news

한어Русский языкEnglishFrançaisIndonesianSanskrit日本語DeutschPortuguêsΕλληνικάespañolItalianoSuomalainenLatina

in 1949, intelligence from the central intelligence agency showed that the number of new long-range bombers in the soviet union was increasing rapidly, and the threat to the united states was increasing day by day. of course, in fact, it was a soviet intelligence scam. the soviet union did not have so many long-range bombers. in fact, the soviet union was still using a large number of tu-4 propeller bombers at that time, which was a copy of the american b-29. (polar bears have successfully deceived uncle sam's intelligence system many times in history, and this time was one of them.) at that time, the interceptors equipped by the us air force, such as the f-86d "saber", f-89 "scorpion", and f-94 "spark", were all subsonic aircraft. the high-altitude and high-speed performance of these aircraft could no longer undertake the mission of intercepting the new soviet bombers. in order to counter the so-called "soviet long-range bomber threat", the us air force proposed the requirement to develop a new high-altitude and high-speed interceptor that year. this was the "interceptor 1954" project. the reason why it was called "1954" was that the americans expected this new interceptor to be in service in 1954.

after the end of world war ii, the design and construction of military aircraft, especially fighter jets, became increasingly complex. the fuselage structure, engine, avionics system and weapon system could no longer be considered as a single system with independent design, and the coordination between systems must be considered. at this time, the u.s. air force proposed the design concept of weapon systems, which integrated all the subsystems of the entire aircraft during the design phase. the "interceptor 1954" project also used this new concept. the important subsystems of the entire aircraft included an all-weather fire control radar system and an air-to-air missile fire control system. the two systems must be integrated into an airframe suitable for supersonic flight.

in march 1950, the "interceptor 1954" project was given the code name xf-103. in october of the same year, hughes won the contract for the avionics system. the design of the fuselage was put out for bidding by the us air force in june of that year. in january of the following year, a total of 6 companies submitted 9 different designs, of which republic aircraft alone proposed 3 different plans. in july 1951, the us air force announced that convair aircraft, lockheed and republic had won the advance development contract. the three companies would submit their models for the military to evaluate and determine the final winner. however, the us air force later felt that it would be too expensive to allow all three companies to proceed at the same time, so lockheed was eliminated at this stage.

republic's design was based on the all-weather high-altitude defense fighter design they proposed in 1948. the new aircraft is estimated to be able to reach a flight speed of mach 4 (4,160 km/h) at an altitude of 24,240 meters (80,000 feet). because the flight speed is very high, the entire fuselage will be made of titanium alloy as the main material to resist the high temperature generated by high-speed flight. in order to achieve the hypersonic speed of mach 4, its engine system design is also unique. it uses a variable cycle principle similar to the j58 engine on the later sr-71, that is, when the speed is less than mach 2, it uses the ordinary turbojet engine operation mode, and when the speed exceeds mach 2, the duct system surrounding the engine nozzle is opened, so that the high-speed airflow bypasses the main channel of the turbojet engine and directly ignites and burns in the combustion chamber behind it, that is, it works in the manner of a ramjet engine.

to meet this requirement, republic selected an existing xj67 engine for an improved design - the engine was an export version of the british bristol engine company's "olympus" turbojet engine produced under license. the improved xj67 was called the xj67-w-1, and its afterburner was specially designed: it was used as a normal afterburner at speeds less than mach 2, and as a tandem ramjet combustion chamber at hypersonic flight, so it was also considered a ramjet. this is the origin of the rumor that the xf-103 was a "twin" aircraft, but in fact the ramjet was just a component of the xj67-w-1.

the maximum thrust of xj67-w-1 is 6800 kg, and the afterburner thrust is 9980 kg. this performance was quite advanced at the time. later, the j58 on the sr-71 was successful by adopting the same design. but at that time, the technical difficulty of developing this variable cycle engine was far beyond the level of the us engine industry, and the development ultimately failed. xf-103 finally adopted the ordinary j65 turbojet engine, which greatly limited its high-altitude and high-speed performance. after the speed exceeded mach 2.5, the turbine was significantly affected by the airflow passing through it. the traditional means of controlling the engine turbine speed with the throttle was not effective, and the engine had a tendency to overspeed out of control. therefore, the maximum speed of xf-103 was limited to mach 3. many years later, the mig-25, which also used an ordinary turbojet engine, encountered the same problem. the failure to develop advanced engines made the speed advantage of xf-103 disappear, which became one of the main reasons for its cancellation.

in order to reduce drag and avoid any airflow interference, the xf-103 fuselage design is very smooth, with almost no visible protrusions, including the traditional canopy has been changed to a side window, so that the aircraft has almost no forward vision, the pilot must use a periscope to observe the front, and the integral ejection escape capsule is used, and the escape capsule is ejected downward. the main wing is a short delta wing design, the horizontal tail is also a short triangle, and there is a vertical stabilizer under the belly that can be folded during landing.

the xf-103 can carry six aim-4 "falcon" air-to-air missiles and 36 unguided rockets in the weapon bays on both sides of the fuselage. the air-to-air missiles are guided by a radar installed in the nose.

republic completed the full-scale model of the xf-103 in march 1953 and submitted it to the us air force for review. in june 1954, the military awarded republic a contract to produce three prototypes, but the production process was very slow and republic encountered major difficulties in the processing of titanium alloys. due to the considerable technical risks, the plan to put the xf-103 into service in 1954 was no longer possible. later, there were budget overruns, which reduced the prototype production plan to only one. in addition, the xj67-w-1 engine also encountered a series of delays and was eventually cancelled. finally, in august 1957, the us air force completely cancelled the xf-103 development plan.

convair, which was competing with republic, enlarged the failed xf-92a fighter and eventually generated a new f-102 interceptor design. the technical risk of this interceptor was much smaller than that of the xf-103. the u.s. air force believed that the f-102 was quite reliable, and quickly reviewed the design and put it into production for test flights.

looking back, the xf-103 left more lessons than experience. because republic was too bold and innovative in its design, which was seriously out of touch with reality, the xf-103 failed to achieve the expected performance. when the first generation of practical supersonic fighters (f-100) had not yet entered service, republic was eager to develop a hypersonic aircraft with a maximum flight speed of mach 4. this step was indeed too big. variable cycle engines and titanium alloy structural processing had exceeded the level that the us aviation industry could achieve in the early 1950s, so the failure of the xf-103 was doomed at the beginning of its development.