Bluefields Nicaragua 'report'
By DanB, Section Wind Posted on Thu Mar 27th, 2008 at 04:23:45 PM MST
I bumped this back up due to lots of comments by Mathias from BlueEnergy group.

Below is the note I sent back to the folks at BlueEnergy about our visit and their machines, mostly technical stuff.  Well get a nice webpage about the trip up soon.  Basically - they have been building/installing Hugh Piggott's 12' wind turbine.  They have several problems - mainly stator burnouts, but also... wood swelling/rotting rapidly (especially the plywood tail) - guy wires rusting away - lack of quality control etc... We built a very similar machine to Hughs with pipe (it looks more like our 10' machine) that fits the same blades as Hughs, and a stator from the same mold.  The main difference, we installed bigger magnets and wound the stator with thicker wire/fewer turns.  So this below is a bit of rambling I wrote the day after we got back. ------------------------------------------------------------------------------------ Hi To all! Again, we had a great time there cannot thank you (Mathias, Guillaume, and all the other folks down there) enough for having us/putting up with us :-) We were quite comfortable - the food and the company was excellent.  To be honest - I wish I could've stayed a fair bit longer.  Our trip home went smoothly - one bag got lost and our flight into Houston was late so we missed our next flight but they got us on another one so the wait wasn't too long.  If you do anything like this again (book tickets) - there is almost no chance that a 45 min layover can work out, there's quite a lot of waiting in line, getting bags inspected etc.  Even if our flight from Managua to Houston had been on time, we'd have still missed our next flight.  But again, it worked out fine!  We came home to very happy dogs...  20 deg F, and a small snow storm. Here are a few of my thoughts about the machines and much of this is redundant - I said all this stuff in Bluefields to one person or another. I especially look forward to Hugh's comments...  I am always full of misconceptions!  The old design had a good chance of working out I think but with very little safety factor, and winding with 12 gage wire would've been possible and you could've cast the stator thin enough to have the correct 120 rpm cutin speed.  The stator that Seb made very carefully with 11 gage was too thick and the best  you could hope for was cutin around 130 -140 rpm.  The 'old' stators were all were all too thick and I think all the old machines were cutting in at 140 and running too fast overall.  I think that running too fast delays furling and I'm not surprised they burned out. The experimental machine we made with larger magnets was interesting to me.  The magnets are 2" diameter x 1/2" thick.  We wound with 37 turns using two strands of 14 gage in hand - slightly larger coils.  The stator came out nice and thin, and a 21mm airgap got us lots of mechanical clearance (close to 2-3 mm on each side of the stator I think) and a cutin speed of 120 rpm exactly. Mathias plotted power curves for Seb's 11 gage stator, and the new stator using the larger magnets.  It was interesting to me that at any rpm after cutin, the new alternator (larger magnets) produced almost twice the power.  Even more surprising to me was that it didn't seem to be stalling badly after we raised the machine.  I was quite certain that it would stall dismally unless we added resistance to the line - this didn't seem to be the case as we did see sustained output of 500 Watts and over 750 Watts at times in seemingly light winds.  While I've not watched many of these 12' machines, it did seem to be running nice and slow and Mathias/Guillaume both thought it was running a good bit slower than the older design.  We never did really see it furl which worries me -  although I suspect the problem may be the friction between the tower top and the yaw bearing - it was fairly tight.  I look forward to hearing updates about both the machines that went up on Saturday. Rough calculations of the resistance in the 3 stators... The old one with 13 gage must be around .6 ohm The one wound with 11 gage (which will always be too thick) is about .4 ohm The one for larger magnets (two strands of 14) must be around .3 ohm - slightly lower than the 11 gage stator but the coils are larger so there is a bit more surface area for cooling I think. We normally wind our coils on a form that's slightly thinner than the finished stator - we did this on the stator for the larger magnets and it came out nicely.  Other stators made in bluefields were all too thick - the wire that crossed over the coil (the start) always sticks out and cracks around the coils (especially from stators that get hot) are common.  We even saw this on Seb's 11 gage stator after testing it on the test stand.  During that test if I recall the surface temp got up to  slightly over 200 deg F. I'm sure I've messed up somewhere in my figures... I usually do :-) I was surprised how much trouble you've been having all along, getting castings out of the molds.  We tried several mold releases and nothing seemed to work well until we actually waxed the mold (candle wax) and then used mold release over the top of that.  Once we did that the stator came out easily.  I can only figure it's the resin you get there - we've never had such problems.  We even tested how the resin would come off plexiglass with mold release on top of it - the resin actually slightly melted the plexiglass!  We use plexiglass sometimes for lids on molds and I've never seen such a thing.  So - perhaps it is good practice to wax the mold, then use mold release and with a bit of luck perhaps that problem will be solved.  I also noticed this morning a new post on fieldlines where a fellow built a new 10' turbine and made a mold for his blades.  He also waxed the mold 3 times (he didn't go into detail what sort of wax) and then used mold release.  This might help solve problems with your blade mold. The test bench for alternators you built... It's a wonderful thing! 5 Horsepower 3 phase motor with a variable speed controller belted to a shaft/coupler to drive alternators. I wish I had the power here to build something so precise.  One problem was the steel framework to which the alternator bolts.  The front magnet rotor fits right inside it with very little clearance.  We didn't realize any problems when testing alternators with the smaller magnets (although I expect there was a problem...) =- but with the larger round magnets it cogged/induced eddy currents very noticably.  So it needs to be modified so that there is no conductive material (especially steel) in such close proximity to the magnet rotors.  Another problem with the test stand is the belt drive.  It's not realistic to deliver 5 horsepower at such low rpm through a single V belt - so...  a new pulley on the motor and two V belts should solve that problem.  I was also worried about the size of the shaft that drives the alternator - it's 1" threaded stainless steel if I recall, and it may need to deliver 5 horsepower at about 300-400 rpm.  After a bit of research yesterday I think it may be not so bad as I thought, but it's marginal at best and I do worry about fatigue especially where the large pulley is welded to it.  A larger shaft couldn't hurt but what you have might work forever, I have no idea :-) The metal frames... So we adopted our design made mostly from pipe to the 12' machine and I was happy with how it 'looked' and hopefully it will work/furl well.  I don't think it's easier to manufacture than the older design (or Hughs new design) given the tools in  your workshop, although it's probably not 'lots' harder.  It looks neat to my eye - other than that I'm not sure there's much advantage.  One problem is dealing with all the weird pipe you get.  All your pipe is shed 20, thin walled stuff and even then the sizes do not seem consistent (3" pipe in your shop seems to vary by 1/8" in diameter between different pieces).  The other problem with that design (and in general) is... all your pipe is galvanized.  It should be common practice to make sure that zinc is ground off in the area you're cutting with a torch - or welding, I think this is a big safety issue, the fumes are very toxic.  Furthermore - the welds will be of higher quality if you grind that stuff off first.  The galvanization also causes problems with the cutting torch... and the cuts don't come out as well as they would if the zinc was ground off. And again - I am worried about the tail on the machine that was built 'mostly' according to Hughes new design.  I think the tail boom he calls for is from 48mm (2 inch) sched 40 pipe (that seems quite heavy to me actually) and the one they fabricated there is 1.25" sched 20 pipe. I'll stand by my bet that it falls off in 1 year :-) . Tower stuff... I think your towers look really nice overall.  Considering all the work involved and the concrete etc...  I think every tower should have a pole cemented in the ground (similar to the pole thats stuck over the stump of a tree at inatec) with a 'V' to catch the tower when it comes down to catch the tower when it comes down and keep the blades off the ground. I saw 3 towers get lowered and every time at least 1 (if not more) people were standing under it in the most likely fall zone.  Then - once lowered... supporting them with chairs and stuff while 2 or more people are pounding/prying on the blades to get them off scares the hell out of me.  It seems like very little more work and cost to make it such that nobody ever needs to be in the fall zone or working under a lowered tower that's not safely supported. Tools... Seems you're getting enough funding now that some nice tools are coming in!  New fluke meters - new welders etc... Some really basic stuff would probably improve some things greatly! When we were there... the drill press is almost unusable because the chuck is so worn out - the teeth are practically gone so the chuck key is almost useless.  The bench grinder barely has any stone left.  It would be nice to have more soapstones (longer ones... and the people in the shop call it 'chaulk').  A carbide 'scribe' would be useful.  A compass that holds a pencil would've been nice.  A new tip for the cutting torch would also be nice - the one there is pretty worn out.   For cutting steel - a portable band saw is very handy.  another good  tool cutting pipe/angle iron is a horizontal band saw.  Some small/medium size metal band saws can tip up to serve as either a horizontal band saw or a vertical band saw.  These are very handy I think. Overall though I realize this is all a work in progress and I cannot imagine how much improvising you must've been doing 3 years ago! Thoughts about the two failed machines we brought down... Set Net burned out - and if I recall... the bearing had lots of play in it.  When they were assembling the new machine (Hughes new design) it was clear that the folks working on it did not understand how to adjust tapered roller bearings, they had it way too tight.  This is the sort of thing that should be inspected before the machine goes out. We discussed this...  every machine should have a thorough inspection before it goes out the door.  Some of the things that should be checked... -airgap -cutin speed -bearing adjustment -torque on the bolts (we should come up with specific torque specifications for hardware throughout the machine to be consistent) -make sure proper hardware was used. Are there lock washers, washers etc in the places where they're required? The machine at Pearl lagoon  - a badly worn out bearing.  Wheel bearings in lots of newer cars (including this hub) use ball bearings so there is no play side to side at all - I think the reason they do this has to do with not being able to have any slop in wheels that have anti lock brake sensors.  (Volvo went to ball bearings as soon as they introduced anti lock brakes).  In my experience the ball bearings are stiffer to turn and wear out much sooner in cars, and I think they should be avoided unless they're fairly massive. To date, I have never experience a bearing failure in any machine we've built.  At any rate - the people at that school at Pearl Lagoon must've been hearing very obnoxious noises from the wind turbine for quite some time before it: chopped into the stator overheated it's magnets finally locked up. I'm astounded that nobody at Pearl lagoon had the sense to shut it down, it could've been such an easy fix - now it needs a complete rebuild. Rusty Guy Wires: I was amazed how badly they rusted.  The tower at Pearl Lagoon is 3 years old and doubt the guy wires will last another two.  It is interesting though that a couple of the guy wires  look much better than the rest - so obviously some manufacturers do much better than others. Perhaps the plastic coated stuff you used at Set Net will be much better... I would be curious to know how old the lamp posts along the street between the house, and inatec are - those guy wires looked to be in very good shape (perhaps they are very new).  Maybe going with galvanized cable that has fewer strands of much heavier steel wire would help. Lots of fun there testing things/gathering data!  Some of the stuff off the test stand seemed to me... a bit of a waste of time, there are charts and formulas that could've got better data.  But it is fun to see actual results line up with the 'laws' of physics and you seem to have plenty of cheap labor! ;-) 'a month in the lab can save you an hour in the library'  (I plagerized that clever quote from somebody on fieldlines recently) So there are some of my thoughts... I'm sure I'll have more :-) . Again   - say hi to everyone in Bluefields and extend our best wishes and thank you so much!  I would be happy to go back any time and we look forward to you visiting us here!

Bluefields Nicaragua 'report' | 45 comments (45 topical, 0 editorial)

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#1) by psycho D on Thu Mar 6th, 2008 at 04:04:26 PM MST (User Info)

Welcome back guys, you can drink the water again android

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#2) by DanB (danb@*no spam*otherpower.com) on Thu Mar 6th, 2008 at 04:10:51 PM MST (User Info) http://www.otherpower.com/

Nice to see you here android ;-) Yes, we had a great time down there and it is nice to be home & feel confident about drinking water. [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#3) by electronbaby (roy<at>windsine.org) on Thu Mar 6th, 2008 at 06:26:52 PM MST (User Info) http://www.windsine.org

Glad everyone is back. I KNOW you had fun. :-) Im curious to see what Hugh has to say also. Have Fun!! RoyR KB2UHF

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#16) by scoraigwind (magnet@scoraigwind.co.uk) on Sat Mar 8th, 2008 at 12:37:13 AM MST (User Info) http://www.scoraigwind.co.uk

Well I have obviously been following this with interest and I did respond to the Nicaraguan guys about this already.  I regret that as Dan says, there is very little safety margin with my 12 foot design.  Nowadays I actually use 16 inch magnet rotors and thicker wire.  Bigger magnets work well as a fix for the existing rotor size but are a relatively expensive solution compared to making the rotors/stator bigger.  And a bigger stator has more surface area for cooling. There are plenty of things to go wrong with the axial flux turbines (as with all small windmills) especially in a tropical climate where corrosion of metal and electrics, saturation and rotting of timber, high temperature and humidity make for challenging conditions.  It's going to be interesting to watch blueEnergy get on top of these issues.  Dan and his crew certainly gave them a leg up in the process. The machine frame built from pipe is very elegant to look at, and looks are important.  Pity about the galvanised pipe. Using 1 1/4" pipe for the tail without any bracing is rather too optimistic.  My old A frame tail design is extremely robust but so heavy that it requires a very small angle of inclination.  This makes it rather vulnerable to small inclinations in the tower changing the furling behaviour.   And soggy plywood makes it worse!  I like using a 20 degree angle now, and 1 1/2" pipe works nicely as a single boom tail for the 12 footer. I have had a lot of new ideas since the 2005 edition of my plans (How to Build a Wind Turbine) and I am trying to get them into print.  The problem is to get the process finished.  I am preparing a 'wind turbine recipe book' for publication this year which will have my updated design ideas.  Using these ideas in courses helps me find out what works for people.  Its mainly about making the machines easier to build rather than improving their performance at all.  And keeping well within the envelope so as to prevent burnouts! Hugh Piggott http://www.scoraigwind.co.uk [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#22) by DanB (danb@*no spam*otherpower.com) on Sat Mar 8th, 2008 at 09:50:42 AM MST (User Info) http://www.otherpower.com/

Hi Hugh - thank you for your comments. ' I regret that as Dan says, there is very little safety margin with my 12 foot design.' I tend to feel the same way about the 10' machines we've been building for the last couple years with 1" x 2" block magnets.  Most are fine but there have been a couple burnouts and the safety factor is small.  ' Nowadays I actually use 16 inch magnet rotors and thicker wire.  Bigger magnets work well as a fix for the existing rotor size but are a relatively expensive solution compared to making the rotors/stator bigger.' I'm not convinced that its a more expensive solution actually.  There is a compromise there.  Larger magnets make for a smaller/lighter weight machine.  Less steel, less resin, less copper, less time to manufacture (slightly) - but  yes, higher magnet cost. There was also the issue of trying to save time/cost using existing molds - magnet rotors that are already cut out etc...  ' And a bigger stator has more surface area for cooling.' That is true, although I think we cut the heat in stator in half which is a big safety factor. 'There are plenty of things to go wrong with the axial flux turbines (as with all small windmills) especially in a tropical climate where corrosion of metal and electrics, saturation and rotting of timber, high temperature and humidity make for challenging conditions.  It's going to be interesting to watch blueEnergy get on top of these issues. ' Yes, the climate is tough there.  They get more corrosion in 1 year than we do in 20 I think.  'Dan and his crew certainly gave them a leg up in the process.' I hope so.  Another week or two would've been great.  I am glad though that they plan to come here in the summer (some of them). 'I have had a lot of new ideas since the 2005 edition of my plans (How to Build a Wind Turbine) and I am trying to get them into print.  The problem is to get the process finished.  I am preparing a 'wind turbine recipe book' for publication this year which will have my updated design ideas.  Using these ideas in courses helps me find out what works for people.  Its mainly about making the machines easier to build rather than improving their performance at all.  And keeping well within the envelope so as to prevent burnouts!' Cant wait to see the new books!!!! [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#24) by zrmb13 on Sat Mar 8th, 2008 at 11:43:11 AM MST (User Info)

They might try axle grease on the cables.  They grease the cables on the cranes on ships, those cables are exposed to salt spray constantly and I never see rust.  I bet regreasing once a year when the genny is down for annual checkup would do the job. DB [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#36) by blueEnergy group (contact@blueenergygroup.org) on Tue Mar 25th, 2008 at 11:58:17 PM MST (User Info) http://www.blueenergygroup.org

I too look forward to seeing the new books! Cheers, MJ -- blueEnergy www.blueenergygroup.org [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#35) by blueEnergy group (contact@blueenergygroup.org) on Tue Mar 25th, 2008 at 11:56:50 PM MST (User Info) http://www.blueenergygroup.org

Hugh, after finally getting a chance to delve into the calculations I can now see that the original 12 ft design does have little to no safety margin.  That being said, we at blueEnergy are equally responsible for not having built our machines to a high enough quality standard, thereby bringing extra problems on ourselves.  We are not a huge group of wind experts, rather we are an organization working in very difficult conditions, trying to provide opportunities to people who had none before. We are constantly improving but we are certainly guilty of not having a good enough understanding of what required tight tolerances and what could be done more loosely. We start our project without the level of intuition needed to know which parts needed to be paid close attention too.   But we are getting better at this.  And our core capacity level and infrastructure are growing, allowing us to build better quality machines.  We still have a long way to go for sure, but given the challenges and roadblocks we have faced, I have very happy with our progress.  If you can continue to support us with your legendary patience and expertise, I know we'll get there. -- blueEnergy www.blueenergygroup.org [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#17) by hvirtane (hannu_markus_virtanen(at)yahoo(dot)com) on Sat Mar 8th, 2008 at 01:41:10 AM MST (User Info) http://web.archive.org/web/20050404022706/www.cc.jyu.fi/~hvirtane/cooker/

making the rotors/stator bigger. And a bigger stator has more surface area for cooling. This sounds a really good idea. What about some materials like (even) sand or ceramic powder added into the stator resin? -Hannu [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#4) by spinningmagnets (velmis1450bc(at)aol(dot)com) on Thu Mar 6th, 2008 at 06:28:21 PM MST (User Info)

This is very inspiring information! How did "bluefields" and "blue energy" pick their name, what does it mean? (using the color "green" is trendy!) You mentioned there are many tools that are worn out (drill chucks, grinder stone wheels, etc). I have heard of there being occasional "difficulties" getting parts or funding to the group someone may want to help in other places. Is there a dependable organization that can ensure that donations will get to people like this?

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#37) by blueEnergy group (contact@blueenergygroup.org) on Wed Mar 26th, 2008 at 12:06:32 AM MST (User Info) http://www.blueenergygroup.org

spinningmagnets, I chose the name blueEnergy because the original vision for blueEnergy was to use Piggott turbines to purify water using UV technology.  If water and wind have a color (you may feel free to argue that they don't :) ), it's blue - so I went with blueEnergy. It was either going to be blueWind or blueEnergy.  And in the end "green energy" is over-used at this point, so I thought blue might be a better choice. By the way, it's only coincidence that the word blue appears in both our name and our host city.  Or at least it wasn't a conscious association. blueEnergy is a nonprofit, very literally.  We accept donations directly and in fact most of the "nice tools" DanB referred to were from a donation from a French construction company that just arrived days before the Otherpower crew arrived.  If you would like to make a donation to support our efforts, either monetary or equipment, please do not hesitate to contact me at mathias.craig@blueenergygroup.org or (415) 509 - 0155.  I can guarantee that we'll get your donation on-site and into use! Cheers, Mathias -- blueEnergy www.blueenergygroup.org [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#5) by jmk on Thu Mar 6th, 2008 at 07:25:06 PM MST (User Info)

When you went to the round magnets did you have to use a larger diameter rotor, and stator, or did you use the same size? I believe the rotors were 14" with 16 1 by 2 by 1/2" magnets. Also, How thick did you make the stator in standard terms. I have a hard time with metric. I like the twice the power. I would like to build an alternator like that for mine so it would cut in sooner, or the same as now with a wider gap. I have a Hugh 12 footer and my stator is a bit to thick too. I am dangerously close with my air gap, but it helped a lot to slow down the blades to around 360 rpm. It would be nice to have that with a larger gap. I bet I was over 500 rpm before. I am about 11/16" now and was about 13/16". My stator is almost 9/16" thick with the wire coming out over the coil. I like the idea of winding it smaller in thickness. Glad you guys had a good time and a safe return. jmk

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#6) by Old F on Thu Mar 6th, 2008 at 07:43:35 PM MST (User Info) http://www.oldf.homestead.com

(I'm astounded that nobody at Pearl lagoon had the sense to shut it down, it could've been such an easy fix - now it needs a complete rebuild ) Dan I am not surprised at all  It never fails your in the middle of a rebuild an some one will come up to you an say that thing has been making hells own noise for the last 3 weeks be for it quit working I have worked as a maintains tech  for 30 years an have seen this happen over an over again     Makes you want to pull your hair out

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#38) by blueEnergy group (contact@blueenergygroup.org) on Wed Mar 26th, 2008 at 03:18:29 PM MST (User Info) http://www.blueenergygroup.org

It's also worth pointing out that wind power is a new technology for these people. They may have heard strange noises, but there are a lot of strange noises in the jungle and you don't necessarily want to go out and investigate all of them. We have a long ways to go in our training programs to sensitize people to wind power technology... but we're committed to making it happen.  It will just take time. Cheers, Mathias -- blueEnergy www.blueenergygroup.org [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#7) by tecker on Fri Mar 7th, 2008 at 06:37:00 AM MST (User Info)

Looks like hope .

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#8) by Boss (brians.outfit(at)gmail.com) on Fri Mar 7th, 2008 at 06:41:52 AM MST (User Info) http://www.outfitnm.com

Great report and welcome back to North America. Did George get a sunburn? Not all that different than arc burns. Glad to hear the pups faired well, how about y'all's mills?   Brian Rodgers

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#9) by hvirtane (hannu_markus_virtanen(at)yahoo(dot)com) on Fri Mar 7th, 2008 at 07:52:10 AM MST (User Info) http://web.archive.org/web/20050404022706/www.cc.jyu.fi/~hvirtane/cooker/

A really nice report from the field. My feeling is that somehow the design is a bit too delicate. Quite small problems with constructing will put the machine to fail completely. Maybe the problem is mainly with the quality of the work needed. Sometimes I'm wondering if better bearings like ball bearings with the furling tail would make the furling system more reliable. Another thing I've been thinking about would be to use more blades and less speed... but then you would have more difficulties with building even slower speed generator... - Hannu

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#10) by DanB (danb@*no spam*otherpower.com) on Fri Mar 7th, 2008 at 08:31:50 AM MST (User Info) http://www.otherpower.com/

I think really the problem is - like you said, the machine has very little safety factor in the alternator.  The origional design calls for a 24V stator that comes in around .6 ohm.  So at rated  output (1000W) the stator needs to dissipate close to 1000W and it's not up to the task.  By using larger magnets we cut that figure in half which should add quite a lot of safety factor I think. [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#11) by Flux on Fri Mar 7th, 2008 at 09:22:15 AM MST (User Info)

Hannu I don't think it makes a lot of difference with mounting the tail on ball races. It doesn't do any harm and it may have a much longer life but it makes little difference to the furling. Using ball races for the main yaw may help slightly but it does also encourage it to yaw about more. Again I am not sure it is an advantage  as far as control is concerned. There seems to be no way to make furling a precise process, variations of 2:1 in the current in the region of furling seems to be unavoidable and the thing ultimately has to survive the highest of these currents. The relative heating in the high peaks does depend very much on the site. Turbulent sites may have little energy in these peaks but on a good clean site in a good wind area the high peaks may continue for many seconds or minutes. Usually as the wind becomes more severe most machines drop power beyond furling, these tend to survive but those which hold peak current or worse those where current continues to rise are likely to cook. One big problem is that variations in construction does seriously affect the prop speed, power curve and the furling characteristics. The axial machine is very forgiving in that it will work with vast differences in construction whereas a badly wound radial just won't work, the thing will not go together if the coils won't go in the gap. Other factors such as line resistance also also have similar effects and when several factors come together you may get a machine that performs badly but never burns out at one end of the range and at the other you may get wonderful performance with short life. If you can't have quality control then the only cure is to drastically over build it, expensive in the short term but with little effect in the long term running cost. I think under these circumstances with limited facilities and skilled labour adding bearings to tails any yaw would drastically increase the risk of failure rather than help. Flux [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#15) by jmk on Fri Mar 7th, 2008 at 08:10:35 PM MST (User Info)

I can understand everthing Flux said. That's a once in a while thing for me. I think overbuiding and weather proofing is a must for them, and everyone with the corosive climates has alot more to deal with. Here is where the standers should get set. jmk [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#40) by blueEnergy group (contact@blueenergygroup.org) on Wed Mar 26th, 2008 at 03:22:56 PM MST (User Info) http://www.blueenergygroup.org

Our philosophy is to overbuild and keep working at improving capacity levels so the quality level of the work continues to rise.  In time we can re-evaluate whether we can scale back our "overbuilding" if our quality reaches a respectable point. Cheers, Mathias -- blueEnergy www.blueenergygroup.org [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#39) by blueEnergy group (contact@blueenergygroup.org) on Wed Mar 26th, 2008 at 03:21:03 PM MST (User Info) http://www.blueenergygroup.org

I think it is a robust machine design, given that the builders understand that some parts do require some precision.  Any dynamic machine will have this requirement.  As we get better at understanding which parts require precision and which parts don't, our machines will get more and more robust while still staying "realistic" given our working conditions. Cheers, Mathias -- blueEnergy www.blueenergygroup.org [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#12) by Boss (brians.outfit(at)gmail.com) on Fri Mar 7th, 2008 at 10:10:24 AM MST (User Info) http://www.outfitnm.com

Perhaps a thick dough-nut of bronze sandwiched between the tower top and the main turbine mechanism (yaw bearing) if wear is a concern, and freeing movement further isn't.   Brian Rodgers

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#13) by TomW on Fri Mar 7th, 2008 at 10:29:48 AM MST (User Info)

Dan; I can't help thinking fully sealed, wet environment AC motor conversions would handle the environment better than the open axial flux design? I think they cool better, too if you run them at high outputs. Probablly not an option for the location. But, if you have to rebuild the axials a lot, importing something more durable to convert may have advantages. Just thinking out loud. TomW "Education consists mainly of what we have unlearned."--Mark Twain

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#18) by tecker on Sat Mar 8th, 2008 at 08:17:10 AM MST (User Info)

Now your hitting on the area of improvment . I've always Questioned the open frame aproach to this design and wouldn't think of putting open connections in a wet (or salty wet) environment or moveable metal bearing surfaces in same Not a good idea at all. [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#20) by DanB (danb@*no spam*otherpower.com) on Sat Mar 8th, 2008 at 09:33:54 AM MST (User Info) http://www.otherpower.com/

I dont see this as a real problem.  All the parts of the axial flux alternator are basically water proof - corrosion in the alternator is not a problem.  Tapered roller bearings are better suited and much more robust than the ball bearings in say.. a 5hp 'weather proof' electric motor, and properly adjusted they should last quite a long time.  The bearing failures we saw there..  one was a 'cheap' ball bearing of a 'cheap' chevy salvaged from a junk yard with plenty of miles on it before it was used in the wind turbine, I expect the other one was not adjusted properly because it was new and less than 1 year old (there was  no corrosion in the bearing or the spindle). so far as other exposed metal bearings (pipe over pipe for the yaw and perhaps the tail pivot)... they are well greased, they have sloppy clearance and I doubt corrosion will be a big issue there (didn't seem to be on machines 3 years old down there). I actually think the open design of the axial flux has advantages.  If it does get wet.. it can dry out.  I noticed the rectifier box at the top of the tower on one machine (3 years old) - all sealed up with silicon caulk, was half full of water!  In my mind, a 'sealed' motor may actually have more problems - water will get in eventually, I can picture rusted steel laminates etc.. Thinking about bluefields Nicaragua...  the cost of a 5 hp motor to be converted would be way out of the picture, much less expensive to build from scratch.  It's one thing if you're building 1 machine and happen to find a scrap motor to play with - they don't have 'scrap motors' around there though. At any rate - from what I saw, the climate did not pose problems with the open axial flux design, most of the  problems had to do with the fact that the alternator was just a bit too small for the job, and lack of attention to detail in manufacturing. [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#23) by tecker on Sat Mar 8th, 2008 at 10:45:29 AM MST (User Info)

The Hub is good to go . With Stainless and painted parts your going to be pleased with the proformance .A cover for the these units seem to me a essential mod to keep the weather out .Frankly I may be unqualified to talk too much about the axil because I don't have one flying .  I have adopted the axil for the motor gensets here at my shop though .Every now and then somthing gets sucked in to the air gap and it has some velocity as it flys out . I haven't had any damage to speak of but covers are in the making there .It's just the tail hidge  the open frame stator  and exposed airgap that doesen't seem to fit the power numbers you have achieved with this unit.It may be unimportant to those with skills of your level . Maintainance is just a part of the plan  .   [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#31) by electronbaby (roy<at>windsine.org) on Mon Mar 10th, 2008 at 11:09:39 PM MST (User Info) http://www.windsine.org

sealing the rectifier box with silicone should not be a problem as long as a small weep hole is drilled in the bottom. This will allow any condensation (from temp changes) to escape when the temperature rises. It allows it to breathe. That should solve that problem. Have Fun!! RoyR KB2UHF [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#19) by hvirtane (hannu_markus_virtanen(at)yahoo(dot)com) on Sat Mar 8th, 2008 at 09:33:22 AM MST (User Info) http://web.archive.org/web/20050404022706/www.cc.jyu.fi/~hvirtane/cooker/

I think that it would be good to cover the alternator by a plastic cover. Something like 'craftskills' have done: http://www.craftskills.biz/index.htm Maybe the tail boom bearing and the yaw bearing could be made of hard wood. On the other hand some people are telling to be able to make it with a fixed tail and furling anyway. Please see: http://www.tlgwindpower.com/tlg500_whyisitbetter.htm     - Hannu [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#21) by DanB (danb@*no spam*otherpower.com) on Sat Mar 8th, 2008 at 09:42:35 AM MST (User Info) http://www.otherpower.com/

I think you are trying to solve problems that don't exist here!  They need to work on solving the problems that confront them.  Corrosion is not a problem with the alternator or the yaw bearing, or the tail bearing.  3 year old machines down there look fine (other than stator burnouts).  corrosion is mainly an issue with guy wires, cable clamps, and turnbuckles. [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#26) by hvirtane (hannu_markus_virtanen(at)yahoo(dot)com) on Sun Mar 9th, 2008 at 01:06:16 AM MST (User Info) http://web.archive.org/web/20050404022706/www.cc.jyu.fi/~hvirtane/cooker/

I didn't think about corrosion problems so much when suggesting better bearings for yawing and the tail. My idea was that maybe making the furling system to work as smoothly as possible with simple means would help. Maybe the furling system is sometimes stuck in a position. With a friend of mine here to build such systems we have used really good bearings. But I think that Flux is right. A small fault with the tower top tilting a bit will make a bigger difference. For preventing the rust I'm in the agreement with the means already suggested. Grease. Tar would help as well and maybe cheaper locally. I think that always when a design is done in a location and then shifted to another location, some adjustments are needed. Some things, which are easily and cheaply done somewhere are difficult or expensive to be done in another location. If high level quality control is needed with some parts, that will easily create problems. In my eyes the local conditions there seem to be nice. I mean housing, workshops, food etc. look nice. I have been living in much worse conditions. This overall design by Hugh and DanB I like really much. It is easily adjusted to local conditions and almost all the parts can be made in simple workshops. I think that the most delicate thing and the most difficult thing to get working properly is the furling system. The other thing to cause problems easily is the high rotational speed, I think. Is there anybody out there, who has tried something similar as the furling system of 'tlg' wind machines? What about making the furling system to tilt the machine upward? Is it easier to build reliable? For problems of protecting the machine of too high speeds I think that one way would be to use such blades, which will become quite unproductive with strong winds. - Hannu [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#27) by DanB (danb@*no spam*otherpower.com) on Sun Mar 9th, 2008 at 06:44:32 AM MST (User Info) http://www.otherpower.com/

I read the page at TLG about furling, to be honest - I don't think it can work at all.   I think he's also got some other stuff wrong on that page when he talks about less losses transmitting AC through the line than DC.  There are advantages to keeping the rectifiers near the batteries - but DC can be transmitted with fewer losses over less wire than AC. [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#29) by hvirtane (hannu_markus_virtanen(at)yahoo(dot)com) on Sun Mar 9th, 2008 at 04:11:31 PM MST (User Info) http://web.archive.org/web/20050404022706/www.cc.jyu.fi/~hvirtane/cooker/

TLG about furling, I've been wondering about that issue for some time.   Could he be right that the balance would shift, when the wind is stronger and the wind rotor is going faster..? Probably a bit; the wind rotor would become less and less effective, the stronger is the wind, but the tail would stay as much 'effective' as with lighter winds? - Hannu [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#30) by DanB (danb@*no spam*otherpower.com) on Mon Mar 10th, 2008 at 09:30:21 AM MST (User Info) http://www.otherpower.com/

I don't think it could work Hannu.  Actually - I made 1 machine that way years ago when I still misunderstood how the furling system should work (and it didn't furl). TLG's suggestion that the extra moving part is problematic... I disagree.  I've never seen problems with the tail pivot. [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#32) by hvirtane (hannu_markus_virtanen(at)yahoo(dot)com) on Wed Mar 19th, 2008 at 02:29:33 AM MST (User Info) http://web.archive.org/web/20050404022706/www.cc.jyu.fi/~hvirtane/cooker/

Hello from Vietnam. I'm sorry I did not have the possibility to respond earlier. I have traveled to Vietnam for a solar cooking project. I am not sure, if it works or not with the way TLG has done it. I think that if the sizes and angles of the parts are correct, it will work. There should be quite lot offset of the wind rotor and the tail with a quite big angle, to get it working. In my opinion the wind rotor should furl to the direction starting 'against the wind'. On the other hand, I think that there is quite a possibility that the bearing of the furling tail system would jam sometimes, if the bearing isn't made accurately. - Hannu [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#33) by jmk on Sat Mar 22nd, 2008 at 07:05:24 PM MST (User Info)

There is added forces to the tail if it doesn't stay with the wind. I would think one that folds would last longer. jmk [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#41) by blueEnergy group (contact@blueenergygroup.org) on Wed Mar 26th, 2008 at 03:25:23 PM MST (User Info) http://www.blueenergygroup.org

I'm in agreement with DanB here, I don't think the open alternator has caused us any problems.  And trying to seal anything here is a risky proposition.  Without a very good approach we'd likely cause more harm then good... and again, I don't see why we would want it in the first place.  I've always wondered why Craftskills goes through all the trouble - might just be an aesthetic thing. Cheers, Mathias -- blueEnergy www.blueenergygroup.org [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#14) by ghurd on Fri Mar 7th, 2008 at 10:45:28 AM MST (User Info)

With $150,000 homes and their incomes, it's no wonder they can't get new tools! G-

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#42) by blueEnergy group (contact@blueenergygroup.org) on Fri Mar 28th, 2008 at 12:33:59 PM MST (User Info) http://www.blueenergygroup.org

A lot of the difficulty in getting new / working tools is the logistic side.  There are no mega hardware stores in Bluefields that carry what we want.  And finding things in Managua is possible... sometimes... maybe... come back next week... As we've gotten better at handling the logistics and better at fundraising, we've been able to start replacing the tools.  With a little more time and elbow grease, we should get all we need in there. Just a point to clarify - blueEnergy doesn't own any the houses or even our shop.  They are all leased or donated monthly spaces. Cheers, Mathias -- blueEnergy www.blueenergygroup.org [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#25) by blueyonder (windwoodgood at yahoo dot co dot uk) on Sat Mar 8th, 2008 at 04:41:28 PM MST (User Info)

thanks for the great story you guys.  the first chapter was great. it was just like a documentary.  sending back pics about the place was a great help in understanding  what you were up  against.   in short you were up against poverty .   i saw that in the tin shacks. toilet on the end of a jetty type thing.    the folks themselves looked great .i bet thay were so happy to see you guys arrive.    but now the guys from the USA have gone.        and now i am enjoying the thoughtful forum going on here. its great.    every one is trying to add a bit help.    but i understand how things can be as them folk are so short in resources.   in a perfect world if all the metal work was stainless all the plywood was marine ply.    and every twelve months a new stator was fitted.    a workshop full of engineers and tools.    boxful's of hubs and bearings. wouldn't it be a perfect place.    so when you guys went out there to help and offer advice .    that is the best thing bluefields can have .    i cant offer any advice .maybe only a box of zerk fittings and a few grease guns.    so welcome back to the fold.   and now i need ask .what was the reaction of the dogs.   naw i dont need ask that i already know .    thay all just went mad with happiness and knocked every one over.    its a great feeling to be welcomed home bye a bunch of dogs lol.    don't they just lick you to death.    i am still struggling to build my windmill.  get my tower sorted out and erected.    wiring batteries etc its never ending.     be good to see the outcome of what you did to help out there.    great site great forum.       thanks again for the great share you guys did .blueyonder. its a ill wind that dos no good

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#28) by DanB (danb@*no spam*otherpower.com) on Sun Mar 9th, 2008 at 08:03:01 AM MST (User Info) http://www.otherpower.com/

Hi Tecker 'in a perfect world if all the metal work was stainless' yes, they dont really have much problem with pipe/angle iron rusted out - they paint it well and maintain the paint.  'all the plywood was marine ply.' That is what they use, trouble is it absorbs moisture/swells up - gets covered with mold/gets heavy (which delays furling).  To some degree they've solved that by fiberglassing over all the plywood.  I am surprised how well their wooden blades are  holding  up.  3 year old blades look like new.  '  and every twelve months a new stator was fitted.' No..  Stators shouldn't wear out.  Done right I dont see why a stator cannot last forever.   ' a workshop full of engineers and tools.' Theyre lacking in that dept.   ' boxful's of hubs and bearings. ' They do have that bit!

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#43) by blueEnergy group (contact@blueenergygroup.org) on Fri Mar 28th, 2008 at 12:41:43 PM MST (User Info) http://www.blueenergygroup.org

Yes, it's really important to remember that everyone is approaching this small scale wind challenge from a different place.  A lot of disagreements aren't about who's right or wrong, it's just that people are in different places (physical, financial, and cultural).  What works in one place doesn't necessarily work in another.  That's the thing about "appropriate technology"... it means technology adapted to any particular situation.  We work in a poor, low education, hot, humid, saline, war-torn, natural disaster-prone space.  That is a hard space to work in, to put it mildly.  We would definitely be more effective with more resources and we have worked hard in the past 4 years to accumulated what we needed.  There is still a lot of work to do.  Next is accumulating the right knowledge and experience so that the technology and resources can have an impact in the real world, and help people in their day to day lives.  Hugh, the Otherpower crew and Ian Woofenden of SEI, among others, have been infinitely patient and generous with us in helping us build up this capacity base.  As we say around here - Siempre Adelante! Cheers, Mathias -- blueEnergy www.blueenergygroup.org [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#34) by blueEnergy group (contact@blueenergygroup.org) on Tue Mar 25th, 2008 at 11:45:54 PM MST (User Info) http://www.blueenergygroup.org

DanB, thanks for the great report and sorry it took me so long to respond.  I read your report right when you sent it, but I just got a chance now to read it slow and really let it sink in.  It was a pleasure hosting you guys; it gave me the perfect excuse to spend a week in the shop!  I was like a kid in a candy store... You are welcome back any time and don't worry, we'll make it happen.  That's what we do. It's fair to say that we have a long ways to go to get to where we want to be.  We don't have the expertise needed yet, but what we do have is drive and the will to get there.  We are good at organizing and making incremental improvements.  Now that you've seen the environment (human, natural, political, etc) we work in, you know the challenges we face.  Our operation is a far cry from setting up a shop in anytown USA. We will continue to consult with the experts and soak up all the knowledge and experience we can until we are in a position to deliver on our lofty goals.  We're glad you guys at Otherpower are a part of that and we look forward to continuing our partnership for many many fruitful years. Cheers, Mathias -- blueEnergy www.blueenergygroup.org

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#44) by tecker on Sat Mar 29th, 2008 at 06:45:12 AM MST (User Info)

You are giving these folks an advantage they would not have known . I can see the work has been over the top kinda difficult. I just what to say good luck . [ Parent ]

Re: Bluefields Nicaragua 'report' (3.00 / 0) (#45) by blueEnergy group (contact@blueenergygroup.org) on Tue Apr 1st, 2008 at 10:50:01 AM MST (User Info) http://www.blueenergygroup.org

Thanks for the encouragement tecker! Cheers, Mathias -- blueEnergy www.blueenergygroup.org [ Parent ]

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