blade progress (lots of pics)

[kitestrings]

Greetings,

Here's an upadate on the progress on our blades.  I'll let the pictures give a snapshot, but briefly it is a 15' rotor.  The material is local (north-eastern VT) balsam fir; rough-sawn 4"x 14".  Pretty nice light, straight-grained wood.  Strong for it's weight.  Air dried and far from clear stock, as you can see.

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I made pexi-glass templates for station layout.  They seemed to work well both for shape, but also for transfering dimensions to the rough blanks.

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One of my favortie timberframing tools - I haven't heard mentioned here - is my 'slick'.  It's basically a long-handled chisel that you pare with (and never lend out).  I don't think I'd do it without one, though I'm less comfortable than with a draw-knife that many prefer.

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Still lot's to be done, but for now, thanks to all here for help and inspriation, and to Dan for the platform.  regards, ~kitestrings

[Norm]

Nice looking job....makes me tired just looking at the pics
BTW where are you? ....that first pic almost looks like pilot mountain,NC in the
background.

[taylorp035]

Those look just like mine, only 3x bigger    Very nice.  Must of tired out your arms making such large blades. 

[prasadbodas2000]

really great work there....thank you very much for sharing....

[nekit]

Excellent craftsmanship.

[birdhouse]

very nice blades!  looks like you put in plenty of fore thought to make sure they came out exactly as intended, and also put in plenty of elbow grease with all those hand tools!  i hope they were sharp! 

what design tsr were you going for?  and what's you plan of attack for sealing/painting/finishing? 

adam

[kitestrings]

Folks,

Thanks for the responses, and kind words.

We're in northeastern VT.  The 'Northest Kingdom' as it is referred to locally.  Geographically we're on a ridge smack-dab between two utility scale wind projects.
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The first is under construction and we can now see the first towers and turbines.
http://www.sheffieldwind.com/sheffield/about.cfm

The second just received PSB approval, and will/would be the largest in our state, but is a pretty hot local topic:
http://www.kingdomcommunitywind.com/

The design TSR was 6.5.  It is a 16-pole axial, and we're using the MS 'Classic' MPPT controllers.  We're (Neilho, my son & I) aiming for a cut-in (58V) around 95 rpm.  My original plan was to carve this set, single piece, make any adjustmens, then do a final set that is laminated and a composite wood core with dacron Ceconite/West Coast System.  Jim (Sencenbaugh) has had good long-term results with this.

Regarding blade finish on these... it seems like one of those topics where you ask three experts, and the only thing two will concede is that the third is an idiot.  Right now, this is the genral approach, though I haven't been impressed with blade tape overall.  I'd prefer brass shim-stock, but how to attach it?
http://homepower.com/article/?file=HP100_pg138_QandA_6

Nekit, how's your new mill working?

kind regards, ~kitestrings

[SparWeb]

Regarding blade finish on these... it seems like one of those topics where you ask three experts, and the only thing two will concede is that the third is an idiot.  Right now, this is the genral approach, though I haven't been impressed with blade tape overall.  I'd prefer brass shim-stock, but how to attach it?
http://homepower.com/article/?file=HP100_pg138_QandA_6

kind regards, ~kitestrings

I find that the leading-edge protection used for small aircraft propellors is ideal for these wind turbines, too.  I have a clear vinyl plastic tape, 2" wide, that sticks and stays stuck to the LE's just fine through rain and snow.  IIRC, 3M Scotch Abrasion-resistant tape.

[kitestrings]

SparW,

The reports I'm hearing are that the outdoor grade (UV protected) polyurethane tape is better than the vinyl plastic.  Have you used both, or have a preference?  We've used 3M tape (not sure which product #) - all of which are sometimes called 'helicopter tape' - with okay results.  There also seem to be tihckness options from ~6-14 mils typically, and even ~42 mil if you look at 'millitary' grade stuff.

I haven't had any issues with it coming off.  It adheres well enough, is flexible and easy to work with.  My compliaint with it is that it has a tendecy to yellow - I assume UV breakdown - over time and become brittle.  I've also had small 'hangnails' develop adjacent to nicks that cause noise, and I would assume added drag. 

Someone on the board talked about replacing it every year.  I'd like to aim for a 7-10 year refinishing schedule.

~kitestrings

[SparWeb]

That might have been me, who said "I replace it yearly".  A little overdue this year...  Actually all I do is lower the tower, check things over, and fix as required.  Replacing tape is so easy and removes doubt over the subject so why not?  Besides I bought a 36 meter roll so if I don't replace the tape on the blades it will just be a box of dust by the time the year 2093 comes around.

My mistake:  3M Ployurethane tape # 8672, UV resistant.     http://www.aircraftspruce.com/menus/cs/3m_uleadingtapes.html

[scoraigwind]

I agree, it's a lovely piece of work.  I worry a little bit about the knots that run across the blade like this

It's hard to see how bad it actually is, and it's close to the tip so there will not be a lot of stress there but this kind of defect right across the blade can be a fatal weakness.