Thanks for the replies - Tall Paul I know the specs are competing - that's the problem! If they weren't then I could just select either a fat symettrical with a plank ailerons, or on the other side of the spec - go for a really low drag thin glider airfoil.

Errr.. Devices do work:-

Leading edge slots increase AofA before stall by up to 10 degrees on models
You can get an increase in co-efficient of lift of 100% from well designed flaps- and a corresponding increase in drag- useful for steep landing approaches

- see Andy Lennon Rc Airplane design


If High alpha stuff is handled by power then why don't competition funfly models have thin wings? Here in the UK we have a national funfly championship - and amongst things there is a climb and glide component. People enter with planes like Limbo Dancers, Cougars - with 18-20% thick wings AR's of around 3.5-4. These wings are great for maximum roll-rate and high AofA before stall - much in the same way that deltas have a high AofA before stall. I think a major aspect to the way these planes fly is their wing design - even though i find it aesthetically/aearodynamically "ugly"!

As far as flaps go for increasing drag and lift - well they do work as well. I know because I have tried them out - and I'm talking about Lennon again here. I and designed a plane with my father with full-span split flaps and spoilers for roll control.

Split flaps were 30% of chord, spoilers were about 12% of chord starting at 70% back on the upper edge of the wing.

My new plane will employ some different techniques but may employ full span flaps.

Flaps like these helped me in last years carrier deck/spot landing comp massively. The approach glide angle could be so steep and slow I could just drop the plane on a number and the plane would barely roll forward.

My position is that really high AOA stuff - e.g. manouvers approaching prop hanging, are indeed covered by power to weight ratio on these planes, but if you analyse why these planes do well in some aspects of deadstick competition - e.g. deadstick aerobatics, triple thrash (3 loops, 3 rolls, 3 touch and gos in the shortest time), limbo (loops underneath a limbo poll), it is to a large extent because of their low wing loading, tolerant sections to high AofA and low AR.

However the downside to at least the latter 2 attributes is a terrible glide. They glide like bricks - albeit sinking a lot slower. My idea is to build a design which breaks the mold by employing some aerodynamic theory.

If I keep the wing loading really low, use a thin section - work out how to make a thin wing strong enough for this kind of flying, and then think about how to increase the drag on demand rather than having it always on - then I think I may have an interesting proposition.