There was a Naval Air Station at Port Columbus (airfield) just outside of Columbus, Ohio.
This was the station of reserve squadron VF-692 (later VA-692?) The following is a long posting by
David A Doll, who was eventually an aviator in that squadron:
https://thebrownshoes.org/story/david-doll
Search for "Carmichael" and you will find a section on Doll's recollections of a most unforgettable character, the architect Dan Carmichael.
Also in Columbus was a factory for North American, Air Force Factory 85.
It is mentioned in this link about the airport (now John Glenn Columbus International Airport).
https://en.wikipedia.org/wiki/John_G...tional_Airport
https://www.globalsecurity.org/milit...ity/afp-85.htm
I suspect that is where Carmichael was a "test pilot", perhaps not "full time". He may have been a navy acceptance pilot for new naval aircraft being produced there.
Brief mention at the top of the page (scroll up for the preceding page) on Carmichael as CO of VF-692 (a single pilot prop plane reserve squadron) in 1956:
https://www.google.com/books/edition...sec=frontcover