formula and Old Smokey's CAS formula are equivalent.