art wrote:
At first I was considering the actual wire length
in the braiding b ut that influence became little
compared to the current pertabutations.

Sounds like you are working on a self-resonant coil
and need to know the length of time for the current
to flow from end to end.

Both sides of the argument are wrong on that one.
The current does not jump from one end of a coil to
the other in a very small number of nanoseconds as
one "expert" has asserted which implies a VF close
to 1.0. Neither does the current follow the wires
directly round and round the coil as asserted by the
other side which would imply a VF around 0.01.

The actual measurable VF of a coil seems to be just
about double the round-and-round argument side as
there is indeed some coupling between adjacent coils.
A typical 75m Texas Bugcatcher 6" dia, 6.5" long,
4 tpi coil has a VF of around 0.02 making it about
40 degrees long at 3.8 MHz.
--
73, Cecil http://www.w5dxp.com