Mike Coslo wrote in message ...
N2EY wrote:
In article , Mike Coslo writes:


Brian Kelly wrote:

Mike Coslo wrote in message

...


1500ºC is 2732ºF, over
a thousand degrees hotter than the melting point of steel!


"That's hot!"


. . WTF . . ?!

The atmosphere does indeed heat up in the area known as the Thermosphere


Does other odd things too. Bouncy, bouncy!

Space, or near space is a very strange place...

If you don't believe me, here is some info from NASA. They give even
higher values as a maximum.


"That's hot!"


http://liftoff.msfc.nasa.gov/academy...tmosphere.html

and

http://en.wikipedia.org/wiki/Thermosphere

gives a nice explanation of the Thermosphere, and there is a bit of info
there as to why Amateurs should be interested in it.


A good question is "Why doesn't everything that passes through the
thermosphere burn up?" Because they don't. In fact, despite these high
temps, things passing through this region would "feel" cold.


Would you rather stick your hand into water heated to 200 degrees F or air
heated to 400 degrees?

Why should Hams know about the Thermosphere?


'Cause it's hot? ;-)

If it wasn't hot, we wouldn't have the ionization that allows us to
communicate all over the world on HF.



You *don't* understand some *very* basic
things about the atmosphere, things that you should know as a Ham.


This whole thread got me thinking about how balloons work and how much helium
costs and such. One thing I found out is that 1000 cu ft of helium can be had
for about $200. A bit of $$ for an individual launch but not much if split up
amongst a group.

And of course you don't need that much per typical launch.

I'd seriously consider using hydrogen instead of helium. Hydrogen
would be a terrible choice for use in party balloons but in a
controlled situation like this outdoors and handled properly hydrogen
can be used quite safely. Hydrogen is used in large volumes throuhgout
the industrial sector and it's being used in experimental hybrid
vehicles. If the pros in the auto biz don't have a show-stopping
problem with hydrogen being used as fuel for the interstate kamikazis
neither do I. Propane is nasty stuff too but propane-powered vehicles
have been out there for 40-50 years.

I believe it's much cheaper than helium.

With hydrogen you wouldn't have to inflate the balloon as much to get
it airborne which in turn means that the balloon would be able to fly
higher before it pops. "Higher stretch ratio", etc.

Another thing was the lifting power at high altitudes and low pressures, and
the concept and behavior of a balloon open at the bottom that's not filled all
the way with gas. Fascinating.

Those balloons get BIG before bursting. I've seen some video of it. I
haven't seen what happens to the form of the zero-pressure balloons,
though. Certainly the zero-pressure balloons are a fascinating example
of a self regulating system.

- Mike KB3EIA -

w3rv