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Forum Index : Windmills : Exit one turbine. Storm damage.
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Had a bit of a storm super cell pass through here today, crap flying everywhere. I was in the shed shutting down the power when the storm was at its worse, rain was deafening, only lasted 5 minutes. A few minutes later I was back up at the house and looked out to my windmill. It was gone. Mast still there, no windmill. Found most of it about 15 meters from the tower, where it crashed into the ground next to a old farm windmill tower. 
Found 2 blades, one about 50 meters away, in perfect condition. The other about 150 meters away, with a obvious dent from a tower strike. 
Cant find the other blade, its not within 200meters of the tower that I can see. Did a bit of a forensic investigation. All blade shafts show signs of bending back ( paint off front face, where metal stretched ), and one blade shows a tower strike. So I guess a wind gust bent the blades back, one or two impacted the tower, deformed and rotated around the shaft, shearing the rivets and headed into the sky. With a blade or two gone, the thing would have been seriously out of balance and self destructed very quickly. So much so it lifted itself off the top of the tower, breaking a 4mm stainless wire cable ( the furling cable ) in the process. The furling cable shot down the inside of the mast and exited near the cable tie off, none of it was left inside the tower. All blades came off the shafts, despite the number of rivets I had used and the fact I needed a sledge hammer to press them together. The turbine hub is destroyed, but did stay together. Not one piece of metal is straight, all bolts are stretched and even a few nuts have lost their treads and slipped over their bolts. The F&P shaft is bent, about 5mm out. Front magnet hub broken, both stators are cracked, but should be repairable. Rear hub has a few broken magnets. Tail hinge bent and the tail boom broke in half. Not much left to salvage 
I'll put up a spare single stator windmill tomorrow, and look at building a new dual. Bit sad to see this one die, its been a good performer for me and has survived a few storms with wind gusts over 100kmh in the past. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| MOBI Guru  Joined: 02/12/2012 Location: AustraliaPosts: 819 |
My sympathies Glenn. In a big storm a year back, I lost a blade of an Air-X turbine on a 10 acre block. I never found it. Thought I recognised the mill tower in the photo. Reminiscent of the days I used to make them. I get very nervous when I have to do paddock work near the wind farm turbines on our farm in strong winds. A number of blades down our way have already been damaged and I've seen how far bits of the blades have been flung. My little 500watt OEM mill makes me duck for cover when it get up around 600RPM. I have had to winch it down a number of times in strong winds. I always lay it down when going on trips away. All that aside, if a mini tornado comes through with no warning, nothing will save the back yard turbine from certain destruction. Been there! David M. |
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b351267 Newbie  Joined: 08/02/2010 Location: AustraliaPosts: 27 |
I know how you feel..... Don. Don There is always a 'Plan B'. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
The U bolts held, but all blade shafts had slipped a few mm before things went bang. Considering the abuse this thing has survived in the past, it must have been doing some serious RPM today. 
My regret is I didn't make the shafts for this windmill like the one's I've made previously. I prefer to fit a solid steel core into the tube about 500mm. It gives the U bolts something to bite into that wont crush, and strengthens the first 500mm of the blade root, where its under most stress. These blades only had a short core, just past the outer edge of the hub. Its after the core ends that these blade shafts bent, causing the tower strike. But, this was an extreme event, and maybe something else would have failed. This is the bent turbine hub plate. It was made from 6mm Bisalloy 80, which is about 3 times the strength of regular mild steel. I'll see if I can bend it back into shape with a large sledge hammer, but I have my doubts, so might have to get another one made. 
Took the dog for a walk around my property boundary, then into the neighbours place and across the road. No sign of the missing blade. 
Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
I had lightning strike within 15 metres of the house too yesterday. No damage to solar etc. fortunately, did take take out ADSL modem. Some underwear that needs cleaning though, heard it hit and then several very loud arcing sounds just after. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Hi Glenn, Well Mate chin up, put it all down to the learning curve of windmills , I know how you feel all to well, and the rebuild process is slow, some give up and some get on with it to take on Mother N again. I would be interested to see some pics of the rivet holes in the blades and tubes? For 3 blades to all slip of the tubes at the same time is rare . In the pic of the blade hub it looks like the all-thread has been striped that holds the blade hub to the back plate PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Yeah a few of the nuts have torn off threads, in several places. Things have bend and broken that you would not expect to. There's a chunk taken out of the tail fin, which had separated from the rest of it and was a few meters away. The more I look the more it looks like a grenade went off. Wish I had seen it happen. Putting together the single stator windmill this afternoon, will drop the tower later to see what was damaged up there, but from the ground it looks OK. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
looks like mine when tower lifted off...... Phill can make me new bits for blades etc but i went with 2x 200W solar panels instead..... all in $400 will last a long time and do about the same if not better than the dual stator mill.... No fun to watch though! Luck favours the well prepared |
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| domwild Guru Joined: 16/12/2005 Location: AustraliaPosts: 873 |
Sorry to read and see this mess. Makes me wonder why I have even been thinking 6mm for the hub is over engineered! Managed to get a SS tube for my build over which I slipped the 25.4mm (1") exhaust tube, this might just be a bit safer. In 50/50 hindsight: Angling the hub so that the props do not drop down vertically but that the lowest prop, once bent back does not hit the mast. However, once a prop bends back that far it will hit the mast regardless. Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1329 |
Hi Glenn, I've just read your post - my sympathies along with the others; not a good present for the New Year! The worrying thing about this is that there's only going to be a greater frequency of these 'freak' events - they'll be relatively normal in a few years. Just thinking about the home turbines - would it be possible to design the hub to automatically lock the blades right back in a serious blow? The 'sensor' to control it is already there in the voltage or current being generated and maybe regenerative braking could be used to stop/lock rotation before folding. Solar panels aren't exempt from damage either. Down here in Melbourne last Xmas we had a stormcell that produced hailstones the size of a small fist with strong winds sending them in sideways. Around my area most skylights were smashed, mine included, and half the roofing of polycarbonate decks and garages. Cars caught out in it were seriously damaged - pretty bad news for the insurers! I don't know the extent of damage to panels but it must have been considerable. Greg |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Bummer! I feel your pain. It was a year ago, December 19th, that an EF-2 down-burst tornado took my barn roof and house roof to Oz (not YOUR Oz) and all but destroyed my 2012 RV parked out back of the barn; all within about 7 or 8 seconds! $21K in damages. The wind can be ferocious at times. That said, I'm almost done building a new house, so I hope to get a move-on with my ginormous VAWT, which I think will stand up to wind gusts better than a HAWT atop a tower; we'll see. Again, sorry for your loss. . . . . . MAC Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Yeah Pete I think its critical the first 500mm or so of the blade shaft be solid or thick walled pipe. It was the pipe bending that started the self destruction of my mill. The centrifugal forces had given the U bolts a hard time, but they held, and the mill may have survived if not for the bending pipe. Once he blades hit the tower, its all over. Looking at the blade that struck the tower, I can see how it was deformed by the strike and tore itself off the shaft. The blade opended up from the inside, pulling out the rivets and heading skyward. The rivets are missing from it and its shaft. The other two shafts, and one blade, have the rivets cleanly sheered off, but still in place. The single stator mill is up and running. Its a 80 series with a staggered stator, a 1X8C and 1X6C. For a bit of fun I added a light to it. Something I've been thinking of doing for a while, using a 10 watt bulb I could turn on from the ground. But for now I added a little $2 solar garden light 
Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Midwoud1 Newbie Joined: 25/12/2012 Location: NetherlandsPosts: 23 |
Hi Glenn , Sorry you lost your windmill in a storm. Can be a good idea to make active pitch-controlled blades. It looks more complex as it is. And I see several people are able to make it. We live in a digital world 2014 and the electronic components are assisting us . It has saved my windmill in 6 heavy storms. The Arduino controller does the work. There is a manual switch so in case... the wife can set the blades in feathering position , as soon you hear on the forecast that there is a storm aproaching. Rgds. Frans . |
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wallablack Senior Member  Joined: 10/08/2011 Location: AustraliaPosts: 164 |
It hurts a bit when something you created yourself flies to pieces or fails.... It looks as though the build effort and quality was there though so maybe your next one will be a storm reckoner! Foolproof systems do not take into account the ingenuity of fools. |
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