Cecil, W5DXP wrote:
"Dr. Corum`s VF equation predicts a VF of approximately double
Richard`s----."

I wonder why? Dr. Terman wrote that the wave follows the turns in a
coil. My recollection of common solid-dielectric coax VF is about 2/3
that of free-space due to the fense plastic.

Twice the velocity factor in a coil requires a wave traveling faster
than light or taking a short-cut around the turns.

I often learn from my mistakes. Where did I err?

Best regards, Richard Harrison, KB5WZI