An Introduction

[CBabcock]

Hello Everyone,

I'm new to the forum (though been a long time lurker) and would like to introduce myself.  My name is Corey Babcock and I've been playing with wind machines for over 20 years now.  My experience with wind started in the early 90's in grade school when I found an old 6 volt Wincharger in my uncle's scrap metal pile on his rural farm.  I successfully restored the old pre REA machine and was hooked for life.  I've had many mentors along the way: Mick Sagrillo, Paul Gipe, Elliott Bayly, Ian Woofenden and Hugh Piggott to name a few.  I would have to say that I credit Mick with being responsible for this addiction setting in as deep as it had since he was very willing to put up with a young kid asking countless questions and always responding to snail mail letters and the occasional visit to his house.  He truly is someone who I still look up to to this day.  They all helped me with my many, many home built turbines and countless other turbines that I picked up second hand that needed to be repaired.  I actually own the Bergey 850 that Paul has on his website that he used for independent testing of small wind machines.  That machine is going back in the air this spring after running for 10 - 15 years untouched at my parent's property.  Ian was kind enough to help a youngster with getting a few articles published in Home Power and served as my "personal editor" a few times over the years.  Great guys!

After graduating high school, I entered into the "big wind" business as a turbine technician for the worlds leader in utility scale wind- Vestas.  I was a tech for Vestas for about 5 years and traveled the world before taking on a job with a local owner of a small windfarm of Vestas 600 kW turbines where I served as his one and only tech for close to 12 years.  Today I serve as the site supervisor for a 3rd party O&M company where out of our shop we are contracted to take care of 80 turbines totaling nearly 60 MW of capacity.

10 years ago this year, I married my sweetheart and 9 years ago we bought an acreage where we still reside today.  Of course all of my small wind machines ended up filling up one of the outbuildings which serves as my personal shop.  I have flown and destroyed many, many commercial turbines in the 8 years we've been here.  Too many to list actually.  Hence the reason I am on here.  I am building my version of a bullet proof (as much as it can be) turbine after having a brand new Bergey XL.1 crash after less than 5 months of run time.  My site is pretty good; the annual average windspeed here is nearly 17 mph, I have very little obstacles to cause turbulence and it can definitely get crazy at times.  The Bergey crashed in our last blizzard a few weeks ago where my NRG anemometer clocked a ten second gust of 87 mph at 70 feet and caused the yaw shaft on the turbine to fail.  That was my last straw.  Time to quit tinkering with other peoples' turbine designs, aka-manufactured turbines.  I'm building an 11 foot machine and using tilt-up furling.  I've seen a lot of comments on here about people having hard feelings towards tilt-up furling.  I've built a lot of small machines over the years and the ones I've used it on have always survived the worst that could be dealt to them.  Why, I don't 100% know, but that's what I'm going with on this machine because I know I can make it work.  I think that it's just like horizontal furling- you have to get the geometry and thrust loading right or it will not work when you want it to.  As for the balance of the system, I'll be running a 24 volt machine as I am grid tied via an old, old Trace SW4024 that keeps on ticking day to day.  The rectifier and charge control will be homebuilt and will definitely be way overkill. 

My apologies for the long first post.  I got rambling a bit..

Corey

[Flux]

Welcome aboard.

You have probably seen some of my comments on vertical furling. The problem I found was that when it was near furling speed, when it yawed one way it held the alternator down but when it yawed the other way the gyro force lifted the alternator. On a turbulent site it spent its time slamming up and down violently. On a very clean site this may not be a big issue ( I have never had one of them).

The accepted way to solve this is with a damper on the alternator but this is bolting the stable door after the horse has gone. The correct way is to devise an effective yaw damper ( not easy but should be possible) or throw the tail away and go for servo yaw.

Having got rid of the gyroscopic link from yaw to nodding you should be able then to get the force balance to work and get it to furl on output and  not yaw reaction.

It may be true that with the alternator damper these machines can survive hostile conditions but many haven't. If you can solve the yaw damping you may be on to something. I always intended to try but never got around to it.

Flux

[kitestrings]

Welcome Corey,

It seems like a logical design to me.  Probably best suited to small machines.  I think attention to detail on the hinge point is also key.  You got a lot of mass (some of it spinning) and now we want to rotate it about a pin connection.  Sounds simple, but like most things the devil is in the details.

Good luck with it.  ~ks

[Mary B]

Corey you wouldn't happen to be located in SW Minnesota? That last snowstorm here was rough. When I thought about building a similar machine I was going to use some simple air cylinders as dampers. Precision valve the in/out to set the damping rate.

[CBabcock]

Hi Flux:
"On a turbulent site it spent its time slamming up and down violently. On a very clean site this may not be a big issue ( I have never had one of them)."

Yes, turbulence and it's rapid changes in direction will definitely cause the machine to nod up and down.  Just like it causes the tail on a horizontal furling machine to rapidly swing off to the side when the rotor stays put.  Turbulence kills any wind turbine, regardless of what speed control is being used.  My site is pretty clean- the tallest thing for several miles is a fence post and my tower is a 70' Rohn SSV.  I've found that if the machine is running in clean air, the tilt-up furling works quite gracefully.  Yes, there may be a few swings in yaw of 20* to 30* in sudden gusts when it furls vertically, but if you ask me, that may also be helping things a bit as it is also somewhat furling horizontally in these reactions.  Just my weird thinking I guess...

MaryAlana:
Yes, I am in SW Minnesota.  Right on the notorious Buffalo Ridge.  I agree, that last big snowstorm was a doozie.  I also have a second Bergey XL.1 on a 65' tilt-up tower and the tower was actually distorted in that 87 mph gust.   I did my best to straighten it back out yesterday since it finally warmed up to a bearable level.  I too am considering installing installing some air dampeners on this machine to help with keeping things as smooth as possible.

Back to the grindstone!
Corey

[Mary B]

I am up NE of Marshall 27 miles, don't get quite the same winds as the top of the ridge but it gets bad. My weather station said 72mph. People told me I way overbuilt my solar panel frame, main beams are 4x6's... you have to live here to know how violent the winds are.

[CBabcock]

MaryAlana:  You wouldn't happen to be on the district 5 ARES net by chance? 

Corey
KD0MVD

[Mary B]

Sure am W0AAT

[SparWeb]

Corey,
Welcome to the group.  Awesome credentials; pretty soon you'll be the mentor.

Tilt-up furling has been done a few times by small WT manufacturers, Parris-Dunn comes to mind.

A few homebuilders have done it to.  They have mixed results but the ones I've read have been satisfied.  A peculiar behaviour, other than those Flux mentioned, is also the "walk-around-the-block" trick, where the moment of a +gyro direction yawing coincides with up tilt furling motion during a gust, so it does a 360 (or more) until it settles down again.  Slip rings are a welcome feature.

My approach to "bullet-proof" has been to convert industrial motors that can take 1800 RPM and 60 locked-rotor amps and run them as wind turbines at ~500 RPM and never peak above 40 Amps.  Nothing against the cast axial stators but under your weather conditions....   The Axial-flux design as per Hugh Piggott is a specialist at medium wind speed ranges with the advantage of the ability to "tune" for manufacturing variations.  I don't think an axial will address your problems.

Further thoughts on a bullet-proof turbine for extreme wind speeds and possibly very strong gusts is to have NO furling at all, and design for stall regulation, backed up with a generator that can maintain rotor load at any forseeable RPM without a meltdown.  The compromises may involve a loss of low-wind speed energy delivery.  Also a problem I don't think you have.

Clearly you moved to that acreage to take advantage of the wind resource there, so best of luck with that goal, hard to hear about the failures with it so far.  I look forward to helping you reach your goal in the future.

[ruddycrazy]

I will confirm Sparweb's last posts in saying I have 2 motor rewinds going, my 1.5kw and the 4kw. both have seen gales where trees have fallen down and my towers have stayed put. Motor rewinds are really bullet proof as like the F&P once they get to a certain speed the current goes down and the BEST part they are still going after a violent storm.

By the way I did get an email from Keitan(Neo mag company) so they did say prices are down so for custom 3 phase conversions they may be back on the cards.

Regards Bryan

[CBabcock]

Hi SparWeb

"Welcome to the group.  Awesome credentials; pretty soon you'll be the mentor."

Thanks!  I hope that maybe someone will glean some info from my experiences over the years.  Even after all these years, I'm still learning.  Good stuff, what other hobby can you have that keeps the mind moving in so many ways?


"Tilt-up furling has been done a few times by small WT manufacturers, Parris-Dunn comes to mind."

Yes!    I love that machine!  I have a 6V one that has been on display in my shop for eons now.  Great little machines.  If I recall correctly, they built up to a 12 footer.  LOVE the old Pre-REA turbines.  Been a collector for years and have a small handful of Winchargers and such.


"Nothing against the cast axial stators but under your weather conditions....   The Axial-flux design as per Hugh Piggott is a specialist at medium wind speed ranges with the advantage of the ability to "tune" for manufacturing variations.  I don't think an axial will address your problems."

Here are some of my thoughts- Yes, the axial alts have their weaknesses, overload being a major one of them.  A very large number of the failures I've had have been mechanical.  For the electrical / overloading end, I'm planning on having my machine being fully furled by about 20-25 mph.  I've got the frame all welded up and it has an offset from the furling pin of about 6 inches (plenty in my experience).  The rotor is pre-canted to a 10* angle vertically when in it's normal "home" position to help with the onset of furling.  Fully furled, the rotor will be at 80* from horizontal.  Springs will help in holding the turbine in it's normal running position and to increase the resistance to furling as it progresses.  I'm not too worried about the peak power that I get out of the turbine as the higher windspeeds are always less common and I'd rather have the machine produce what it will up until the 20-25 mph range and then just "get out of the way and hide" when winds increase beyond that.  Probably 65% of the time our winds are below the 20 mph range, but when it decides to get windy, it usually does in a big way.  40+ mph for 3 or more days straight is not uncommon.  I actually held Ventera's 24 hour production record when I was testing their 10 kW machine for Elliott Bayly at my home and hit 294 kWh to the grid in one day.  I'm not looking for a cure-all with the axial, just something that I can build in my modest shop and not dish out another grand when it blows up.   I'm winding my stator up as we speak.  75 turns of #13 are going into it (24 V machine).  I'm fudging a bit from Hugh's and the Dan's plans as I'm also using a 1750 lb. axle which incorporates a bigger hub (5 on 4.5), leading to a bigger center hole, leading to more room for copper.  Hopefully the equation equals a bigger cushion before meltdown.  My main objective has been to make the thing as mechanically stout as possible.  The furling pin is an 1.5 inch tube, .25 inch wall with greaseable needle bearings in the ends of the tube and thrust bearings on the ends between the uprights.  The whole frame is .25 inch plate and already weighs more than the XL.1 it will be replacing.  The children's story of The Tortis and the Hare comes to mind here. -Wait, maybe that's because I just read it to my 2 year old... 

I know it's a bit ugly at this point, but here's where I'm at with the frame:





"Further thoughts on a bullet-proof turbine for extreme wind speeds and possibly very strong gusts is to have NO furling at all, and design for stall regulation..."

One of the windfarms that I oversee is a group of 750 kW NEG Micon turbines.  These machines are stall regulated.  No furling, no pitch adjustments, no nothing.  They have the blade angle pre-set to stall at a peak power and they have to live with it.  Here's the problem- stall works up to a point.  This winter, we were experiencing some extremes.  25-40 degrees below zero and 50+ mph winds were very common all of January.  The month's average windspeed was well over 10 m/s (over 22 mph).  These Micon turbines were constantly faulting out on errors because they were overproducing and stall was not setting in and holding on as it should.  These 750 kW turbines were hitting well over 1 MW during these conditions.  Some of them even peaked at over 1200 kW.  From what I've found, stall works, but only to a point, and then the rotor will start to overpower the load.  If you push the limits, stall will break free if the conditions warrant.  And, that would be a time that I would desperately regret not having furling.  This is also the exact reason I plan to incorporate a pull cord of sorts to furl the turbine manually from the tower base and not rely on dynamic braking.  -There's no better way to stop a turbine than to get it out of the wind.  They figured that out nearly 100 years ago.

More to come as things progress...

[CBabcock]

Mary:

Feel free to give a shout-out if you hear me on the Tracy repeater sometime.  Every once and a while, I'll try to give out my call on the way home from work around 3:30 to 4:00, but I only have a 10 minute drive so may miss anyone who comes back...  Otherwise, I'm usually in the shop (with the radio cranked up) after the weekly net.  I'd love to chat sometime about your system.

Corey
KD0MVD

[midwoud1]

Corey:

Most of us are working with the furling tail system to keep Rpms between the limits.
Lakota 1KW windgenerator has a tiltback , seems to work well.
I have running an active pitchcontrolled 1Kw ,3mtr.diam prop. 90 deg feather. Self regulating
Variable like Vestas and Enercon.
3 years working good ,low maintenance .
A bit extra time and work to make ,but it survived 11 Bft gusts and gale ,because it can be set in full feather. Happy stator.

http://www.youtube.com/watch?v=Y6CEBIzXdmc

http://www.youtube.com/watch?v=9jaz3soqXLo

http://www.youtube.com/watch?v=RiQiqi5jzVs

  - Frans -

[Mary B]

I almost always have the rig scanning so call a couple times. Where I am located I can copy repeaters all the way up to St. Cloud and also the 25/85 in MPLS, the Mankato machine etc. Once I get a tower up and get the antenna to 40 feet that should extend that even further.

[SparWeb]

A Nordtank breaking loose in the gusts - that's one way to get your wind farm in the Youtube hall of fame.  Yikes.
Were they the 44m or 48m models?

I thought of your posting when I read this month's HomePower magazine.  Maybe you've seen it.  A letter from Mr. Sagrillo himself responds to a reader's questions about siting a turbine near the edge of a bluff.  For a moment I thought it was your own question he was answering!  But I point it out because you would likely take an interest.  If you don't have a copy I can sum it up for you later.

Did you say you live on a ridge?  The upward component of the oncoming wind could play games with a tilt-up furling system.

[Mary B]

Look up Buffalo Ridge Minnesota to see some pictures of where Corey is. Parts of the ridge are 1500 feet, I am at about 1125. The rise is pretty gradual for a lot of it so upward component shouldn't be that bad

[SparWeb]

Yup
The long multi-bladed shadows give it away don't they?

Minnesota...  I was about to post something off-topic (due to looking at it from Google Earth) but I think I'll save it for the pub.

[ChrisOlson]

I played with a couple tilt-back turbines a few years ago and never had exceedingly good luck with them.  The forces on the head imposed by the rotor being able to move in two planes during high loading is too great for them to be very reliable.

I also agree that stall regulation, for the most part, does not work.  We get the 70-100 mph nor'easters here off Lake Superior and there's an Endurance turbine that went up a few miles from here.  This thing is stall regulated and IMO they don't even have big enough bolts in the tower base flange on that thing for this part of the country:



The GE 1.5's that they put up on the North Shore didn't last thru the first winter here before they were turned into junk.  So on the next windy day I plan on taking a drive so I can watch that Endurance turbine self-destruct.

[Frank S]

Chris O; I know scale can be deceiving when the only thing to scale by is the unistrut located quite some distance  away in the foreground. it trying to blow up the pic  the resolution gets too grainy. but it looks to be a 48 bolt pattern with a 3.5 to 4 diameter bolt center to bolt center distance
 The flanges look to be about 2" thick,possibly 2.5"  the bolts look to have a dia. of less than half the thickness of the flange.
  Unless there happens to be a secondary bolt pattern inside  of say 36 to 38 bots of the same diameter. I would be like you I'd like to be the fly on the wall when one of those  winds blows.
 I notice as well that it is a non gusseted flange.
 Increase the flange diameter a few inches, increase the bolt diameter 1 1/2 times gusset between then let the wind blow. JMO

[midwoud1]

Several Endurance windturbines went down in England , in a 50 mph gale.
It looks that the studbolts at the base ring ,are low grade and small diam.

[midwoud1]

Windturbine collapse

[ChrisOlson]

This is what I am hoping to get a video of.  If I can catch it on camera as it goes down when the spinning blades hit the dirt it will be really cool.  I took one look at the base flange on the tower, it took me all of 15 seconds to assess it, I snapped a quick photo, then immediately retreated to a safe distance from it.

[CraigM]

See the studs / nuts holding that blade on the hub?



I'm responsible for the fasteners used in the hub assemblies on GE wind turbines. I have 150,000 plus in inventory at any time and they all have material certs, manufacturing certs, heat treat certs, inspection docs, lot numbers and a butt load of other red tape.

If the blade snaps off they come gunning for me. I make sure my paperwork ducks are in a row, deflect them back to GE engineers and live to fight another day.

[DamonHD]

You must be the life and soul of parties you attend and I'm sure that you could ... ahem ... talk the nuts off anyone present!

Seriously, I'm impressed.  Riveted in fact.

Now I must bolt before I screw up.

Rgds

Damon

[ChrisOlson]

Windturbine collapse

Frans, why does it say that Endurance turbine was "controversial"?  Were the locals complaining about it when it went up?

The one they put up here wasn't controversial.  It won't become controversial until it goes down.  They sited it about 40 meters from a large warehouse building because it's a privately owned turbine.  The warehouse is SW of the turbine so when it goes down in a nor'easter it will land on the warehouse.  That will be really cool.

Frank S the bolts used on that base flange ring are grossly inadequate and are stretch to clamp single-time torque type.  I'm guessing the tower is an IEC 61400-2 Class 2b - 8.5 m/s at hub @16%, 59 m/s max spec.  It's easy enough to get an engineering stamp on that tower against that spec.  Have no clue what engineer approved it on that site.  We'll find all that out when it comes down and lands on the warehouse.

[clockmanFRA]

Have a look at this thread from our European Sustainability Forum....

http://www.navitron.org.uk/forum/index.php/topic,19284.0.html

As you can see there are lots of more Photographs, and lots of discussions from installers and Engineers.

Conclusion, I think, the Turbine was installed by a Civil Contractor that was used to putting steel building structures up, but had no idea of the Forces involved when the Wind gets blowing. 

[ChrisOlson]

clockmanFRA - interesting read.  But still, if the machine was put up by a civil contractor the tower and foundation is still certified to a loading spec.  The contractor has nothing to do with that and just has to obey the engineer's instructions on bolt torque, etc..

My personal opinion after looking at the one here is that the tower is a Class 2b design and not suitable for wind speeds over 60 m/s and continuous high fatigue loading over 8.5 m/s.  It is easily possible to get wind speeds higher than that in localized areas due to microbursts, or terrain channeling wind.

So the flange bolts simply failed.  The type of bolts I saw on the one here are stretch to spec type, good for one tightening, and if ever loosened have to be replaced.  They are torqued to a spec, then turned an additional number degrees to place the bolt under tension and relieve the stresses in it.  All it takes is for one of that style bolt to pop and the rest will go.  It's not rocket science really - just exceeding the design limitations of a particular component (that happens to be a critical component).

The G-3120 that is near us appears to have the identical tower that one in Europe had.  I wouldn't trust that tower with that turbine on it any further than I could throw it.  And my concerns on the one looked at here are now backed up after reading about this one that went down in Europe.

[midwoud1]

Hi Chris
 Controversial .The residents made protest before it went up .They were afraid of noise and visual nuisance.

   http://www.telegraph.co.uk/earth/energy/windpower/9837026/Wind-turbine-collapses-in-high-wind.html

The turbine should withstand 116 Mph ,it went down with 50 Mph.

Rgds.  - F -