English: The Boeing X-32, left, and the Lockheed X-35 competed for the DoD contract to produce the Joint Strike Fighter (JSF) in 1997. Both companies received $750 million grants to build prototypes.The new single-engine, Mach-1 capable aircraft needed to be stealthy and provide robust situational awareness to the pilot during attacks on ground targets and when fighting in air-to-air engagements. It also needed to meet the specifications of the U.S. Air Force, U.S. Navy and U.S. Marine Corps as well as nation partners. Lockheed won the competition which would eventually produce the F-35 Lightning II. (photo / Boeing)