I am trying to design a plane using the Jedelsky EJ 85 airfoil and build the wing simply using two balsa sheets. Unfortunately my software does not have any polars on this kind of airfoil at negetive AOAs.

Can somebody please help me obtain polar charts for this or a similar airfoil that shows Cl as low as .05 (presumably neg AOA)?

Thanks

I can't say I've ever seen any polars but I can tell you with certainty that they would be very, very ugly at super low or negative lift coefficients. At higher speeds or in a very low Cl there will very much be a large separation bubble on the lower surface.

If you're looking for very low lift coefficients then an airfoil with far lower camber value would be the way to go. The Jedelsky is not an airfoil intended for fast or aerobatic stunt flying.

As a suggestion of what it would be like look at polars that you can find for airfoils with comparable camber and thickness. You'll find that the drag on all these rises fast as the Cl approaches 0.1 and lower.