PVC versus wood

[windrules]

On a recent post I was disapionted with my genny performance.One question that comes to mind after this post is there a marked perfomance difference between props made from PVC pipe compared to a carved wooden prop.Has anyone ever tested or experiened the difference.I have built many PVC props in varying diameter pipes from 6 to 10 inch.I have never built a wooden one yet (they look scary to me) .My performance allways seems to be disapointing and thought maybe it is something I need to look at!!!The performance rating of the pvc curve looks OK in theory but wounder in reality if the airfoil of a carved blade is far superior.Nobody seems to have asked this Question before, so could be interesting.

Thanks again guys,

Mos

[Norm]

   You must have missed that one that TomW posted

about PVC blades and I'm inclined to agree they're akin to pinwheels....spin like crazy until you put a load on them...still there are so many varying factors ...it might do well to really do a comparison study of PVC blades and Jerry blades which seem to work quite well for Jerry and others that have used them.

    I like to think PVC pipe is perfectly suited for making blades for the old style muilti-bladed windmills blades about a foot long and 2inches wide with a radius about like this parenthesis (

and the trailing edge bolted flat against and inner and outer ring about 36 blades on a 5 ft diameter ring will be sufficient for me.

    As so many others have posted ...think big, but start small....if you've never made a wood blade what's stopping you? You don't have to make a real big one try a 3 or 4 footer for practice.

                  ( :>) Norm.

[Jerry]

Here,s 2 gennies with the $15 Mike mod Jerry blades. Hope this works cause the last time I tryed to post pics it didn't.

I've seen charging start at 5 mph and 1200 watts at 45 mph from these blades.

                       JK TAS Jerry

[windrules]

Jerry thanks for the pics.Do those blades have an airfoil shape or are they just curved.If they are just curved wouldn't the performance be similar to a PVC pipe blade.(they do seem to have a nice twist)I know you have had exelent results with them from previos posts.The PVC blades I have used seem to spin OK even on a genny but my output always seems lower than expected.

Regards,

Mos

[Norm]

  From what I can see they have a slight curve overall with sharper rounded curve on the leading edge basically ...which is why I think PVC pipe is better suited for a multi-bladed windmill like I said before ....

   My opinion....If you really want to get serious

and want to make some electricity either make one of wood following a tried and true pattern get Hugh's book on how to carve blades and have at it!

   If you want plastic just get some Jerry blades.

   I don't think you'll ever be satisfied with PVC pipe ....unless you can figure how to bend the leading edge......

                    ( :>) Norm

[nack]

Having seen any number of PVC water pipes age gracelessly and then explode, I would be scared of using PVC pipe for something that actually moves.

[Jerry]

Hi Guys

Gues I should list a few specks on my blades?

They are made of ABS plastic. Total lingth 22.75" this icludes a 2"X2" mounting tab. The tab has 3 mounting holes #10 size in a triangle patern. This mounting tab is .25" thick.

The root is 5.375" wide 3/8" thick . I round the tip anywhere from 1.5" to 2"s. When the aluminum sheet metal suport is added the entier lingth of the blade is usable. Then the root becomes 5.5" wide. The sheet aluminum support I use is 5.375" long.

This support is absolootly nessesary or the blade will break in high winds. I've tested them to 68 MPH with the support without breakage.

The root is to be mounted at 23% to 25%.

The blade has a cup, a twist and a tapper. They are very light 9 OZ.

I purchased a set of Factory blem carbon fiber blades from Lakota. These blades are incredable. I was surprized to see that other than lingth my blades fit the Lakotas like a gluve.

Lakota 7FT mine 4FT 1 inch.

I belive there thinness is responsable in part for there excelent preformance.

I've never done any RPM tests. But that will change. I just purchased an infered remote TACH.

Next will be an ofical Anamomitor(splg)/ wind gage and the completion of my wind tunnel.

Hopefully by this fall. Then we'll see the #s start to flow?

                              JK TAS Jerry

[Jerry]

PS the tip end is less than 1/8" thick and has a slightly rounded knife edge.

                              JK TAS Jerry