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Forum Index : Windmills : White Pointer AXFX
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Fingers crossed for you Trev. I do have reservations about the magnets staying in place, and the stator strength around the 3 bolts. But at least you have the alternator finished and up in the air, quite a few steps ahead of mine 
The only way to see if the design will stay together is to get it up in the air and start testing, well done. Keep us posted on how it goes. Looks nice. 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 |
Trev Congrats job well done. Looking forward to progress reports. Sweetness all the way. 
Love your work. May the wind Gods bless you. Jim |
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shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210 |
Your work is very tidy trev very smart looking mill that will put plenty of amps out!! wish i could build that neat! |
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| Greenthumbs Regular Member  Joined: 05/12/2008 Location: AustraliaPosts: 40 |
Hi Trev, It looks great, Finally you got to finish it. 
Hope you did not build any of it after you had drunk that Bottle of wine I sent you.
Ar even with a few under your belt you still couldn't build a bad turbine. 
Keep up the good work. Regards Damien |
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Trev Guru  Joined: 15/07/2006 Location: AustraliaPosts: 640 |
All is well here, cyclone Yasi is passed. A little more wind at times since yesterday afternoon. Some leaves and small branches were blown off. Nothing significant. We were not in direct path. AXFX (&F&P) was down for the potential blow. I just put the AXFX back up this afternoon. I have the 2.5m aerofoil blades on it and just did some measuring. Wind speed at ground level fluctuating between 8 & 15 km/hr while current fluctuating between 1-2 A at 48v battery nominal. It appears that these blades do not have enough torque for the AXFX. I did have the 2.9m composite blades on to start with. It furled too soon. I checked the weight difference between the old double F&P tail and the new one. I had to add about 150g to make them the same. I added 200g to the new one, so was then 50g heavier than the old one. It still furled too soon. I added angle to furl hinge, it is now 30 degrees of vertical. Normally set at 20 degrees. It then would hold OK but would get up speed and then turn out of the wind. The tail furl stop needs to be shorter (which I have done now with the 2.5m aerofoil blades) to allow the tail to have greater resistance to the blades wanting to turn out of the wind. With the 2.9m composite blades, it possibly would be better to have the tail longer too. I don’t know what the wind speed was, it was really up & down, but I have seen the AXFX with the 2.9m blades hit 12A, and then turn out of the wind. Here is a picture of the AXFX with the 2.5m aerofoil blades. The sky still is the results of cyclone Yasi. 
Trev @ drivebynature.com |
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| Trev Guru Joined: 15/07/2006 Location: AustraliaPosts: 640 |
I have added 200mm to the length of the tail. The furl angle stop bolt adjusted to give greater resistance to the wind wanting to turn the blades out of the wind. It seems to track the wind better. Still no real output yet. Low wind. I am chasing some capacitors to use as a doubler. I want to try some caps before I consider making a new stator.  
 
Trev @ drivebynature.com |
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| Trev Guru Joined: 15/07/2006 Location: AustraliaPosts: 640 |
About a week ago the AXFX developed a knock. So dropped it down. It sounded like bearings. Of course I did use bearings out of a washing machine. I went and bought some new bearings. Once I loosened off the tension on the bearings the noise stopped. I stripped the machine down anyway. The old bearings felt good once I had them out. I think that the side load on the bearings was the problem. I made up a steel pipe spacer to go between the bearings on the shaft. I put the new bearings in. I changed the propeller shaft offset. It still did not track the wind like it should. It normally has about 25mm offset. I have drilled new holes so the offset is now only 12mm. The caps also turned up. So they are fitted as well.  
 
 
 
Trev @ drivebynature.com |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Trev Yikes! Nice work! . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| Trev Guru Joined: 15/07/2006 Location: AustraliaPosts: 640 |
I always have the dream of making something easier. I bought some alloy aerofoil extrusion from Phil a long time ago. Thought it would be easier for blades (and cheaper too than my own fibreglass blades). They were 2200mm long, and with the hub, made a diameter of 4.6m. The idea is to catch the low wind, which is what I usually have here. The extrusions are easy enough to assemble. I fitted them up with mild steel 25mm about 300mm long into the hub I machine. I already had the hub made. It didn't take very long to fit the blades and hub together. Being so huge I could not check for balance. I was relying on the extrusions to be of equal length and distance, thus equal weight in each blade. Swapped the blades over on the White Pointer AXFX. They seemed a bit flexxy and thought they would not last. But oh well, it is a test so up we went. The blades started spinning before the tower was right up. Balance seemed ok. They seemed to spin at reasonably high speed, but did not get any real time to watch them. As the tower neared the top, the blades started hitting the welded brackets where the cables tie on. A big mistake! I should have had more bolts through the blades and steel bar. 1 bolt allowed the 2 outer skins to seperate allowing the blades tips to flex. The tower was up and straight back down.  
 
 
 
Trev @ drivebynature.com |
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| Trev Guru Joined: 15/07/2006 Location: AustraliaPosts: 640 |
All three steel bars were bent. Two blades were bent in the middle. All 3 blades were damaged where the steel bar goes in. The steel bar was bent and the guage on the press went up to 10 ton to straighten them. I tried the blade under the press but the thin trailing edge looked like it was just going to roll over so did not put much pressure on it. I hammered the bends in the blade. Cut them back to a length of 1600mm. So would be close on 3.4m diameter now. Re assembled in the hub with 3 bolts through blades and steel bar. The two blades that had the bends still have the bends in them and now with uneven spacing between blades, balance would not be right. To balance, I just ground the end off the blades appearing to be heavier. Refitted to White Pointer AXFX. The wind was blowing, but not real strong. We pulled up the tower and some rough weather had come in quite quickly. Note the change in sky colour. The wind had picked up and while we got the tower bolted in place (scary as I did not know how the blades would handle it), Dale (son) was watching the amp gauge - 30 amps! As soon as I could get to the gauge I saw 25 amps! I went for the wind speed guage. I measured up to 20km/hr, but I am sure the wind had dropped off some by then. There was quuite a lot of wind speed fluctuation and consequently amps too. I can't check wind speed and amps at the same time, so I don't really have any solid data. The best I had seen with wind up to 20km/hr was around the 14 amp mark with the 2.9m diameter fibreglass composite blades. The next morning the blades were still on. Back to quite wind and beutiful blue sky. Another lot of cloud came up quickly and the sun was shining on the White Pointer F&P single motor 2.5m machine and looked great with the dark sky background. So I took a photo of it too. On most days since, the AXFX may be doing 1-2 amps while the F&P 2.5 is sitting still. When the wind picks up and gets the F&P 2.5 running, they both do 1-2 amps each. When the wind speed ramps up the AXFX ramps up amps quickly and outstrips the F&P 2.5 easily.  
 
 
Trev @ drivebynature.com |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Trev Yeah I think 3.5M diameter is about the limit for those blades. Its the strength of the mounting that becomes the problem, not the blades themselves. Are you running the steel tube the full length of the extrusion? Have you seen Gills article about blade balancing. http://www.thebackshed.com/Windmill/articles/TurbineBalance. asp It works for any size turbine, since you hang it flat, not upright, so you could use the technique it to balance a 5 meter turbine! Good to see your getting some wind up there. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Hi Trev, Well looks like the good and bad that you have finally decided to use the blades. Putting the 2.2m blades on 300mm solid mounts was, "as you said a BIG MISTAKE" , the absolute minium would have been 1/2 the blade length of steel tube and solid inside the tube for 1/2 of the tube . That would have been 1.1m of tube on 500mm solids + what goes into the blade hub . Also there should have been 3 to 4 bolts or 8-10 rivets over that length. The mounting system I designed to mount the blades is described on the link to the Alu Bades and is load tested to 4~6 Tonns HERE , to run a set of these blade @ 4m+ , I would be thinking along the lines of 6+ Tonns of centrifugal force as a design minium Where you have cut them back to @3.4m, I think you will find you have more than enough power in light wind and enough power in a blow to burn your AXFX if you are not careful. My Ax @ 3.15 regularly sees over 2Kw in 10m/s and easily make power @ 1.5m/s. I would not recomend putting up blade sets that are not balanced or checked for tip run out , the alu blades are not exactly the same weight, there can be up to 10g per mtr difference in weights which will tear things apart when it gets going in a good wind. The other thing to pay special attn to with thes blades is the AOA is set correctly and exactly the same on all all blades , I chased an out of balance wobble for weeks which turned out to be one blade at a 1deg difference causing a differing lift pattern at a certian RPM . Whether the blades are timber,aluminium,pvc,fiberglass they should be balanced correctly and set to run true at the tip and the Angle of attack set correctly. PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
Geez Trev brave move given the number of posts regarding the strength requirements that exist for large diameters. The ones I got from PhillM pre assembled have SS tube 3/4 of the full length and the solid stubs further than he recommends too at almost 1/2 the blade length. Result is a blade that although heavy is bulletproof, so is the mounting, hence the 3m blade set probably getting close to 15KGS.... That concerned me at first but in reality makes no discrenable difference to the turbines performance and "events" of 40m/s are survivable. PhillM's comments on the blade angles were why I chose to not use your hub as I did not have the required tooling to get the hole drilled in exactly the right spot to achieve the correct angle on every blade. A mechanism that bolts the blades in a hub similar (to yours) with fixings achieved without drilling holes in the structural fixing of the blade (ie the solid rod) made more sense as it allows for that fine adjustment to take place and hence forces from incorrect tracking kept to the minimum possible. Luck favours the well prepared |
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| Trev Guru Joined: 15/07/2006 Location: AustraliaPosts: 640 |
No steel tube, I see no benefit of steel tube. The alloy extrusion is like an 'I Beam' by itself. Adding weight in steel tube only makes it heavier and centrifical forces then are greater. A 19mm solid bar inside the 25mm x 3 wall thickness tube is much weaker than 25mm solid. The weak point is at the hub. This is where the 25mm solid bar bent. I don't believe that the 300mm length of bar is a problem. My problem was that I should have put in at least 2 bolts through the extrusion/solid bar to stop the extrusion outer skins seperating and allowing it to pivot on one bolt. I assumed the extrusion internal shape would hold it. I had to hit the bar in with a hammer. It was tight. Yes Glenn, I have seen that method of balancing. I just assumed the extrusion to be of similar weight. I do agree that the blade set does need to be balanced properly. The angle is no problem, they are set exactly the same. Phil, with big heavy blades, I would want my mill furling at 10 m/s, thats 36km/hr. That happens about once a year here. Karl, 15kg is heavy. I never weighed this extrusion set, but the weight does concern me some. My fibreglass 2.9 blades are only 1.5kg each. Karl, with the hole for the bolt in the hub, I drilled a 1/2 inch hole in the steel bar that allows for twisting. All good advice, thanks guys, I have made note. For now I have the shortened extrusion fitted with 3 bolts through the extrusion/steel bar and only one bolt through the hub/steel bar. The bar is the same pieces, straightened as much as possible. They are 25mm diameter and 300mm long, about 60mm in the hub and the rest in the extrusion. With bar slightly bent and 2 of the extrusions bent, they are not true at the tip and are not equal spacing at the tip. But they are static balanced. They run fine. Quiet too. I do have concerns about the alloy fatigue issues as well. Only time will tell how that goes. Trev @ drivebynature.com |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I have to comment that the steel tube is a designed structural part of the extruded blades, both PVC and Aluminum. When I first drew up the profile I intentionally removed the any webbing around the "hole" because the steel tube would provide the strength needed in that area of the blade. Without it, the blade has very little strength and will bend and break, simple as that. I also believe too much emphasis is placed on turbine weight. I remember in the early days of the extruded blades I was copping a lot of flack because they were considered too heavy by some. But 3 years later the extruded blades have proven themselves as good performers. Its true a set of well designed and carved carved timber blades can outperform the extruded blades, but that takes a different skill set, of which some of us dont have, plus a time cost. Just my 2 cents. I put a lot of time and thought into those blades, and earn nothing in return other than knowing they work when used as designed. 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 |
Trev A man of your talents I know will get the White Pointer Mill up and running with the ALU EXT blades it's just a matter of time. (Just my thoughts) I am sure you've probably thought of this already, be sure to get MORE than enough blade to mast clearance cause they will flex. I know my first mill hit the ground hard because of lack of clearance. Your blade set is bigger then mine so you will need lots of clearance. Looking at your photos in my opinion you need more clearance. These blades can produce some serious torque you may not need a 3 meter set. I started with a (8 foot)or 2.4 meter blade set but after realizing the power I got out of these blades I reduced down to a 2.1 meter (7 feet) with this arrangement I achieve more RPM and an earlier cut in at lower wind speeds. I think you and I have the same idea about blade weight. I try to keep my blades lighter then most for obvious reasons. My blade set is 2.13 meters (7 feet) I use a 1" solid ALU extruded rod which is (6") or 0.18 meter shorter the blade. I use three bolts at the root end and then add a couple of rivets nearer the ends. I have a single stator 60 series, neo set up which will maintain 600 to 700 watts during a heavy blow. Yup I am sure some will save naaaaa to the ALU but it works for me. Again just my thoughts. Jim |
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