Re: Screw size and speed

[VBra676539@aol.com]

In a message dated 7/21/99 6:06:39 PM, SFreihof@aol.com writes:

<<n a message dated 7/21/99 6:58:50 AM Eastern Daylight Time, 
wolfe19@megsinetnet writes:

<< For ducted fans, both undrewater and above water, if the cowling is 
relitivley close fitting, efficancy can be markedly improved.  the propeller 
don't have the spill off at the tips creating those wingtip vortecies.  >>

The propeller shroud is called a "Kort Nozzle."  I haven't been able to find 
much information on design or sources for supply.  Anybody else?

Stan>>

It's only a Kort if the prop is shaved to a "square" tip and the clearance 
between tip and nozzle ring is minimal (like a sixteenth or so). They use 
these things a lot on big torque ships (tugs and the like). Most information 
I have seen is from pump manufacturers who often use this sort of thing for 
lift pumps in the groves down here. I'll ask around for sources.
Vance