In April 1938, Hull was called to active duty with the 2nd Bombardment Group at Langley Field, Virginia, to help publicize the capabilities of the new B-17 Flying Fortress.

He conceived the interception of the Italian ocean liner Rex over 600 miles at sea as part of a training exercise, and on May 12, 1938, flew on the lead bomber in what turned into a hazardous but highly successful mission.

Just prior to returning to active duty with the Army Air Corps Hull served in the Sperry Company as Assistant to the Vice-President.

Gen. Ira C. Eaker to England as his A-2, and served in both the Eighth Air Force and the Mediterranean theater as a combat intelligence officer during World War II.

In 1969 he was awarded a patent (US3440635) for a radio press-button alarm, portable, car based or static, which sends a coded signal to tell receivers nearby the source of the alarum.