ORIGINAL: da Rock
ORIGINAL: ol_seabee
I just kind of scanned this thread so excuse me if it's been mentioned but can't the outside ~10%-20% of the wing be semi-symmetrical?
"flying tips" is that common?
You betcha. If you're talking about changine the airfoil from root to tip, that's done all the time. It's very, very common in full scale, and happens all the time with models. Matter of fact, one of the greatest features of cutting foam cores is how easily you can create a wing that starts with one airfoil at the root and changes progressively to a different airfoil at the tip. And the usual reason to do that is to make the tip stall at a slightly greater angle of attack.
This adea was use by Ron Chidgey on his aerobatic models -in 1970/80 time frame
Depending on whom you talk to it helps
frankly I never saw it as benificial -theory says yes on very large craft -full scale
On our own pattern models we have gone to 10% tips and no washout /semisymm/ whatever
they land at a walk -
it has to do with low wing loadings an lower aspect ratios which ar more forgiving
The primary cause of tip stall is that the model looses directional control - so one wing "leads" the other at critical low speed
You can proove this by doing "recovery high controlled fly bys and reaching a stall- if a bit of rudder is trimmed in - the model will fall off to one side. "tip stalling"
some small well designed tip ends also work to prevent the problem -I found full scale aerobats now also doing this here is an example