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Old 10-22-2010, 04:13 AM   #15
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Join Date: Oct 2007
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RE: Operating a twin on one engine and fuel economy

A stationary boat propeller generates a huge amount of turbulence behind it, and turbulence is drag. A freewheeling boat propeller does not generate as much turbulence behind it, thus less drag. The MIT study made this very clear.

What every study I have seen is that a really truel free spinning prop, (no tranny drag , no strut drag , no bearing drag) might have less drag than a locked prop.

BUT like the helocopter (at the end if its fall the drag from auto-rotation is huge) the slower than ideal speeds of the dragging prop is worse than the locked prop.
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