Originally Posted by
Owain Glyndwr
hawk37
As you say, HN39's chart is type specific, and I am not sure the small increase in L/D between 0.2M and 0.5 is at all typical - certainly for the aircraft with which I am familiar the drag and L/D are virtually constant up to about 0.6M where compressibility starts to kick in.
I could imagine it could potentially be related to the Reynolds Numbers. With some airfoils Cd decreases significantly with increasing Reynolds Numbers (and thus L/D increases) while others don't react much.
Last edited by henra; 19th August 2013 at 20:00.