[Land-speed] Polar Moment

[neil at dbelltech.com]

Elon;

That might work. The TPS sensor would need a big pulley to keep its rotation
angle within limits. With a big pulley the drag of the TPS sensor might not
be to much of a factor.

Regards, Neil   Tucson, AZ

-----Original Message-----
From: Elon [mailto:saltfever at comcast.net] 
Sent: Thursday, January 17, 2008 12:05 AM
To: drmayf at mayfco.com; neil at dbelltech.com
Cc: 'Ed Weldon'; 'Don McMeekin'; 'Keith Turk'; 'land-speedsubmit';
NT788 at comcast.net
Subject: Polar Moment

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. . .