If it were in free air, it would simply be a vertical dipole, but since the
ground is below it, the electrical lengths of the bottom leg is changed, right?


It's not a dipole over a perfectly reflecting earth because: 1) the top section
is series excited from the center of the coax feed line through a network, 2)
the outer cover of the coax feed line is directly connected to the top of the
bottom section, and 3) the bottom of the bottom section is connected to the
ground system through another network, usually just a capacitor.

This results in the current distribution being changed such that: 1) the
horizontal field is greatly increased over that of a 180 degree radiator, and
2) the vertical field is greatly reduced over that of a radiator which is
taller than 180 degrees.

Ordinarily, a 225 degree radiator has the maximum horizontal field, but such a
radiator also has a very significant vertical field ... significant enough to
cause loss of primary service area due to the reflected vertical field being
approximately equal to, but of opposite polarity to the horzontal field at its
extremes.

Hence, 200 degrees is normally the tallest conventional vertical radiator used
for Class A stations.

And, Class A stations which use an unsectionalized radiator taller than 200
degrees do so at their peril.

(There are only two such cases within the U.S., and I don't know of any outside
of the U.S.).



KSTP's Franklin is not a Frankin on account it is 179
degrees over 179 degrees.

What does this do to the pattern in real terms?


Nothing, which is why I also stated that a true Franklin and a Franklin-type
sectional which is just a tad shorter than a true Franklin (the KSTP day
radiator case) BOTH have an efficiency of 510 mV/m/kW at 1 km.