Thread: Discussion Efficiency of a ducted fan
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Old Jan 31, 2008, 08:24 PM
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Edina, MN, USA
Joined Oct 1999
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Efficiency is and always will be power out divided by power in -- same units above and below!

Power in is easy -- use a Whattmeter.

Power out isn't hard either; though two measurements are needed -- thrust & e-flux velocity -- speed of the exit flow!

Propulsion power is thrust times e-flux velocity.

Use a Kestral 1000 or similar.
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