# Realistic air velocties regarding a wing while in flight

1. Sep 24, 2015

### Bill_Nye_Fan

I want to know what values would be realistic for the air velocities both going over the top of an aerofoil and going underneath an aerofoil (that is, the velocity over the top of the wing should be greater than the velocity over the bottom by a reasonable amount). Also, the plane is traveling at a unchanging altitude and is moving at an average velocity of 250 m/s.

Sorry if this doesn't really make sense, I just really need to know. I will clarify any questions you may have about this. Thank you guys for your help.

2. Sep 24, 2015

Do you have access to a library like at a university? If you check out the book Theory of Wing Sections by Abbott and Von Doenhoff it has that sort of data tabulated at the end in appendices for a number of different airfoil shapes.

3. Sep 24, 2015

### Bill_Nye_Fan

It really depends on the shape though. The value of $u/U_{\infty}$ over the top of an airfoil is going to be less than 2 and greater than 1. Usually it's going to peak in the range of 1.2 to 1.5 or so. On the bottom it is usually somewhere just below 1 for most of the chord length.