X-3 Stiletto

The Douglas X-3 Stiletto is a 1950s United States experimental jet aircraft with a slender fuselage and a long tapered nose, manufactured by the Douglas Aircraft Company. Its primary purpose was to investigate the design features of an aircraft suitable for sustained supersonic speeds, which included the first use of titanium for major airframe components. The aircraft was intended to have a maximum speed of around 2,000 mph (3,200 km/h), but it was underpowered for this purpose and could not even exceed Mach 1 in level flight. Although it was a disappointment, Lockheed designers used data from the X-3 tests for the Lockheed F-104 Starfighter which used a similar trapezoidal wing and was capable of Mach 2.