page_title: Saab 37 Viggen
section_title: Further development
hierarchical_section_title: Saab 37 Viggen / Development / Further development
caption_attribution_description: A Saab SF 37 Viggen (no. 37951) in the air over airbase F 13 Bråvalla.
context_page_description: The Saab 37 Viggen is a retired Swedish single-seat, single-engine, short-medium range combat aircraft. Development work on the type was initiated at Saab in 1952 and, following the selection of a radical delta wing configuration, the resulting aircraft performed its first flight on 8 February 1967 and entered service in 21 June 1971. It was the first canard design produced in quantity. The Viggen was also the most advanced fighter jet in Europe until the introduction of the Panavia Tornado into operational service in 1981.
  Several distinct variants of the Viggen were produced to perform the roles of strike fighter, aerial reconnaissance, maritime patrol aircraft and a two-seat trainer. In the late 1970s, the all-weather fighter-interceptor aircraft JA 37 variant was introduced. In November 2005, the Viggen was retired from service by the Swedish Air Force, the only operator, having been replaced by the newer Saab JAS 39 Gripen.
context_section_description: As the initial AJ 37 Viggen was being introduced to service, further variants of the Viggen proceeded to complete development and enter production. In 1972, the first SK 37, an operational trainer variant with a staggered second canopy for an instructor, was delivered to the Swedish Air Force. On 21 May 1973, the first prototype of SF 37 Viggen, a tactical reconnaissance variant featuring a modified nose to accommodate seven sensors, conducted its first flight.
  While other variants entered production during the 1960s, Saab continued the development of the more capable all-weather interceptor version of the aircraft, the JA 37. In 1970, Sweden's air defenses had been closely inspected and it was determined that the prospective JA 37 Viggen was highly suited to the role. In 1972, the Swedish government authorized the development of the fighter-interceptor variant to proceed, which was followed by several major contracts for the JA 37's further development. A total of five prototypes would be produced, four of which being modified AJ 37s and one being a sole pre-production JA 37 model, to test the control systems, engine, avionics, and armaments respectively. In June 1974, the first of these prototypes conducted its maiden flight; later that year, an initial order for 30 JA 37s was issued by the Swedish government.
  The JA 37 Viggen featured various changes from its predecessor, including revisions to the design of the airframe, the use of the more powerful RM8B powerplant, a new generation of electronics being adopted, and a revised armament configuration employed; the principle externally visible changes from most earlier variants were a taller tailfin and the underfuselage gunpack arrangement. The JA 37, in addition to its principal aerial combat mission, also retained a secondary ground-attack capability, and was better suited to low-level operations. In November 1977, the first production JA 37 Viggen conducted its maiden flight. Operational trials for the new variant were conducted between January and December 1979, which resulted in the type being introduced to operational service that year. According to Flight International, at the time of the JA 37's introduction, it was the most advanced European fighter then in service.
  In April 1964, the Swedish government revealed its budget proposal for the Swedish Air Force, in which it had been envisioned that 800 or more Viggens would be produced, which was in turn intended to allow all other combat aircraft then in service with the Swedish Air Force to be replaced with this single type. However, a combination of inflation and other factors eventually reduced the total number of aircraft manufactured to 329. By 1980, up to 149 JA 37 Viggens were projected to be built, and the line to be closed within the decade as the Swedish aerospace industry changed focus to the impending Saab JAS 39 Gripen, the Viggen's eventual replacement. Over time, advances in computing, such as the microprocessor, had enabled greater flexibility than the physical configuration of the Viggen, so further development of the Viggen platform was not viewed as cost-effective. In 1990, production of the Viggen ceased and the final aircraft was delivered.
  In May 1991, a SEK 300-million program to upgrade 11 AJ37, SF37 and SH37 Viggens to a common multirole variant, designated AJS37, was announced. Amongst the changes involved, interchangeable armaments and sensor payloads were implemented in addition to the adoption of new mission planning and threat analysis computer systems. The onboard ECM systems were also improved. Specifically, the implementation of a new stores management system and MIL-STD-1553 serial data bus, similar to that used on the newer JAS 39 Gripen, allowed for the integration of the AIM-120 AMRAAM air-to-air missile; an upgraded Ericsson PS-46A radar was installed, and a new tactical radio. On 4 June 1996, the first upgraded prototype JA37 Viggen performed its first flight.
  In 1996, according to Swedish air force material-department chief General Steffan Nasstrom, the various upgrades per
caption: An SF 37 Viggen in flight, 1977
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