Crossflow VAWT tinkering

[TomW]

Above we see the frontal view showing the main components. Two 30 volt tape drive motors [TDM] as a top and bottom generator-bearing combination. Rough sawn oak frame with plywood wing ribs and 4 mm corrugated plastic skin.

This is a closeup of the high tech TDM mounting setup.

Here you can see the 5/8th tdm shaft to 3/4" pvc coupling i made by sawing 2 cuts into the PVC and shoving the motor shaft into it with a shim of plastic flex tubing and clamping it with good old hose clamps.

I learned a lot while putting this together. For one thing the plastic does not conform well one way but does OK the other. One side is much smoother than the other. PVC is cheap and easy to work with but too flexible for a final unit.

It has an alignment issue with the 2 motor / bearings which I will look into today.

Its dimensions on the wing are 2 foot diameter by 2 foot tall. I know it needs multiple wings to self start and that is the plan eventually. Typical for me this is a mockup and test of the basic idea and to find building pitfalls before trying a full size 3 wing unit.

Cheers.

TomW

[RogerAS]

Hi TomW,

Are the motors wired in series to get up to charging voltage? I mean it seems a VAWT would be spinning way too slow, or am I missing something?

I've been playing around with the idea of a VAWT for some time, but getting an RPM high enough to make useable electricity seems to be a quest.

Just curious,

RogerAS

[TomW]

Roger;

Well those motors are just bearings now. Not wired at all. However, my plan is to wire them in series in the real unit. Furthermore I have a pair of 40 volt TDMs and they have 2 sets of brushes in parallel that are 90 degrees apart on the commutator. I was toying with the idea of rigging the 2 sets of brushes in series internally to get more volts per rpm per TDM and perhaps series the outputs of those.

These TDMs do get to charge volts about 300 RPM so it is within the realm of reality to get them going fast enough to charge with a small diameter  and tall vawt.

My wind situation is so poor that I have decided that HAWTs are never going to work for me here so I have shifted from HAWT to VAWT research. There is a guy from France "trentman" who constructed the full size one from picoturbines plans and he has gotten good output from the purpose built genny on it. His is 4 feet in diameter and 6 feet tall or more. Maybe I can convince him to post about it here.

Pictures of his are available online too:

http://op.servepics.com/cgi-bin/album.pl?album=trentman

More info on the wing construction is available in a PDF I got from Picoturbine.com:

http://www.picoturbine.com/pt250-blade-plan10A.pdf

Cheers.

TomW

[RogerAS]

TomW,

I'm in the same boat with low wind speeds. Except for a few months in winter we in the Ozarks are breeze challenged!:-)

I have 6 of those plastic 55 gallon drums and a good set of pillow block bearings. Since I'm blessed with an abundance of tall straight hardwoods I think I could easily build a tower. One thing that has me sortta confused is the plates the wing (drum) halves are mounted to. How does one assure the flatness? I mean without really stiff material wouldn't the whole thing wobble pretty bad?

Anyway, I'm really interested in this project. Keep us posted!

RogerAS

[TomW]

Roger;

If you mean the ribs that the skin is attached to I think stiffness may be an issue but once secured the skin stiffens it a lot. I used a snug hole and cross pinned the wings to the "drive" shaft through the plywood wing ribs with screws.

The original picoturbine plans call for 4 angle brackets per rib to connect it to the shaft. I just pinned it and i think its plenty strong enough for a 2 foot unit.

You need to realize that as size increase stress on components go up exponentially too.

Cheers.

TomW

[hvirtane]

Hi,

there are good books available concerning

Savonius rotors made of drums.

One of the best is:

Savonius Rotor Construction.

J.A.Kozlowski.

VITA USA.

1977. 0-86619-062-7.

Available from

http://www.vita.org

'PicoTurbine Deluxe Windmill Plans' text

is a good one. Available from

http://www.picoturbine.com.

- Hannu

[troy]

A single set of 55 gal drum halves will give you good torque, but will be a little slow on RPM's.  One of the main factors that affect rpms on a savonius is the aspect ratio (height/width).  A tall skinny savonius will go a lot faster than a short square one of the same frontal area.  Of course, if you stack three drums, your aspect ratio also goes up proportionally.

If you guys come up with a good low wind design, I'd think real hard about building one, as Indiana is also wind challenged.

Best Regards,

troy