Next message: Pierre Boucher: "Re: Bowditch 1995 Table 18"
All the formulas that are based on (old/new) (possibly raised
to some power), or the log equivalent (log old - log new)
(possibly times some factor) are insensitive to the units
used -- tonnes or grams, knots or meters/day, etc -- as long
as old and new are measured in the same units.
The formula for rpm->speed has the magic numbers 60
(presumably minutes per hour) and 6080 (presumably
feet per nautical mile), revealing that pitch is
measured in feet per revolution.
As a programmer, I would add parentheses to this
formula so the reader doesn't get confused:
rpm = 6080/((pitch/(1 + % slip)) x 60) x speed in Kts
and might even reorder it (without changing the meaning) to
rpm = 6080*speed in Kts * (1+%slip)/(pitch*60)
A mathematician might notice the RPM formulas are related by
the approximation (1+%slip)/(1-%slip) = 1, which is valid
for reasonable (small) values of slip, to the precision we
need.
-- Bill
