Author Topic: Hugh Piggott ‘Jumping tails’!  (Read 4167 times)

0 Members and 1 Guest are viewing this topic.

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Hugh Piggott ‘Jumping tails’!
« on: January 15, 2017, 04:07:46 AM »
Just when I thought I could get back to some Capital jobs/tasks!

A couple of days ago, here in Normandy, France, 50 minutes from the Atlantic coast, we had some appalling severe gusting/squalls  winds at about 100mph.

It only lasted 2 hours and left most roads around here un-drivable, with the bare winter trees down and branches all over the place.

My satellite dishes got thrashed and have had to be reset, my boys like their TV and Internet, but lots of debris everywhere with the sound of chainsaws in our valley.

My 3 Turbines are 3.7m, 12 footers, to Hugh Piggott design.

No 1 has survived an official Hurricane winds some 8 years ago, so I was surprised to see its tail had lifted off.
No 3, Is my latest and has only been up 2 ˝ years, but its tail came off and broke when it hit the ground, so new ply tail vane required.
No 2, (photo 2) Has my modification on it, as its tail jumped 3 years ago. Nothing fancy just a 4mm diameter woven bronze line, I suppose a good stainless steel fishing trace line would do, and just 2off 6mm bolts one on the tail arm gusset the other on the main frame tail spigot.  The tail can move about as designed but cannot lift away.

I will start repairs tomorrow and modifications and see if the blades struck the tail as it jumped ship. I will keep my fingers crossed on that one.

And all those bushes growth around the base of my Turbines will now all be hacked back to basic cattle hedge. Although a small battle with her that must be obeyed will probably ensue, and a compromise will be reached.
Everything is possible, just give me time.

mbouwer

  • Full Member
  • ***
  • Posts: 184
  • Country: nl
Re: Hugh Piggott ‘Jumping tails’!
« Reply #1 on: January 15, 2017, 05:39:52 AM »
I would like to talk about real nice improvements for your turbines and really help you to make them.

Regards Rinus

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #2 on: January 15, 2017, 07:55:11 AM »
Hi mbouwer,

Thanks for your offer, I am here in Normandy, PM me if you want to visit, you would be welcome.

I believe that Hugh's design is as effective as a machine as you can get. Its Simple, very robust, reliable and very importantly for me, its very cost effective.

I had hoped that showing my turbine failures and modifications might encourage other builders to be aware of my particular turbines short comings.

Mine have been up many years, and major failures have been relatively minimal. They have pumped out Mega Watts after Mega Watts with just a general service once a year.

I love my Turbines and will keep them working for as long as possible, but in this day and age, the Price and quality of PV is at such a level that constructing more Turbines here is NO longer cost effective.

I have hundreds of tasks that I need to do here, as well as putting up another 15kW of PV.
Everything is possible, just give me time.

Ungrounded Lightning Rod

  • SuperHero Member
  • ******
  • Posts: 2785
Re: Hugh Piggott ‘Jumping tails’!
« Reply #3 on: January 15, 2017, 08:08:10 AM »
You might want to short the ones that lost their tails until you can get them down.  Otherwise, if you have another storm and a gust happens to spin them up, they might start "wind seeking", stay spun up. and become unfurlable.

It's a small risk, but why not reduce it?

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #4 on: January 15, 2017, 08:15:10 AM »
Yes they are all shorted out.

Interestingly, at first light and it was still windy and without tails, the Turbines were just lightly turning backwards.
Everything is possible, just give me time.

Ungrounded Lightning Rod

  • SuperHero Member
  • ******
  • Posts: 2785
Re: Hugh Piggott ‘Jumping tails’!
« Reply #5 on: January 15, 2017, 09:00:50 AM »
Interestingly, at first light and it was still windy and without tails, the Turbines were just lightly turning backwards.

Sounds right.  I'm guessing they're facing roughly away from the wind.
 - Blown downwind - like a tailless downwind turbine.  Probably substantially off from directly downwind because of the offset of the mainshaft axis vs. the yaw axis.
 - The blades would not be as efficient (doubly so because they're not spun up) but would still "airscrew" and even get some lift (thought he wind attachment would be poor and it might shed vortices and make some noise).  Something like startup when the wind picks up from calm, but even less efficient.
 - Shorting the mill produces strong braking forces, but the mill has to turn a little to generate them.

Is that how they're behaving?

I'd expect them to be fine in this mode, even in very high winds, until you can get them down.

mbouwer

  • Full Member
  • ***
  • Posts: 184
  • Country: nl
Re: Hugh Piggott ‘Jumping tails’!
« Reply #6 on: January 15, 2017, 09:06:55 AM »
Over the years it is always nice to read about your turbines.
I agree what you say about the Piggott design.
What to do to make them so ridgid to make them resist the heaviest storms?

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #7 on: January 15, 2017, 09:20:49 AM »

Sounds right.  I'm guessing they're facing roughly away from the wind.
 - Blown downwind - like a tailless downwind turbine.  Probably substantially off from directly downwind because of the offset of the mainshaft axis vs. the yaw axis.
 - The blades would not be as efficient (doubly so because they're not spun up) but would still "airscrew" and even get some lift (thought he wind attachment would be poor and it might shed vortices and make some noise).  Something like startup when the wind picks up from calm, but even less efficient.
 - Shorting the mill produces strong braking forces, but the mill has to turn a little to generate them.

Is that how they're behaving?


Yes, spot on ULR.

I love your explanation for the braking...... "- Shorting the mill produces strong braking forces, but the mill has to turn a little to generate them."

I have sometimes bamboozled EE's by showing them actual hands on, a PMG freely rotating and then shorting it out and asking them to rotate it. It leaves them puzzled,  ..... haha!
Everything is possible, just give me time.

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #8 on: January 15, 2017, 09:26:43 AM »

What to do to make them so ridgid to make them resist the heaviest storms?

Yes,  its always a compromise. Go OTT, (over the top) on design and hardware and manufacturing investment, against simplicity and achievable returns.
Everything is possible, just give me time.

frackers

  • Sr. Member
  • ****
  • Posts: 362
  • Country: nz
  • Is it finished yet?
Re: Hugh Piggott ‘Jumping tails’!
« Reply #9 on: January 15, 2017, 07:25:23 PM »
I've got a length of studding running up inside the pivot - nut each side to fix it to the pivot pin on the back of the mill head and a large washer and a couple of lock nuts (to allow for working tolerance)  at the top so I have some 5-10mm 'float' but the tail can't jump.

If I have time tonight, I'll get a photo of it.
Robin Down Under (Or Are You Up Over)

kitestrings

  • Hero Member
  • *****
  • Posts: 700
Re: Hugh Piggott ‘Jumping tails’!
« Reply #10 on: January 15, 2017, 08:32:21 PM »
Sorry to hear/see this.  Hopefully no blade damage, otherwise the repairs should be pretty manageable.

We've had some hellish winds here in too this winter.  Our 9-yo came in the other night saying, "Dad I'm scared...and I can't sleep."  I was wide awake myself, thinking we might wake up in Kansas.  When I see these storms coming, I furl the thing up and turn the load bank on at the controller.  They still turn slowly, as you say you need a bit of rotation to brake.  This keeps everything calm; including me.

Good luck.  ~ks

kitestrings

  • Hero Member
  • *****
  • Posts: 700
Re: Hugh Piggott ‘Jumping tails’!
« Reply #11 on: January 16, 2017, 08:12:32 AM »
I suppose you could drill through the top of the hinge piece and drill and tap a retainer, but I like that the method you have doesn't expose anything (new) to weather.

Ungrounded Lightning Rod

  • SuperHero Member
  • ******
  • Posts: 2785
Re: Hugh Piggott ‘Jumping tails’!
« Reply #12 on: January 16, 2017, 11:50:00 AM »
I suppose you could drill through the top of the hinge piece and drill and tap a retainer, but I like that the method you have doesn't expose anything (new) to weather.

I'd be inclined to weld a thick washer (or stack of them) to the tail hinge pin just below the outer portion of the hinge, with enough clearance so the hinge still rides on the top of the pin rather than the washer.  Then I'd have an extension of the tail shaft reinorcement that passes the washer and has a nut welded to it over a hole.  I'd put a bolt, with a jam nut, through the hole so it sits beneath the washer(s), after grinding off the threads on the end so it is a rod, rather than a threaded shaft, below the washer.

Result would be a locking pin to hold the tail on.  Normally it would just ride around below the washer - no friction.  But if something tries to pull the tail hinge cup off the pin, the bolt bumps into the washer and keeps it from moving up more than a fraction of an inch.

Nothing to wear out by flexing, or by rubbing except momentarily when the hinge is trying to come apart.  And a minute with a wrench unlocks it if you want to remove the tail.

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #13 on: January 17, 2017, 01:44:39 AM »
Hi Frackers,
 
Yes, please post your pics of your tail arrangement.

Everything is possible, just give me time.

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #14 on: January 17, 2017, 02:04:15 AM »
Thanks KS,

Firstly, apologies,  I am going to write my observations in a simple way here, so others that are doing a Hugh Piggott might learn from my misfortunes.

If I was doing another Hugh Piggott, design 3.7m, 12 footer, I would do a securing bolt arrangement for the tail on its spigot, or something similar to what ULR is discussing.

As you can see in the below No 1 Pic, the high end stop, fully furled, (when blowing like h.ll the tail furls and pulls the blades out of the wind), has over the past 9 years been riding up the turbine main head tube, gently removing the hammerite paint.

On my Number 2 (see Pic 2) and 3 the high end stop is rearranged to allow a geometric stop point that won't force the tail off. Sadly on my Number 3, it was still insufficient.

I think that in real high winds, and especially vicious gusts, the slightest of vibrations just keeps the high end stop at maximum and just keeps wiggling upwards until, oh dear. So the woven cord on No 2 seems to work okay as just limiting the lift off distance, and I doubt if there is really much force trying to brake the woven cord.?
Everything is possible, just give me time.

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #15 on: January 17, 2017, 02:13:04 AM »
Thanks ULR there is logic in your suggestion.

For me, as KS says, "doesn't expose anything (new) to weather" and boy water and rust gets everywhere.

I will try and nurse this No1 for another 9 years, and every 12 to 18 months a good service etc.
Everything is possible, just give me time.

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #16 on: January 17, 2017, 02:30:56 AM »
Pics this morning, minus -4c.

The nearly 9 year old No1.

No Blade strike, whew!

Tail back on. But the nose cone is removed at present, as I did some re-tightening yesterday afternoon/evening.

Will re-balance the blades today and fit the bronze woven cord to the tail. Still need to check the Electrics in case any damage was done to coils, I cant see any, but will multi meter, need to check rectifiers and unwind the centre mast 3 cables etc.
Everything is possible, just give me time.

Adriaan Kragten

  • Full Member
  • ***
  • Posts: 110
  • Country: nl
Re: Hugh Piggott ‘Jumping tails’!
« Reply #17 on: January 17, 2017, 02:32:50 AM »
The problem that the vane arm can be lifted at very high wind speeds originates from the following effect (information about the inclined hinge main vane safety system is given in my free report KD 431 of 2009). The aerodynamic force acting on the vane blade is almost perpendicular to the vane area. When the vane arm is in its bottom position, the vane blade is vertical and so the aerodynamic force only has a horizontal component. When the vane arm has rotated 90 degrees around its axis, the vane blade makes an angle with the horizon which is the same as the angle of the vane hinge axis and the horizon. This means that the aerodynamic force acting on the vane blade will get a vertical upwards component. The weight of the vane arm and the vane blade together normally prevents that the vane arm if lifted because of this vertical component. However, at very high wind speeds there will be a lot of turbulence which will make that angle of attack in between the wind direction and the vane blade can become really large and this in combination with a very high wind speed may result in an upwards vertical component which is larger than the vane weight. Then the vane arm will be lifted if there is no stop to prevent this.

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #18 on: January 17, 2017, 02:40:42 AM »
Thanks Adriaan for putting that into a very understandable written form.

So, a Tail spigot and the Tail tube should really have some sort of securing system.

It took me nearly Nine years until it actually happened.
Everything is possible, just give me time.

frackers

  • Sr. Member
  • ****
  • Posts: 362
  • Country: nz
  • Is it finished yet?
Re: Hugh Piggott ‘Jumping tails’!
« Reply #19 on: January 17, 2017, 04:02:29 AM »
Hi Frackers,
 
Yes, please post your pics of your tail arrangement.

Well I tried 3 times and after the upload of the 4 pictures (each one about 200k so under the limit)  I get a blank screen and nothing posted to the board.

I'll put them onto another board or my own website as I know that works...
« Last Edit: January 17, 2017, 04:07:36 AM by frackers »
Robin Down Under (Or Are You Up Over)

frackers

  • Sr. Member
  • ****
  • Posts: 362
  • Country: nz
  • Is it finished yet?
Re: Hugh Piggott ‘Jumping tails’!
« Reply #20 on: January 17, 2017, 04:13:40 AM »
Hi Frackers,
 
Yes, please post your pics of your tail arrangement.
My mill has been down for over a year now - I've decided solar is safer, especially with 150-160km/hr winds forecast for tomorrow (at least on this side of the country we won't be getting the 400-500mm of rain they will get on the West coast!!) - as you can see from the cobwebs and that there are bits in the garage and bits in the barn!!

I actually described it incorrectly - the securing stud is on the tail section, threaded into the 10mm thrust plate o the top of the tail bearing.

First of all the pivot on the mill head. Nothing special, directly out of the Hugh Piggott book for a 3m mill, set at the recommended 20deg.
http://gilks.ath.cx/gallery3/windy/IMG_5285

This shows the back stop, adjustable to determine initial attack of he mill into the wind - the end stop being width of the gap in the tail half of the hinge.
http://gilks.ath.cx/gallery3/windy/IMG_5286

This is the bottom view of the tail half of the hinge with the 8mm stud and big washer and lock nuts that goes through the mill head tube. Note that this is propped up in the barn so it would be rotated 90deg when fitted.
http://gilks.ath.cx/gallery3/windy/IMG_5287

This is the view from the top of the tail, the studding is threaded into the top thrust plate and held with a lock nut.
http://gilks.ath.cx/gallery3/windy/IMG_5288

Pretty simple but dependent on being as per Hughs book to have the thrust plate to achor the stud and the tubular inner part of the hinge to have the stud come right through and out the bottom.
Robin Down Under (Or Are You Up Over)

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #21 on: January 19, 2017, 01:17:42 AM »
Thanks Frackers,

As you say "Solar is safer". Especially at its present low cost.

I find that I have to drill small drain holes in any closed tube, its amazing where the rain manages to accumulate.

Everything is possible, just give me time.

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #22 on: January 19, 2017, 01:24:40 AM »
My No 1 is up and running again.

Here is a pic of that new woven bronze cord with stainless nuts and bolts.  The tail is in high end, ie its at max furling position when in max wind conditions.   The tail can move around freely but can no longer lift of its spigot.

I see the green moss has moved in........
Everything is possible, just give me time.

clockmanFRA

  • Sr. Member
  • ****
  • Posts: 468
  • Country: fr
    • Echorenovate
Re: Hugh Piggott ‘Jumping tails’!
« Reply #23 on: January 19, 2017, 01:36:31 AM »
Just slightly off subject...

Here is a pic of my unwinding the 3 cables that go up the inside of the tower process.

With the mast down, I use a measure to get the distance of the plug from the tower.  Keeping the 3 cables taught but not to much of a strain, I measure and make a note. Then I unwind the way the cables have wound themselves.  The distance starts to get bigger, I keep checking until when winding has reached the sweet spot distance that the distance starts to go the other way.

Average unwinding each year seems to be about 25 to 30 turns.

That's a short out Plug in the end of the cable socket, all live in that grey connection box where the cable to the Turbine to the Power shed comes up.

Everything is possible, just give me time.

Adriaan Kragten

  • Full Member
  • ***
  • Posts: 110
  • Country: nl
Re: Hugh Piggott ‘Jumping tails’!
« Reply #24 on: January 19, 2017, 06:36:07 AM »
Winding of the cable in the tower is not caused by rotating of the wind in one direction. In one year the wind direction makes only about three full rotations. I have measured about 40 head revolutions in one year. It especially happens in reagions with turbulent winds like it is the case for my test field.

Assume that the rotor is turning really fast and that suddenly the wind speed slows down to almost zero. In this case the angle of attack becomes negative and this means that the thrust reverses. So now the thrust has a tendency to pull the rotor frontwards and sometimes this results in a full rotation of the head. The rotation is right hand seen from above if the eccentricity of the rotor is at the right side of the tower. I call this the propellor effect. I have seen this happening several times during heavy winds. The direction of the cable twist is in accordance with this effect. It only happens for wind turbines for which the rotor is placed eccentrically. So if there is no swivel in the cable you need a connector which can be released regularly. I make a loop at the bottom of the cable and if this loop is twisted too much, the connector has to be released. If there is no loop, the cable can brake as it shortens because of the twisting. The advantage of a lattice tower is that the cable is visable and that twisting of the loop is earlier seen than for a cable in a tubular tower.

kitestrings

  • Hero Member
  • *****
  • Posts: 700
Re: Hugh Piggott ‘Jumping tails’!
« Reply #25 on: January 19, 2017, 01:31:59 PM »
Quote
I find that I have to drill small drain holes in any closed tube, its amazing where the rain manages to accumulate.

We have a two-section, telescoping tail boom to allow for adjusting the length.  I had to drill a weep hole at the underside of the boom where it meets the hinge section because snow would melt and follow the tube.

Quote
I've decided solar is safer...

and easier, and less expensive...but entirely too dull IMO ;).

DamonHD

  • Administrator
  • SuperHero Member
  • *****
  • Posts: 3545
  • Country: gb
    • Earth Notes
Re: Hugh Piggott ‘Jumping tails’!
« Reply #26 on: January 19, 2017, 01:57:31 PM »
This is FieldLines after all, so while solar is simple and safe, let's keep some wild AC in our hearts!  B^>

Rgds

Damon

PS. I will be standing right back here behind you on this insulating mat under a shelter watching out for blades being shed!