undercamber wings

[Erfolg]

Although it has been suggested that speed doe not matter, I am not sure that is absolutely obvious.

In general due to the chord dimensions for models, in theory the Re values will be laminar, in reality for most models transitional. Larger chords will be turbulent. The data often available is not for models but full size, although some data has been derived for models by Eppler etc.

At the sub sonic region, things are different, at supersonic and beyond, things are very different.

It is interesting that to keep energy losses as low as possible, great efforts are often made to keep full size wings laminar. At a practical level this is difficult to do and maintain .

In general I would say, avoid sharp leading edges, or flat blunt leading edges (unless you want to achieve something very specific). Try to keep the wing smooth without lumps and bumps.

I always reassure myself in the knowledge that birds no nothing of circulation theory or Bernoulli and do OK, perhaps it has taken many thousands of years, to get there. Yet to total around my field, I an not after any great efficiency, just predictable handling.