X-3 StilettoX 3 Stiletto NASA airplane model. The X 3 twin turbojet, the sole model constructed, was developed to evaluate the capabilities necessary for sustained supersonic flight at high altitudes. Additionally, it served to assess the application of novel materials like titanium and innovative construction methods. On October 20, 1952, the X 3 took off for its maiden flight at Edwards AFB, California, and achieved supersonic flight in June 1953. In contrast