[Land-speed] Polar Moment

[Elon]

Great idea, Neil. Even if you don't have a swimming pool you could use
something like 10"-12" irrigation PVC. Cap it at both ends and fill with
water. A single sawhorse in the back yard could set plane angle. I guess
diameter has to be big enough (or model small enough) to be free of side
wall influences. Ed's idea of a model railroad tract sounds interesting
glued into the bottom of the PVC pipe. Some of the current data loggers are
fairly inexpensive. Innovate's SSI-4 is $129. You could also record temp,
barometer (a MAP), etc.
I think Mayf has a LM-1 data logger for his O2 sensor. Maybe borrow his :-).
Sample rate is 12/sec. Instead using a light-beam underwater why not hook up
a string or piano wire to a used TPS sensor or other EFI sensor. $1-$5 used
from the wrecking yard.
-Elon

-----Original Message-----
(1)  drmayf [mailto:drmayf at mayfco.com]
snip . . . How would you time the roll down the ramp? A second or two might
mean a big difference in perceived performance.

(2) neil at dbelltech.com wrote:
My idea is to do the drag measurements with a minimum of instrumentation.
Simply build a smooth ramp and place it in a swimming pool at a known angle
and let the model roll down the ramp for a measured distance. . .