Grumman-581 wrote:
For conversion of speed, I'm using 6076 ft per nm, 3.14159265358979 for
pi, 9.80665 m/s^2 or 32.17398421 ft/sec^2 for g...

Whoever is selling you your floats, doubles, and long doubles must be
making a killing.

Interestingly on g, I'ver seen sources that quite it as being defined
as 9.80665 *exactly* and others that quote it at 32.1740486...

http://en.wikipedia.org/wiki/Gravity_%28Earth%29 has the definition of
9.80665 m/(s^2). It does vary with where you are on the planet as well
as how far you are above it.
http://en.wikipedia.org/wiki/Acceler...due_to_gravity has a few more
details.

For some reason, I had thought that the 39.37 had been defined as an
*exact* value...

http://en.wikipedia.org/wiki/Inch#International_inch says that the yard
is defined as 0.9144 m. 0.9144 is exactly 36 * 2.54, so the correct
statement may be that an inch is exactly 2.54 cm. 36/0.9144 is
39.370079 according to the calculator; rounding off to 39.37 is a
whopping 0.0002% error.

Standard disclaimers about using Wikipedia as a reference apply.

With regards to higher velocities and decreased values of time for the
360 degree circle, even with a 1 second 360 degree circle and 500 kts,
the values match to more digits than I really need (i.e. 88.26219913
and 88.26219912 degrees respectively for SI and US measurement units)...

Your protractor salesman must also be living quite well.

Matt Roberds