Ham
Ballooning FAQ
or
"What little I know about ham ballooning"
by Dave Mullenix, N9LTD
Return to Links to Balloon
Related Information Page
note: Dave is in the process of building this FAQ. If
you have information you can add contact him at his email
address.
This is mostly stuff I learned from Joe, WB9SBD, who
got me into this mess. I've chased a half dozen of his
Near Space Science (NSS) balloons, helped him launch
several of them and balloon meistered two launches for
the High Altitude Radio Project (HARP). This is version
1.0 of the FAQ, so please excuse any mistakes or
omissions.
THE MOST IMPORTANT RULE
Rule #1 for those interested in getting into ham
ballooning: Join a group that's already launching
balloons to learn the ropes. I can't tell you everything
you need to know in a FAQ. Don't try to learn it all
yourself by trial and error, learn it from someone who's
actually doing it! Start by volunteering to chase the
balloons. Chasers are ALWAYS welcome. Special DF
equipment is not necessary. There comes a point in every
flight where the balloon is laying on the ground and its
range is so short that nobody can hear it. That's when
lots and lots of people are needed to drive around until
they pick up the signal. Once the balloon can be heard,
people with DF gear can start tracking it down. Balloons
often land in trees and marshes, so hunters and tree
climbers are always welcome on chase crews. Bring your
hip boots.
Then help with a few launches. See what's involved in
filling and launching a weather balloon. Get a look
inside the payload box to get an idea of the construction
required.
Then find out who in the FAA the group contacts when
arranging flights. The regional FAA office will probably
have one person who handles most of the ham flights and
he will be MUCH more comfortable with your request to
launch if you tell him you've been working with a group
that's had several safe and successful flights and are
following their procedures.
Here's a list of what our group has been using for
ham balloons and where we find what we need. As I said
above, I got most of this information from WB9SBD.
BALLOONS
We use Totex weather balloons. They seem to be the
best quality. We purchase them from:
Kaymont Consolidated Industries, Inc.
21 Sprucetree Lane
P.O. Box 348
Huntington Station, NY 11746
Phone (voice): 516 424-6459
Phone (fax): 516 549-3076
Balloons are sized by their weight in grams. Kaymont
currently carries two sizes, 800 and 1200 grams. The 800
gram size will lift 3-4 lbs to 100,000 feet. The 1200
gram size will take a full six pound payload to 100,000
feet. Prices are about $45.00 each for the 1200 gram
balloons. Kaymont accepts telephone orders and credit
cards.
BATTERIES
Only one type of battery will do: lithium. Nothing
that is available on the commercial market approaches
lithium's power per pound. We normally purchase military
surplus lithium battery packs. They contain 10 D cells in
a series/parallel arrangement that produces 15 volts. The
packs come apart very easily into two 5 cell strings. The
D cells themselves are connected with welded tabs that
can be easily cut and soldered into whatever voltage and
amp/hour combination you need. The D cells are 3 volts
each, so 3 will give you 9 volts, 4 will give 12 and 5
cells will give 15 volts. The cells in the battery packs
will typically be out of date, but lithium cells have an
excellent shelf life and we've never been disappointed.
You can expect 6 AMP hours from each 3 volt D cell.
I connected a single 3 volt lithium D cell to a 10
Ohm resistor, put a Radio Shack RS-232 VOM (lent by Don,
K9LYE) across it and let my computer log its progress.
The voltage "rose" slightly for the first half
hour to 2.81 volts and it then stayed there for 22 hours
before it started to drop! It didn't drop to 2.5 volts
until 24 hours after starting the test. I put a 5 ohm
resistor across a second D cell and the voltage stayed at
2.78 volts for 12 hours. That's 6000+ mah per cell! A 5
D-cell pack will provide about 3.3 watts for 24 hours or
6 watts for 12 hours. You really need about 12 hours of
capacity. That gives you four to six hours for the flight
and another six hours to recover the payload when it
lands.
Here are our results for various resistances across a
single 3 volt lithium D-cell:
Life Watts Watts
Peak Peak in per per
Ohms Volts Amps Hours cell 5 cells Notes
------------------------------------------------------------------------
10 2.8 .28 24 .78 3.9 (Lifetime measured to 2.5 V)
5 2.78 .55 12 1.53 7.6 " "
3.3 2.75 .82 8 2.25 11.2 " "
2.5 2.71 1.08 6 2.92 14.6 " "
0.77 2.46 3.20 2:14 7.87 39.4 (Lifetime measured to 2.0 V)
(That 0.77 ohm load was a mistake. I thought I had 4
10 ohm / 10 watt resistors in parallel. One of them
turned out to be 1 ohm. Boy, did it get hot!)
We order our lithium batteries from:
S & G Electronics
618 S. 62nd St.
Philadelphia, PA 19143
Phone (voice): 215 474-7663
Prices run around $15.00 per pack of 10 cells.
S&G accepts phone orders, but not credit cards.
They will ship C.O.D., however. S&G is a real mom and
pop outfit and very nice people to do business with.
GAS
(EOSS NOTE: We STRONGLY
recommend avoiding use of hydrogen because of its
explosive properties. If you are considering it, only do
so with the assistance of an EXPERT in its use. EOSS has
never flown hydrogen and we have always been able to plan
our payloads for the lift properties of helium. Also,
EOSS rarely pays for the gas. We are usually working with
an educational institution or paying customer who foots
the bills for consumables and we insist on helium as an
ironclad safety factor at our launch sites as we usually
have a crowd of students and visitors present at these
events.)
We use Hydrogen because it's cheaper (about $20.00
per cylinder versus $40.00 for helium) and has more lift.
Also, we're not too bright. Hydrogen has two drawbacks:
it burns and it explodes. On the other hand, it's not
super vicious. Your balloon will be delivered with no air
in it. Don't let any get in while you're filling it and
the hydrogen can't explode in your balloon. If the
balloon bursts while filling it indoors, get out and let
the hydrogen dissipate for a while. Don't flip the light
switch on the way out. Try to do your inflation in an
old, leaky building just in case the balloon pops. An old
barn with lots of holes in the roof is ideal for working
with hydrogen.
Buy hydrogen (or helium) at any welding supply shop.
You will need the biggest tank they have, size K or T,
which will typically come up to about your shoulder. Put
another way, it will just barely fit into the back seat
of a Ford Taurus. Try not to get into any accidents when
you have a tank full of high pressure hydrogen in your
back seat. In the event of a serious traffic accident,
you needn't worry about being injured. You will die.
Either size tank will fill a 1200 gram balloon with
gas left over.
You should have a regulator for your tank to lower
the 2000 pound plus pressure to a few pounds, although in
an emergency you can tape the filling hose to the outlet
of the tank and then open the valve "very"
carefully. I've seen it done, but I don't recommend it.
You can rent regulators at the same welding shop you
buy your hydrogen at. If they don't have hydrogen
regulators, you can use a nitrogen regulator with a
$15.00 adaptor the welding store can sell you. Helium is
used a lot, so they will probably have helium regulators
in stock. ARRANGE FOR YOUR GAS PURCHASE AT LEAST TWO
WEEKS BEFORE FLIGHT. The welding shop may need time to do
a credit check on you. If not, they will require a $50 -
$100 deposit on the tank. You have to rent the tank, they
won't sell it to you. Regulators typically rent for about
$5.00 a week. You'll also have to rent the tank at about
a dime a day. The welding shop will give you a hazardous
material form that MUST be carried in your vehicle at all
times the gas tank is on board or you are liable for a
multi-thousand dollar fine.
INSTRUMENTATION
The best instrumentation is a GPS receiver sending
its data to a packet TNC and a transmitter. This will
send you the balloon's latitude, longitude and altitude.
They're wonderful! Note, however, that many GPS receivers
won't work above 60,000 feet. This is because of export
regulations designed to keep Saddam Hussain or somebody
like him from using a GPS receiver to improve the
accuracy of a Scud missile. The actual regulations ban
export of GPS receivers that can measure speeds in excess
of several hundred miles per hour at altitudes above
60,000 feet. Motorola GPS boards are reputed to work
above 60K feet at typical balloon speeds. Most
manufacturers can provide you with versions of their
firmware that will work above 60k feet, but you will have
to sign a non-export agreement.
Note also that the accuracy of GPS signals is
purposely degraded to about 100 yards horizontally and
300-500 feet vertically to keep Russian ICBMs from using
them to achieve the +/- 10 yard accuracy necessary to
take out a hardened missile silo. This will make your
readings, especially altitude, jump around a bit.
Make sure your GPS receiver has a NMEA output. This
is a 4800 baud RS-232 ASCII output in a standardized
format. It was originally designed for use on boats, to
let things like LORAN receivers work with autopilots. If
the GPS receiver can be programmed to send lat, long. and
altitude every minute or so, you can connect this output
directly to the TNC input and let her rip. APRS programs
are designed to handle this data format. However, if the
receiver sends its data constantly, you will have some
overflow problems feeding a 1200 baud TNC.
webmaster note: When written, the GPS info above was correct.
However, the purposeful degradation of GPS position fixes through Selective
Availability (SA) which introduced the 100 yard inaccuracies has been suspended
for several years. In fact, with the adoption of the
Wide Area Augmentation System (WAAS)
accuracies are now commonly in the range of 16 to 25 feet. The 60K altitude
limit is pretty much gone too. A new paradigm of speed, altitude and perhaps
other
WAAS analysis site
GPS units that work over 60K feet
CHEAP ALTIMETER
Thanks to Kevin, WB9YHB, we now have a cheap
electronic altimeter. He spotted a Microswitch pressure
transducer in a MECI surplus catalog that provides a 1 to
6 volt output that is linearly proportional to pressure.
The catalog blurb:
PRESSURE TRANSDUCER Absolute pressure sensor for
0-15 PSI range. 45PSI maximum overpressure with 0.333
volts per PSI sensitivity, .75% linearity. Three wire
PC mount. Mount holes 2-1/16 O.C. Includes spec
sheet. Mfg: Microswitch Mfg P/N: 142PC15A MECI PART
NUMBER: 540-6206F
It's a whopping $2.95, unless you order 10 or more
when it drops to $2.50 ea. It's small, light and runs off
8 to 12 volts. It only requires one resistor. I ordered
ten of them in Dec, 1994 and they had about 700 left.
Hurry and get yours now. :)
MECI
340 East First St.
Dayton, Ohio 45402
1-800-344-4465 9am-6pm EST Mon-Fri Visa/MC/Disc/AmEx
CHEAP FLIGHT COMPUTER
Computers don't come much cheaper than Parallax's
BASIC Stamp. This $39.90 device is a printed circuit
board the size of a large postage stamp containing a
microprocessor, 256 bytes of EEPROM, 8 programmable I/O
lines and a 5 volt regulator. One end of the board has a
pair of sturdy clips for a 9 volt battery, which will run
a STAMP for several days. Small as the board is, half of
it is a prototype area containing a 10 x 14 array of
isolated plated through holes for your circuitry.
The Stamp has a 4 MHz clock and comes with a built in
Integer BASIC interpreter. You write your BASIC program
on a PC using Parallax's special BASIC editor and then
download it to the Stamp's EEPROM with a cable that
connects to your parallel port. (Don't know if a Mac can
use the BASIC Editor when running a PC emulator.) The
program starts immediately and it restarts every time you
connect power afterwards.
Each of the 8 I/O lines can be independently
programmed as a TTL/CMOS compatable input or output. An
output pin can source 20 ma and sink 25 ma. Each pin can
also be an RS-232 input or output at speeds up to 2400
baud. (Note, the output is 0-5 volts, which isn't
"true" RS-232, but it works with everything
I've tried so far.) The inputs work fine with standard
RS-232. The "RS-232 interface" consists of a
current limiting resistor.
Parallax's application notes show how to connect an
ADC0831 8 bit analog to digital converter chip to the
stamp. This is an 8 pin chip with a serial interface that
connects to the Stamp with just 3 wires. We currently use
two of them and two Radio Shack thermistors (p/n 271-110)
to read inside and outside temps. The data is sent to the
ground by Morse code, also generated by the Stamp. My
next generation board will use a ADC0838 chip, which has
8 inputs. The Stamp also has a Radio Shack reed relay
mounted on it which snaps pictures with a 35 mm camera
after every ID. The 831s and 838s are available from
Digi-Key.
A Cheaper Flight Computer
Parallax has actually found a way to make a BASIC
Stamp for even less money! The BS1-IC is a 1.4 x .4 inch
PCB with surface mounted parts and 14 pins sticking out
of one side so it can plug into a socket like a SIP.
(Single Inline Package) It contains EVERYTHING a standard
Stamp has except the 9 volt battery clips and it's only
$29.95!
A More Powerful Flight Computer
Parallax is promising the Super Stamp (or Stamp II as
they call it) in Feb 1995. (It was originally promised
for Nov 94.) This is another surface mount board, with
the form factor of a 24 pin DIP. It will have 16 I/O
pins, a 20 mhz clock, 2k EEPROM, 9600 baud RS-232, DTMF
encoding and decoding, built in A/D and more. Time will
tell if they deliver it all. The price is to be $49.95.
Parallax BBS and FTP site
The Stamp manual, application notes and programs are
available on the Parallax BBS at (916) 624-7101 or by
anonymous FTP from PARALLAXINC.COM
Avoid the BASIC Stamp Programming Kit
Parallax will be happy to sell you a BASIC Stamp
programmer's kit for $99.00. It contains a cable to
connect the Stamp to your PC's parallel port, a manual, a
set of application notes and a disk with software. The
manual, application notes, software and pin out for the
cable are available for free download on their BBS and
FTP site. On the plus side, the programmer's kit comes in
a really neat cardboard box, which I've gotten a lot of
use from.
PINOUT for the PARALLEL PORT to BASIC STAMP CABLE
DB 25 BASIC BS-1C
Connector STAMP (Stamp SIP)
2 3 5
11 2 4
25 1 <<< 3 (GROUND - Marked <<< on Stamp)
All of the BASIC Stamp products are available from
Digi-Key or you can order from Parallax at (916)
624-8003.
35mm CAMERA
What's the world look like from 100,000 feet? A
camera can tell you. A few 35 mm cameras can
automatically snap a picture every ten minutes, but we
couldn't find one. Next best is triggering a camera
electrically with a reed relay driven by a BASIC Stamp
output pin. We use a "Canon Sureshot esprit".
If you remove the bottom screw nearest the tripod
hole, you can remove a small plastic plate that uncovers
a flexible printed circuit board. If you hold the camera
upside down with the lens facing away from you, you will
see a horseshoe shaped ring of circular solder pads with
one pad missing at the top. Number the pads
counterclockwise starting with the pad to the left of the
missing pad. Short pads 1 and 3 together and run a wire
from pin 1 and pin 2 to the normally open contacts of the
reed relay. Close the relay contacts for 1 second and
you'll take a picture.
NOTE: You will have to either use wire thin enough so
that you can replace the plastic plate or you'll have to
cover the hole where the plate was with black electrical
tape. If you don't, a light leak will fog one corner of
each picture.
Which way to point the camera? Well ... if you point
it down, you get great aerial photographs of the earth
below you. It's a lot of fun spotting familiar places and
just plotting the balloon's course after the flight by
finding landmarks on the pictures. On the other hand, if
you point the camera horizontally, you get some
magnificent photos at high altitude. Your balloon will go
so high that the sky will be black and you can see the
curvature of the earth on the horizon. Your choice, I
guess.
BASIC BALLOON CONSTRUCTION
The basic balloon setup is one weather balloon, five
to ten feet of 50 lb test cord, one parachute tied to the
cord at its apex, another five to ten feet of cord tied
to the parachute shroud lines with a radar reflector
attached to its middle and the payload. You HAVE to have
the parachute and radar reflector - FAA regs. Ditto for
the 50 lb (max) cord.
RADAR REFLECTORS: We now know for certain that just
hanging a space blanket from the package won't work. They
barely show up on FAA radars. Best bet: a styrofoam
corner reflector covered with space blanket material.
Look in a boating catalog for models. Hints: forget
aluminum foil, it's too heavy. Ditto for cardboard. Space
blankets (very thin aluminized mylar) work fine and are
featherweight. Get them from sporting good stores.
Payloads
REDUNDANCY! Live by that word! Have at least two
transmitters. Each transmitter should have its own,
totally separate power supply. If your package isn't
transmitting when it lands, you aren't going to find it.
One transmitter can be a milliwatt rig running from a 9
volt battery. Hint: you can buy oscillator modules from
Digi-Key for a few bucks each that have frequencies in
various HF ham bands. They run on five volts and draw
next to no power.
It gets down to 60 below zero Fahrenheit at 40,000
feet. An insulated package is necessary. A styrofoam beer
cooler is light, cheap and a great insulator. If it's
well sealed, things will stay quite toasty inside. Our
lowest inside temps have been about 32 F. with a leaky
package (lots of antennas sticking out through holes that
weren't sealed with goop) to about 70 F. with very tight
packages. Our HIGHEST internal temp was 132 degrees F
with a very tight package containing two transmitters
that used a total of about ten watts from two battery
packs. Remember, about 1/2 of all the power your
transmitter draws stays inside as heat.
Put an audio beeper on the outside of the package.
This will help you zero in on it if it lands in dense
brush or woods. MAKE SURE THE BEEPER CAN BE TURNED OFF
FROM THE OUTSIDE AND PUT PROMINENT INSTRUCTIONS FOR DOING
SO ON THE OUTSIDE OF THE PACKAGE! We had a farmer find
our package and take it back to the farmhouse. The
beeping was so annoying that he put it in a metal granary
to muffle the sound - and the signal we were tracking
went to zip! Luckily, we had our address on the package.
PUT YOUR ADDRESS AND PHONE NUMBER ON THE OUTSIDE OF
THE PACKAGE! Mention a $50.00 reward to the finder. So
far, we've had one package found by duck hunters, who
promptly switched the transmitter off. A second package
wound up in a metal granary and a third had its single
set of batteries die on the way down. (Remember what I
said above about trial and error? These are some of the
errors.) We got all three back because people found them
and called us.
DON'T PUT AN ON/OFF SWITCH FOR THE TRANSMITTERS ON
THE OUTSIDE. You WANT that signal to stay on so you can
track it down!
Put "HARMLESS HAM RADIO TRANSMITTER" on the
outside. After all, many people get concerned when a
package bristling with antennas and going "BEEP BEEP
BEEP" parachutes into their bean field.
The Federal Aviation Administration (FAA)
Unmanned Free Balloons are covered under section 101
of the Federal Aviation Regulations (FARs) along with
Moored Balloons, Kites and Unmanned Rockets. Call your
local control tower and they will mail you a copy of this
section. Be prepared to play some telephone tag.
NOTIFYING THE FAA: The FAA wants to know about your
flight at least one week in advance. If this is your
first flight, call them a month in advance and talk
things over with them. You will typically want to call
the local "Center". Here in Wisconsin, we call
Chicago center. If you can't find their number in the
yellow pages, under Department of Transportation, try
calling the local airport control tower. Be prepared to
play some telephone tag. If other people in your area are
flying balloons, ask them who they talk to and get the
number from them. (See The Most Important Rule above.)
The FAA center will want to know when you intend to
launch, where from (distance and direction from a town on
a map), how high you expect to go and what direction you
expect it to travel in. This last part can be hard to
answer a week in advance, but generally it will follow
the prevailing winds in your area. Here in Wisconsin, we
always guess that the balloon will travel to the south
east. You should also leave your number in case they have
questions. If the person you want to speak to isn't in,
be sure to leave your name and number so they can get
back to you.
24 hours before launch, you have to call your local
Flight Service Station (FSS) and file a Notice to Airmen
(NOTAM) giving the launch site, date and time, expected
max altitude, expected rate of climb, expected direction
of travel and landing spot. Your local FSS will have an
800 number. These people can also give you the winds
aloft if you ask. Most pilots have no use for winds aloft
over 30,000 feet, so tell the FSS that you're launching a
balloon and ask for wind speed and direction for as high
as they have data for. This will typically be about 50-60
thousand feet. Try to get the winds aloft for a reporting
station to the west of you because 24 hours later, those
winds will have likely moved to your location.
Call FSS the morning of the launch for current winds
aloft. You can then get a pretty good idea of where it's
going to go so your chase crew can position themselves
accordingly.
Call the FSS as soon as you launch and give them your
estimated climb speed. They probably won't need to hear
anything else from you until the balloon goes above
60,000 feet. Once above 60k, you're in uncontrolled
airspace and the FAA doesn't have to worry about you, so
tell them when you pass 60k. Call them again when you
descend below 60k and when you land.
The Launch Mechanics
First of all, you need to know how much gas to put
into the balloon. What you want is enough gas to lift the
balloon, your payload, radar reflector and parachute plus
six ounces to one pound of extra lift. One pound of extra
lift will give you about a 1000 foot per minute initial
rate of climb. This will give you about a 2-3 hour ride
to 100,000 feet. On a very calm day with slow winds
aloft, you can put in six ounces of lift and get a longer
trip up and more usable time at high altitude. Here's the
WB9SBD method of achieving the desired amount of lift:
- Construct a simple scale by suspending a strong
rod from a rope tied around its middle.
- Hang your payload, parachute, radar reflector,
suspension cables and EVERYTHING else that will
fly EXCEPT the balloon to one end of the rod.
- Hang a one or two gallon plastic jug from the
other end of the rod.
- Fill the jug with water until the rod is
balanced.
- Add six ounces to one pound of extra weight to
the payload end. (Hint: bread comes in one pound
loaves - a WB9SBD discovery)
- Add enough water to balance the rod again.
You now have a jug of water that weighs exactly as
much as what your balloon will have to lift plus 6 to 16
ounces extra.
FILLING THE BALLOON
Fill the balloon indoors or in an area that's very
well protected from the wind. You don't want to have to
fight the wind because the balloon is very fragile and it
will burst. Look for an old barn or airplane hanger. Be
aware that the balloon will just barely clear a barn door
when it's filled. A home garage door isn't high enough.
Spread a tarp on the ground to protect the balloon
and spread the balloon out on the tarp. Handle the
balloon with gloves.
Lay the gas tank next to the balloon. (It can't fall
over if it's laying on the ground.) The regulator
manufacturers recommend that you crack the valve slightly
to blow out any dust before screwing on the regulator. Be
aware that the threads on hydrogen tanks are
"backwards" - you turn them counter clockwise
to tighten them. (This gave me a bad moment on my first
solo launch.) Run a hose from the regulator to your
filling adaptor.
THE FILLING ADAPTOR: This is a piece of plastic
tubing wide enough to be a snug fit into the open end of
the balloon - 1.5 to 2 inches should do it. PVC pipe is
fine. Somehow neck the other end of that tube down to the
point where you can attach the hose from the gas tank to
it. Also put a hook on the tube - perhaps by epoxying a
piece of coat hanger wire to the side of the tube, near
the end where the hose attaches. Now tie some twine from
that hook to the jug.
Start the gas flowing and the balloon will start to
inflate. Try not to get any air into the balloon,
especially if you're using hydrogen! When the balloon
lifts off the ground, the jug of water will keep it from
going anywhere.
Continue to fill the balloon until the jug
"just" lifts off the floor. You now have enough
gas in the balloon to lift your payload, parachute, radar
reflector and connecting cords plus the extra six to
sixteen ounces of water you put in the jug.
Sealing the balloon: using heavy twine, tie the
balloon neck off tightly above the filling adaptor.
Remove the adaptor. Tie the neck again, four to six
inches below the first piece of twine. Tie your payload
cord to the neck between these two pieces of twine. Now
bend the neck over double and tie it again, twice. You
will now have the neck of the balloon bent over double,
with the payload suspension cord nestled in the bottom of
the bend and the whole thing securely tied. You're ready
to launch. (You can use tie-wraps instead of twine if you
wish, but they're heavier.)
IS EVERYTHING TURNED ON?
Check now! Is your transmitter transmitting? Can you
talk through the repeater? Is your GPS sending data? Is
your audio beeper beeping? Is your IDer IDing? It's best
to have a checklist because you will feel
"very" foolish if you launch with something
turned off! (Don't ask me how I know this.)
The Launch
Take the balloon outdoors with somebody else carrying
the payload and parachute. Stretch the payload out
downwind from the balloon, with somebody holding it. You
can then just release the balloon or let it out hand over
hand until you're holding the payload, then let go. It's
best if people hold the payload, parachute and radar
reflector to keep them from being dragged along the
ground. Now call FSS and let them know you've launched.
The End
Oops, deadline's up and this has to go out. I remind
you once again that this is version 1.0 of the BALLOON
FAQ. I promise you that I've left things out and made
mistakes. If you have additions, corrections or
criticisms, please send them to:
djmullen@facstaff.wisc.edu e-mail
n9ltd@WD9ESU.EN53IE.WI packet
(608) 249-7130 Clear Skies BBS
Dave Mullenix, 2502 Brentwood Pkwy, Madison, WI 53704 Snail Mail
end of faq
last edit
02 March, 2008 (on
EOSS pages)
maintained by Rick von Glahn, <webmaster@eoss.org>
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