"Ian Jackson" wrote in message
...
In message , Edwin Johnson
writes
On 2015-04-23, Oregonian Haruspex wrote:
On 2015-04-18 08:38:31 +0000, gareth said:

How about a tethered helium balloon instead? This way you don't have
to worry about powering the thing. Bell wire will handle 100 watts all
day without turning into smoke.

This sounds like a neat experiment, which one of our members tried on
field
day. There are several problems in the electrical side of things, but more
importantly on the physical side. As you rise in altitude the wind speed
will increase, generally speaking, and perhaps change directions. If the
day
is completely calm especialy above the tree line, say 100-200ft, then the
balloon will remain straight up. But launching a balloon in a 10mph wind,
which becomes 15-20mph above the tree line, leads to interesting
developments with the tether wire/cord definitely sloping and perhaps
being
pushed into surrounding objects such as trees, power lines (eh gads!)
which
can cause it to break or other things. So you need plenty of space with
few
impediments for the balloon to catch on as it ascends. You certainly can't
predict a perfectly calm day, so this can be an unpredictable venture. ha

See
http://www.allsopp.co.uk/
Is there any practical way to put back the Helium in the bottle in case of
success
or not too complete failure ?
This will surely lower the cost of experimentation.