Alternative Blade Materials

[mustang19432001]

The other day I was thinking (scary thought I know)... and no this isn't about the wind tower... I looked at a long list of used towers for sale including a 140' guyed tower in Montour NY for $2,500 http://www.usedtowers.com/GUYEDTOWERS.htm. Not in my budget this year... but that's old news.

The new idea boggling my mind is an idea for a turbine... quite possibly one of those enroll-me-in-the-funny-farm ideas. I know PVC is tough, but I don't know if it can handle 100+ mph winds when at 10'+ lengths. I started to think that one could take a length of PVC and screw or bolt (both with recessed holes) aerofoil ribs to it and rotate the ribs to fit the necessary twist. Once the ribs are in place staple screw or resin dry fiberglass sheets or strips to make the shape of the finished blade... then go to work with the resin and fiberglass. I'm guessing that with the combination of PVC and fiberglass would make for a strong composit blade. Or maybe instead of fiberglass rivit aluminum sheets. Also in mind is an idea to have the blades feather in the ball park of a given rotational speed. But that's a topic of discussion for a later date.

I also have an idea that might give the Betz Limit a run for its money (yeah... did I mention the funny farm???) if it works the way I think it will. But that's something I'll explain when I try my first turbine. (that day will be a good day indeed)

Thanks again. Mustang.

There are none so empty as those who are so full of themselves. Yours Truely.

[Sparky01]

Yes that has been done before. Do a search for PVC blades. Where are you located? I have about 80ft. of 4ft 3 sided tower left that I may get rid of at some point. I live in Unity Maine.

Scott

[DanG]

If you are seriously tubular minded just use the PVC as a mold - go oversize one or two steps to maintain circuference. If glassing I might look at incorporating fiberglass rod or fence stakes outward from solid cast root clamp area to better control  turbine disc distortion on furl or turbulence...

[mustang19432001]

One idea I have for anchoring the blade to the hub (if this is what you're refering to) was to slip the tube and bolt it to steel tubing that is a size larger than the PVC. The steel tube would then be rigged to the hubs feathering device. As for the tube itself it's merely the central frame for lack of a better word, with the ribs holding the shape. (this is all ofcourse if I inturpreted your thoughs correctly)

[mustang19432001]

I live in southern Vermont... That's as specific as I get... I'm sometimes a little over cautious about discribing where I live.

As for heigt... can one add heigt to a tower 80' will clear the tree tops by 10' in some places. AH HA... I could weld some 5' sections of steel tubing in the middle of the tower every 10' or so and slide a tube down the middle and essentially make one VERY long telescoping tower. Then for guy lines have three tubular booms hinged at the top. To make a long story short the booms would have guy lines coming down to the tower AND up to the extending tubular tower. The tower would be extended with a winch of some sort. AS for what would hold the tubular tower in place for an extended period of time I'm not sure. This would make it easier to put up and take down the tower for maintenance and experimentation.

This is alot of thinking... my brain is taking a nap... odly enough I will be signing off to take one too.

Thanks again.

[winston]

http://venteraenergy.com/

I saw one of these at the Midwest Renewable Enegy Fair last weekend

very impressive

it used a glass impregnated poly propylene blade with a unique feathering design

the outer third of the blade would rotate in high winds limiting the RPM to 280 (it was a centrifugal govenor set up with a spring)(there is a pic on the above website)

the machine was set up on a 20 foot tower at the show --it was whisper quiet and started in very light breezes --about 7 or 8 mph

it apparently has withstood 70 to 80 mph storms with no damage and it never furls or shuts down but keeps putting out maximum wattage

at this time they only have a grid inter tie version --later a charger version