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       #Post#: 2848--------------------------------------------------
       Power = Torque x RPM
       By: lynx wind Date: May 21, 2014, 6:43 am
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       A lot of people get excited when they see something turning in
       the wind and assume they can just hookup a generator or pump.
       It's not obvious from watching but sometimes there is little to
       no power other than that to overcome friction in the bearings.
       This isn't discovered by the novice until everything is hooked
       up.  What happens is the load is too great and the wind just
       blows around the blades.  Build enough failures (like me) and
       then you start building for power.
       A lot of torque with no rpm is "0" power
       High rpm with no torque is "0" power
       A proney brake is used to test torque at different rpms.  Then
       the torque is inserted into a formula with rpm to determine
       power (HP).  Ideally the load will match closely to the power at
       different windspeeds so the turbine doesn't stall.  There may
       only be 1 watt at low speeds and 200 watts at higher windspeeds.
       Make sure whatever you hook up to a wind turbine can handle
       this large range of power input.  The lower end is more
       critical.
       #Post#: 2861--------------------------------------------------
       Re: Power = Torque x RPM
       By: lynx wind Date: May 21, 2014, 12:09 pm
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       I tried to keep it simple.
       We could use Horsepower, Watts or Joules.  All are a measure of
       force against an opposing force over time.  The point I was
       trying to make is that you need to be careful in assuming things
       that spin have much power.  For instance the original VAWTs I
       made looked cool but had very little power.  A Lenz type VAWT
       has to be very carefully designed and matched to a load or it
       stalls.
       A skyscraper has a lot of surface area but doesn't move so has
       no useable power.  An attic vent spins like crazy but has little
       power.  Hawts develop very little power when turning slow.  A
       lawnmower engine wont even run below about 1200 rpm.
       So for instance if you were to try to grind grain at 1 rpm with
       a VAWT you need to make sure there is enough torque at 1 rpm.
       Or if you were trying to grind grain with the same VAWT in a 30
       mph wind that same grinder has the capacity to handle the power.
       
       I think the triathlete beats the weight lifter.  He smacks the
       big Russian on the side of the head and runs - win!
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