Airfoils designed for reverse flow This question might seem strange as almost all aircraft have the air flowing over the wing in only one direction. However if you wanted to design an airfoil would have a good L/D in the forward flow direction, but would also generate lift, or at least not have excessive drag under reverse flow conditions, how would you go a about finding such an airfoil?

The Aerobie flying disc uses an airfoil that looks like a fish. The fish tail creates stability in a spinning disc, but also quite a bit of drag I believe. If stability is not a concern, I think another airfoil shape may provide less drag. 

https://en.wikipedia.org/wiki/Aerobie

http://www.aerobie.narod.ru/aerobie.htm
You would copy the cross-setional shape of the frisbee plastic disc toy, which generates lift as it spins and travels through the air by using a shape which looks like the leading edge of a wing no matter which way it is pointing. a wing with two "leading edges" like this is not as efficient as a wing with a tapered trailing edge, but it works well enough to fly significant distances and provide fun for its users.