In 1955, the X-1-2 was modified to include a new thin wing and a low-pressure fuel system. The most visible change was a raised canopy that replaced the original flush windshield on the aircraft, called the X-1E. The modified aircraft made its first glide flight on December 12, 1955, and its first powered flight three days later. Over a three-year period, the X-1E made a total of 26 flights, reaching a speed of Mach 2.24. National Advisory Committee for Aeronautics (NACA) pilot Joseph Walker was the pilot for flights 1 through 21, while John McKay made flights 22 to 26. The final flight occurred on November 6, 1958. This was also the last flight by an X-1 aircraft.