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Old Jan 10, 2007, 01:11 AM
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Grumpy old git.. Who me?
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Joined Mar 2006
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Eric,
I think the original question was asking why everyone quotes output power from the battery (in Watts) rather than quoting thrust (in Kg / pounds or whatever)...
I think he has a very good point because quoting power in Watts in the wires between battery and motor neglects all the inefficiencies and ducting losses in the total system, which as you point out can vary considerably from one system to another...
Ultimately it does not matter a jot how much power we put into the motor, it is how much thrust that we get out that governs performance. I still think my analogy to car gas consumption is valid... If I claimed my car was fast simply because it used lots of petrol (gas) then people would think me insane.

By the way; a 'Watt' is a measure of 'power'... Not just electrical power but any power. It is equal to one Joule of energy per second (in an electrical system it is also equal to Volts x Amps as you said)

Steve
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