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#Post#: 5304--------------------------------------------------
Re: Alunimum wings for diy 75
DIR By: maximoney1
Date: January 29, 2015, 1:14 pm
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Agreed CG, but for the likes of lynx making lots of repeatable
airfoils, the steel i'm thinking of (at my work) can be doubled
over to form a curve, but it could not be creased. If this was
supported at 1 inch centres, or even a solid shaped block) it is
not going to deform one iota. The skin that the expanding foam
makes also adds to the overall strength(within the thin
aluminium sheet)and is extremely tacky when forming until it
sets. The stainless steel sheet would be extremely durable, able
to churn out numerous airfoils to exactly the same spec every
time, with the airfoil shape tailored by the fixings to the
support ribs behind. This effectively only needs to be timed
until this 'skin' sets rigid, as generally after that there is
no more expansion, only curing within. Further more, creating a
mould lengthways, three airfoils could be created at the one
time, depending on the method adopted for inserting the foam.
Just a thought.
#Post#: 5306--------------------------------------------------
Re: Alunimum wings for diy 75
DIR By: maximoney1
Date: January 29, 2015, 3:43 pm
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CG, you say hard blades run faster, but i see your sail
experiment with a tsr above 2.
Out of curiosity, comparing a 3 bladed vawt with blades of 6inch
chords versus a 5 bladed vawt with 3inch chords, which would
likely run faster, at 'comparable' diameters, angle of attack &
weight?
#Post#: 5307--------------------------------------------------
Re: Alunimum wings for diy 75
DIR By: maximoney1
Date: January 29, 2015, 3:55 pm
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@CG
You mentioned stong & light weight, so how about instead of the
aluminium skin, you could spray the steel former with photomount
adhesive(just to give a temporary light bond) and then lay a
crossply of your ripstop nylon(just so that it initially
maintains the shape of the steel former mould, and then the
expanding foam would push the nylon tight to the steel. Whether
it could be accomplished with a machine finished surface would
be tricky.
#Post#: 5309--------------------------------------------------
Re: Alunimum wings for diy 75
DIR By: maximoney1
Date: January 29, 2015, 4:12 pm
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CG, if the steel former was lined with clingfilm first perhaps?
Also for strength you could add a structure similar to pic
attached, before the foam was sprayed in, but keep weight light?
I was thinking of these indoor plant stakes, which are about as
thin as barbeque skewers, but much stronger(sometimes have
difficulty breaking them, they have to be chopped). You could
vary the amount of them to get the best stiffness/flexibility
profile for the length of blade?
Just thought i would try and contribute something as a thanks
for all the help i've had off you guys. :)
HTML http://www.imageupload.co.uk/images/2015/01/29/img103.jpg
HTML http://www.imageupload.co.uk/5hdn
#Post#: 5311--------------------------------------------------
Re: Alunimum wings for diy 75
DIR By: maximoney1
Date: January 29, 2015, 4:29 pm
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Yeah fair comment CG, easy from the armchair. Might try it, but
unfortunately at present, i'm convalescing after a hernia op, so
no stretching, lifting etc etc, plus it will be a few weeks
before i can lay my hands on the stainless steel. If i'm
successful, i will post some pictures....if not i will probably
skulk into the background, never to be heard of again....lol.
The stainless i can get might be a little thick for bending to
the chord length i'm after, but i can make the blade bigger just
to prove if it would work??
I thought the cling film skin, might come clean away from the
steel mould though???
#Post#: 5314--------------------------------------------------
Re: Alunimum wings for diy 75
DIR By: maximoney1
Date: January 29, 2015, 4:40 pm
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LOL CG,
I guess i will have a lot of that!
Just thinking, i dont have any ripstop nylon, but i do have the
fabric that is used in the garden to surpress weeds, i guess a
few plys of that would demonstrate whether it might
work....adapt to the materials at hand eh!
#Post#: 5322--------------------------------------------------
Re: Alunimum wings for diy 75
DIR By: lynx wind
Date: January 30, 2015, 6:39 am
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A lot of materials would work, including Tyvek, garden weed
stopper, aluminum flashing, and others. UV from the sun and
high winds are the enemies. Especially the corner where a lot
of the load is taken is going to need to be very strong.
#Post#: 5328--------------------------------------------------
Re: Alunimum wings for diy 75
DIR By: sut
Date: January 30, 2015, 7:42 am
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LOL there are no failed around here, just tried the wrong
thing!
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