Saab JA 37 Viggen

Summary

Description

Development work on the Saab 37 Viggen began in the early 1950s, intended as a replacement for the Saab 32 Lansen in the attack role and later for the Saab 35 Draken as a fighter. Saab's design team pursued a relatively radical delta wing configuration, with operation as an integrated weapon system in conjunction with Sweden's STRIL-60 national electronic air defense system. The aircraft was also designed to operate from runways as short as 500 meters. The "37-annex" facilitated access to advanced U.S. aeronautical technology, accelerating both design and production. The aerodynamic design was finalized in 1963. The prototype performed its maiden flight on 8 February 1967. In the following year, the Swedish government ordered an initial batch of 175 Viggens.

The first production AJ 37 Viggen was delivered to the Swedish Air Force in July 1971, with the Skaraborg Wing (F 7) being the first to receive both the single-seat attack and twin-seat training models, replacing their existing Lansen aircraft. Conversion training involved a minimum of 450 flight hours and the use of dedicated simulators, which proved to be a decisive factor in easing the transition. By May 1974, the Swedish Air Force had two operational squadrons and a third nearing operational status, with safety and reliability levels reportedly exceeding expectations despite the aircraft's complexity.

The Saab 37 Viggen was designed with several unique features, including its aerodynamic configuration that combined an aft-mounted double delta wing with a small, high-set canard foreplane equipped with powered trailing flaps. This configuration was selected to satisfy the conflicting demands for STOL performance, supersonic speed, low turbulence sensitivity at low level flight, and efficient lift for subsonic flight. Constructed using a bonded metal honeycomb structure with extensive use of aluminum, the airframe was designed to withstand the stresses of no-flare landings, while the rear section of the fuselage, downstream of the engine nozzle, featured a heat-resistant titanium ring. Avionics included the CK 37, the world's first airborne computer to use integrated circuits, which served as the integrating unit for all electronic equipment. Later variants adopted the Singer-Kearfott SKC-2037 digital central processor and an Ericsson PS 37 X-band monopulse radar, enhancing the aircraft's capabilities.

The Saab 37 Viggen could accommodate a weapons load of up to 7,000 kg on nine hardpoints, consisting of one centreline pylon, two fuselage pylons, two inner and two outer wing pylons, and two pylons behind the wing landing gear. The centreline pylon was the only one plumbed for carrying an external fuel tank. A pair of air-to-air missiles were intended for the outboard wing pylons, which were more lightweight than the other attachment points, and the pylons behind the landing gear were used on the JA 37D for BOL countermeasure dispensers. The AJ 37 was typically equipped with seven hardpoints and could carry rockets such as the 135 mm M56GP armour-piercing, the M56B with high explosives, and the M70 with a HEAT warhead. It was designed to carry two RB 04E anti-ship missiles, with an optional third on the centreline pylon and, alternatively, two Rb 05 air-to-surface missiles which were later replaced by AGM-65 Maverick television-guided missiles. The JA 37 fighter interceptor featured the Ericsson PS 46/A radar to guide the medium-range RB 71 Skyflash air-to-air missiles and could carry up to two RB 71s on the inner wing pylons, often combined with four RB 24J air-to-air missiles, while an Oerlikon KCA 30mm cannon was carried in a conformal pod under the fuselage, along with 126 rounds of ammunition.

Throughout the late 1970s and 1980s, further variants were introduced, including the SK 37 operational-conversion trainer, the SF 37 overland reconnaissance model, and the SH 37 maritime reconnaissance version. By September 1980, the JA 37 fighter-interceptor model was introduced, becoming Sweden's primary air defense platform for many years, designed to be simple to maintain even by conscripted mechanics. Despite Saab's marketing efforts, the Viggen saw no export sales, including a blocked sale to India in 1978 due to the United States not issuing an export license for the RM8/JT8D engine and other American technologies. In 1994, the replacement of the Viggen by the Saab JAS 39 Gripen began, with the last front-line Viggen formally retired on 25 November 2005; a few aircraft were kept for electronic warfare training against the Gripen until June 2007.

Main Variants:

• AJ 37: Primarily a single-seat ground-attack fighter aircraft with a secondary fighter role.

• SK 37: A two-seat trainer aircraft with no radar and reduced fuel capacity.

• SF 37: A single-seat photographic reconnaissance aircraft with radar replaced by a battery of cameras in the nose.

• SH 37: A single-seat maritime reconnaissance and strike aircraft, equipped with PS-371A radar.

• JA 37: Primarily a single-seat all-weather interceptor fighter, with a secondary attack role and a 10 cm stretch in the fuselage.

Technical specifications

Current operating countries

No country is operating the JA 37 Viggen in 2025.

All operators

Sweden

Armament

Missiles payload:

• Air-to-Surface AGM-65 Maverick
• Air-to-Air Medium-Range AIM-120 AMRAAM
• Air-to-Air Short-Range Raytheon AIM-9 Sidewinder
• Air-to-Air Medium-Range Skyflash

Photo of JA 37 Viggen

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