Why does Skyaak Fly?

Why does Skyaak fly?

I asked the eminent Aerospace Engineer Dr. David Simpson, Head of the Institute for Aerospace Research at the National Research Council in Ottawa this question. He wrote me back a very thoughtful response which said in part, "The overall advantage of this aerodynamic approach ( using two ring-wings riding in tandem on an inner shaft: my insertion ) will be to gain structural weight savings without sacrificing aero efficiency and of course reducing the vortex induced drag." You can read his entire letter by clicking HERE.

OK. I get the part about gaining structural weight savings. The ring-wings are really lightweight and have tensile ( spring) strength that is partly thanks to the amazing plastic as well as the design. :)

I also understand the part about reducing ‘vortex induced drag’. Reducing drag is good is aeronautic design. The thing is, after flying the Skyaak around for many many hours and seeing how well it works with a really good throw, I can’t help but think that there’s something more going on.

First of all, look how much wing surface there is before they get rolled up:

That’s quite a bit of wing. About 114 square inches each, or 228 square inches in total. 228 square inches of wing surface for a 24" long flyer is a decent ratio. So there’s no lack of wing. When it’s rolled into its trademark ring-wing shape, it still has the large surface, only now it starts doing weird things in the air when it’s thrown properly. It spins on its axis, for one thing. And it seems to create its own vortex that is rides on, if that’s possible. We’ve seen the thing falter a bit and then correct itself in flight, as if it is riding along on a dynamic stream of air. I would sure like to get this thing into a wind-tunnel to find out more about its aerodynamic properties.

I’m certainly no aerospace engineer. I’m just going by first-hand experience here. I can tell you though that the Skyaak does some very interesting things in flight that I have not really had explained clearly by anyone I’ve asked to date. Why exactly does this configuration work so well? Why does it fly in such a stable trajectory? What are the actual physics of the thing? Does anybody know? I asked my buddy Cam Tetrault ( respected R/C airplane-model builder and video artist) this very question and he thinks the Skyaak is basically a pimped up biplane, only the gap is closed between the two wings to form a ring. And there’s two of them. I guess that’s a beginning, but it still doesn’t explain the whole dynamic. I’m determined to find out in more detail why this configuration works. While it’s great fun to simply enjoy tossing it around to the oohs and aahs of witnesses, the chronic tinker-er in me wants to know more. The more clearly I understand the aerodynamic features, the better I can make it work.

Later, Michael.