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Old 02-16-2005 | 09:11 AM
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rmh
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Default round vs flat

I recently built a small 3D model , which featured a very scalelike aerobatic airfoil.
I did this because the model was almost exactly same size/shape weight as many of the flat foam 3D models I have flown.
(The model is very inexpensive)
Anyway In flying it, I wanted to see if there was any noticable difference in how it performed -- due to the nicely shaped wing.
The one notable difference was absence of wing flex - so it was quite smooth and steady at higher speeds .
Higher being probably 20 mph.
The big question tho for me was -- how would it react at slow speeds - bordering on a stall.
Two of us flew it and as far as we could tell --it got "loose " at the same speed as other same size/weight flat wings .
Here is what I mean.
You can fly any of these easily down to the speed whare stall sets in -- BUT --if you try to hold it there -- it starts dropping from side to side - and will snap out if great care is not exercized .
HOWEVER-- If you apply power -then raise the AOA to past 45 degrees - the control becomes easier.-- until you reach an almost vertical hover -when it really tames down.
All in all -other than the inherant stiffness of the curved airfoil - we found no improvement-or inferior character in the wing.
Wing loading by the way was about 8 oz per sq ft.
I just did another model with wing loading of just under 4 ozs (3D model.) Exactly same type results in stall angle - just slower .