Author Topic: Secure those turnbuckles! (Read 4780 times)

jimovonz · « **on:** March 14, 2007, 01:45:23 AM »

This is a 'temporary' installation I put up quite a while ago. The 2.5m turbine sat atop a 10m high 2" galv pipe pole and powered an attached array of weather equipment as well as a computer and a wireless link (remote weather station). The temporary installation was intended to last a couple of months until I got rid of the pine trees occupying the permanent site about 200m away. About a month ago some kindly sole decided to steal the laptop that ran it (about a two kilometre walk behind a locked gate up a steep hill. Thankfully they considered the 2 x T105's a bit much to carry and pretty much left everything else alone) so I haven't been to concerned with it of late. The turbine was left shorted out but is a cheap Chineese model I have imported with a undersized alt that gets away in winds over ~20k/h even when shorted. The furling mechanism appears to be fine.

I have preached to many a folk on the necessity of securing turnbuckles after seeing a number vibrate free and usually at least tape them up as a stop gap until I wire them properly. For what ever reason I never secured the ones at this site.

We have had winds gusting over 80k/h (as measured at another similar site I have not too far away) for the last couple of days. I was working close by today so decided to check up on this site and found this:

(click images for high res)

As you can see the eye from one of the turnbuckles securing a top guy wire has vibrated free and consequently the tower has toppled. Two of the blades have broken off at the root and were found approx 30m away. Luckily I have imported a few of these turbines and have parts to fix it. All of the other equipment managed to avoid getting damaged.

So if you have unsecured turnbuckles out there, take this as a warning and get out and secure them!

wdyasq · « **Reply #1 on:** March 13, 2007, 07:08:01 PM »

Wonderful job Jim ... thanks for sharing.

Although I hate to see damage like you show it is instructive to those who may think, 'I tightened the nut on the turnbuckle... that should do it.'

There is a reason turnbuckles on airplanes have safety wires on all the pieces.

Ron

wooferhound · « **Reply #2 on:** March 13, 2007, 07:14:44 PM »

I used to change the lightbulbs on 1000 foot TV towers. all the turnbuckles on those towers had wires going through them too , , ,

Phssthpok · « **Reply #3 on:** March 13, 2007, 07:32:35 PM »

A little off topic, but I have a question about those turnbuckles in your photo.

It's kind of hard to tell but it looks like the bottom portion of the turnbuckle has a 'hook' where it's attached to the anchor. Is that correct?

The reason I ask is that I can get turnbuckles for free at work (scrap) but there's a hook on one end, and I wasn't sure if this was generally accepted as safe. It is possible to get some extras, ans swap over the hoop end, but even though they're free, they're a bit of a pain to actually salvage.

willib · « **Reply #4 on:** March 13, 2007, 09:59:10 PM »

Jim , that is a beautiful site for a turbine!

what is on the tip of the left blade in the bottom photo?

jimovonz · « **Reply #5 on:** March 13, 2007, 10:13:01 PM »

Hi willib, yep a great site for a turbine. More images from/near the site can be found at http://www.mce.co.nz/gallery/gallery.htm

I think its more of a case of whats that NOT on the tip of the left blade... What you see is the damage caused be the tip hitting either the tower or one of the guy wires. It shouldn't be too much drama to repair both of the blades. I have been wanting to try shortening the blades on this model turbine to increase the RPM and try and get more out of the small alt it has (coupled with my prototype MPPT controller!)

willib · « **Reply #6 on:** March 13, 2007, 10:49:25 PM »

wow i allways thought Atlantis was a myth

beautiful

snuffy · « **Reply #7 on:** March 14, 2007, 12:03:29 PM »

I think you will find the threads backwards if you try to swap ends with the hook.

jimovonz · « **Reply #8 on:** March 14, 2007, 12:54:31 PM »

Yes, thats a hook end attached to the anchor. I wouldn't like to comment on the reliability of these compared to '2 x eye' turnbuckles, but I have always used them and it has not been an issue so far...

As the opposing ends of a turnbuckle have opposite threads I think you will have trouble swapping ends - maybe if you have turnbuckles made by different manufacturers you might have some luck.

BT Humble · « **Reply #9 on:** March 15, 2007, 01:55:38 PM »

The reason I ask is that I can get turnbuckles for free at work (scrap) but there's a hook on one end, and I wasn't sure if this was generally accepted as safe. It is possible to get some extras, ans swap over the hoop end, but even though they're free, they're a bit of a pain to actually salvage.

You can always weld a short piece of rod across the hook to make it into an eye.

That's what I'm going to do with the 8 turnbuckles on the tower in Vanuabalavu, anyway. I'm not happy with the way I left it last year:

http://www.smallsolar.org/success/mar2006/

BTH

BT Humble · « **Reply #10 on:** March 15, 2007, 01:58:26 PM »

That's much the same turbine as the one installed at Vanuabalavu (the 2.1m/200W version).

I thought that it was reluctant to furl because the yaw bearing doesn't have enough offset and the tail was too heavy. I was going to try sawing 6" or so off the end of the boom, and maybe replacing the tin sheet tail with a plywood one, do you think it's worth trying?

BTH

jimovonz · « **Reply #11 on:** March 16, 2007, 02:41:08 AM »

I think that the offset could be larger but I have not had any problems with these units in high winds. They tend to wait for the wind to change direction to start the furling process. I think that the blades in standard trim are so inefficient in higher winds that it isn't an issue (unless the noise bothers you!). If you have not done anything to properly balance the blades then you might get issues from the vibration (which is pretty bad on some of mine before balancing!) I am not sure about using ply wood to reduce weight - the existing tail is not that heavy. You'd probably have to make the tail both smaller and shorter to make much of a difference This obviously would effect the tails ability to keep it oriented into the wind. It wouldn't take much to try out a different/lighter material - just swap it back if it doesn't perform any better!

I have yet to get a unit on a proper testing rig to get decent numbers, but I get a significant increase in RPM and decrease in noise when I modify the blades. I have had around 600w out of the 200w unit into a matched load (66V,9.2A,650RPM) but with my current buck converter design only manage around 35A into a 12V battery. The 200w rated alt reaches around 10A without too much trouble but its doing it pretty tough from there on - no matter what voltage system you have. The 200w turbine is designed for 24v with the so called 12v version just having a different set point on the regulator. I have seen as much as 12A when its pushed really hard so this means that the 12v system maxes out at around 150W. Into a matched load the alt is much more efficient so you can potentially spin it up faster and get more out of it for a given loss/heat rise. For this reason I have been looking to increase the furling point rather than decreasing it.

From memory the standard (~1mm^2) cable that comes with the 200W turbine adds a bit over 1 ohm/phase to the 2ohm/phase resistance of the alt. I replace this with 4mm^2 cable. You would be very lucky to put one of these together and get anything like a reasonable balance so doing that should be high on your list too. I ditch the controller (a good 2 out of 3 are DOA anyway!) and have made my own based on a picaxe and some FETs. I haven't finalised the design as I'm still hoping to incorporate some form of MPPT control. I have made a number of simple shunt regulators just on the 08M proto board. Unless you have a very exposed site the 4m pole that comes with the 200w version doesn't do it much justice. I guess you have already figured that the anchoring system that it comes with is woefully inadequate...

BT Humble · « **Reply #12 on:** March 16, 2007, 02:59:55 PM »

What blade modifications did you make? I was thinking of rounding off the tips to try to lessen the "whistling", since it's located near some inhabited buildings.

We'll be lowering the tower for servicing purposes, so I'll look at balancing the rotor then, too. We're flying out of Sydney on Tuesday morning. ;-)

BTH

jimovonz · « **Reply #13 on:** March 17, 2007, 08:14:02 PM »

As you can see in the pic above, the blades are now tapered. Because of the curve in the profile this also gives it twist (you have to cut off and reform the leading edge) much like you get with PVC pipe blades. This has the effect of increasing the TSR and you would also assume this would be at the expense of startup torque - though its never been an issue for me (even with the the most tapered blades) The blades in this pic were the very first I modified and I tapered them from half way along the length down to half the original width at the tip. The later blades are tapered from closer to the root and are narrower at the tip. The tapered blades definately run faster though as I said I don't have the hard figures yet. The alt on this turbine is quite under sized for the 2.1m blades and I believe benefits from the higher RPM. I intend to use the broken blades from the above turbine to test the alt with smaller diameter blades (they are all broken at the root) to see if there are any gains to be had.

The noise seems to mostly be caused by the flat spot just under the leading edge. Some of the blades have a pronounced ripple in the surface as well as a general roughness. I sand the blades once I've finished and give them a coat of epoxy (mainly to stop the fibres that run along the length from pulling free - they end up looking like fur). Rounding the tip also helps though the effect is more pronounced once the blades have been tapered.

Here is a photo of an unaltered blades profile. The blue profile at the top is an approximation of this, while the one at the bottom shows what I remove (yellow) and what I end up with.

This pic shows the hub/blades (unaltered) from the 2.2m and 2.5m turbines:

antw · « **Reply #14 on:** March 18, 2007, 12:44:44 PM »

Does this wind turbine

http://www.trademe.co.nz/Browse/Listing.aspx?id=91962206

look like it comes from the same family as your ones? It is a 2.7m diameter 500w turbine. Seems to have the same straight blades that your ones do. Is the $NZ1150 asking price fair? I have a 24v system and am looking for a turbine for the upcoming NZ winter.

Thanks

Antony

jimovonz · « **Reply #15 on:** March 18, 2007, 01:33:34 PM »

Hi Antony. Yes this turbine comes from the same factory as the ones I have imported and is exactly the same design with a larger alt + blades. I would only recomend these turbines to those who are happy to tinker/modify and are reasonably knowledgable. You would be much better off building your own - saving money and ending up with a better quality turbine. There is quite a bit of work to do to bring these turbines up to scratch. You will need to buy or make a decent controller/rectifier for these turbines. The 6m mast is on the low side for getting reasonable results. None of the steel work is adequately protected from the environment. You will need to replace the main bearings for long term reliability. I'm sure it would also benefit from the other mods I have mentioned. Although I haven't got experience with this specific model turbine I would take all the specs 'with a grain of salt'. If you know what you are getting and get it for the right price then these turbines are OK. For those who buy these unaware and who don't have the knowledge these turbines will only cause dissapointment and hassle. I would have to say that if I had to pay that price I would not buy one.

23skadoo · « **Reply #16 on:** March 18, 2007, 09:44:43 PM »

I have also purchased one of these Chinese turbines. I had to balance and trim the blades, replace the controller, replace the turbine bearings and give it a good coat of durable paint. I did not use the supplied pipe tower. As mentioned a good unit to learn about wind generation and associated subjects. After a lot of work it is now running well. The attatched site gives some good information.

http://www.ecoinnovation.co.nz/links.php?code=8

jimovonz · « **Reply #17 on:** March 19, 2007, 02:54:13 AM »

Hi 23skadoo, what model do you have and what sort of output are you seeing?

helowrench · « **Reply #18 on:** March 23, 2007, 04:46:19 AM »

http://aircraftspruce.com/catalog/appages/cliplocking.php

In aviation we have a tendency to use theis style of locking turnbuckles, I am sure that you could find an aircraft junkyard and get them substantially cheaper (especially if you tell them that you are not going to use them on aircraft and do not want them certificated)

Rob

23skadoo · « **Reply #19 on:** March 25, 2007, 08:28:14 PM »

The turbine has no markings except the name Greenpower on box. It was purchased from Jaycar electronics in Australia. The maximum output I have seen is 360 watts.

It seems to spin fairly fast to get above the 24v of the batteries then the output current rises fairly quickly. I would like to see it charge at lower RPM so I am thinking of using a step up transformer at the 3 phase output. A 25% increase in input voltage to the control box would make it a lot more efficient. Not sure if this would work in practice but it would be the easiest fix I can think of.

News:

Author Topic: Secure those turnbuckles! (Read 4780 times)