Author Topic: Crash (Read 3563 times)

behoof · « **on:** October 04, 2009, 04:53:10 PM »

Hi all,

I figure it wouldn't be right not to share the bad with the good and this, for me, is really not too good.

But first, I wanted to thank everyone for all the help and advice they've given me and mention how important this board and the IRC are to me.

Well, for me, it's back to the drawing board. I had just finished up the set of 10 foot blades, replacing the 12 footers I tried first, and configured it for 1-Delta, got it up for a few days and it was actually working great.

Then we had some serious winds (gusts to 45mph) and on the end of the gin pole where I had an earth anchor made of cemented in plowshares and chain down thru it all and welded to the steel in the cement, a link of the chain stretched and let go allowing the tower to flex over and finally bend at about 13' up. I heard it crash and needless to say I am not happy.

So, even though I had gone out about an hour before the crash to check for any vibration or issues due to the winds of that day and finding nothing amiss went back inside.

This is the result of an anchor chain link letting go (probably wasn't welded when manufactured I'm guessing), you can see the chain hanging off the end of the gin pole standing up in the air.

When it hit it went into the ground about a foot.

The alternator cracked like an egg sort of and when it hit it hit squarely on the ground because it drove all the windings and segments forward so they flew straight forward down the armature without damaging the arm. Not even any scuffing on the magnets. Lucky <--

This is a picture of the bad guy before I brought it down after the crash.

Another angle

Now with all that said it's back to work for me. I guarantee you I will NOT have one spec of non-first class hardware nor and I say this emphatically, any Chinese parts. I could have double safety'd this and that or done this and that but suffice it to say, a part failed and it hit the ground at about Warp IV. Not gonna happen again if I can help it. Already have the plans in motion to get it back up, just gonna be a few changes and thanks to TomW's generosity I'm moving along on my Axial Flux jenny too.

I'd also like to add something that I'm sure most of you already are aware of, "NEVER UNDERESTIMATE the power of the wind!" Double, triple check everything all the time. I had this tower up and running another mill for almost three years with no problems until I went to the chain setup instead of my other ground anchor further out which is a small block chevy block with a 1" ground anchor thru a cylinder and more than a yard of cement. Don't trust anything when dealing with the wind.

Thanks again to everyone and I'll post again as I progress.

behoof

Janne · « **Reply #1 on:** October 05, 2009, 01:31:52 AM »

Hi,

That sucks big time. Seeing a good months or 2 worth of work go down in the ground in a heartbeat is not fun. But it's a good thing you shared your mishap, so mayby others can learn from it. I think many times people simply don't report any failures, because there seems to be so few posts about them. I agree with you on the force of the wind.. the minimum I would accept for rigging would be to first calculate the stress in the worst storm you can imagine, and then multiplying the strength required with at least 2.

On the bright side, the damage to the 2 blades and tower doesn't seem irrepaiparble, so mayby you still can salvage a good portion of it for the next (and better ) version.

Volvo farmer · « **Reply #2 on:** October 05, 2009, 02:20:01 AM »

Bummer.

Thanks for sharing though. I'm just starting to appreciate the power in the wind and now I'm really glad that there is no chain anywhere in my anchors.

Actually this post reminds me that I need to get a big roll of safety wire... Today!

SparWeb · « **Reply #3 on:** October 05, 2009, 07:44:23 AM »

I know all TOO WELL how it feels. Heartbreaking. Having suffered my own "learning experience", if there's anything I can contribute to help, just say the word.

I see fragmenting in all of the blades, but maybe the mounting is salvageable?

behoof · « **Reply #4 on:** October 05, 2009, 08:41:29 AM »

Janne,

Thanks for the message but none of the tower or blades survived, they're junk, totally.

So, I just keep moving forward.

Of course, this wind thingie IS NOT and addiction LOL.

Talk to you,

behoof

behoof · « **Reply #5 on:** October 05, 2009, 08:44:30 AM »

Steven,

Yes, the blades are all pretty broken and unsalvageable. Fortunatly the armature survived so now looking for another Baldor of the same flavor to stick it in, think I found one, waiting for the guy to get back with me, here's hoping.

And thank you for your kind offer of help, since you live so close, stop by for a coffee when I get set to raise up the new one <smile>.

Talk to you,

Skip

SparWeb · « **Reply #6 on:** October 05, 2009, 11:40:12 AM »

You need another Baldor? Let me know if your lead doesn't work out. I can send you a picture tonight. The stator ID measures 4.43", about 3" long, has 36 teeth, 9 wires coming out to the connection box already (star-point on wires 10-11-12 could be cut if you want to).

ghurd · « **Reply #7 on:** October 05, 2009, 01:01:21 PM »

Ouch.

Sorry to see that 'Hoof.

G-

fabricator · « **Reply #8 on:** October 05, 2009, 05:15:21 PM »

Ouch! That hurts, I hate to stomp a guy when he's down but, that chain set up seems kinda strange, all the guys are attached to a kind of spreader and the chain is attached to the gin pole?

behoof · « **Reply #9 on:** October 05, 2009, 05:59:14 PM »

Steven,

I haven't heard back from the guy that was supposed to get back with me re: Baldor, so I don't know if there's anything there or not. My best guess is NOT.

What I have for numbers on my Baldor 3hp 3ph set up is:

Baldor Catalog #VM3611T (that's the one I used originally)

What I have for the arm and stator written down is:

36 Segments in stator

Stator length 4.750"

Stator I.D. 3.983"

Armature that I made:

Armature diameter with magnets on it 3.926"

Also have a question about blades, I have that 12' set I took off to put on the new 10 footers... wondering what sort of performance: TSR and such I'd get by just cutting off (heaven forbid I even said that LOL) a foot on each blade. My reason to ask is of course the fact that the angle of attack gets greater as we move down the blade. I based those blades on Alton's Calculator for 2 blade system.

Talk to you when you can,

Skip

behoof · « **Reply #10 on:** October 05, 2009, 07:05:27 PM »

The chain is welded and secured to a plowshare then buried in cement and the chain was for the purpose of helping hold down the 200 pound 4"x4" square 20 foot gin pole. The spreader for that side of the guys was above and attached to the gin pole on its topside then the chain for the ginpole anchor with its half inch turnbuckle was below.

richhagen · « **Reply #11 on:** October 05, 2009, 09:22:33 PM »

Sorry to hear about the mishap. Glad no one was hurt, and just the mill and tower were damaged. I had read your previous posts, and am sorry to see a bunch of that hard work get ruined. Hang in there, version 2.0 will be even better I am sure. I once had a tiny test rig weighted down on my flat roof blow off and take out the windshield of a car of mine, not quite the same amount of work in it, but I remember the frustration pretty well. Never underestimate the power of nature. Hang in there, Rich

SparWeb · « **Reply #12 on:** October 05, 2009, 10:29:53 PM »

Not a match then. The one I have is catalog # M3211T (maybe close from Baldor's point of view, but miles apart for us).

http://www.sparweb.ca/3_Gen_MoCo/Baldor/Baldor_DataPlate_s.jpg

http://www.sparweb.ca/3_Gen_MoCo/Baldor/Baldor_Rotor_s.jpg

http://www.sparweb.ca/3_Gen_MoCo/Baldor/Baldor_Stator_s.jpg

I checked the rotor again; its diameter is 4.43" so this stator is way larger than you can use with your rotor. Almost a 1/4" gap, there.

The blades are a bit of a puzzle, too. If you calculated from Alton's website, but you only fed in 2-blades, and you now use three, then I guess you'll have more chord than you otherwise want but maybe the angles aren't too far off from ideal. How about going back to his site, putting the numbers you actually have in to the calculator and compare what comes out the end?

Really, you can either just "get it close" or analyze it to death. I go a bit much for option #2 but I was born with a pocket calculator in my hand. If you can give yourself a near hurricane-proof furl system then you can live with the oversize rotor. I personally wouldn't put a 12-foot prop on a converted 3-HP motor, no matter how good a genny it is, especially without a lot of confidence in the furl.

If you stuck perfectly to the prescribed TSR, then cutting off the ends changes the TSR in proportion to the change of diameter. The "TSR" is an acronym for "tip speed ratio", but actually its a factor for any point on the blade you want. If you want X angle of attack at the tip and the same X angle of attack at mid-span, then you want "Y" TSR for the tip, but half that TSR (Y/2) for half span to make the angle of attack the same at both places. Thus a blade with TSR=8 has the twist for TSR=4 at half-span. If you cut the blade in half, then the new tip, which was half-way, will have a TSR=4. For the same wind speed it will be optimally loaded at the same RPM as before, but now that you've cut off half the diameter, there is 1/8 the power available to turn.

It all changes if the generator over- or under-loads the rotor, letting it either run too fast or too slow. Now that perfect TSR calculation goes out to lunch. Since you're on the big rotor side, the generator is likely to under-load the rotor, unless you cut dramatically. That's why I say the furl has to work, because otherwise there's nothing taming the wild beast. This situation is fine for places that normally don't have a lot of strong wind, or suffer long periods of low winds. If that's what you get then you're still on the right track.

scoraigwind · « **Reply #13 on:** October 06, 2009, 02:34:15 PM »

Chain works very well on anchors, but it has to be strong enough. This chain obviously was not. So we can learn from this, what size chain was it that was not strong enough in this case? 1/2 inch chain would seem like a good choice to me, but I also do not know the tower height and gin pole length.

thanks!

behoof · « **Reply #14 on:** October 07, 2009, 09:01:05 AM »

Hi Hugh,

The center of the jenny was at 62' and the gin pole length was 24' of 4"x4" square tubing 3/16" wall. The guy lines were all 1/4" SS on the holding sides and the lifting side is 5/16" cable with quality thimbles, clamps and turnbuckles.

The chain in question is 5/16" link coated (probably Chinese from ACE Hardware). It is welded to a single bottom plow 5' in the earth with 1000# of cement for bedding.

It appears that one of the links wasn't welded together well as the chain is still attached to the plowshare and to the end of the gin pole as seen in the one picture of it standing vertically after the crash. There is still a missing link. This chain, even if it is only near Grade 70 should have held to around 4700# working load with a proof of 18,800#(of course ACE doesn't offer ratings). I just think it was an unwelded or poorly welded link and was galvanized with the rest and just stretched. None of the other links look stressed or misshapen.

I'm mostly just faulting myself for not double safety-ing the lifting side. I have another ground anchor set back from the one in question that I had used with this tower and another mill for almost 3 years with no trouble.

Woulda, coulda, shoulda <sigh> we learn as we go. I'm just sad that had I just put a small safety rope (even something light would have done it I think) to the empty ground anchor, I wouldn't be having this conversation.

As said, we learn as we go and I hope that my misfortune is of good use to others, it certainly is to me.

Be Well,

behoof

Boss · « **Reply #15 on:** October 25, 2009, 01:20:35 PM »

Sad news indeed, sorry about that.

It is a good thing that you posted this though. Literally the weak link in the chain caused the problem.

Almost seems logical

Here is how we handled the gin pole base tie down

That is a 9/16 inch "U" bolt around the gin pole and 1/2 inch thick steel bottom plate.

Now that I have bragged about ours I better go out right now and check the nuts are still tight, knock on wood.

Lucky thing my dog Cujo was watching closely, otherwise we might have screwed up.

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