How does a single surface wing work?

[mortonj69]

http://www.ezonemag.com/articles/2003/jan/demoiselle/demoiselle.shtml

you see the single surface wing in the model above

what properties do single surface wings have in comparison to normal airfoils

why does a single surface wing work?

I use single surface wings made of foamboard

i just want to know why i should consider making a full airfoil shape

[Sparky Paul]

"Single surface wings" deflect air downwards just like curvey surfaces do.
As to going to a full airfoil shape, that depends on what you want.
The single-surface has its uses for slow flight.
An intermediate step is to put a leading edge droop on the foamboard, to give it some camber.
If you want more speed without having to add too much more motor, then a conventional shape will do the job, but it can be at the expense of losing the slow-flying capability.

[BMatthews]

All proper airfoils have a camber line that is the curve that is halfway between the upper and lower surfaces. The NACA 4 digit airfoiils are "made" by bending a symetrical airfoil of given thickness around one of these camber lines. So a single surface is just a camber line with a 0 thickness shape.

And more importantly for models like this Demoiselle model they are lighter as you don't have the second covering layer. Yes you get more drag from the exposed "stuff" hanging out but at the very low speeds these models fly at it's not a big deal.

Sorry to butt in Sparky but you missed the lighter weight bit. Thought I'd toss that in.... :D