reynolds numbers being? i know a math term, but specifcally.
Reynolds number (Rn) is a fluid dynamics term. In order to test airfoil profiles, you have to ensure that they are tested at the proper Rn. Generally speaking, you can approximate the sea level Reynolds number by multiplying the Velocity (in feet per second) X 9000 X lenth (in feet). The length would be the chord length. There are more technically accurate means to determine Rn (which I will use for this test) but this will get you in the ball park. So, for example, if the FW-190 tip chord is 4 feet, then the Rn at 200mph at sea level will be approximately 293 fps X 9000 X 4 = 10,548,000. This is often represented in a scientific format as 10.5E6. Most of the airfoil analysis software requires the Reynolds number to compute lift and drag numbers.