Ed Lenz Vertical Axis Wind Turbine

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See https://www.thebackshed.com/Windmill/articles/Lenz2.asp

Kostas Latoufis Comments on Ed Lenz and Dan Connell Turbines

Hi Marcin,

If one is going to self-build a VAWT then it should be the Ed Lenz
design. It is the only one that has been around for long enough. And
looking at the wind tunnel tests the efficiency seems good.

Yet, wind tunnel tests can be pretty tricky and such efficiencies would
be expected from a Darrieus three bladed vertical axis rotor with
slender blades. I would prefer a power curve measurement which is more
easy to conduct and the result can be trusted.

The HAWT school of WT design has a lot to say about VAWT:
www.wind-works.org/cms/index.php?id=116

> Unloaded and not set high, but survived the two worst winters in > Massachusetts history, apparently.

Unloaded tests are not indicative as the torque on the shaft is almost
zero so there are no stresses on the blades. The main problem with VAWT
is that they have forces acting on the blades in the horizontal
direction which causes fatigue and failures on the blades, but I do not
have evidence for this, it is one of the disadvantages I have heard of.

In addition the rotors in the links are quite small, they produce up to
100W, and I wander what would happen if these were scaled up to 1kW or
more.

Personally, I would want a 500W to 1kW design to be installed somewhere
for 2-3 years at least (preferably 5 in order to make sure all
maintenance issues will have occurred), and see a measured power curve.
This can be done anywhere and at a low cost. So I would encourage Dan
Connells to do that.

Cheers,
Kostas