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November 19th 04, 03:27 AM

(Len Over 21) wrote in message ...
In article ,
(William) writes:

(Len Over 21) wrote in message
...
In article ,
(William) writes:

They need a way to burst the balloon on command (i.e., nichrome wire
wrapped around the balloon plug, a receiver, and a battery),
metallized RADAR reflectors on the instrument chain, and FAA clearance
to launch.

The "command burst" receiver better have some secure coding to
it or some jughead will burst-command it beforehand.

Make that "CBer." There are no jugheads in the amateur service. 8^0

Riiiiighhhht...especially the morsemen who would never Ever
do any wrongness! :-)

A corner-cube reflector can be done with aluminum foil on a balsa
wood frame...just three mutually-perpendicular planes in that
corner cube, less than a foot in any dimension and still good for
skin tracking.

Maybe Kelly could diagram one on the back of an envelope for us?

I've made them. They weigh about a half ounce or so for
1-foot sides (good for reflections down to transponder
frequencies of 1.1 GHz and up to X band. Little ones for
X-band (and some C band) search/weather radar can be a
few inches on the side. Balsa wood strips for the edges
and ordinary kitchen aluminum foil for the reflector.

Corner cubes are extensively used in optics/laser benches.
Those are just three planes of reflectors, each perpendicular
to the others. No matter the azimuth or elevation of the
source, a reflection goes back on the same direction vector.
Ideal for a positive radar return in any azimuth or elevation.

According to Mike, the FAA is "accommodating." :-)

They've lost all sense of jumor since 9/11

The air controllers weren't too happy about the comms outage
(including the backup system) at the Los Angeles Center, either!

Back in the 60s the weather folks used to loft a quarter million or
so weather balloons per year...with little transmitters in them and
telemetry done with extremely low-cost electronics. Good example
of doing things simply and for low cost per launch.

They still do. It is called a rawindsonde and the rawin observations
are transmitted over the weather networks and shared worldwide. These
ballons often reach 10MB, but the payload is much smaller than most
EOS amateur projects.

I had one cluttering up the workshop since the 60s. Military type by
the markings. One-shot battery, a simple aneroid bellows driving a
printed-circuit rotary switch to kick in temp and moisture and light
sensors, all of them variable resistive types that changed the rep.
rate of a simple pulse modulator for the combination RCA pencil
triode and cavity oscillator assembly and inverted ground-plane
antenna.

That must be why the ground operator had headphones and counted
clicks. It's a lot different today.

Not quite. The USAF launched this one I had in the mid-1950s.
Guess where? :-)

They used a tracking radar receiver on the ground and recorded
the telemetry frequencies (of the rep rate) for altitude, temp,
and humidity. Azimuthal accuracy was as good as the boresight
of the tracking antenna (with some corroboration of altitude by
tracker's elevation at close ranges).

All of that went in the dumpster long ago except the
translucent plastic sleeve on the Xmter assembly went two weeks
ago (found it in a box of junk after sorting out the workshop).

Best place for all that stuff.

Perhaps. :-) RCA's tube works had a steady producion of
pencil triodes with crimped-on cavities formed by thin sheet
metal. They made millions of units over a couple decades.
Was a fairly cheap combination tube & cavity.

Those same pencil triodes were later used in a small boat
radar unit made by Bonzer. Flattened disk kind of radome,
had a planar array of helix antennas inside. A few miles range,
good for very small boats.

The experiments can be just
about anything you can think of that can be done at that altitude. Most

launches are multi-mission, with both science and Ham fun stuff on
board. And of course the Ham fun can be scientific too.

Hams have had fun ballooning for quite a while, but the advent
of
inexpensive GPS has changed things dramatically. We now fully expect to

get our payloads back! That wasn't the case not too many years ago.

The balloon is usually one of the latex weather balloon
variety. Zero
pressure balloons can be used too, but since they are designed to go up

and stay up for a long time, that would be a more complex proposition.

You need to do some math on that before envisioning such a "low-
cost" approach to get to 100 Kilofeet. Those 8-foot (typical)
"weather balloons" aren't going to get up that high, not even a mass
of them.

You need to consult some (free for the asking) density values of
the atmosphere and some back-of-the-envelope figuring first. Note
that you have to allow for the lifting gas expansion with altitude.
It
is far from the same at 100 kilofeet versus sea level.

Lots of expansion.

Tsk. Mike hasn't consulted a Standard Atmosphere table set yet.

100 kilofeet he will NEVER make with some surplus latex weather
balloons.

Get sponsor, buy new.

Mike is still NOT going to make 100 kilofeet altitude with "latex
weather balloons." [that was his original statement and, by Rules
of Engagement in this newsgrope, he MUST follow that EXACTLY
or be termed a "failure" or "defunct"]

The payload uses Amateur radio for command and control. At the
heart
of

the system is a GPS unit in conjunction with a packet radio. The
telemetry data is sent back to earth and kept track of with a computer.

The computer lets us know where the payload is, where it is going and
how fast, and predicts the landing site. Oh, and it's freeware.

That's going to be a minor cost item. As you will find out, the
balloon structure, its support infrastructure, and lifting gas will
cost more than you think..

It all adds up. Might be good idea to get a sponsor.

Tsk. He gots the "recycling" spirit. Maybe he has a new way
to "mine" helium out of the air or ground? [collectors around some
heliarc welders might work? :-) ]

I was a forecaster for a "round-the-world" balloon venture. They lost
their helium due to a fabric tear. Couldn't find enough replacement
helium in Argentina.

Most helium still comes from Texas. :-)

In addition, the packet radio can send back other info as the
mission
may desire. The mission is often controlled by a microprocessor. To
date, a lot of balloonatics use basic stamp controllers.

Often a repeater is put on board. A small one has a lot of
coverage at

100,000 feet! There is usually a VHF beacon, and occasionally a 10
meter
beacon also, although that is not as prevalent as it was before GPS.

Two words: Payload weight.

You can't get up in the blue sky with lack-of-detail blue sky ideas.

If it were that easy, lots and lots of folks would have done so a
half century ago.

And all of those gps, beacons, packets, thermistors, pressure
transducers, and video cameras and ATV transmitters operate off of
heavy batteries. Luckily the ascent and descent won't be that long,
and the batteries can be scaled back from what is normally required
with one caveat. You'll want the beacon to be operable for several
days, if possible.

Mere details. It is "doing science!" It is "inexpensive!"

One-shot batteries are one source, but they ARE truly one-shot
and can't be recycled afterwards.

I'm sure our multi-disciplinarian engineer who's "been there and back"
could do it.

Absolutell! :-)

The experiments vary. One of the favorite devices for the grade
and
middle school kids is something called a pongsat. This is an experiment

that can be anything that will fit inside a ping-pong ball. Sounds
weird, but there are plenty of small scale experiments that fit the
bill... er, ping-pong ball.

The balloon lifts the payload to the predetermined altitude,
and
bursts. The payload drops, and the Ham comms can continue during
descent, although the first few moments after burst can be pretty weird

as the payload often does some pretty strange gyrations until the
parachute can grab some atmosphere. Drops like the proverbial rock.

All this time, the GPS is keeping track of the whereabouts of
the
payload.

Commercial grade GPS recievers are designed to not work above 60,000
feet. Crazy precaution against strapping one to a missile and using
it as a guidance system.

No sweaty-dah. Seal the GPS unit in more balloon material, it stays
in a local pressure regardless of the vehicle altitude. More or less.

The ascent and descent shouldn't be more than 4 - 5 hours.

Descent much faster. :-) That weather balloon will probably
go POP before 50 kilofeet.

[someone finally noticed that those balloon things filled at near
sea level DO get rather BIG at high altitude...like, no kidding?]

Then at landing, it turns into a foxhunt as the hams use the
beacon transmissions to find the payload. With the advent of us getting

used to the software and the precision with which the GPS can determine

the location, it is not too uncommon for the recovery team to witness
the landing.

Launch of one of these things does not take as much
bureaucratic red
tape as most people think.

You've done that? You are going to the edge of the stratosphere and
think you can do so freely? Ain't quite that easy.

And it can be done for surprisingly little money.

"Surprisingly little" is a highly subjective term. Real projects
have
quite objective, finite budgets.

The people that are needed are of course Hams, and people with
some
programming experience. People with experience building things, and a
meteorologist can't hurt! People that don't mind a drive on a weekend
day to serve on the recovery team. Plenty of subteams, such as payload,

publicity, science, visualization, integration, education liaison. Even

people that might just want to feed all the other reprobates.

Sounds like you've already filled the "executive" position. :-)

This is real stuff. This might spark the interest in science in
some
youngster. And that is not only a career choice, but a service to the
country. American scientists are becoming pretty rare.

"Becoming pretty rare?" Not quite as any visit to academia will
show but feel free to get opinionated.

Its great publicity for Amateur radio.

It will get ham radio noticed, but what is written up by journalists
may not be what you expect.

Free ballooning has been going in the USA since 9 January 1793,
the first American flight by Frenchman Jean-Pierre Blanchard,
lifting off from the Walnut Street Prison in colonial Philadelphia.
That was witnessed by none other than President Washington.
[from "Lighter Than Air Flight" by Lt. Col. C. V. Glines, USAF,
Franklin Watts Inc., NYC, 1965, data from pp 29-35] That's over
two centuries of time...

And we can innovate and experiment. Radio is a pretty mature
science
now. It's doubtful that any of us are going to invent a grand new
communication scheme, or an antenna that does DC to daylight, or even
one that is a whole lot better than what we have now. So What we need
to
do is to integrate what we have now, and do some innovation with it. We

also need (or at least should) prove our worth to the community.

That we can do it while having fun is a real bonus.

You can have all your innovative fun doing many, many things.
Until you find out what helium costs to lift the total balloon (the
balloon itself, its payload, its carrying structure, its all going to
be a pipe dream having no more basis than enthusiasm.

Check out the prices for helium with a gas supplier, plus what it
takes to haul to HEAVY gas cylinders to a launch area, plus the
metering system plus the filling system plus whatever else. All
that after you've investigated what the actual lifting capacity will
be in terms of ounces per cubic feet of balloon. [I said ounces,
not pounds...lighter than air does not mean negative weight]

You could get "efficiency" by going for hydrogen gas...which is
offset by very direct DANGER from many and varied sources.

Yikes! If they use the nichrome wire on the balloon plug trick...

Hydrogen is a very efficient lifting gas. It CAN be generated by
amateurs...chemistry amateurs. Getting into the balloon is going
to be tricky.

Friend of mine had a hydrogen generator for launching balloons on
Antarctica. I guess it was cheaper/less weight than hauling in
helium.

Surplus catalogs used to sell the little generators but haven't seen
them in years.

It's high school chemistry time. Electrolysis...separate oxy and
hydrogen from water via electrickery. Takes a while for any sort
of H volume but that can be automated. Water cheap, electricity
relatively cheap. [some hams extremely cheap...[

Still going for 100,000 foot altitude? Start thinking in terms of
the balloon exapanding to something on the order of EIGHT times
in size at altitude maximum. That's visible on some of the high
altitude research balloon flights of the 1960s using lots and lots
of plastic sheet for balloon material.

Your project may need a virgin...such as Richard Branson...to
help start it off.

Now, if you are REALLY thinking about this whole thing, look into
"Project STAR" and a little thing like a model airplane that crossed
the Atlantic (from Newfoundland to the Irish coast) during the 38
hours in August 9, 10, and 11, 2003. Laugh all you want but a few
guys from around DC managed to do that through GPS guidance
on board as an autopilot. You can read about it at

http://tam.plannet21.com/index.htm

Pictures and stuff to guide you even if you are not into model
flying.
38 hours (approx) of powered flight using only 5.5 pounds of fuel,
flight path of 1882 miles. Radio control only for take off and
climb-
out, then landing in Ireland...the rest entirely on "autopilot." It
had
some means of reporting its position to earth via satellites. That
alone would be of interest to anything else involving GPS location
or guidance.

Search around on the huge NASA website for atmospheric info,
especially for density versus height. You could do an approximate
curve of payload + balloon weight versus cost of helium in hundreds
of cubic feet to whatever altitude limit. That will give you some
realistic viewing into feasibility of it all.

Sounds like fun. Dense air operations in the eastern states may pose
a big problem.

Not to worry. Air carriers are on the "Victor" ways above the max.
balloon altitude. General Av types will be in the denser altitudes
and props will chop it up nicely. :-)

I wouldn't count on it. Maybe CAPman can fly by with a skyhook and
snatch the descending package before it becomes FOD for the General Av
types?

A large budget bump there...CAP is unlikely to pay for the
snatch aircraft fuel, maintenance costs, etc.

Anyway, this entire thing is highly doable as it's already been done
by amateur radio operators for at least a decade.

Well, YES, it has. Thing was that Mike was making out like it was
something "new" in going to "near space!" NOT with surplus latex
weather balloons he aint. A mylar or other polymer film gasbag,
yes, but the ground support for anything sizeable is going to be
MUCH larger than realized for that "near space" altitude.

Then there are all of the high-power amateur rocket types who
regularly get FAA approval, have telemetry, and a good set of binocs.
I participated once with another amateur and they were thrilled with
our ability to communicate from the launch area to the pick-up area.
Today, FRS and cell phones can probably fill that niche. Ooops!

Darn it! Brian! You said some naughty words! You will now be
lectured interminably by the S. :-)

Len, so one part of the project, the corner cube reflector, is easily
fabricated using inexpensive materials. Excellent. No need to bother
Kelly. I'm sure he's much too busy gearing up for field day or the
sweeps.

Regarding the latex balloons, the little PIBAL balloons are not going
to get there, if those are the balloons that Mike is referring to. I
don't know what kind of fabric the rawinsonde balloons are made from,
but they routinely get to 100mb, and often get to 10mb (~30km). Mike
just needs to get whatever is currently available and go with it. It
will work.

I think planning several launches, each with increasing difficulty, is
a way to tackle the problems and see what works and ~who~ works.
Nothing sent aloft should be so valuable that it cannot be lost, and
expect losses. A receiver for the command burst, a beacon transmitter
for tracking and recovery, and a telemetry recorder (internal temp,
external temp, and pressure) will verify the attained altitude. He
can play with the cross-band repeaters, atv cameras, and hyperspectral
imaging during a later launch.

The problem of congested airways is still there. He might consider
having a trained group of DFers locally/College Station to recover the
package, and move his launch site and crew to Indiana to tame that
problem. If he does it with the Scouts, they are always mobile, and
actually like going places for a purpose. And Scouting opens doors
that might otherwise be closed.

All highly do-able if he gets the right volunteers and sponsorship.