Cold War

Saab 37 Viggen – Sweden’s Thunderbolt in the Sky

The Saab 37 Viggen, a remarkable icon in the realm of aviation, has etched its place in the annals of aeronautical history for its avant-garde design and remarkable performance.

This single-engine aircraft, primarily designed and built by Saab AB, played a crucial role in maintaining the sovereignty of Sweden’s airspace during the later part of the 20th century.

The word ‘Viggen’ translates to ‘The Thunderbolt’ in English – a fitting moniker considering its power, speed, and resilience.

The double delta wing was an iconic part of the design.
The double delta wing was an iconic part of the design.



The Saab J 35 Draken was introduced in the 50s and represented the pinnacle of interceptor technology for its time.

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With its distinctive double-delta wing configuration and powerful engine, the Draken was primarily designed to defend Swedish airspace against high-altitude bombers.

An Austrian J-35 Draken on fullafterburner showing off its colours.
The Saab Draken was also way ahead of its time. Photo credit – HoHun CC BY-SA 4.0.

However, as the geopolitical landscape evolved during the Cold War, Sweden’s defence requirements began to change.

The need for a versatile multirole aircraft that could handle air defence, ground attack, and maritime roles became increasingly apparent.

This shift in strategy required an aircraft with advanced capabilities that the Draken simply could not offer.

In response to these evolving demands, Saab AB began developing the Saab 37 Viggen in the early 1960s.

The Viggen was designed to incorporate state-of-the-art technology that could cater to the multirole demands of modern warfare.

It was envisioned to have superior speed, greater manoeuvrability, enhanced electronic systems, and a larger weapons load than the Draken.

Despite being designed in the 60s this fighter still looks modern today. Photo credit - Brorsson CC BY-SA 3.0.
Despite being designed in the 60s this fighter still looks modern today. Photo credit – Brorsson CC BY-SA 3.0.

In response to this requirement, Saab AB, a renowned Swedish aerospace company, designed the Viggen, which was introduced to the Swedish Air Force in 1971.

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The Viggen marked a significant departure from the conventional designs of its time, featuring a double delta wing configuration and a forward canard, making it highly distinctive.

The aircraft was built around a powerful Volvo RM8 turbofan engine, which was a modified version of the American Pratt & Whitney JT8D engine.

The double delta wing configuration was one of the key design elements that set the Viggen apart.

This design combined two delta wings with different sweep angles – a steeper inner section and a shallower outer section. This unique configuration offered several advantages.

Firstly, the double delta design helped improve the Viggen’s lift-to-drag ratio at high angles of attack, increasing its manoeuvrability at various speeds.

The wing configuration gave the Viggen the ability to perform high angle of attack manoeuvres. Photo credit - Alan Wilson CC BY-SA 2.0.
The wing configuration gave the Viggen the ability to perform high-angle of attack manoeuvres. Photo credit – Alan Wilson CC BY-SA 2.0.

It also allowed for short takeoff and landing (STOL) capabilities, which were crucial considering the specific requirements of the Swedish Air Force to operate from short and potentially damaged runways.

Furthermore, the aerodynamic efficiency of the double delta wing configuration made the Viggen an excellent high-speed aircraft, while still providing stability and control at lower speeds.

This combination of high-speed performance and low-speed control was vital for the multirole nature of the J-37’s operations.

The Viggen

Underneath its unique airframe, the Saab 37 Viggen was powered by a single Volvo RM8 turbofan engine, generating a thrust of approximately 28,100 pounds with afterburner.

This made it possible for the aircraft to reach top speeds of up to Mach 2.1, or around 2,231 kilometres per hour.

The RM8 engine. Photo credit - Andrzej Otrebski CC BY-SA 3.0.
The RM8 engine. Photo credit – Andrzej Otrebski CC BY-SA 3.0.

The aircraft’s operational range was impressive, with a combat radius of 1,000 kilometres, making it highly effective for a variety of missions.

The Viggen boasted a service ceiling of around 18,000 meters, allowing for high-altitude operations too including photo-reconnaissance.

The PS-37/A radar was a vital component of the Saab 37 Viggen’s advanced electronics suite.

Developed in Sweden during the late 1960s and early 1970s, it represented a significant technological achievement for its time.

The radar was a multi-mode radar, capable of air-to-air, air-to-ground, and air-to-sea operation, fitting the multirole nature of the Viggen.

This versatile radar allowed the Viggen to engage with a wide range of targets effectively across different mission profiles.

In air-to-air mode, the PS-37/A radar had a look-up/look-down capability, enabling the aircraft to detect, track, and engage airborne targets above and below the aircraft, even against the ground clutter.

This feature was especially crucial for the JA 37 interceptor variant of the Viggen, which was responsible for air defence roles.

In air-to-ground and air-to-sea modes, the radar could assist with navigation, target identification, and weapons delivery, making the Viggen a capable ground-attack and maritime strike aircraft.

Variants and their Roles

The Viggen came in several variants, each designed for a specific role in the Swedish Air Force. The AJ 37 was the initial attack version, equipped to engage ground and naval targets with a variety of weaponry.

An SF-37 Viggen. Photo credit - Rune Rydh CC BY 4.0.
An SF-37 Viggen. Photo credit – Rune Rydh CC BY 4.0.

The SF 37 and SH 37 variants were designed for photo-reconnaissance and maritime surveillance missions, respectively.

The JA 37 interceptor variant was introduced later in 1979.

It had an enhanced engine, updated radar, and increased weapon load, specifically geared towards air defence roles.

It carried the Skyflash missile for BVR engagements and the shorter-range Sidewinder missile for close-quarters dogfights.

The SK 37 was a two-seat trainer variant, meant to train pilots for the Viggen’s high-performance flight envelope.

In the mid-90s, a few of these were converted into the SK 37E electronic warfare training aircraft, commonly referred to as the ‘Viggen Jammer’.

Operational History

The Viggen first entered service with the Swedish Air Force in 1971, beginning a distinguished operational career that would span 34 years. Its initial variant, the AJ 37, was an attack version designed to handle ground and naval targets.

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The Sk37 Viggen is a twin seat trainer version. Photo credit - Airwolfhound CC BY-SA 2.0
The Sk37 Viggen is a twin-seat trainer version. Photo credit – Airwolfhound CC BY-SA 2.0

The aircraft’s advanced electronics and navigation systems allowed for all-weather and nighttime operations, a significant advantage at the time.

In 1972, the SF 37 and SH 37 variants entered service.

The SF 37 was designed for photo-reconnaissance missions and featured advanced photographic equipment in the nose.

The SH 37, on the other hand, was a maritime patrol aircraft with surface search capabilities and the ability to carry anti-ship missiles.

In 1979, the JA 37 interceptor variant joined the Swedish Air Force.

The JA 37 was a key component of Sweden’s air defence strategy, tasked with defending Swedish airspace against potential threats.

This variant boasted several upgrades over the previous models, including an improved engine, a more advanced radar system, and increased weapons load.

Equipped with the longer-range Skyflash missile and the shorter-range Sidewinder missile, the JA 37 became a formidable air-to-air combatant.

A Viggen with Skyflash missiles. Photo credit - Lennart Johansson CC BY 4.0.
A Viggen with Skyflash missiles. Photo credit – Lennart Johansson CC BY 4.0.

The Skyflash was an integral part of the aircraft’s armament, particularly for the JA 37. This medium-range, air-to-air missile was designed to provide beyond-visual-range (BVR) interception capabilities, a crucial aspect of modern air combat.

Originally based on the American AIM-7 Sparrow missile but upgraded – the most significant improvement of the Skyflash over the Sparrow was the incorporation of an active radar seeker, developed from the one used in the shorter-ranged AIM-9L Sidewinder missile.

This active radar seeker allowed the Skyflash missile to ‘lock on’ to a target and track it independently, without continuous guidance from the launching aircraft.

This meant that once the missile was launched and had locked onto a target, the aircraft was free to manoeuvre or engage other targets.

The missile had a range of approximately 50 kilometres and could reach speeds of up to Mach 4.

In the hands of the Saab 37 Viggen, the Skyflash missile became a potent tool in Sweden’s air defence strategy, and was important to its success, providing a robust long-range interception capability.

A JA-37C. Photo credit - Mike Freer GFDL 1.2.
A JA-37C. Photo credit – Mike Freer GFDL 1.2.

It greatly enhanced the Viggen’s air combat effectiveness, allowing it to engage with airborne threats from a safe distance.

The Viggen also underwent a series of upgrades in the late 1990s and early 2000s to extend its service life and improve its capabilities.

These upgrades included the integration of modern weapons systems and enhancements to the aircraft’s radar and avionics.

However, by the turn of the 21st century, the Viggen was beginning to show its age in the face of rapid technological advancements in military aviation.

In 2005, the Viggen was officially retired from service, replaced by the Saab JAS 39 Gripen, a more modern multirole fighter.

Is The Saab Viggen Still In Service?

No, the Saab Viggen is not still in service. It was removed from the Swedish Air Force on 25th November 2005. However, the Air Force kept using a few aircraft in use until June 2007. As of now, it is no longer an active military aircraft for the Swedish Air Force. Saab JAS 39 Gripen is the successor of the Saab Viggen.


The Saab 37 Viggen, with its innovative design and multirole capabilities, represented a significant leap forward in aviation technology during its time.

The cockpit of a J-37. Photo credit - Per80 CC BY-SA 3.0.
The cockpit of a J-37. Photo credit – Per80 CC BY-SA 3.0.

The aircraft’s unique double delta wing configuration, powerful engine, and advanced electronics allowed it to excel in a variety of roles, making it a truly versatile tool for the Swedish Air Force.

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Though the Viggen was retired in 2005, and replaced by the even more advanced Saab JAS 39 Gripen, its legacy continues to influence modern aircraft design.

It stands as a testament to the technological prowess and vision of its creators, and it remains an iconic symbol of Sweden’s aviation history.

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  • Crew: 1
  • Length: 16.4 m (53 ft 10 in)
  • Wingspan: 10.6 m (34 ft 9 in)
  • Height: 5.9 m (19 ft 4 in)
  • Empty weight: 9,500 kg (20,944 lb)
  • Gross weight: 16,439 kg (36,242 lb) (AJ37 17,000 kg (37,479 lb))
  • Max takeoff weight: 19,274 kg (42,492 lb)
  • Powerplant: 1 × Volvo RM8B afterburning turbofan, 72.1 kN (16,200 lbf) thrust dry, 125 kN (28,000 lbf) with afterburner
  • Maximum speed: 2,231 km/h (1,386 mph, 1,205 kn) at 36,100 ft (11,003 m)
  • Ferry range: 1,820 km (1,130 mi, 980 nmi) internal fuel only
  • Service ceiling: 18,000 m (59,000 ft)
  • Rate of climb: 203 m/s (40,000 ft/min)