Microship Status 11/17/93
by Steven K. Roberts

IN THIS ISSUE:

INITIAL PRESSURE-VOLUME STUDY (Gerken)
CALL FOR PARTICIPATION
MISCELLANEOUS DEVELOPMENTS
LITERATURE RECEIVED


INITIAL PRESSURE-VOLUME STUDY
by James Gerken

I've finished plugging in the numbers, and I have an idea on the size of
the pressure reservoir needed. Given that the requirements are: 2 psig
(the g stands for gague as opposed to absolute pressure... to convert from
gauge to absolute, add 1 atm or 14.7 psi.), 20 cubic feet pressurized
space, and 35-100 degree Fahrenheit temperature fluctuations:

By converting into SI units: 1.136 atm, 566 liters, 274.82-310.93 Kelvins.
Using the ideal gas law, Pressure * Volume = Number of moles * Temperature
* a constant R, I arrived at the conclusion that with the given temperature
change, the change in amount of gas in the system would be 3.3 moles. I
then calculated the volume needed to store that amount of gas with a safety
factor of 1 at various pressures.

At 100 psi, 23.7 liters = 0.84 cubic foot @ 77 fahrenheit
" 130 " 18.3 " 0.65 "
" 200 " 11.9 " 0.42 "
" " " 10.9 " 0.39 " 35 fahrenheit

I also came up with my general conception of how I would rig up a system
for this and it looks something like this:

_______ ____ ____ ______ ______
>---| Fish |---|Pump|---|Trap|---|Dryer|----| Tank |
|Filter | |----| |----| |-----| |130psi|
|-------| \--|---/
R 15psi
Air bus |
---------|------|-------------|-----------|-----/
| | C C
| |
R 2psi R 2psi
| |
/---|---\ /----|---\
| | | |
\_______/ \________/
| |
P 4psi P 4psi

where R stands for regulator, C means check valve, and P is a pressure
relief valve.

(Editor's note: check valves allow one-way air passage only -- they're
"air diodes." It would be nice if regulators include this functionality,
but I don't know if they do. The pressure relief valves allow venting from
overtemp conditions. --SKR)


CALL FOR PARTICIPATION

Note that the above was contributed by one of the project participants. I
want to start doing more and more of this -- I'm busy enough without
writing a chapter a day in the Microship Project History book. If you're
involved in this, please occasionally update me with a short summary of
your work. I'll edit as necessary and post to the whole group under your
byline (and it will become part of the Microship archives).


MISCELLANEOUS DEVELOPMENTS

Jerry Wong is gathering product literature from autopilot vendors:
Raytheon, Robertson, Navico, Autohelm, Cetrek, Alpha, and Benmar.

I'm negotiating a half-hour TV feature about the bike, and another about
the Microship, with the French TF-1 network. Brigitte Chwala, in the ECE
Undergrad office, is helping with this -- she speaks fluent French. If the
deal goes, anyone working on the project will have a shot at on-camera time
and 15 minutes of fame in France.

Apple's Mike Clark sent the special SCSI terminator for the Mac IIFX, and
Frank Araullo is working on finding a case for the add-on Quantum drive.

Mark Reynolds of Sobstad Sails visited the lab yesterday to see BEHEMOTH
and discuss the design of the rig. He'll be in contact with Robb Walker
over the next few days to get up to date on the overall marine architecture
of the sytem.

The San Diego Boat & Sportfishing Show is happening Nov 18-21 at the
convention center: Noon-9 on Thurs and Fri, 10-9 on Sat, 11-6 on Sun. If
you are interested in boats and want to meet some vendors, this may be
worthwhile.

Today I did a test posting to the vast and weighty nomadness alias (nearly
2,000 names). About 10% of them bounced, which was a sufficiently
overwhelming experience to keep me dancing with the listserv all evening.
<shudder>


LITERATURE RECEIVED

The NMEA 0183 "Standard for Interfacing Marine Electronic Navigational
Devices" is now on hand, thanks to Frank Sharp. It includes addenda on
autopilot interface standards.