Wind Generators, a cautionary tale.

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artemis07

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Nearly two years we were unfortunate enough to be caught in an 100knot "event". The wind generator ran out of control causing the blades to shatter sending shards, at very high speeds (hundreds of knots), in all directions. Luckily they all missed me. On returning to the UK I informed the makers who immediately refuted my complaint. It was impossible they said, they are indestructible they said. They accused me of not fitting it properly, which wasn't true. They said I hadn't used their equipment so the blades had touched the mast, I had used their mast. Incidentally, their performance graphs stopped at 40 knots so I presumed they hadn't tested their product above this speed.

Anyway, fast forward to this year. I started chatting with the crew of boat which was caught in the same "event". Their wind generator blades also shattered, they actually saw them disintegrate and regarded themselves lucky not to be injured or even killed. It was the same make as mine and also used the maker's mast.

Be warned, if you have a wind generator and winds of 60 knots or more are expected put a physical brake on it. The 100knot "event" was not expected. The wind generator had an electrical brake but the regulator "fried" before the fuse melted.

The good news, new blades were fitted and a very expensive new regulator was purchased (from the wind generator manufacturers). It works perfectly.
 
I presume the event was at Vliho. If so, the Air-X on our boat (then under different ownership) also self-destructed at the same time, the blades shattering into shards. I didn't bother to replace them since it was one of the noisy ones.
 
macd said:
I presume the event was at Vliho. If so, the Air-X on our boat (then under different ownership) also self-destructed at the same time, the blades shattering into shards. I didn't bother to replace them since it was one of the noisy ones.
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Well that is most interesting. Our Air-x marine managed to work loose on the pole and due to that a blade broke off-gone. I have removed the other two and notice stress cracks on the blades just below the holes for the two bolts. On route to me from BARDEN are a set of blades and the new bolt kit.

We shall be keeping a very close eye on it now.

Thanks

Peter
 
Wow that was lucky to miss being hit by those flying bits of blade.

We had a blade break and fly off our Air-X a few years ago. Luckily no one was nearby to get hit by the flying blade. It had broken at the bolt hole and when we inspected the remaining 2 blades we found stress cracks around the bolts. There was also a lot of corrosion around the bolts due to dis-similar metals next to each other in a salt environment - the stainless bolts inserted into the aluminium blade hub. The corrosion had created a powdery substance which built up under the blades around the blade bolts and we're guessing this pushed up against the blades and caused the cracks.

When we fitted the new blades we put a coating of Duralac (boron cromate paste) around the bolts to provide a barrier between the 2 metals. We now also inspect them every 6 months or so to check for corrosion and stress cracks.

Nichola
 
Any chance it was a Rutland 913? I always take ours down in winter as I wouldn't trust it over a Scottish winter where 100 mph winds aren't exactly unheard of in exposed areas. We had warning of a sudden bit of bad weather a few years back and I lowered the sprayhood, tied everything down and made certain the Rutland was tied off with rope. Just as well, we had at least 80kn gusts at home and probably more down on the boat.

I met two other owners who had not tied off their 913s. We met a chap in Ardfern who'd had a 913 half-way up the mizzen mast and it had exploded. Ceramic magnet fragments hit the deck and one blade went right through his radome. The second one was in the yard at Ardrossan at end of the season and he had virtually nothing left of his 913 after it came apart.

I never managed to find out what windspeed 913s were designed to survive but do remember that the output graph only went to 40knots (pretty irrelevant above that anyway). I remember doing a quick calculation to work out the speed at which the blade tips would go super-sonic. Can't remember the exact figure now but remember something a bit over 7,000 rpm. Never bothered to try to relate rpm to windspeed though.

I certainly wouldn't want to leave my wind-gen running in winds much above 40kn, but you don't always get warning.

I also remember reading something about Rutland 913 blades bending in strong wind (they all will) and Marlec warning about the diam. of the support pole. I guess they were claiming OP used a large diam. pole and so the blade tips would hit it as they bent back in a gust.
 
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Similar event in the yard last winter with boat next to us. Don't know the make of the genny but it had 3 blades, round profile body and inverted fin. Lost all its blades in 40-50 kt gusts, one dented a steel rudder on adjacent boat and another blade hit a boat 75-100m away. Fortunately, we escaped without damage.
 
Our blades have arrived for the Air-X Marine. I have managed to remove the turbine from the pole, as it slid off. The holding clamp is another story. I just cannot un-do the bolts. Have put oil on but they are siezed. So shall have to seek an engineer in the local workshop to remove them. Ah well such is life. I thought that I would be able to do it all within a couple of hours. Now seems like a few days.

peter
 
Any wind-generator will shed its blades given sufficient of a wind - my innocuous Ampair 100 did so during the Great Christmas Gale in la Rochelle.
Given this fatal weakness, the x3 capital cost/amp/hr compared to PV panels, I'm surprised anyone still considers using them.
Unless of course they live above 60N under conditions of continuous wind and overcast.

Which sounds like the Scandinavian idea of Hell.
 
charles_reed said:
Any wind-generator will shed its blades given sufficient of a wind - my innocuous Ampair 100 did so during the Great Christmas Gale in la Rochelle.
Given this fatal weakness, the x3 capital cost/amp/hr compared to PV panels, I'm surprised anyone still considers using them.
Unless of course they live above 60N under conditions of continuous wind and overcast.

Which sounds like the Scandinavian idea of Hell.
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+1, I know someone who leaves his Rutland wind genny going 24 / 7, even in winter when the boat is usually ashore.

Now on the umpteenth set of bearings, it shakes the whole boat and sounds like an attacking Stuka !
 
Interesting that it's a Rutland one that disintegrated. I'm surprised, because they are used for unattended operation over the Antarctic winter, where winds well over 100 knots are experienced for long periods! I think that they are usually set up with three blades rather than 6 for that use, but they are certainly capable of handling 100 knots.

From the sublime to the ridiculous, I leave mine operating 24/7/12, and as far as I can see there are no ill effects. It is slightly more noisy than it was initially, but that's because of "slop" in the mounting - I tighten things up and it is quieter. The bearings are fine.
 
AntarcticPilot,

I know the original funder / marketing contact for Rutlands - Aerogen; he is a really nice guy and very profeeional indeed, was a Battle of Britain Spitfire pilot and later Test Pilot.

He would never have anything to do with less than top notch products, maybe the rights were sold away I don't know, but he'd be mortified to hear the tales here from time to time, so I won't tell him !
 
lenseman said:
then replace with new S/S nuts and bolts.
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If you're doing a proper job, and something so expensive surely deserves it, you'd also drill and tap any threads in aluminium and use thread inserts. Being stainless, any gavanic corrosion occurs between insert and mother metal rather than between thread and fastener: it's stronger than the original and they'll always undo without a struggle.
 
We have a 913 and we been caught out a few times , the thing just takes off like there no tomorrow , we expecting high winds to night so no sooner I press the send button I will get off my bum and turn it off .

Dufour385.webs.com
 
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