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Forum Index : Windmills : 65mph/29 ms winds, mill down
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JimBo911 Senior Member  Joined: 26/03/2009 Location: United StatesPosts: 262 |
You people would not believe the weather we have had here the last two weeks. Rain, wind, more rain, more wind, winder etc. totally sucks. The misses calls me at work and says (we have a bad storm moving in from the west what should I do with the mill) I tell her (lets not take any chances just pull the switch and shut it down before the storm gets there) She calls me again about 45 minutes later, it sounds like she’s crying (I am like what the f_ _k) she says (I heard this loud BANG and stepped out to investigate, the mill is off the tower and on the ground, but the round thing with the magnets seems to be ok). I get home and start putting together what the hell went wrong. The mill WAS up 47 feet or 14 meters. I had a debris field of about a million bits and pieces of broken PVC that was only east of the tower about 150 to 175 feet in distance. The mill hit the ground (grass, lawn) about 25 feet south of the tower. The misses and the neighbor both confirm that the mill was stopped and or barely spinning before the storm hit full force. Question is how do you get so many small pieces of PVC spread out so far from the tower and only in one direction? Amazingly the tail, alternator, yaw assembly, blade mounting hub are intact. I am very busy with work these days not much time for the mill or other fun things. FEAR not my fellow mill heads my quest to conquer the wind continues on. 
Jim |
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97fishmt Regular Member  Joined: 19/04/2010 Location: United StatesPosts: 77 |
How did that happen eah? |
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GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Jim, looks like YAW box failure, Possibly vibration induced metal fatigue. I have seen a similar PVC confetti blade scene, with PVC blades only a few days old. This is a dual rotor AxFx mill ??? Is a shame to find a mill this way. You will get it rebuilt I am sure. Gordon. become more energy aware |
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Andy R. Newbie  Joined: 07/05/2010 Location: United StatesPosts: 18 |
Gee, you even have a tail that furls. That's better than me. |
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| KarlJ Guru  Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
30m/s is pumping! This is the F&P so at those windspeeds there would have been no stopping it (I cant remember if you put brakes on it) That said, a real shame. Good news is Phill has a wee ripper for peanuts send him a PM. They haven't been released to market yet but for you, i'm sure it will go in the mail tomorrow. Good to see what survived (lots) so a new set of twirlers and she's away again. Chin up bud, loooks to me like it happens to the best of them karl Luck favours the well prepared |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Jim, Is this the F&P you made similar to mine. My F&P ran away even when electrically braked in high winds, 100kph+. I don't have this alternator any more, as I rebuilt the electricals with a Dual AxFx inside the brake drum style housing. No trouble in high winds now. It is probable that your mill did get away and the forces on the mill head ripped the unit from the pole. Gordon. become more energy aware |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Thanks guys for your comments and concerns. Gordon Yes, this is the F&P modeled after yours. I think you have it right, run away mill. Karl Thanks for the heads up about Phills hardware. She will fly again I can promise you that. To all. After much thought and some investigation work this is what I believe happened. The mill ran away with the very high winds, the brakes just weren’t strong enough to keep it at safe RPM. The blades spinning at God only knows RPM bowed enough to smack the mast. I would like to believe that she would have survived the heavy winds if not for blade contact. The photo with the mast on the bench (9th photo from the top) showing where I made an earlier splint repair of the coupling shows the contact area. You can see the (right)metal splint is bent at the bottom right and the entire area has the white markings of PVC. The last photo shows the cut in the solid aluminum rod where she hit the metal splint. I do believe that the energy released from the hit was absorbed by the lower mast mount area and she came down. I am happy to say that the alternator, hub plate, rod mounts and yaw came out in good condition. I got lucky with the tail still intact. One cannot proceed with repairs and up grades if one does not know what went wrong. 1. First and foremost up grade braking to a system that will, with out a doubt stop it no matter what. 2. Lack of clearance blades to mast. 3. Underestimated the amount of blade flex. 4. The mill, and mast should have NEVER came down regardless of winds or blade contact, mast up grades are in order. I know I can have her up and flying again soon but until I get a firm grip on a full stop mode she will stay on the ground, hummm that could take awhile. 
Jim |
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| domwild Guru Joined: 16/12/2005 Location: AustraliaPosts: 873 |
Sorry to see this PVC confetti. Have a stiff drink and a cry, we all joined in. I read the F&P mill because of its reactance cannot be locked electrically any more once a run-away has been noticed. Did it furl OK? Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Domwild I was at work when the storm hit so I can not tell you if the tail was doing it's job correctly. This may sound funny but at first I could not believe the misses wasent watching the mill as the storm rolled in cause I know I sure the hell would have been, but then again it's my mill not hers? If I was watching I could have learned a lot. Give me that drink my friend! Jim |
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| KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
Sounds like the post mortem has gone well. Dare I say aluminium tube for blade support? your actual findings support my belief is hobby towers, your was one of the best and yet still copped it. This is why mine is small -touch wood! Karl Luck favours the well prepared |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Ok all you mill heads out there I am back in business. Took a bit longer to get things repaired and or upgraded it’s been kinda busy around here. Extremely high winds, a tail that did not function properly, not enough blade to mast clearance, a shorted stator that did not hold, helped cause a run away mill which all played a part in the demise of my mill, oh I almost forget the part where the guy that built the thing screwed things up lets not forget him. All though I had to admit to my self, that after hitting the ground my mill was still in good shape with only the blades and blade cores needing replaced. Modifications 1.Purchase new blades,install and balance accordingly. 2.Modify yaw assembly to increase blade to tower clearance. 3.Decreased the swept area to increase RPM and lower torque. 4.Modified the tower mast to increase strength and rigidity. 5.Increased mill height from 47 feet/ 14.3 meters to 53 feet/ 16.1 meters. 6.Increased tail length, reduce tail weight. 7.Use caps to load mill in very high winds. I know some windmill fans like wooded blades but I prefer the Alum blades. Phill was kind enough to send me a new set of Alum blades. When the angle of attack is set correctly these blades are very efficient and quiet. I can actually see when the lift affect kicks in, as a sudden increase in RPM can be observed. After flying a single stator 60 series F&P with neo magnets I feel strongly that this blade set can easily apply more than enough torque to over power this alternator. Any one who has built and flown a windmill for any length of time has watched as storms have moved in and tried to rip it off its perch. (Not Fun) After seeing mother natures furry it become clear that being able to control or totally stop it from spinning is VERY important. In an attempt to increase RPM and lower, the torque I have decided to decrease the swept area from 8’4” feet/ 2.5 meters to 7’3” feet/ 2.3 meters. So far this mod seems to have worked well. I increased the clearance from blade to mast by simply lengthening the top and bottom steel plates of the yaw assembly. I also increased the blade clearance by increasing the blade angle by having the top plate slightly shorter then bottom plate. 
Having the blades strike the mast is one thing but having the mill hit the deck is unacceptable. I have ground mounted PV and solar thermo panels that could have been damaged by the mill. I still wanted to use my original Hugh Piggot pipe over pipe design yaw assembly which used a section of 5’ long 2” OD schedule 40 water pipe that was 5 feet long this arrangement did not have enough rigidity or strength. Using Alum I machined an adopter bushing so the 2” could be mounted in side a section of 3 ½” IMC electric conduit this bushing is used to secure the lower or bottom end of the 2” pipe. The 2” pipe extends into the 3 ½” IMC conduit pipe approximately 2’. The mill still yaws on a section of 2” pipe but it only protrudes out of the top of the 3 1/2 IMC conduit approximately 18”. It is much stronger and has past some testing in very high winds so far. 
Ok on to the tail and side furling stuff. I know that the tail did not furl as planned so I replaced the original ¾ pipe with lighter square steel tubing. I also lighten and shorten the lower support strut. Sorry no photos. She’s been up and flying now for about a month and in that time the wind has hit as high as 37 mph or 16.5 ms. No flex in the tower, plenty of blade to mast clearance, she did furl about 1/3 the of what should have been 100 % furl so I increased the alternator offset. Now the tail is furling early and will bring the rotor RPM to a slow spin in high winds. I have been using the tail fin to adjust the tail weight by moving it closer to or father from the alternator. As of now she furling early so I will be moving the tail fin out to the end which should put me right where I want to be. I have bunch of caps that I am now using to control the mill in very high winds so far they bring the mill RPM down nicely. No more shorting for this iron core machine. I have posted a video on U tube for all interested in viewing my mill. Keep in mind this is my FIRST video. http://www.youtube.com/watch?v=Pedc_feswyc I am happy with theses mods so far so good. Jim |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Problem with the u tube link. May this will help. http://www.youtube.com/watch?v=PeDc_feswyc Jim |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Jimbo Looks to be a good res-erection and you will be really happy with the Alloy blades I am using them and they are great. The only thing is the pipe end screw couplings, I have found that they are a semi steel, somewhere between cast iron and nodular cast and as a result not as strong at the steel pipe and do not take welding to well as they are inclined to crack at the weld. Also where the pipe is threaded there is a marked loss of strength in the pipe, I think the sleeve fitting or a bolted flange is even better for easy removal. Glad to see it all up and running again. All the best Bob Foolin Around |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
VKA4YQ Yup there just always seems to be the weakest link some where. So far so the mill has taken some serious punishment from high winds and so far shes still smiling at me and I have been smiling back.  Jim |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Jimbo I think there is something not quite right with the tail furling. The tail shouldn't be swinging from side to side like that, it looks like its missing the bottom stop. There are two stops to limit the swing of the tail. As the tail swings up, fully furled, a stop ( metal tab or something ) will stop it swinging too far and hitting the blades. And there should be another stop at bottom of the tails travel, that stops the tail when its directly out the back of the turbine. In light or no wind, the tail should be pointing down wind from the turbine. It looks like your tail is swinging past that point, I might be wrong and its a optical illusion 
Nice video, very helpfull. Watching these windmills running and furling makes it easy to understand how it all works. A video is better than 100 photos. Good to see it flying again. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Hi Glen I have stops for the tail there not rubber using steel at this point in time. I was very careful to be sure how far the tail would lift before it made contact with the blades. It may in fact be to much travel toward the blades which now brings the blades to a very low RPM. I just finished moving the tail fin to the furthest point on the tail shaft this should help with the furling and help keep things under control I will keep a watchful eye if need be I will adjust the stops accordingly. During the taping of the video the winds where getting high topping out at 37 mph/16.54 ms As of now I am pleased how she can through a very wind 24 hours. Thanks PS. Glen would you place a link of my video in the (Show your wind mill trend) for me. Jim |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Thanks JimBo and Gizmo for posting that. The video showed me at last how the furling works, much more so than the many photos posted on this forum that just show the mechanical details. I have never built a hawt for location reasons but am still interested how it works. Gizmo's comment "there should be another stop at the bottom of the tails travel" has me intrigued how that may be done in practice. Since the tail has to be able to swing each side of this 'middle' stop, is it just some snap arrangement like the ball and spring on drawer catches? Klaus |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
The tail dont swing either side of centre only one way, and as it swings the boom of the tail elevates upwards as it rotates through the 90 degree arc. This is because the tail pivot pin is not vertical and has a lay back angle on it, causing the boom to elevate as it swings. The bottom stop is there to stop the tail going past centre as it returns back down to its resting position, being directly back behind the mill. Pete. Sometimes it just works |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Jim, good to see your mill up again. I have to say that your windmill behaves really differently to mine when furling. There are some major differences in the Yaw construct to mine as well. I do have video of my mill furling during storm conditions now. Will see if I can get it viewable. Utube link A main difference is the offset side, in relation to the direction of rotation, and the resultant direction the mill furls to. Visible from my avatar pic, and on my build photos posted here on the forum. The blades are of course completely different, being tapered and twisted high aspect design. My windmill furls like this, The fin stays tracking the wind quite closely, and the alternator swings to the side and back during furling. There is the anemometer to compare with, that shows the turbulent nature of the wind. On your video, it seems like there is no smooth transition from into the wind to furled, but a movement of the whole mill head to a new position, and then the tail moves. This may be a result of turbulence or the video or other aspect. My windmill is in turbulent air and the tail does not wag the same way. I had the electrical brake activated at the end of the clip, to show how well the alternator slows the blades in stormy conditions. Power output when the brake was applied was about 1kW into the 48V battery. I think the only way to really show the furling process is from directly under the windmill, and not from the side, but this does come down to how confident one is with the windmill. Not much fun getting out in the wind with snow on the ground. I have never really had any issues with furling, but my mill is designed to furl reasonably early, so high rpm effects with relatively heavy blades are not encountered. Gordon. become more energy aware |
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| JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Mr. Tinker Yup it took awhile for the furling thing to finally sink in for me to. It's kinda like a fight between the blades and the tail. The mill wants to turn out of the wind but the tail says (nope you have to keep facing into the wind). Then the tail decides to give way and starts to raise up, however the tail is still facing the same direction of the on coming winds while the mill turns out of the wind. Gordon Nice video. That must be your AXFX mill, talk about a quick shut down, she really slows fast. Your correct about looking directly up from under it's easier to see how the tail follows the anemometer. Not hard to lye in the snow just have to dress with lots and lots of layers, but again I may be to old for that. In my video the tail fin needs to be moved to the end of the tubing at it's present position it doesn't force the mill to face directly into the on coming wind and it allows the mill to turn out of the wind much to early. I did have the fin all the way back but I didn't get enough furl. I then increased the alternator off set and moved the tail forward so now it furls to much, to early and to often the fin needs to move back which I have done and now awaiting more WINDS. Truth is I never really gave it a thought about the blade rotation and the direction the mill turns out of the wind is there a rule that dictates how they should relate?? Hummm Jim |
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