Thread: Discussion Efficiency of a ducted fan
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Old Jan 31, 2008, 05:58 PM
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Texas Buzzard
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McAllen,Texas
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Good stuff

Quote:
Originally Posted by Odysis
Thrust per power is only usefull if you're comparing two fans of the same size, with the same outlet. A large fan running slowly will produce x thrust much easier than a small fan flat out.

Real efficiencies need to be non-dimensional, i.e. power out divided by power in. Only with non-dimensional numbers can you scale up and down without too many concerns
.........>>><<<<<........

Yes I was comparing two fans, but using the Same Motor. They both had the same I.D. but one had the option of having 5 blades rather than 3. Both are purchased with 3 blades per fan.

Am I correct in saying the 5-blade fan turning at the same rpm as the 3-blade fan will draw more current, Thus more Watts??
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