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#Post#: 1375--------------------------------------------------
360 watt Gull
By: lynx wind Date: January 31, 2014, 8:08 am
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Thank you all so much for contributing to this forum and
knowledge base.
It looks like we have optimized the LJL working together. This
simple little device is being used all over the world now and
being made in classrooms as a teaching tool. Pretty much around
the globe.
I would like to turn my attention to a larger Gull. A 500+ watt
unit seems too large. A 360 watt unit seems about right. It
would be 60" x 60". Should it be a DIY kit, a partially
complete kit or a fully made quick finish kit?
I like the idea of the aluminum blades like Sut has made
supported by a few formers attached to the blade tips and rotor.
I am really happy with the Gull alternator design. The 360
alternator will have 18 awg 9 coils and 1x2x1/4" magnets. I
like the fiberglass spars and three piece bolt on rotor design.
The pole mount will need to be really strong like a steel lamp
post on a strong foundation.
#Post#: 1376--------------------------------------------------
Re: 360 watt Gull
By: crazyguy Date: January 31, 2014, 9:03 am
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@LYNX
I like @sut blades also but I tried to stick stuff to aluminum
with 5 minute epoxy and it just popped right off when I pulled
on it.
This winter has been a rough one but I have learned a few things
.. enjoying it ;D
When choosing materials to fabricate things make sure their
coefficient of expansion/contraction is the same. In using the
polypropylene Coroplast I found that when cold it really shrinks
a lot, just like the vinyl siding on my house. So gluing things
that expand and contract a lot due to temperature changes can
affect the bonding with glues and adhesives.
Just like the Nylon string trimmer supports on my seagull, I
kept snapping them for no reason, I thought nylon was supposed
to stretch then spring back to it's normal size, but when
exposed to extreme temperatures cold or hot it fails.
If rib formers are used for the blade profile and skin is
attached, I would like to see mechanical fasteners, like nail
gun staples or rivets or something like that.
I have subjected an experimental blade to many tests, it had
wood rib formers just like the seagull and the skin was bamboo
veneer.
(grain going with the span) It was water proof and was reliably
fastenable to the ribs. The maple veneer I used in the beginning
was nice as a piece of furniture but when subjected to the
elements it warped and became wavy,no matter how many coats of
resin or paint I used.. The bamboo is not wood , it's grass, and
all the fibers go in one direction , making it excellent along
the span of the blade for strength. And it forms very easy, it
just follows the curves of the airfoil perfectly, with no
effort.
I like the single phase alternator, it's versatility is great.
My laminated rotor on the seagull is very nice, strong and
stiff, but I would assume with a 5'x5 ' VAWT you wouldn't be
using wood.
Just some of my thoughts. I don't know how your 160 is made but
I would stick with that construction type.
#Post#: 1378--------------------------------------------------
Re: 360 watt Gull
By: lynx wind Date: January 31, 2014, 10:26 am
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@CG Thanks for the comments and suggestions. This could be a
DIY but at this size I am not sure wood is a good choice, even
bamboo.
I need SUT to chime in here, hopefully he hasn't frozen. I can
see having a sheet metal firm cut the exact size rectangle I
need for a 10.25" long Chord. Because we trap the blade between
rotor and blade tip we can use a former at the middle and both
ends to keep the shape. This aluminum will be a lot stiffer
than flashing. How to draw the TE together? Maybe it could be
spot welded to keep a nice clean back edge. Right now I use
styrene palstic sheet and it holds its shape very well and is
adhered to foam and hot melted at the TE. I think aluminum
could be used instead without the need for the foam.
I would increase the diameter of the fiberglass spars to 3/4"
The alternator has a 1/4" thick magnet plate 12" diameter. The
stator is 1/2" thick with 9 coils and is 14" diameter. The
shaft will be 3/4" and 10" long riding in a permanently lubed
hub. I can see having this hub bolted to a steel pole.
#Post#: 1379--------------------------------------------------
Re: 360 watt Gull
By: lynx wind Date: January 31, 2014, 10:41 am
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Here is a drawing of the Gull 360 blade assembly. The former in
the middle could be adhered to the spars or attached with set
screws. The formers on the ends will screw into the rotor and
blade tips.
#Post#: 1380--------------------------------------------------
Re: 360 watt Gull
By: crazyguy Date: January 31, 2014, 11:40 am
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I was thinking of "female" formers on the outside rather than
"male" on the inside. They could double as winglets or end
plates.
Also 3/4" spars that are solid fiberglass would probabley be
more expensive and heavy than carbon fiber units. Ive seen some
in hobby shops and was surprized how affordable they were.
#Post#: 1381--------------------------------------------------
Re: 360 watt Gull
By: lynx wind Date: January 31, 2014, 12:04 pm
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The spars are hollow fiberglass. The ones for the Gull 160 are
1/2" OD with a 1/4" ID. The Gull 40 has 1/4" OD with a 1/8" ID.
Could put formers on the outside, I haven't done that in the
past.
#Post#: 1382--------------------------------------------------
Re: 360 watt Gull
By: crazyguy Date: January 31, 2014, 1:22 pm
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the external formers could corral the tension from the bent
aluminum plus act like wind guides over the airfoil. And they
would look cool. 8)
I thought the fiberglass rods were the solid driveway markers.
my mistake.
Also The shaft would be nice if it were machined rather than
stock rod.
on my diy seagull I used a sched 40 (domed) pvc pipe cap 1"
to hide the threaded shaft, nut & washers on the top of the
rotor.
#Post#: 1391--------------------------------------------------
Re: 360 watt Gull
By: sut Date: February 1, 2014, 2:52 pm
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Well I am all but frozen ! I have been so busy keeping the snow
off driveways haven't had time to think much . I have not had
any trouble so far with my setup on diy wings (not like its
spinning everyday ) Every thing is staying put. I think you
forget that the wings are silicone to the rotor and blade tips
which also helps keep things put and together . The wings are
stiff and hold their shape with out even gluing them to any of
the inside supports, so after you do it makes it a real solid
wing . I would like to have this diy windmill set in some place
that could be tested with a lot of wind. What I should do is
just unload it and see if it comes apart at the seam! least then
I would know its weak spots. (I know its not the best way to
test )
#Post#: 1393--------------------------------------------------
Re: 360 watt Gull
By: lynx wind Date: February 1, 2014, 3:31 pm
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If you want to unload it, just double or triple the battery
voltage. If you were to load it on a 36 volt battery it will
tend to run up at much higher speed. I guarantee if you unload
it completely it will kill itself.
How do you join the TE of your aluminum blades? Is it possible
to spot weld aluminum sheet?
#Post#: 1395--------------------------------------------------
Re: 360 watt Gull
By: sut Date: February 1, 2014, 6:07 pm
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Well I guess you can spot weld the TE but you would have to be a
better welder than I ! But now a days they have improved welding
by leaps and bounds ( I will go into my local welding supply
shop and ask them ). If it was sheet metal I could do it~! but
aluminum is so fickle with its low melting point and you can't
see it change to liquid like metal and I don't own a tig welder
to try and weld the aluminum.
I just glued my TE with that 5 minute epoxy( I really liked
your idea about folding the TE over ) Now I have not tried to
pull it apart by hand! so I don't know if you can . I am sure
they make some other epoxy for doing just that, but I have not
had the time to investigate further. I have the new coil of trim
stock (which is thinner than the stuff I used on the first set
of wings )with the new set of wings I will try the fold(TE) and
a different set of lighter formers on the top and bottom of the
wing I am just waiting for this cotton picking snow to stop for
a week or so.( looks like another long night ahead)
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