Douglas X-3 Stiletto

Built by Douglas Aircraft Company for USA in 1952. It's purpouse was to test influence of long hypersonic flights on aircraft's construction, performance of short wings and suitability of titanium as material for building aircrafts. As engines, which were originally meant to be used for this craft was too big, it was equipped with lighter, but weaker Westinghouse J34(two). Because of this modification, aircraft wasn't able to break the sound barrier, so it couldn't serve it's primary purpuose. Nonetheless it contributed to designing stronger tires, due to it's very high landing speed(about 130m/s). In 1953 it was sent to US airforce. They just did some wing profiles' tests because of the craft's weak performance. The last flight took place in 1956 and then Stiletto ended up in National Museum of the United States Airforce.