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GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 03:38am 26 Sep 2009
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The hydraulic damper on these windmills should be serviced yearly, preferably replaced. These 2 blade machines are high speed. They make some noise as well.
The whisper200 windmills have just the alternator head with rotor furl up and away, while the tail remains tracked to the winds. I recently saw one producing 1180W. [supposed to only be 1000W max.] The furling mechanism is very stable, but does look a little strange in furl. This is a gravity only system. No springs, or dampers needed. The only drawback is the extra flex cable over a movable tail system.
Downwind machines need to stay downwind to keep stable. The castor action has to be short to reduce top pivot sizing. Any changing of rotor tracking aspect compromises the geometry a lot.
Gordon.
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 04:56pm 26 Sep 2009
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Oh my gosh! I just had a scathingly-beautiful idea on how to make a
simple "feathering" device.
I was studying the picture posted by Wind Friend on the previous
page and seeing the springs made me think that a guy could merely
mount a very steep acme thread inside a like-threaded, fixed piece and
use a strong spring to keep it there. In the static position, the blade
would hold whatever pitch it needed to start (probably pretty steep) and
as the thing spun up centrifugal speed, the blades would individually
want to fly off, compressing the spring and that acme thread would turn
the individual blade's shafts equally, feathering the tips and lessening the
degree of pitch at the root.
Anyone up for spending some serious time on the lathe? I think if it were
me (and it likely won't be!), I'd use the steep thread out of a worm-feed
garage door opener. I'd scrounge through the bone pile of some shop
that changes these things out and get three alike to save years of
machining!
Just a thought.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
KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691
Posted: 07:51pm 26 Sep 2009
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MacGyver, good thinking, unfortunately the garage doors here that use that style of opener just have a smooth shaft and angled bearing in contact with it to get the screw effect.
Good thoughts about the spring too, if a coil spring is fixed at one end the other end rotates, a little, when the spring compresses, maybe that effect could be used to change the pitch?
BTW, while standing at the lathe did you notice your 3 jaw chuck has the sort of mechanism needed to keep three variable pitch blades in sync? Pity they are so darn heavy!
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 10:21pm 26 Sep 2009
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Having watched the furling requirements of a windmill for many years, I am confident that the KISS mechanical principle has to rule. My next downwind mill will only use electrical power controlling means, and all the rotor will need to do mechanically is track the wind direction. The design has to be electrically stiff, with the requirement of the rotor being able to be stopped electrically in any winds. Fortunately a dual rotor AxFx alternator is easily designed to fit this requirement.
Gordon.
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 12:03am 27 Sep 2009
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KiwiJohn
I know I said I wouldn't be building one of these feathering mechanisms,
but the more I think about it, the more I want one.
Up to now, I've merely set my blade pitch steep and put up with the noise.
My windmills pump air and it sometimes takes a bit of a bump to get
them going against a pressure head. A feathering mechanism that starts
out with a large angle of attack and then feathers out to less pitch might
be just what the doctor ordered.
To that end, I'm going to start a new thread so this one doesn't turn into
something further off topic.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
willib Newbie Joined: 24/09/2009 Location: United StatesPosts: 14
Posted: 01:05am 27 Sep 2009
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Hi All,
I'm new to this forum.
I've popped in from time to time only as a guest though.
anyway
Macgyver If you look inside a rear wheel of a bicycle
with a coaster brake,
it has a thread similar to a lathe lead screw.with a
matching collar "nut" , not really a nut , but i don't
know what else to call it.
The thread and collar is made of hardened steel
Hope this helps .
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 02:51pm 27 Sep 2009
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I'm with Gordon when it comes to the 'kiss' furling principle.
Most hubs have the axis of the blades directly originating at the center of the hub. But is that essential? Why not mount the blade axis at a slight tangent to the hub center? One could then easily rotate all 3 or whatever # blades directly via right angle levers at the end of the blade shaft that meet over the hub center. Either to be controlled from the back by a push rod in a hollow shaft or a single spring at the shaft and centrifugal weights like the ones on single phase induction motors.
This way only a simple and very sturdy blade shaft bearing is required. No fiddling with multiple spring tensions either.Klaus
windlight Guru Joined: 03/03/2007 Location: AustraliaPosts: 331
Posted: 03:10pm 27 Sep 2009
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My Survivor 3000 has a curved part on the lower part of the tail that I suspect is designed to moderate the gyroscopic effect.
best pic I have at this point in time.
allan
"I like this place and willingly could waste my time in it" - (Act II, Scene IV).
niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331
Posted: 09:08pm 29 Sep 2009
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hi Windlight...
thanks for posting the pic...now i,m curious
the survivor tail curve seems angled towards you when you took the pic..so if i,m thinking right the mill should be trying to rotate towards you slightly when it furls
i wondering .....when your standing behind your mill is your prop spinning anti clockwise ?...
this would help me understand things a bit more .....kind of comparing like with like (well almost)
my mill is i suppose really just a dodgy copy of a survivor without the tail ...that also happens to spin opposite to conventional mills (did,nt plan the prop that way ..just was,nt thinking about it at the time.. beer etc..)Edited by niall1 2009-10-01niall
windlight Guru Joined: 03/03/2007 Location: AustraliaPosts: 331
Posted: 11:38pm 29 Sep 2009
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Hi nail I will take some better pics for you and try to post them tonight OZ time.
allan"I like this place and willingly could waste my time in it" - (Act II, Scene IV).
windlight Guru Joined: 03/03/2007 Location: AustraliaPosts: 331
Posted: 10:59am 30 Sep 2009
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Nail here is a better picture, from where you look at it ie the downwind side it rotates anticlockwise, hope it helps.
Allan
"I like this place and willingly could waste my time in it" - (Act II, Scene IV).
niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331
Posted: 02:22pm 30 Sep 2009
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hi Allan
very clear pic...and nice machine
in mine the spin is clockwise giving the opposite rotation precess around the mast to yours ..its nice to be able to make a direct comparison with something that works as it should.....
it seems similar in some ways to how a boomerang works ...
,if the prop goes high the rotation direction will follow the spin (anti clockwise spin ..anti clockwise rotation).........Edited by niall1 2009-10-06niall
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