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#Post#: 4712--------------------------------------------------
Relationship between "Lift Speed" and Weight
By: lynx wind Date: November 11, 2014, 8:31 pm
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Just some food for thought and maybe some stimulation to
experiment.
After building dozens of wind turbines I have noticed that they
all will take off at some point in the windspeed range and go
TSR +1 After building this heavier Gull 175 I have noticed that
it too will break into what could be called "lift speed". I
define "lift speed" as the point at which the wind is strong
enough to accelerate the blades so that they start lifting on
the TE vortices from the previous blade. Much like a sailboat
will sail faster upwind than down.
There is a noticeable shudder as the blades are moving at the
speed of the wind and then accelerate to +1 to 4x true
windspeed. This is where you want to harvest power.
What never occurred to me before was that a heavier built VAWT
will require a higher windspeed to break into TSR1+ or "lift
speed". Seems obvious now, but I had to experience it. What I
still don't know is whether weight has anything to do with upper
limit rpm.
Watching the Gull 175 in a good wind today makes me think a
heavier VAWT may have an advantage over a lighter built VAWT if
winds are good.
But stalling a heavier VAWT below tsr 1 yields very little power
(10-400ma) Getting up over tsr 1+ and higher yields much higher
amp readings because all blades are making power. torque x rpm
= HP
1 HP = 736 watts If torque is tripled and rpm is tripled, then
watts are 9x higher in the same windspeed.
#Post#: 4714--------------------------------------------------
Re: Relationship between "Lift Speed" and Weight
By: sut Date: November 12, 2014, 7:40 am
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What you need is some wind tunnel time or smoke on a stick to
actually see where the wind is going and what it does ! Or you
need 2 windmills one with your original design and one with the
175 design and watch the readings coming of of both and compare.
very interesting stuff you have observed
#Post#: 4717--------------------------------------------------
Re: Relationship between "Lift Speed" and Weight
By: sut Date: November 12, 2014, 9:43 am
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Another thing I have observed was that since I have put the
heaver 160 alt on my diy 75 I notice that it spins slower and
is slower to respond to wind gusts, now it could just be my
imagination (I am talking about it when its unloaded ) so the
load is not in play .
#Post#: 5938--------------------------------------------------
Re: Relationship between "Lift Speed" and Weight
By: berlinDamma Date: April 30, 2015, 12:15 am
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Read, listen and think on it.
#Post#: 6114--------------------------------------------------
Re: Relationship between "Lift Speed" and Weight
By: Paulsticx Date: April 23, 2016, 2:56 am
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This is a contentious issue for a long time. Thank you to share
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