He was selected for the X-15 program in 1958, and made his first flight on November 4, 1960. Over the next six years, he made 34 flights in the X-15, the most of any pilot. Commemorative cover with a cachet honoring the X-15 program, signed under the cachet in blue ballpoint by Rushworth. In fine condition, with small address label affixed to lower right. RRAuction COA.
