On Sat, 25 Apr 2015 16:42:02 +0200, bilou wrote:

"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.

The cost of Helium will continue to rise. Once used, it is effectively
gone for ever as it will leave planet Earth to mix with the rest of the
Helium in space. What we have now is from reserves that come from nuclear
reactions within our planet, and that is all we have got!

Perhaps it's time for us to be less flippant over using this
irreplaceable wonder element!