Turbine blades and the Materials at hand..

[Howland]

Quick question if anyone could offer their advice,

I've recently begun scouring my resources for suitable equipment to build a wind turbine based on the "Axial Flux" design (4' blades). The only suitable piece of wood I've been able to secure is a 19' plank of Oak... yeah.

Ideally I planned on using maple or cedar, but on my budget that's a real strain.. So I'd like to know if anyone's experimented with denser woods?

Efficiency problems, like a rise in the cut in speed?

General strain on the machine?

Is it worth investing in a lighter wood?

Wouldn't be wise to doom the project from the start, eh?

[Flux]

Other than the waste of a nice piece of oak I don't see any problem.

The increased weight will mostly be at the centre, if you make it to plans there is not a lot of wood out towards the tips.

It will add to the gyroscopic forces and increase the load on the bearings and things generally, but it is a small low speed and not very stressed machine and I don't think there is cause for concern.

It will not significantly affect start up or low speed performance, it certainly will not alter the cut in speed.

The requirements are so modest that I would have thought you could find some cheap softwood somewhere, the odd knot here and there will not cause any problems on a small machine.

Flux

[Howland]

Thanks flux, just what I needed to know.

[wdyasq]

Practical advice Flux

Ron

[Frank]

Hi!,

I would suggest, if you use hard wood, to laminate it. Meaming to cut it in slat of about half inch and once you have enough for the width of your blade, glue them together.

Why?

Because from a full piece of hard wood as you take wood off to sculpt your blade, the tension in the wood might throw off the shape you originally wanted to give to the blade.

When laminated, the tension in the wood is released before gluing them together.

With soft wood, the tip of the blades will bend in high wind and you will probably dammage the blades on the mast.

Laminated hard wood produces rigid blades and are stronger when furling occurs.

Frank

[scoraigwind]

I can usually find a piece of pine in a builders timber yard that has few and small knots.  But yesterday I spent a lot of time and couldn't find any.

Spoke with the forklift truck drivers and they had plenty ot tell me but the gist was that you can buy expensive wood, but trees have knots, and that's what I would be buying.  I almost gave up and then tried the pile with 33 mm (1 1/4") planks and found an absolutely beautiful piece of 6" board about 15 feet long.  What a relief.  

Life is not always easy.

[georgeodjungle]

some hard wood dealers through a way the wood the good stuff is wraped in.

like there in hanover pa. or oakland ca.

also cabnet and truss makers do to. like in beckworth ca.

not to mention free fire wood.

sums to nice to burn.