Hi Guys, is there anyone who could help me design an optimum wing aerofoil section for a small pylon class we run in the uk called club 2000, its effectivlly a scaled down version to Q500.

Ive been looking through thease threads on aerodynamics, flow sections, laminer seperation, high reynolds no, etc and im afraid im a complte fish out of water in understanding all of the above, ive tried but its a bit like chucking me in the space shuttle with every warning light on red and 30 seconds to impact.


I can supply all the other info, weight, speed etc..............Hopeing someone can help

Many thanks

Darren

I'd stick to using tried and true airfoils designed by others that already know how to optimize the shapes to achieve the best pressure distributions and lift curves. It's not like there isn't about a bazillion options.

The first step would be to get access to Xfoil with a nice interface. That would be to download Profili2 and pay the pittance he asks for unlocking the advanced features so you can gain access to the Xfoil portion. From there it's about trying to determine what lift coefficient you'll be needing in the turns. Find an airfoil with a low drag Cd at a Cl of 0 but that has the best Cl with minimum Cd. You'll also need to take your chord and figure out the average speed range for your racing class to find the Reynolds number you're running with. Keep in mind that goes down a little thanks to extra drag in the turns.

Once you do this look at the lift drag polars for the Selig 6061. It has the sort of polars I'm talking about. A very consistent drag polar from Cl=0 to up around Cl=.8 with only a slight increase at it goes to Cl=.9 and then it gets draggy. On the straights you'll be running at extremely close to a Cl = 0 and in the high G turns at a Cl = around 0.8 to 1.0. You want to pick an option that fits with your rules and yet has an even and low a drag polar for the Re in question yet that extends up to as high a Cl as you can get without getting draggy at the Cl = 0. At high speeds and in level flight your Cl may be as low as .01 or even less.

You can play with what your Cl will be by learning to use a handy little tool called Foilsim. A quick google on the name will take you to the NASA site with Foilsim. YOu may need to install or update your Java to run it.

Thanks for your reply, perhaps I should have worded it as design or find the optimun wing section, but thanks for the usefull information youve given, ive had a look at the profili2 site and looks very good, and yes it is a pittance he asks, a nice suprice in comparison to some others, ill go through everything youve suggested and ill see what I can come up with, perhaps you guys could help out with the results i find.
I promice it wasnt an attempt to be lazy and to get someone to do the work for me, im just one of those that doesnt grasps the therotical side of this very well, give me the plans and ill build anything thrown at me, or give me the sticks and ill get the plane through the eye of a needle at a 100 paces, lol
again thanks for your advice, much appreciated
Thanks

I don't think I could SEE a needle at 100 paces .

Now that that's over. Good luck on your design! I'd add something, but BMatthews pretty much covered it all.

Here's a link and a diagram to ponder.

http://www.mh-aerotools.de/airfoils/hdipolar.htm

The diagram is pulled from Profili and shows what you're looking for in a good airfoil for your racing application. Note how the left side lines form sort of a sideways "bucket". THis is typically reffered to as the "drag bucket" or "minimum drag bucket". Note how the low drag actually extends down to a Cl of 0 and eve a little lower. Yet it promises to maintain a low coefficient of drag up to around a Cl = 0.8. This is an excellent performance and it shows you an airfoil that will have a consistently low drag over a wide range of flying attitudes found on a race course. The curves down around Cl=0 to Cl=.02 or so are representative of the model in level flight. THe CL=0.8 area is representative of the model under high G loads in a tight turn at high speeds.