[PSUBS-MAILIST] prop size

[JimToddPsub at aol.com]

Right; I meant to say all other things remaining the same.  
 
 
In a message dated 9/5/2013 5:26:27 P.M. Central Daylight Time,  
piolenc at archivale.com writes:


On  9/6/2013 1:34 AM, JimToddPsub at aol.com wrote:
> Hi Marc,
> I think  the premise is that for a /given power input/, a larger diameter
> prop  is going to /result/ in a lower RPM, not that there is an inherent
>  advantage in lower RPM within the scope of the question.

If the pitch  is kept the same, then that's true. Otherwise, up to the 
cavitation limit,  speed is an independent variable. And for the reason I 
gave it is  advantageous to keep it higher rather than lower. Of course, 
at some point  you will encounter diminishing returns, where the power 
saved by reducing  swirl is eaten up in additional friction drag.

Calculate, calculate,  calculate...

Best,
Marc
-- 
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