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#Post#: 2510--------------------------------------------------
Re: Diy75 Re-Build
By: lynx wind Date: May 1, 2014, 5:30 pm
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Wow! One day's work
That looks really good. It should perform well. I have had
very good results just painting the blades as long as they have
spars. The paper should give them a nice finish and strength.
It could be the smaller magnets aren't keeping the rpms down
enough. Maybe run this with your boost circuit to load it more.
Great work. keep us posted.
#Post#: 2512--------------------------------------------------
Re: Diy75 Re-Build
By: nessprojects Date: May 1, 2014, 6:21 pm
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@ jerrym
It was only tested at 800rpm in the workshop with no
blades.....That's how I worked out the 40w.
#Post#: 2513--------------------------------------------------
Re: Diy75 Re-Build
By: sut Date: May 1, 2014, 6:30 pm
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Yes Nice job !!! Has anyone ever given any thought about
removing the plywood that sticks out in between the top and
bottom wing ? I know its not a lot but may be it would remove
some turbulence around the outside and also make it look taller
than it is ( sleeker )
#Post#: 2516--------------------------------------------------
Re: Diy75 Re-Build
By: nessprojects Date: May 1, 2014, 8:07 pm
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@jerrym
well it would be a nice concept with sticky out wings but I
reckon the constructional problems would be massive. (just my
point of view on this). As it stands you only have 1 moving
part.
@Sut
I also think that taking the extra wood away would start causing
the wood to split easily.
@LW
On the day of the test it did have the boost circuit in line but
I had it on a switch so I could test ' with or without ' but
with all the action kicking of at once I do not know what it was
switched to.
also.... Is there a good or a bad chord for a given diameter
?, Seem to think I read it somewhere that it was called '
solidity ' or something like that.
#Post#: 2517--------------------------------------------------
Re: Diy75 Re-Build
By: lynx wind Date: May 1, 2014, 9:43 pm
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@Nessprojects
From my experience a solidity for this type of VAWT should be
about 50%. Take the chord length of all blades and divide by
diameter.
I have built VAWTs with diameters of 10" - 6' and they all run
very well with a solidity of 50-60% If you go less solidity
they will run fast but don't start until winds reach 15mph+
I have built VAWTs with high solidity and torque is high but
speed is restricted under tsr 1.5 (power = torque x speed)
A good compromise and what I found works very well is about
53-54%
Smaller diameter VAWTs run faster, but swept area is reduced.
Going taller solves this but then structural challenges mount
(insurmountable)
Going big diameter and shorter hurts swept area and speed.
The Seagull 175 with a 48" height on a 40" diameter should be
optimal.
#Post#: 2518--------------------------------------------------
Re: Diy75 Re-Build
By: nessprojects Date: May 1, 2014, 10:07 pm
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Many thanks for that info and all understood, Seems this
re-build will put it about 75% solidity so reducing the amount
of speed (tsr) but could be a good thing for my area.
Tests will tell .....
Just to add that I tested some glue called 'no nails' to glue
polystyrene to wood.....Tests were good so that's what will be
gluing this turbine together. Only one problem with it is that
it is a heavy glue(weight wise) so minimal glue will win the day
I hope.
No Nails was a error....See Reply #22 slideshow for details.
#Post#: 2520--------------------------------------------------
Re: Diy75 Re-Build
By: nessprojects Date: May 2, 2014, 5:28 pm
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@ jerrym
See my day 2 video below, it shows a picture of the glue. Only
one problem with it was that it was supposed to be used before
2010 (Oh well, Tuff).
Here is my slideshow of day 2, Just needs a good paint and some
wind to test her out.
Typical...Not a breath of wind to give her a try
tonight....Arghhh.
Final size is 24" diameter and a blade length of 22".
HTML http://youtu.be/8100AxgNiOY
#Post#: 2521--------------------------------------------------
Re: Diy75 Re-Build
By: lynx wind Date: May 2, 2014, 6:12 pm
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Looks great.
It would be a good bit of information to know at what windspeed
this dimension VAWT starts up and if it spins up quickly. I
think you probably have hit on something for your high wind
area. Now we just need to get you some better magnets. : )
#Post#: 2522--------------------------------------------------
Re: Diy75 Re-Build
By: happygolucky Date: May 2, 2014, 6:24 pm
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very nice rebuild..!nice video too.
#Post#: 2524--------------------------------------------------
Re: Diy75 Re-Build
By: nessprojects Date: May 2, 2014, 6:45 pm
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@ LW
Yea these magnets were removed from another PMA so surplus to
requirements.
Just for info a 2" x 1" x 1/2" neo magnet has a lift force of
about 25Kg each.
My round ones have a lift force of 15Kg each so they don't do
too bad. The coils were also adjusted slightly from your plans,
They were wound around a 1" diameter former.
My large Hawt has 16 of these 1" magnets and I did see 240W into
a cheap 300w GTI.(6 ft blades)
Conclusion is though that nice big magnets do make a difference
and lower the resistance of the coils when using thicker wire.
I will keep you all updated with power from this conversion.
@ jerrym
Thanks for the name ;D ....It was stored well above freezing
but don't even know where I bought it from, time will tell if it
holds up.
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