Thanks guys for the replies.

I built the Chipmunk wing based on my assumptions. Afterwards I had the opportunity to inspect a full size Harvard and I noticed that the wing was semi-symmetrical at the root, progressed to flat bottom at the tips and had washout. I do understand that the Harvard was designed as a trainer and not an aerobat but based on my understanding, it looked like they went the wrong way. Now I know better.

But, my Chipmunk flys just great. I guess it could be that the mysterious Reynolds numbers are in play mitigating what might be a bad situation if it were applied to a full size aircraft. To test this, I suppose I could just build two more wings. One with the progressive going the other way and one with a fully symmetrical foil non progressive. But, maybe I'll try that on a smaller, purpose built aircraft. Something in a 1/2A size.

OK, here's another question. I've recently received two kits. One is actually an ARF from Wattage, the Extra 330L. Extremely well made, it looks very close to scale including a nice semi-symmetrical foil that looks exact scale as far as thickness. Should I twist in some washout?

The other kit is a Cap 232 from StevensAero. This is a gorgeous laser cut kit intended for electric power. The airfoil is much thicker in comparison to the Extra. Looks much thicker than scale. I've seen the videos, performance is spectacular, even as an electric. A very low wing loading seems to be the key.

It would seem to me that model aircraft could benefit from much thicker airfoils than we normally see today. I'm talking about aerobats. With our high revving motors that bog on the up lines and unload on the down lines, wouldn't a really thick airfoil mediate this effect?

Maybe I'll build an extra uh, Extra wing with a thicker, fully symmetrical foil and see what's what.