Republic XF-103
cancelled American military plane project of the 1940s-1950s
The Republic XF-103 was an American project to develop a powerful missile-armed interceptor aircraft capable of destroying Soviet bombers while flying at speeds as high as Mach 3. Despite a prolonged development, it never progressed past the mockup stage.
Development
In 1949, the USAF issued a request for an advanced supersonic interceptor to equip the Air Defense Command. Known formally as Weapon System WS-201A, but better known informally as the 1954 interceptor, it called for a supersonic aircraft with all-weather capability, powerful aircraft interception radar, and air-to-air missile armament. Republic was one of six companies to submit proposals. On 2 July 1951, three of the designs were selected for further development, Convair's scaled-up XF-92 that evolved into the F-102, a Lockheed design that led to the F-104, and Republic's AP-57. AP-57 was an advanced concept to be built almost entirely of titanium and capable of Mach 3 at altitudes of at least 60,000 feet (18 km).
A full-scale mock-up of the AP-57 was built and inspected in March 1953. A contract for three prototypes followed in June 1954. Work on the prototypes was delayed by continued problems with the titanium construction, and more by continuing problems with the proposed Wright J67 engine.
“Republic XF-103” enters the record as cancelled American military plane project of the 1940s-1950s. Crown Archives preserves that source wording while asking what Republic, XF-103 and cancelled can confirm, complicate or overturn.
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Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Oct 25, 2025. The linked authority identifier is Q1807615. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1949, 1954, 1951 and 1953.
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This entry incorporates text from “Republic XF-103” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.