Benesh VAWT Blades Made! :)

[warpsta]

Here's a picture of the finished blades:

I left one of them unpainted to let you see the construction method.

Essentially I stretched some wire mesh across my formers (the end pieces) and fibreglassed them inside and out. I like this construction method, it makes for a really robust yet light weight blade. I'm thinking that my next project will involve a HAWT with this method of blade construction. So what have I learned?

1. Before fixing the wire mesh to the formers, it makes life much easier if you roll the mess into a nice tight cylinder first, this makes the end result much more uniform.
   
2. When fixing the fibreglass, don't expect it to go round corners too well. It will form to a curve but not to a 180 degree bend, such as on the leading/trailing edges. If you try to form it over a bend you may well end up with the fibreglass lifting away from the mesh just before the bend.
   
3. It makes life easier to allow the fibreglass to extend beyond the blade edge an inch or 2, then when the fibreglass is placed on the other side allow this to extend beyond the edge by about the same amount. This makes for a very strong edge, although it will have to be cut.
   
4. ALWAYS WEAR GLOVES when cutting, sanding or otherwise handling fibreglass. I've had a few little bits embedded in my hands and a large, very sharp piece stabbed my hand to a depth of an inch when I was sanding them down. Leading to a very painful and potentially very serious injury.
   
5. I found that a fret saw was the ideal piece of equipment for cutting off the excess on the edges.
   
   

Overall I'm very pleased with the results, although there are a couple of bits which have de-laminated and will need further glueing. This happened when I was cutting the edges although it's not too serious. The paint job was supposed to be camouflaged pattern, but I bought the managers special paint from the local car accessory shop aand it has ended up looking more like a ladybird. I think the name is going to stick

Next job is to cut out some round pieces to keep the wind on the blades then the alternator and mounting frame. It's nice to see progress at long last.

[feral air]

Pretty progress, way to go!

[feral air]

I can't leave it at that so here's some questions...

1. What does each rotor weigh?
   
2. What are the dimension? (width and height of the openings, diameter and anything else you care to include)
   
3. Do you like that you can still see the mesh as much as I do? That's just too cool.
   
4. Have you thought about mating it to a motor conversion?
   
5. Have you thought about making a giant version yet?
   
   

take it easy

[hvirtane]

Looks really nice.

Do you have pictures of the work process?

How many hours did it take to make it?

- Hannu

[Norm]

Yeah,I'm curious too especially the dimensions.

 I'm partial to Savonius myself....need more

power? you just get bigger or more barrels !

[feral air]

6. Approximately how thick is the fiberglass? Double the thickness of a cereal box or so? take it easy

[warpsta]

To answer your questions feral air:

1. Each blade weighs approximately 12 lbs (5kg) although one is slightly heavier than the other one by about 1 lb. I do not really have the means to weigh things accurately. I suppose I must have used more resin on one blade than the other as they were made identically.
   
2. Each blade is 23 inches in diameter (58.5cm) and they stand 3 feet tall (92cm). The overlap beyond the rotational axis is 1.5 inches (4cm) which makes the overlap 13.7% of the total blade width (or 6.8% depending upon how you work it out). The opening is 9 inches (23cm) across in a straight line from leading edge to trailing edge. The narrowest part of the blade (straight across the axis of rotation) is 4 inches (10cm).
   
3. I didn't make it so that I could see the mesh, but now that the blades are finished it does make them look rather industrial. I suppose I like that.
   
4. No I have not considered mating the blades to a motor conversion, the ethos behind this project was to use as many used and very cheap parts as possible. The most expensive parts were the magnets followed by the wire for the stator, I didn't want to scrimp on the power generation. The rest is from scrap cars, begged parts etc. So far I have spent less than £100 on this project.
   
5. One thing at a time
   
   

I shall take your advice and take it easy.

[warpsta]

Sorry I don't have any pictures of the work process, if you look at my previous diary entry you will see some of the assembly of the blades. The rest was basically cutting the glass fibre mat to size and putting the resin on. The best method for applying the resin is by using a cheay throw away roller, it gets nice even results. Then just let it set and do the next bit.

It was taking 4-5 days for the resin to set because it was so cold here but I reckon that you could probably complete the fibreglassing in a day if it was warmer.

I started by fibreglassing one section on the outside, then the inside of that section. Then the outside of the opposing section then the inside of the opposing section. It's quite straight forward although you do develop a knack for fibreglassing after a short while.

I have absolutely no idea how many hours it has taken to get this far, this projec has been ongoing for 6 years now! I don't monitor the time when I'm working, I enjoy it too much

[warpsta]

6. The fibreglass/mesh sanwich is about 3mm thick

[SparWeb]

I like your method!  I made VAWT blades by cutting foam with a wire, then fiber-glassing over it all.  A long process for sure.