North American Aviation X-15A-2 56-6671 engine ignition, 3 October 1967 Published on October 2, 2013 in 3 October 1967Full resolution (1600 × 1261) ← Previous Next → The North American Aviation X-15A-2 56-6671 ignites the XLR99 engine after being released from the mothership, Balls 8, 3 October 1967. (U.S. Air Force)