Wind Turbine build-weekend

After the disaster that befell my first attempt at DIY wind-power I joined a weekend course run by the excellent people at V3 power to learn how to build a horizontal-axis machine from scratch following the design by Hugh Piggott of Scoraig Wind

'Stella' as she was christened, is a 3 metre blade-diameter 3-phase 24volt machine that has a theoretical output of 1KW/h in moderate wind, and was build by 9 of us over 2 days using basic tools and methods. Everyone got a chance to weld metal, carve blades, wind coils, and get dirty hands regardless of background or prior experience...a true 'social-engineering' experience!


Workshop 1: Fabrication of the turbine chassis from scrap steel and rear wheel hub from a Vauxhall Astra








Workshop 2: Building the pair of rotors using high-power Neodymium magnets...scary things to handle near anything metallic








Workshop 3: Winding the 9 stator coils (connected in 3 groups of 3 coils to create a 3-phase stator), soldering, and casting in resin








Workshop 4: Carving the propellor blades into aerodynamic profiles from blocks of Ash using hand-tools








Final assembly: The most dangerous part of the operation was the attachment of the second magnet rotor. The two disks each holding a dozen N40-grade Neodymium magnets exert a massive force once the rotors come into close proximity, requiring the use of temporary 'jacking bolts' to very carefully lower the second rotor into place..




At last, after much hard work by everyone, the final bolting-on of the prop to the alternator assembly...she's a big 'un is Stella!





Unfortunately, Murphy's Law prevailed and rather than a windy afternoon on the Sunday to see her truely fly, it rained instead...nevermind, it was a real joy and fantastic team-experience to build her

A big to the guys at V3 power for a geat weekend!



[edit on 2-9-2008 by citizen smith]

Excellent story and congrats on the build.
This is something that I've been thinking about doing and you have given me some great info on it.
Keep up the good work.

Nice report, thankyou!

Did you by any chance receive any schematics, or other documentation that you could share with those of us that cannot take the course?

reply to post by Psychopump

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you beat me too it ......lol.....i was going to ask that....

and to theOP well done , and thanks for posting your experience.


thanks
snoopyuk

[edit on 2-9-2008 by snoopyuk]

I didn't get much chance to take any notes apart from mental ones as the session was so hands-on and involved.

The build followed these plans from Hugh Piggott's book and is jam-packed with how-to's, engineering schematics, electrical and aerodynamic theory, formulae, and calculations

My copy should be dropping through the letterbox in the next day or so, and for a measly twelve quid, is an incedible investment

Very cool! Thanks for posting this. Looks like alot of fun. I like the old fashioned nature of using ash for props but I would think this is one area where you'd want a less fragile material. Would it be feasible to use an epoxy resin or high strength plastic? You could even use your existing blades to make the molds. Not a bad idea if only for back ups. A good storm could snap those wooden blades. I live in NW Florida and this scenario is quite likely. I saw a website last year where a couple built there own but designed the blades to fold when under a thresh hold amount of pressure. It didn't work and the blades snapped first. I don't recall if the blades were rigged to collapse in tandem or individually and I think they used a wind speed trigger rather than a pressure trigger. If I can find it I'll post the link.
Again, very cool post. Inspiring!

reply to post by 1stearthwarden

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The blade-making seemed to be the most intricate and labour intensive part of the whole process, a twisted aerofoil profile aint the easist of shapes to carve, especially for a first-time builder unfamiliar with woodworking hand-tools, to get the three blades as close to identical as possible.

You'd be surprised at just how hefty and solid each blade is, and I guess the reason for using a wood like Ash is that the structural properties of the wood allows for flexing along the grain under load, much like a Yew longbow-limb

I'm not sure what performance comparisons have been made to solid wooden blades by building the aerofoils as a skinned spar & rib design and then doped with fibreglass mat and resin for added strength, but that would seem to be the easiest way to get the fine tolerance needed between the blades...that's going to be the method I'll use when I get started on building one

Rather than using rotor-brakes or collapsing blades, the surprisingly simple design of the chassis and tail unit allows the whole unit to furl sideways out of the wind once a ceratin wind-speed is reached so protecting the turbine from over-speed damage

I hope you're inspired to the point of breaking-out the overalls and get tinkering in the shed

What happened to the working model Cit X?
Did they not make each person a prototype or are you now bracing yourself for a solo building session????

Looks damned cool man

1* from me.

Was the finished product tested? Did it work?

Only the one machine was built over the weekend and as far as I know, is to be sold at some point (the guys mentioned they'd use the profits to help subsidise the course costs for those who can't afford the full session fees)...a complete unit (minus tower/battery bank/rectifier/etc) was going for around £1,500 which may seem expensive but when you figure-in the man-hours we all put in, then that seems like a good price

If you were to just buy the 'reciepe book' and never had the hands-on build experience it would be a bit of a daunting task, but i'm raring to get building my own and confident that I'll get it run the first time...i'll be posting my exploits when I do though



We ran out of time on the sunday to get it properly mounted and tested...not to mention the effect of 'sods' law' in that there was no wind that day...just rain

The alternator was tested by spinning-up by hand to test each of the three coil phases on a multi-meter to check if it would generate voltage...it put out around 6 volts per phase when spun by hand...would have been lovely to see 'Stella' fly and generate electricity though!

I'll email the guys who ran the session to see if they have had a chance to test it in-the-field and get some feedback on the session...i'll post any results I get from them when I hear back