Aerofoil Selection
 

Hi all,
I know theirs alot been talked about this sort of issue but here goes...
I need an aerofoil for an extra 300L, the model will be around the 100" mark and i'll primarily want a model that has a gentle predictable stall for snaps and spins. Secondly it should be good for 3D (this is where i need most of the advice)...i.e. a section that can be stalled predictably and will remain stalled easily (thats what i gather 3D capable aircraft to be doing).

Ok so what aerofoil....i would like to use the fiberclassics extra 330 foil for this but its an in-house special job!!

Any ideas...comments? :stupid:

Aerofoil Selection
 

No one wants to play?

It all depends on what you want it to fly like but I'd look at the Eppler 472 or 473. These were actually used on some of the full sized stuff back a few years ago in the world competition scene. I think the Yak 55 may still be using the 473 from the looks of the pics.

But at 100 inch span you could do a lot worse than to just use the original.

I don't fly the big aero stuff so you can take my thoughts with a grain of salt but I hate to see a post go unanswered.

Aerofoil Selection
 

The Extra's, Edges, and Suhkoi's I've seen have similar airfoil, fat, with the high point forward, and almost straight to the trailing edge.. ala..
This Su-29.. high point at 25%, very rounded leading edge....
Edge 540 very much the same.
In your size, as Ben says, the closer to full-scale you get the better you'll find the plane flies.. Bigger DOES fly better..

Aerofoil Selection
 

Looking at the root where the shadow shows the shape better that sure does look a lot like the thicker of the two I suggested. The 472 here is just over 12% and the 474 is about 16%.

Here's a quick pic.....