> >    But does anyone else have a 'circular slide rule'?  Yep...
> > I got one at a
> > rummage sale decades ago for the math and physics formulas
> > that are on it as
> > well as the periodic table that is on the back of it!!
>
>Ugh. We tried those for a while, but the constant wrist-twisting was a
>killer (hmmm--maybe the precursor to carpal-tunnel-like RSIs?) Yeah, they
>could get more info into a smaller space (the outer rings of a 4-inch
>diameter circ were longer than a 12-inch stick), but they were too hard to
>manipulate quickly.


Out of necessity, I found the opposite to be true. My circular slide ruler
was the Jeppesen Flight Computer. I learned to fly in the early 70's before
the handheld electronic flight computers came about. You had to learn to
use the flight computer with one hand while you flew the plane with the
other. Sometimes things got squirrelly in rough air, but that was part of
the fun.

This "circular slide rule" had the face split into different areas for the
types of computations to be performed. You could run speed/distance/time
problems, compute your fuel consumption/duration, density altitude and true
airspeed. On the flip side you could dial in your course and plot the winds
aloft information for your cruising altitude, and it would give you your
heading.

It's 28 years old and still in my flight bag.

- Joe -