Vance Jaqua wrote:

There was no blade width given - so for comparison I
sized a prop for an IO 320 160BHP curve I have in my
program for a 68 dia 75 pitch which suggested 3.6
width at .9R 4.6 at .7, 5.8 at .5 and 7 inch at .3. I
set helical pitch for the 75 inch and ran it as a
fixed pitch versus the power curve, and turned the
whole blade for various speeds per the table, My
program appears to be more conservative - predicting
less thrust, even with the 10 more HP and the shape of
the curves does not suggest an arch for the fixed
pitch, nor a significant upturn at the end for the
constant speed. The redrawn curves show what was
predicted for whatever it might be worth - I feel the
efficiencis suggested by the other data are
suspiciously high - Vance

I think you are right Vance. I plotted the max thrust from 150 HP assuming
100% efficiency and the curves look a little optimistic at the high end.
Perry, what program are you using?

Paul Lamar
 
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