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Lenz2 wind tunnel tests are done

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windstuffnow:
   The alternators I built for the small one and the rooftop were meant to produce about 250-300 watts maximum.  They drop to 50% efficiency at around 200 watts.   By building an alternator that is more efficient ( less resistance ) it would increase the load on the turbine in all windspeeds.  This, of course, has to be matched as closely as possible to the turbines output.  I don't think its quite as critical as it is with the HAWT which relies on speed to achieve lift.  I think an alternator that will maintain a 50% efficiency at around 400 watts would work fine with the 3 x 4 unit but that has yet to be worked out, it may suffer in lower winds if its to efficient... we'll see!

.

nothing to lose:
Wow.

 Your comming along pretty good on this. Can't wait to see what you do next.

wayne:
Hi Ed

My little 12 inch worked great the first time, just hard time with 2 foot one. Had to play with the dia. Here is a pic of a ceiling fan rewound and hope to get a few watts from the little one. Its -28 here so might just hide in basement and try different things with the 2 foot one. Thought of cutting some foam blocks and playing with center. We see what trouble I get into.
Wayne

wayne:
opps

Ungrounded Lightning Rod:
.  7.38 mph starts charging  2.25 watts

.  10.85 mph 41%     10.56 watts  

.  13.53 mph 38.9%   19.46 watts

.  15.61 mph 30.5%   23.39 watts

.  18.88 mph 31.4%   42.7 watts
Overall average of 35.45%
[factoring in Betz]
.  10.85 mph 68.8%

.  13.53 mph 65.3%

.  15.61 mph 51.1%

.  18.88 mph 52.8%
or an overall average of 59.5% of total possible.
1) If I read this correctly you're comparing energy

delivered as electricity to energy extractable from

the wind, right?  So your alternator inefficiencies

are included, rather than measuring the efficiency

of the rotor alone?
2) Also you've got the alternator's loading controlling

the speed of the rotor, rather than running several tests

at each wind speed with the rotor running at a range of

speeds, to find the max power point.  So a smarter load

might be able to extract more power yet, but you don't

know what the desired curve would be.
Right?
If 1 is true you've gotten even the best claims

for the sandia savonius design beaten by more than

a factor of your charging system's efficiency.

(Even if you were measuring ONLY the rotor you've

beaten the Sandia Savonius claims of 37%.  Cool!)
(You might be "cheating" by using lift to decellerate

air a little way out from your blades, making your

effective cross-section a bit wider than the physical

one.  But this is good.  B-) )

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