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#Post#: 4728--------------------------------------------------
Sail Blade VAWT
By: lynx wind Date: November 13, 2014, 9:03 am
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I haven't even decided if the 175 is going into production and I
am thinking about a new design.
Two rotor plates separated by a 1" spacer. 1 spar and slide on
ripstop nylon triangle sail instead of blades. Sail VAWTs have
been made and tried but too often they are designed with
swinging sails in mind.
The sail blade will work just like our blades but be very light
and only require one spar which can be supported or not.
#Post#: 4729--------------------------------------------------
Re: Sail Blade VAWT
By: sut Date: November 13, 2014, 10:28 am
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Great cant weight to see it in proto type, the wings have me
baffled though the 1 spar is where I loose it
#Post#: 4735--------------------------------------------------
Re: New Design for the DIY75
By: lynx wind Date: November 13, 2014, 5:02 pm
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Just thinking and I thought I would share the thought. I like
the big 175 with the aluminum blades but it needs more testing.
The DIY 75 has the wood spars (not so good) and the fiberglass
blades (bamboo, coroplast, poured foam etc...) I want to try
the sail blades sometime with easy to get fiberglass rods, I
think they would work and be much easier for the DIY. Maybe
even a smaller design for someone to experiment. Maybe a winter
project.
The triangle sail wouldn't exert so much force near the tips, so
it would be more dynamically balanced.
#Post#: 4740--------------------------------------------------
Re: New Design for the DIY75
By: sut Date: November 13, 2014, 6:44 pm
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I wouldn't even think of putting you under my truck @ CG :-\
#Post#: 4749--------------------------------------------------
Re: New Design for the DIY75
By: lynx wind Date: November 14, 2014, 11:12 am
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I do think the spars will bend and lean out, but I don't think
they will break. There wont be a problem with the sail
deforming or bending. But since the spar will carry 2/3 of the
load it will need more material to keep it from flopping around.
That's why I think a thicker thru hole will be needed.
#Post#: 4751--------------------------------------------------
Re: New Design for the DIY75
By: lynx wind Date: November 14, 2014, 1:26 pm
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No, you don't see a boom - there isn't one. The rip stop nylon
is sewn with a sleeve to slide over the spar and stitched all
around. The clew will tie to the rotor, which in effect acts
like the boom of a sailboat. A sail forms an airfoil as it
catches wind.
#Post#: 4761--------------------------------------------------
Re: New Design for the DIY75
By: lynx wind Date: November 15, 2014, 10:46 am
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Great idea to make it collapsible. The army was looking for
something like this about four years ago. They wanted it
fold-able, silent and invisible.
Some thoughts: If indeed the Coanda effect is more in play with
these VAWTs then it shouldn't matter about the airfoil. This
has been my experience and others have found this to be true
with flat blades (Jeff D Miller and others)
First test this morning with the sail VAWT is a nice success.
Not only does it spin up, but it has power too. I think there
is now an even bigger advantage to a central rotor and the
triangle shaped sails. Less dynamic imbalance, and less
pressure at the tips.
The model is made from a foamboard circle, bamboo skewers, hot
melt glue, and some plastic table cloth. The shaft is a 6-32
bolt in a 1/8" ID tube pushed into a 3/4" pedestal.
#Post#: 4765--------------------------------------------------
Re: New Design for the DIY75
By: lynx wind Date: November 15, 2014, 11:54 am
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The blade tips could have a mono-filament attached if it gets to
be a large VAWT. The sunfish sailboat and similarly sized boats
have a free standing rig. A golf club shaft is very strong and
yet will flex without breaking. It is a filament wound
extrusion on a mandrel and is exceptionally strong and
lightweight.
Yes, even on this small and imprecisely cut model you can see
the TE of the sail pulling out and the sail becoming an airfoil
as expected.
Yes, I think it will easily exceed TSR 1.0
Making it fold-able is a challenge, but definitely easier than
with hard blades.
#Post#: 4769--------------------------------------------------
Re: New Design for the DIY75
By: lynx wind Date: November 15, 2014, 7:10 pm
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No, not if the rotor is spinning which it will do. If the rotor
was stopped, then yes each sail blade would probably take a
different set.
No, battens are not used for smaller sails. But, it might be
helpful, don't know.
While spinning each sail blade will try to get fully into the
airstream. This causes the TE to pull outward which pulls at an
angle to the axis. At high rpm, it is like a sail at the
optimum set to a headwind.
#Post#: 4772--------------------------------------------------
Re: New Design for the DIY75
By: lynx wind Date: November 16, 2014, 11:59 am
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Here is a video of the small model of a VAWT using sails. I
didn't spend a lot of time making things perfect. But, it
demonstrates the general idea. I was at Home Depot today and
those fiberglass rods for marking driveways are $1.99 each. I
think the rotor could just be a 24" round disk, but the rods
will need enough support to stay vertical, so maybe added
thickness where they pass through.
The diagram below shows the geometry for a 24" disk and 36" tall
VAWT. The widest part of the sails are 6" at the foot but could
possibly be wider.
HTML http://youtu.be/rSdDH0VwQUA
HTML http://youtu.be/rSdDH0VwQUA
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