The P-47 wing, or What am I looking at?

[Voyager]

So I was curious about the P-47's airfoil (the Republic S-3), and I found this:
http://www.worldofkrauss.com/foils/253

So having found it, what is it telling me?

[engarde]

well, look up the Reynolds number for an understanding of the graphs.

just by pure cross section, the lower curved undersection means poor inverted flight.

this wing seems to have been made similar to the highest lift airfoil, that being a flat bottom, although the leading edge has a sharpish lower curve, suggesting inverted flight is just not a good idea.

the generous curve on top of the leading edge makes me think it was an attempt to keep airflow where its supposed to be at higher angles of attack, a broad smooth curve, not as sharp as the underside.

its not very thick, so speed was a consideration. Note the long run aft, with no obvious laminar flow? A x-section of a mustang wing is very different.

not being an aerodynamics expert, im guessing a wing designed for low drag + speed, with no plans for inverted flight.

[Voyager]

So from looking at the Wikipedia article it sounds like a larger Re indicates a larger wing or a higher speed. Does that sound about right?

Addendum: So digging around for information on the P-51 wing, I found this: http://www.tdmsoftware.com/afd/, which looks really interesting. I'll have to check it out tomorrow.

Addendum to the addendum: http://www.tdmsoftware.com/majewski/.../IL2design.asp

[Art-J]

Keep in mind Voyager, that full size planes operate in Re range of couple of millions - that's why NACA report 824, a holy bible of NACA profiles, has each of the airfoil tested at Re=3, 6 and 9 million. The results with these figures might will be a bit different, compared to 25k-100k (?) range presented on the site you found (maybe it's the data prepared for RC modellers?).

Well, their polars look somewhat "fishy" anyway. I don't know the software they used for obtaining these, but I'd try to find some alternative source.

Cheers.

[Voyager]

It is a site for RC aircraft. So when you say the polars are fishy, how do you mean?

Perhaps a better questions for me to ask is, do you know of good software that's reasonably available?

[JtD]

The cl characteristics look odd. Usually there's no bump on the way up to the cl max. Probably a discontinuity in either the airfoil model or the algorithm used for the calculation.

What do you want the software for? As far as existing airfoils are concerned, it is safe to assume they've been tested, calculated and published already. The already mentioned NACA reports are a good way to start, even if the findings are 60+ years old, the results are still mostly valid.