Tom, K0TAR wrote:
"And aircraft antennas tend to be vertical, at least the ones on the
ground, so orient it that way."

Of course, aircraft need to communicate in all directions around, so
vertical polarization makes sense.

In level flight, VHF aircraft antennas tend to be vertical. See the
submarine Pampanito (at dock in San Francisco as a museum) web page for
SCR 522 specifications. This was an AM VHF radio used in many warplanes
in WW-2. It was supplied with a "1/4-wave vertical antenna". AM and the
VHF frequencies above today`s FM broadcast band, and below the 2-meter
amateur band, are still used for aircraft radio traffic.

Best regards, Richard Harrison, KB5WZI