Robert Aitken "Bob" Rushworth (October 9, 1924 – March 18, 1993) was an American United States Air Force major general, World War II, Korean War and Vietnam War pilot, mechanical and aeronautical engineer, test pilot and astronaut. He was one of twelve pilots who flew the North American X-15, an experimental spaceplane jointly operated by the Air Force and NASA. He flew 34 of the program's 199 flights, more than any other pilot. 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. However, this altitude did not surpass the Kármán line, the internationally accepted boundary of 100 kilometers (62 miles). Biography Early life and education Rushworth was born on October 9, 1924, in Madison, Maine, to parents Walter Aitken Rushworth (1892–1949) and Mabel Julia Rushworth (; 1891–1992). He had one older brother, Cornell Cameron Rushworth (1920–1944), who was killed in action during World War II. Rushworth attended Madison Memorial High School, where he was a class president for four years, graduating in 1942. After attending Hebron Academy, a prep school, from which he graduated in June 1943, and joining the United States Army Air Forces, he studied mechanical engineering at the University of Maine, receiving a Bachelor of Engineering degree in 1951. He also received a Bachelor of Science degree in aeronautical engineering from the U.S. Air Force Institute of Technology (AFIT) in 1954. In 1967, he graduated from the National War College in Washington D.C. Flight experience and military service In September 1944, Rushworth earned his pilot wings and a second lieutenant commission following his aviation cadet training program graduation. His first assignment was with the 12th Combat Cargo Squadron in February 1945, in the China-Burma-India Theater of Operations, where he flew C-47 Skytrain transport combat missions from India throughout the Burma Campaign and C-46 Commandos over the "Hump" in the Himalaya Mountains to Shanghai and Beijing. 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. During Korean War, Rushworth served as a F-80C Shooting Star pilot with the 49th Fighter-Interceptor Squadron at Dow Air Force Base. Following his graduation from the U.S. Air Force Institute of Technology in 1954, Rushworth stayed at Wright-Patterson Air Force Base