My question is, what is the advantage of a single blade?
would this be more for rpm then of torque?  
Anyone got figures on TSR for a single blade of this nature?

The big big big big big big big advantage is that one blade regardless of how wide you make it or whatever else you may do with it will never encounter the wake of another blade excepting its own at which point you may want to try and slow things down a bit(squinting eyes, grimacing mouth, upper body tilting back with shoulder manuvering in front of face type of stuff).

My whole logic train behind this, and bear with, me goes something like this. Achieving reasonable performance at low wind speeds is always a trade off because we attach more or fatter blades to the rotor which quickly brings the solidity factor up and reduces the amount of space between blades for the air stream to re-establish itself before the next blade comes along. To me this problem has become a real pain in the ---. Single blade rotors are known for their high tsr's exactly because they don't encounter these problems till they reach rudiculous speed. I never cared to have a rudiculous speed rotor but then I realized that it doesn't have to be that way. The determining factors in how much lift we can achieve are airfoil L/D ratios, windspeed, and wing area. Period. If you what to increase the lift of a wing you can change one of the above. L/D has been determined by a hopefully good blade design altitude etc, windspeed is fixed by mother nature so all that's left is wing area. Airplane designers moved away from bi and triplanes almost right away because they realized (after good wing design) the best way to increase lift at a given windspeed is to increase area. Sooo, what the heck am I doing trying to attach more blades to get more lift. I've seen data suggesting that a solidity factor of 10% is as high as you should go before you start to induce drag due to interference using a three blade rotor. More blades will only make the situation worse. And here it is, I reason that a much wider than usual blade adhearing to good rules of thumb with regards to the width/length ratio should give good low wind performance and good high wind performance as well because it has good area and is all alone.

You'd be hard pressed to build a single blade wide enough to achieve a 10% solidity without it being a gong show, but the reduced drag of only one blade should compensate leaps and bounds for this. remember we are dealing with low reynolds numbers and small just doesn't work very well.

I would never really suggest this confiquration for a larger machine such as a 30 footer at least not yet because you can fit a real blade on a machine that size.

This is just my latest goofy theory and Norms Idea has made me realize I may be right. The little maple wing rotor will spin by gently blowing on it and it will dissappear if you put it in front of a fan.

That being said, I think a one blader just plain looks dumb! What the heck though, I have changed my blades out so often the screw holes in the plywood hub are all chewing out and I have little area for new holes. Change them ALOT sometimes 3 times a day on the test mill. Might as well try one of these myself :)

I have played with those seed pod wings for many many years, as a kid and even still today when I find them. Maybe that's where we really do need to look for great blade designs. At Nature!

If I can find a nice set of seed wings that ar4e working well maybe I will try to copy those for much larger blades with the next set of plastic barrel blades I build. Maybe make a 1 blade and a 2 blade set and try both.

Balancing a 1 blader should be much easier, another advantage.
.
nothing to lose

  I have one wing that I salvaged from a wrecked plane and the thought had passed through my mind to do something similar.   It's a short wing only spanning about 14ft.  After working out some calculations on the possibilities I soon lost interest in the idea because of the cost of the structure...  In any case small single bladed turbines might be fun to build and learn with but I don't see any extreem advantages to offset the extra engineering to make it work....

Lots of fun in the creation of different devices though...

Couldn't find any in very good shape so I may have to wait until the next time they fall to repeat your experiment. Center of balance was above the "root" at the seed pod and they were too brittle to survive having a pin put through them.

I had the further complications of a girlfriend who thought I was nuts and 3 kittens trying to intercept the wings in flight.

Maybe attach 2 very small Neos on either side of the pin and mount tiny coils on the straw to see how much it would put out, something like the hamster turbine ;)

You caught my intrest and looks like fun. Here is a electric version of a maple seed, it at bottom of page.

http://www.tcrobots.org/members/rjesm.htm