Republic XF-103

Republic XF-103 Thunderwarrior
Design of the XF-103
Type:	Interceptor
Design country:	United States
Manufacturer:	Republic Aviation Company
First flight:	Never happened
Commissioning:	Development canceled in 1957
Production time:	Was never produced
Number of pieces:	no

The Republic XF-103 was a design for a US high-speed interceptor . Republic Aviation developed it in the early 1950s for the United States Air Force (USAF) , but it did not get beyond the model stage. The XF-103 belonged to the so-called Century series ( F-100 to F-110 ).

history

The XF-103 was based on Republics Model AP-44A in 1948, a design for an all-weather interceptor for high speeds and altitudes combined Turbojet - and ramjet engine (ramjet) for the Air Force initially not interested. In 1949 Republic took part in the tender for a new fighter for the USAF (1954 Interceptor) with the revised model AP-57 . Although this design was only ranked eighth of nine in an evaluation by the Air Materiel Command , it was one of the winners on July 2, 1951, alongside designs by Convair (Model 8) and Lockheed (L-205). The order initially comprised the construction of a 1: 1 model ( mock-up ). In November 1951, the Luftwaffe narrowed the selection further for reasons of cost. Lockheed's project was discontinued, Convair was able to continue its work in full and was ultimately the winner of the competition with the resulting F-102 Delta Dagger . Republic was also allowed to continue development, but the USAF has now classified it as a research project. Also in November, the AP-57 received the official USAF designation XF-103 and was also known by the nickname Thunderwarrior . The weapon system designation for the XF-103 was WS-204A.

On March 2, 1953, the Air Force inspected the completed mock-up of the XF-103 and suggested some changes, and in June 1954 Republic received the order to build three prototypes . The development was slow due to technical problems. In early 1957, the USAF initially reduced the program to a prototype before finally abandoning it on August 21, 1957. In total, the project cost $ 104 million.

construction

Since the AP-57 was designed for speeds of over Mach 3 and altitudes of 24,000 meters and more, the technical implementation was a challenge. According to the plans from 1951, the slim fuselage was 22.4 m long and should be made entirely of titanium consist. Its cross-section was round at the front and merged into an approximately rectangular shape towards the middle. The entire rear half took up the drive: A Wright XJ67-W-1 turbojet (a license from Bristol Olympus, UK ) with a thrust of at least 52 kN and behind it a Wright XRJ55-W-1 ramjet . On the one hand, this second engine could be used as an afterburner by directing the exhaust gas jet from the J67 directly into the RJ55. That should have generated a total thrust of around 87 kN. From speeds of over Mach 2.2, the ramjet engine should serve as the sole drive with 84 kN. A large air inlet was located in the middle under the fuselage, with pure ramjet propulsion the air should be routed around the J67 by means of flaps and ducts.

The wings were triangular, centered on the fuselage and swept at 55 degrees . However, the XF-103 was not a pure delta wing , as there were also horizontal and vertical stabilizers with triangular surfaces at the stern . A foldable fin under the stern provided additional longitudinal stability. The angle of incidence of the wings could be changed during flight, as Republic had planned for the XF-91 . The first drafts envisaged a cockpit with a canopy and a streamlined extension. Due to feared thermal problems due to the high flight speed, the cockpit was completely integrated into the fuselage. Even the front windows were omitted, the pilot only had side windows and a periscope system for the forward view , which was successfully tested with an F-84G . A normal ejection seat was out of the question due to the high speed, so that the pilot sat in an escape capsule that should be shot down in an emergency.

Since the XF-103 was primarily intended to intercept approaching Soviet bombers, appropriate armament was provided: six air-to-air guided missiles of the type MX-904 (referred to as GAR-1 Falcon from 1955 ) and 2 × 18 unguided 70 mm missiles of the Mighty Mouse type . For aerodynamic reasons, all weapons were housed in internal shafts behind the cockpit and attached to retractable weapon mounts.

According to calculations from 1957, with the revised drive (J67-W-3), a thrust of 98 kN with afterburner and 166 kN in ramjet mode, a maximum speed of Mach 3.7 and a climb rate of 11,600 m / min (based on sea level) would have been possible .

Technical specifications

Mock-up of the XF-103

• All information is purely theoretical, as no machine has ever been completed

Parameter	Data
crew	1 pilot
length	23.50 m
span	10.50 m
Wing area	37.20 m²
Wing extension	2.96
Wing loading	Minimum (empty weight): 304 kg / m² Nominal (normal take-off weight): 470 kg / m² Maximum (max. Take-off weight): 523 kg / m²
height	5.10 m
Empty mass	11,317 kg
normal takeoff mass	17,466 kg
Max. Takeoff mass	19,443 kg
Top speed	up to Mach 3.7
Rate of climb	11,600 m / min
Service ceiling	24,390 m
Use radius	394 km
Transfer range	2,486 km
Engines	a Wright XJ67-W-3 jet engine with up to 66.75 kN a Wright XRJ55-W-1 ramjet engine with up to 83.66 kN
Armament	6 GAR-1 Falcon air-to-air guided missile 36 unguided 70mm missiles

literature

• Dennis R. Jenkins: Titanium Titan: The Story of the XF-103. In: Airpower Magazine 34/1, 2004.
• Anthony L. Buttler: American Secret Projects: Fighters & Interceptors 1945–1978. Midland Publishing, 2007. ISBN 1-85780-264-0

Web links

Commons : Republic XF-103  - Album with pictures, videos and audio files

• USAF Museum about the XF-103