On Tue, 13 May 2008 00:19:50 -0400, "Jimmie D"
wrote:



Speaking of the trailing wire - I wonder if you could trail a loop - and
use it to generate electricity from cutting earth's magnetic lines of
force - (perhaps to power the aircraft after its up to speed. I think they
experimented with the idea on one of the shuttle's orbital missions, but
didn't hear much about the results.




I think I remember hearing the experiment worked too well and they had a lot
of uncontrolled arcing.
I wonder how much drag this would put on the shuttle.

Jimmie

The wire cutting through the magentic field will generate an EMF - a
potential difference between one end of the wire and the far end but
there is no complete circuit to tap it. If a return wire were
connected to the far end of the wire, it would generate the same value
and polarity giving no net emf (voltage) around the path. If one
could create a loop and rotate it in the field that would be a
different matter. The same concept applies to the voltage developed
between the wing tips of a (metal) aircraft.

Jimmie

The wire cutting through the magentic field will generate an EMF - a
potential difference between one end of the wire and the far end but
there is no complete circuit to tap it. If a return wire were
connected to the far end of the wire, it would generate the same value
and polarity giving no net emf (voltage) around the path. If one
could create a loop and rotate it in the field that would be a
different matter. The same concept applies to the voltage developed
between the wing tips of a (metal) aircraft.


My post was about a possible trailing loop. (Both ends accessable to the ham
on board.)
You don't have to rotate the loop - just to move it.
The aircraft is moving - thus the magnetic lines get 'cut' so to speak, so
emf gets generated.
I also heard it worked 'too well' on the shuttle - that the current was so
great that the wire burned into.

Hal Rosser wrote:
Jimmie


The wire cutting through the magentic field will generate an EMF - a
potential difference between one end of the wire and the far end but
there is no complete circuit to tap it. If a return wire were
connected to the far end of the wire, it would generate the same value
and polarity giving no net emf (voltage) around the path. If one
could create a loop and rotate it in the field that would be a
different matter. The same concept applies to the voltage developed
between the wing tips of a (metal) aircraft.



My post was about a possible trailing loop. (Both ends accessable to the ham
on board.)
You don't have to rotate the loop - just to move it.
The aircraft is moving - thus the magnetic lines get 'cut' so to speak, so
emf gets generated.
I also heard it worked 'too well' on the shuttle - that the current was so
great that the wire burned into.


you can get charging and arcing in orbit from lots of other sources
(impact with charged particles, for instance). It's a pretty big issue
with large things like ISS that can build up substantial charge if
things aren't bonded together. More than one spacecraft has been lost
due to this kind of thing (Japan's Midori-2 is one case I know of).
http://www.space.com/spacenews/archi...ch_111103.html

Jim