I was wondering..

[omega blood]

I was wondering what the advantages of having more than one type of airfoil in a wing? For example it you had a flat bottom air foil at the root and an underchambered foil at the tip ( foils inbetween are extapolated) . I know the question is some what vague but any insight is apreciated.

[Andy W]

This is very common, with full scale at least. Look at commercial jets. Also sailplanes, I'm sure many others.. I've seen models with varying airfoils, also..
You'd want undercambered at the root, however, and a more stable (less likely to stall) airfoil out at the wing.
..a

[Sparky Paul]

Examples of such airfoil changes are the T-6.. NACA 2215 at the root, 4412 at the tip, with 2 deg. of washout..
(this to eliminate the "vicious" stall/spin characteristics of the early versions.)
The B-25 has a similar variation.
Few large full-scales have a common airfoil, root to tip.
Models don't usually need this much attention.
.
Sparky Paul
http://www.angelfire.com/indie/aerostuff
PJB's Seriously Aeronautical Stuff
http://www.networkone.net/~pjburke/index.html

[Tony Oliver]

Another reason to do it is when you have a tapered wing and want the best performance from all the wing. Some sections only work at their best within a specified chord range. If the design has a chord above or below that, you select a suitable section with flight characteristics (operating speeds etc) appropriate to the main section.
In practice, for a wing tip, a slightly thicker (in % terms) version with less camber on the mean camber line will provide a good alternative.

Tony

[omega blood]

Thanks for the insight guys.