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adric22
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Joined: 06/08/2008
Location: United States
Posts: 47

Posted: 01:40am 09 Aug 2008

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I think I found some cheap blades for my turbine. In a hobby store I saw a foam airplane that you put together. The wings were about 2.5 feet long, which would make a 5 foot diameter turbine or so. I'll probably coat them with fiberglass to make them stronger.

adric22
Regular Member

Joined: 06/08/2008
Location: United States
Posts: 47

Posted: 02:48am 09 Aug 2008

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Oh rats! I just realized these darned wings aren't going to work as I wanted. They are the right shape, but they are mirror-image from each other. regular turbine blades should all be identical.

Well, the plane was only $9. Originally I was going to mess with 2 blades and if I liked it, buy another plane so I could get a 3rd blade. But now it looks like what I'll need to do is buy 2 more planes so I can use 3 left wings and maybe take the 3 right wings and make a seperate turbine.

Gill

Senior Member

Joined: 11/11/2006
Location: Australia
Posts: 669

Posted: 04:06am 09 Aug 2008

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adric22,
It would be good if could add twist to the blades such that when fiberglassed they hold their twisted shape. The twist improves efficiency and aids startup especially when cogging is an issue.

Do you think they would take say a 30degree twist without breaking?

was working fine... til the smoke got out.
Cheers Gill _Cairns, FNQ

adric22
Regular Member

Joined: 06/08/2008
Location: United States
Posts: 47

Posted: 02:22pm 09 Aug 2008

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Gill, I had wondered the same thing. But I don't think they'll bend. I had thought about maybe cutting them several times and re-gluing the pieces back to give it a twist, then coating in fiberglass. It wouldn't be as smooth as it would resemble a staircase.

The other problem is, I'm not entirely sure which way it needs to twist. Is there a good photo somewhere of a turbine blade where you can actually see all the angles?

Gill

Senior Member

Joined: 11/11/2006
Location: Australia
Posts: 669

Posted: 04:13pm 09 Aug 2008

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I think this site gives a sketch of the twist in relation to the profile. Also for the angle there is a blade calculator. see here. There are others available on the internet that may have better features though the angles are all about the same to my recollection.

What sort of foam is used? I know some types such as what I know as coolite does not take at all to fibreglass where the fine green or blue one does. I'm thinking rather than cut across, put in 2 or 3 slits lengthwise. I think some sanding would then take out the ripples in the profile. But this all depends on the material.Edited by Gill 2008-08-11

was working fine... til the smoke got out.
Cheers Gill _Cairns, FNQ

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