 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Windmills : upwind or downwind?
| Author | Message | ||||
norcold Guru  Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Note Mobi you had your downwind OEM converted to upwind. My thinking downwind would be more efficient (tracking wise), except for the obvious disadvantage of no furling. Cos my thinking could be way out here. Did you use it downwind before converting? We come from the land downunder. Vic |
||||
Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Down winds are a bit like VAWT's, seam like a good idea at first, but there are more problems than you think. The OEM down wind turbines initially just mounted the turbine behind the tower, but had tracking problems and were even known to spin around to face upwind, run backwards, and keep going  This was because the turbine was flat, for a down wind turbine the turbine itself needs to be shaped like a cone, to it tracks the wind better. OEM fixed this by adding a tail out the back to the shaft, since the shaft went through the alternator. It looked a little weird, but at least it tracked the wind better.
Standing in front of the windmill, while it was running, was noisy. The mast causes a wind shadow and this interacted with the blades as they passed, making a unpleasant thumping/drone noise. I would stay away from down winds. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
||||
| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Downwind modified my 500watt unit to an up wind version before it got to me. My personal opinion is that down wind versions are ok with some sort of yaw drive to control the tracking. That adds to the complexity of the mill that up wind units with a furling tail largely obviate. I agree with gizmo. BTW, when the first wind farm down our way was mooted, a "coning" down wind unit was proposed. As the wind got stronger, the hinged blades were designed to cone together. I wonder why it never got off the ground. (besides high likelihood of blade breakages). Just as an aside, my neighbour is a Vestas mechanical maintainer who has just got back from China learning how to repair the fibreglass blades. Apparently, the blades are damaged very often due to lightning strikes. David M. |
||||
| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Gonna get around to lowering mine and paint the tail( bit of surface rust showing). From your explanation Gizmo will remove downwind from mind. They are still performing roughly as per the 200 watt China one. Still apply brake before wind events, no drama. Will do a bearing replacement while down. Should be interesting if the proposed wind farm goes ahead to my east, cannot really see how they can achieve the proposed outputs they are claiming. The con continues!! It seems such a backward move, when solar can supply so much more consistently, reliably and long term. I shake my head in annoyance and frustration with the short term politics. We come from the land downunder. Vic |
||||
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Crew I've built only one down-wind turbine and it "precessed" about the mount, much like a gyroscope does about its landing. I corrected this by adding a dorsal fin, but it still tried climbing around the tower as wind speed dropped off. It made great "yard art" but I never tied it to an alternator or pump or anything productive and ultimately cannibalized it for parts to build other stuff. . . . . . 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 |
||||
 Print this page |
