Vance Jaqua wrote:

I think this is what Vance is trying to say.

Gee Paul - you are almost as bad as those reporters
that tell us "What the president really said was ---"

No way will a constant speed prop give you twice as
much thrust as a fixed pitch prop in any part of the
flight regime. The most dramatic change is at static,
where the fixed pitch prop typically bogs the engine
down to about 2100 rpm which limits it's power output
to about 77 percent of rated. Flattening the pitch
will let the engine regain that 23 percent but you
will usually not get even that 23 percent gain in
thrust. Also the only way any prop could get 80
percent eff at speeds below about 50mph is if you had
helicopter type blade diameters. I think your table is
using numerous unwarrented assumptions. These cases
can be pretty well simulated with runs of that prop
program you rewrote for QB - Vance

OK you have my program so adjust the rates of change of HP with 
RPM and prop efficiency with aircraft speed to reflect what
you feel are the real world results.

For example what kind of efficiency can we expect at 10 MPH
with a constant speed prop?
I will adjust the efficiency from 10 to 50 MPH in a linear
or other math function and do a separate chart for the constant
speed prop.

So the engine would only bog to 2100 RPM rather than 1986 RPM
What HP do you guess a 100 HP engine would be generating
at 2100 RPM. I can fix that.

Paul Lamar
 
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