problem about solve areocoefficients
 

When I solved teh Areocoefficient of one aircraft by CFX5.7.1, I found it was different when I use M=0.4 and M=0.2.when teh Cl=0.398,Cd=0.0298, M=0.4:and the same case,Cl=0.357,Cd=0.0275,M=0.2.Why??

Regards W0er

Re: problem about solve areocoefficients
 

Those numbers are not far off what you would expect if you just applied the Prandtl-Glauert correction.

Re: problem about solve areocoefficients
 

Oh charles ,but i didn't get the results what differ from the Re number.