The idea for the blades
is coming from this machine.
We made with Taisto Suihonen something similar
with 3 m long 100 mm x 10 mm wooden boards.
We made it with four blades.
For each blade there are seven boards
on the top of each others.
On the tips the boards are 25 mm on the top of
each others.
We cut every second of each of
the crossing boards to get
the blades on the same plane.
Taisto used a power plane to smooth
the blades.
We used normal white glue and some screws to
to fix the boards.
Finally we used a lot of linseed oil
and oil paint on the top.
On the tips we used
some fiberglass resin
to protect them.
In the center there are
two plywood disks
of 8 mm thick on the both sides
of the wind rotor.
The wind rotor is fixed through the center
by five bolts to the nacelle of a
permanent magnet generator.
The generator is quite similar
as the original 'OP Volvo' alternator.
The wind rotor stood all the bad weather
and storms of the Finnish winter
2003-2004 without any problems.
The advantages seems to be
that it never goes very fast
and it starts really easily
with low wind speeds.
On slow wind speeds it works better
than a perfect airfoil three blade wind
rotor with a little bit bigger dimensions,
which was used before this rotor.
The general method how we made it is
something like this:
You can make using this system quite good airfoils by cutting the wooden blades something like this.
I think that it is good to make blades
wide on the tips to get them working
well on really slow wind speeds.
Anybody else made the blades
wider on the tips than on the roots?
- Hannu
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