The Republic XF-103 Thunderwarrior was an American project to develop a high speed interceptor aircraft to destroy Soviet bombers. Despite a prolonged development, it never progressed past the mock-up stage. Design and development In 1949, the USAF issued a request for an advanced supersonic interceptor, known as the "1954 Interceptor" project, or Weapon System WS-201A. It called for a supersonic aircraft with all-weather capability, intercept radar and air-to-air missile armament. Republic wa… (More on Xf-103)