At about age 8, while living in DesPlains, IL, my father used to do some instructing in AT 6's out of Ravenswood Airport. He had spent two extra cycles in San Antonio, TX, during WWII where he instructed on the AT 6 for the Army.
Ravenswood would let him fly their AT 6 for only fuel on a one to one hourly trade off for instructor time...
Ravenswood was just across the street (Touey?) from Ohare, which had begun its growth as a combination military/civilian airport.
Have fun