Following some post-graduate football, Navy flight training and marriage to Callie, all in Pensacola, Duke flew attack aircraft from carriers deployed to the Mediterranean and Western Pacific – including 126 combat missions over North Vietnam. Among his decorations, he was awarded nine air medals for first strike/flight.  He qualified in seven types of USN aircraft, and was a certified flight instructor and test pilot in the A-4 Skyhawk.

Duke retired USN in 1976, and went to work for Martin-Marietta (later Lockheed-Martin) at the Kennedy Space Center, where he was chief of safety engineering for components of the satellite system.  When he retired again in 1994, he and Callie moved to the Dallas area to be closer to family.

Duke was survived by his wife Callie, whom he married in October 1957; sons Ron, Tom, Andrew; and daughter Melanie. All are married, and produced handsome grandchildren.