Ben's Aemetek 100W generator Part 2

[gotwind]

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Had a succesful couple of days.

New removable boom arm design for easy transport - I will be testing it in various locations.

Piece of paper on frame is where the motor will go,too scale.

Tail made from plywood, painted.

Couldn't find any 4" diameter U-bolts, made a couple from 6mm studding.

Got the frame welded up for free:)

4" PVC guttering cut to protect the motor/generator from weather, need endcap.

Ordered a better Stainless steel arbour from eBay.US - looks very well made, 5/8" Left hand thread - $16 + $15 shipping.

Not sure whether to test 6 blade prop first before I make it into a 3 blader.

[CG]

Ben

If you haven't seen my gutter blade posting, please take a look. Like you I live in the UK, and I think my size gutter blades are just right for a 100w turbine. I judge this by the size of Rutand's 913 machine. My blades were not producing electricity, but they did turn over 2LBS of weights. The photos on the posting are not too bad and they will give you some idea of the shape to aim for. I now have a six blader,and I think that is the best configuration. I did try deep flow guttering, which is the same width, but with a greater depth. The extra depth makes the blade asymetric and it takes the shape of a wing. It's just asymetric enough to cause you to decide which way you want the turbine to turn before you cut it out, which is not the case with the symetric shape of the standard guttering blades. I cut much wider blades using the deep flow guttering, but they proved not to be as effective as the narrow blades made from the standard guttering, they vibrated at high speed. I have not bothered to investigate why this is, because deep flow works out at double the cost of standard guttering.

I hope all of this is of some use to you. It's just that here in the UK we don't have to cut up pvc pipe to make blades for small turbines. In the USA they don't seem to use pvc for gutters, that's why you don't see postings from there using it. Guttering is strong enough for small wind turbines, as long as you put root reinforcers on the blades, as shown in my posting.

Best of luck with your project.

[gotwind]

Hi.

Thanks for your comments.

Could you post the drawing here, or email it to me: enquiries@gotwind.org

You should be able to convert it to a .jpg, watch the images on this board, they like to be stretched in an odd manner.

I have read PVC can become brittle over time and ultimatly shatter :/

A coat of paint slows the process down, but you could consider A.B.S tube as a tougher alternative.

I have also noticed wind turbines usually use have an odd number of blades, i.e 3,5

Prehaps someone can explain this?

I think a 6 blader might cause you problems.

Have you seen my DIY wind generator site yet?

http://www.gotwind.org/index.htm

Regards

Ben

[CG]

Ben

As I explained in the gutter blade posting I can't send any plans. I am not on the internet at home, I do all my internet stuff on a public library PC in Cromer. I have a couple of old Acorn computers at home and do all my design work on them using Draw, a vectored arts program built into the roms of the computer; Acorns are not PC compatable. But the shape of the blades is simple enough to copy and there must be a similar type of software for the PC. In designing them I really just looked at the shape of the Hornet blades and widened them a bit.

As for six blades,the Hornet has six, and you have tested the Rutland. Although it didn't seem to do too well it has been around for quite a while now, so it must have something going for it. But at £399 I just think it's a bit expensive for what it does, and there are more modern turbines coming onto the market now that do more for the same money. Also DIY turbines are growing in popularity, and with the advent of electric bikes and invalid buggies using brushless motors it think the cost and availability of generators is going to improve here.

I am also interested mainly small turbines of about 100w to 250w, and spend my time trying to design something easy and cheap to make. PVC guttering seems to be ok for the blades. I have had my blades running for about 2 years and my gutters for about 12 years, so I don't think you have anything to worry about using PVC.

When you get your Aemetek turbine up and running please make a posting with some pics, I am interested to see how it looks and performs.