Parabolic profile for VAWT blades

[feral air]

This is one of those things that makes vawts hard to talk about, imo - I think most people consider the total scoop area and not the diameter or height (those are important measurements too but...).

No consideration is given for the number of scoops in the diameter*height method - it could be 2 or 100 scoops and the result is the same - and 'dead space' isn't accounted for either...

Lets say we made a vawt that has three, 1'x1' scoops. Only it's got a layout like an anemometer so the diameter is 10 feet, a big round number. Is the vawt 10sqft or 3sqft? What if the scoops were 2'x1'? Is it still 10sqft or would it be 6sqft?

I know you got it the first time, Matt, it's just of those things for me - gets me every time. take it easy

[MattM]

That is the thing, like you said, diameter is important.  I would think the leverage of the scoop would play some importance.  Definitely the area of each scoop plays importance.  There has to be some better way to describe one.  Maybe a standard that talks about diameter of the scoop and area of a single scoop would be tenable?  IMO it just feels like saying the area of a scoop is too little.

I know this is off topic, but this is a good place to say it.  If someone wants an efficient vawt then someone needs to create an elliptical vawt.  The arm grabbing the wind would be on the long side and the arm coming around to the front would be the short.  We can use nails and a string to draw an ellipse, so maybe there is some simple way to get the same principle with respect to the arm rotation.  Track-mounted is the only solution I could come up with, perhaps pulled around by a chain.  An elliptical motion is probably the only way a vawt would ever be practical.

[feral air]

Adding complexity to vawts is generally a bad idea. More parts to wear out, more cost, harder to build, etc. IMO, the best designs are the simple ones.

Personally, the Lenz2 is the best vawt design I've seen. It's simple enough for homebrew yet it's pretty comparable to a hawt efficiency-wise. You can't ask for much more than that.

But if you want to talk crazy ideas....

You know those little airplanes on a string from back in the day, right? You grab the end of the string and spin until you're dizzy and the plane sees enough 'relative wind' at the end of the string to lift off and fly around in circles...

So what would happen if it was a vawt spinning in circles and a hawt on the end of the string, so to speak?

If it worked you could get rid of the furling and tail on the hawts, just mount 'em in a fixed position...apply brakes to the vawt (rarely!) to keep the rpm within a tolerable range. I think the trickiest part would be getting the power off the rotor and on to solid ground.

I dunno...take it easy