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Forum Index : Windmills : New wing build
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| Air Bender Senior Member  Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi all At last the construction has finished and the next thing to do is to get it mounted on the tower which should be tomorow, if it stops raining long enough. 
The bracing has gone on, for the bracing across the top of the wings I used 8mm stainles steel rod and for the angled bracing I used 3mm SS rod. All the best Dean. |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi All This morning I got up to a clear sky with no drizly rain for a change, so the new wind mill was mounted. 
But as you would expect we have hardly any wind. We have had a few puffs come through and it has self started a few times and spun for a while. But nothing realy to get exited about. Hopfully soon my son will bring the anometer he built home from the science room at school, or i will have to build my own, and we can get it mounted up as well and I can give you some indication of what it does in different wind speeds. The wind mill is not up in the best location but we do get some very good winds come through at times, lately most of our winds have been coming from the north and east when our predominant winds usualy come from the south west. So hopfully we will start geting some good winds come through soon. All the best Dean. |
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Air Bender This is just a hunch, but you might want to make the top structural support between the blades out of a solid piece of sheet. The reason is, as this thing spins up, the blades are going to want to pull outboard and as they beat into the up-wind position, they'll also want to bend back against the direction of rotation. This may start it wiggling and it may get out of control. With a solid (could be bolted together) top strut tying all three blades together, the chance of a devistating harmonic may be lessened. Like I said; just a hunch. By the way, I like the color, as green is my favorite. You did a very nice job of manufacturing things. . . . . . 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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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi Mac The top bracing may look a bit flimsy, but it is actualy quite stiff. For the wings to bend inwards it will need to bend the wing or the plate at the bottom that is inserted 500mm up into the wing. Before i put in bracing I slightly sprung these plates outward so that the bracing pulls the wings in straight. The top bracing is 8mm stainless steel rod which is quite hard to bend and in the centre of the three peices of rod I have a nut that has holes drilled through the flats that the rod is inserted into and then wilded on the inside of the nut making the centre conections quite stiff as well. When I fitted the mill onto the tilted tower we had to lay the mill over on its side to slide it onto the shaft I had someone holding it up by lifting it on the bracing and there was no movement in any of it at all. Any force from the wind on the wing inwards will be reduced or overtaken by the centrifical force pushing the wings outward so i am hoping that the bracing at the top will OK. I think that by adding more weight into the top of the mill by building something very solid up there will more likely add to the wiggling affect and harminic inbalence at the top. All the best Dean. |
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| smithy Regular Member  Joined: 30/01/2011 Location: AustraliaPosts: 52 |
Only 1 sure way to find out.... let it blow.... Smithy  "The answer my friend is blowing in the wind, the answer is blowing in the wind" Bob Dylan |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I can see where Mac is coming from regarding drag. Although you have struts and wires to stop the blade bending out wards, there is nothing to stop the blades bending back from drag, that is the force pushing at the blades leading edge. At speed the tops of the blades will be twisted back, with respect to the turbine axis. But hang on, just rethinking how a lift type VAWT works, the twist is actually going to be forward! Looking at your last picture, the blade closest to the camera. The top of the blade will be driven to the left, because its lift is driving the blade to the left, and the bottom is anchored to the axis, but the top isn't, so its going to want to lean over in that direction. A fix would be an extra wire from the top mount point on that blade to the bottom mount point on the next blade, to the right in that photo. That way each blade is triangulated and cant get out of shape. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301 |
Hi Dean, It self started a few times,thats great to hear.An added bonus to have mentors helping to make the most of what you've thoroughly done.Cheers Rastus see Rastus graduate advise generously |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi all The back and forward movment at the top of the wings may be a problem. When the mill was on the ground I put a bit of force on the wings and they moved back or forward a couple of inches at the top before the mill starts to tip over. the movment comes from a slight twisting in the bottom rotor arm. The old mill was set up basicly the same and the wings never tended to tilt back or forward even in very strong winds. But this mill is a different beast having the wings twice as high. The bottom rotor arm on the old mill had square tube with 1mm walls and this mill i have the same size tube but with 3mm wall thickness and they are not much longer than the old ones. If this turnes out to be a problem i will have to strenthen it up somehow or add wire bracing in. At the moment I dont have any movment coming from the mill at all, I hoped the wind would kick in a bit yesterday afternoon but it droped out completly and its a dead calm again today. Yesterday morning it self started a few times rocking back and forward on the cogging and broke loose with only a light puffy breeze which wasnt even strong enough to spin the mill up to cut in speed it spun very slowly for an hour or so untill the wind droped right out. So i dont think there will be any problem with starting, I must have got my angles right, you can get lucky some times. by looking at the forcast i dont think we will be getting any wind untill after the weekend which dosnt realy matter as i am at work for the next 4 days were I leave in the dark and return home in the dark, but then i have 4 days off and hopfully the wind will be back by then. All the best Dean. |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi all I am finaly getting some wind today and the mill is putting in a small but much needed charge into the battery. The wind is from the north and very gusty. On the north side we have trees on our fence line and houses close by. In this turbulant gusty wind I dont think the mill is performing any better than the smaller one, but on the other hand I dont think it is doing any worse. This is were I can see the advantage of having a logger. The wind is forcast to swing around to the south west and it is the direction were we get the cleanest wind from and the small mill performed best in, so I will have to sit back and wait to see if there is improvment in this direction. All the best Dean. |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi all I done a bit of streamlining on the bottom rotor arms, still not finished but I put the foils on for a trial run. 
We had a bit of wind today and I think I have gained a few more rpms, and it is spinning up a lot quicker in the gusts. All the best dean. |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi all I have brought the old wings out of there short retirement and have fitted one in between each of the bigger ones, so now I am trialing 6 wings on 6 rotor arms and I have had very good results with the mill reaching cut in which is around 80 rpm in 3 m/s winds instead of 5 m/s which both wing sets were doing on there own. The small wings being piviting two element wings have heaps of torque, help push the rpms up so the big wings reach lift speed and take over which seems to be a good combination. With all the light winds we are having this is more than a 100% increase in the output of the mill with it know puting a small charge into the battery most of the time. Over the next few days they are predicting some good winds from the south west which we havnt had for months. This will be a good change from the north and north west winds we have had for so long know. I am very keen to see how it goes in a good fresh southwestly. All the best Dean. |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
A picture of the latest wing set up. 
All the best Dean |
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| Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301 |
Hi Dean, You should have "bragging rights" with the performance increase you've made so far.The lower windspeed cuttin and longer generating time is the ultimate goal.  well done Cheers Rastus see Rastus graduate advise generously |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Dean, the mast head mounting of your interesting wing wind generator has me intrigued. Do you have a close up pic of the part below the generator? Klaus |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi Klaus 
I built the mast head so I could take the rotor off easy and change the stators. It is basicly just a square with 50mm thick walled S/S square tube across the bottom and the uprights on each side are solid 50mm x10mm S/S, welded to these across the top are two peices of angle that have the bearing housing atached. There is a bit of flex and movement in the tower but not in this top part it is very solid. As you can see I have a good supply of scrap stainless steel. All the best Dean. |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Thanks Dean and, yes, it does look very strong in a close up shot. What do you use to weld the SS steel? Klaus |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi Klaus I do all my welding with a stick welder. I have had good winds from the SW and S at around 25 km/h for the last couple of days and the mill is consistantly spinning at over 100 rpm. Yesterday I fitted the 100s stator, which was reaching cut in but it was not pushing the rpms up much past cut in to start pushing the amps out. I think the 80s is better at these rpms. Im planning to get hold of a 60s stator and rewire it 2x7c, this may be a better option. I will streamline the small wing rotor arms, and I have some ideas for some improvments to the small wings which need to be painted green as well. All the best Dean. |
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| dwyer Guru Joined: 19/09/2005 Location: AustraliaPosts: 574 |
Hi Dean I understand Klaus mention about your welding however if you using stainless welding rods it is the correct way but any general purpose mild steel welding rod will not bond together as might fell apart but again welding stainless rod to mild steel is acceptable please for your safety i dont use any general purpose mild steel welding rod for building windmill tower, parts, or in my workshop i hope im not offending you im just helping :) |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi dwyer I used stainless rods to weld it all together. I have got some strong gusts coming through today, a good test for the mill. During the gusts i get a couple of mm wobble in the top of the tower for a short time and then it smooths out. The wings remain standing true upright with no movement back or forward or in or out at the top, not that i can see anyway. At the moment it dosnt look like it will come apart but it might be a bit soon to tell as there will be a lot stronger winds to come now that it has finaly started blowing. I will keep an eye on it. All the best Dean. |
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| smithy Regular Member Joined: 30/01/2011 Location: AustraliaPosts: 52 |
Dean, I like the idea of increasing the torque for lower wind speed start up. I assume it has been going around now for a while, in your opinion do you think it has capped the upper end RPm of the unit? Smithy "The answer my friend is blowing in the wind, the answer is blowing in the wind" Bob Dylan |
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