He was one of twelve pilots who flew the North American X-15, an experimental spaceplane jointly operated by the Air Force and NASA.

On June 27, 1963, he flew the X-15 to an altitude above 50 miles, thereby qualifying as an astronaut according to the United States definition of the boundary of space.

He also received a Bachelor of Science degree in aeronautical engineering from the U.S. Air Force Institute of Technology (AFIT) in 1954.

After five years with the Reserve and Air National Guard, during which he received a bachelor's degree from the University of Maine, Rushworth was recalled to active duty in 1951.

[5] During Korean War, Rushworth served as a F-80C Shooting Star pilot with the 49th Fighter-Interceptor Squadron at Dow Air Force Base.

This flight above 50 miles qualified Rushworth for Astronaut Wings, though he would have attained that honor sooner had the USAF Man In Space Soonest project proceeded according to plan.

At the time of his retirement as a major general, he was vice commander, Aeronautical Systems Division, Air Force Systems Command, at Wright-Patterson Air Force Base, Ohio, where he dealt directly with senior deputies and managers and assisted the management of major acquisition programs such as the F-5, A-10, F-15, F-16 and B-1 as well as numerous modernization programs like the B-52 and C-5.