The Saab 37 Viggen (“Thunderbolt”, also “Tufted duck”) is a 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 8th February 1967 and entered service in 21st June 1971. The Viggen holds the distinction of being the first canard design to be produced in quantity.
Several distinctive variants of the Viggen were produced to perform the roles of strike fighter (AJ 37), aerial reconnaissance (SF 37), maritime patrol aircraft (SH 37) and a two-seat trainer (SK 37). 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 In November 2005, the Viggen was retired from service by the Swedish Air Force, the sole operator of the type, having been replaced by the newer Saab JAS 39 Gripen.
The Viggen was initially developed as an intended replacement for the Saab 32 Lansen in the attack role and later the Saab 35 Draken as a fighter. In 1955, as Saab’s prototype Draken, the most aerodynamically advanced fighter in the world at that point, performed its first flight, the Swedish Air Force was already forming a series of requirements for the next generation of combat aircraft; due to the challenging nature of these requirements, a lengthy development time was anticipated, with the first flight intended to be no early than the middle of the next decade. Between 1952 and 1957, the first studies towards what would become the Viggen were carried out, involving the Finnish aircraft designer Aarne Lakomaa. Over 100 different concepts were examined in these studies, involving both single- and twin engine configurations, both traditional and double delta wings, and canard wings. Even VTOL designs were considered, with separate lift engines, but were soon identified as being unacceptable.
From the onset, the Viggen was planned as an integrated weapon system, to be operated in conjunction with the newest revision of Sweden’s national electronic air defense system, STRIL-60. It was used as the nation’s standard platform, capable of being efficiently adapted to perform all tactical mission roles. Other requirements included supersonic ability at low level, Mach 2 performance at altitude, and the ability to make short landings at low angles of attack (to avoid damaging improvised runways). The aircraft was also designed from the beginning to be easy to repair and service, even for personnel without much training.
One radical requirement of the proposed aircraft was the ability for it to be operated from straight stretches of rural highways only 500 meters long; this was considered critical to reducing the vulnerability to attack in the event of a pre-emptive strike upon the nation through the dispersal of aircraft from established airbases to more austere improvised landing strips. In order to enable such operations, this imposed several critical demands upon the design, including a modest landing speed, no-flare touchdown, powerful post-landing deceleration, accurate steering even in crosswinds on icy surfaces, and high acceleration on take-off.
In 1960, the U.S. National Security Council, led by President Eisenhower, formulated a military security guarantee for Sweden, promising US military help in the event of a Soviet attack against Sweden; both countries signed a military-technology agreement. In what was known as the “37-annex”, Sweden was allowed access to advanced U.S. aeronautical technology which made it possible to design and produce the Viggen much faster and more cheaply than would otherwise have been possible. According to research by Nils Bruzelius at the Swedish National Defence College, the reason for this officially unexplained U.S. support was to protect U.S. Polaris submarines deployed just outside the Swedish east coast against the threat of Soviet anti-submarine aircraft. However, Bruzelius’ theory has been discredited by Simon Moores and Jerker Widén. The connection also appears doubtful due to the time scale – the Viggen’s strike version only became operational in 1971, and the fighter version in 1978, by which time Polaris had already been retired.
In December 1961, the Swedish government gave its approval for the development of Aircraft System 37, which would ultimately become the Viggen. By 1962, all elements for the project either existed or were close to fully developed; these included the aircraft itself, the powerplant, ejector seat, armaments, reconnaissance systems, ground servicing equipment, and training equipment such as simulators. In February 1962, approval of the overall configuration was given and was followed by a development contract in October 1962. According to aviation authors Bill Gunston and Peter Gilchrist, the project was “by far the largest industrial development task ever attempted in Sweden”. During the 1960s, the Viggen accounted for 10 per cent of all Swedish R&D funding.
In 1963, Saab finalized the aerodynamic design of the aircraft; the aerodynamic configuration was radical: it combined an aft-mounted double delta wing with a small, high-set canard foreplane, equipped with powered trailing flaps mounted ahead of and slightly above the main wing; this would be judged to be the best means to satisfy the conflicting demands for STOL performance, supersonic speed, low turbulence sensitivity at low level flight, and efficient lift for subsonic flight. Canard aircraft have since become common in fighter aircraft, notably with the Eurofighter Typhoon, Dassault Rafale, Saab JAS 39 Gripen and the IAI Kfir, but principally for the purposes of providing agility during flight rather than for its STOL capabilities. Further aerodynamic refinements during the later stage of development included the addition of dog-tooth patterns upon the main wing to generate vortices, allowing for the elimination of blown flaps from the canard. The use of a thrust reverser enabled the sought short landing performance.
During development, Saab had opted to power the type using a single large turbofan engine. Originally, the British Rolls-Royce Medway engine had been selected to power the Viggen, which was then considered to be ideal for the basis for a supersonic engine equipped with a fully modulated afterburner; however, development of the Medway engine was cancelled due to the intended launch aircraft, the de Havilland Trident, being downsized during development. In place of the Medway, Saab chose to adopt a licence-production version of the American Pratt & Whitney JT8D engine, the Volvo RM8, instead. The RM8 was heavily redesigned, using new materials to accommodate flight at Mach-2 speeds, a Swedish-built afterburner, and a fully variable nozzle.
During 1964, construction of the first prototype aircraft commenced; on 8th February 1967, the first of an eventual seven prototypes conducted its maiden flight, which had occurred as per the established development schedule. This first flight, which lasted for 43 minutes, was flown by Erik Dahlström, Saab’s chief test pilot, who reported the prototype to have been easy to handle throughout. Writing at the time, aerospace publication Flight International described the flight as having been “Sweden’s astonishing unilateral stand in the front rank of advanced aircraft-building nations…”
Each of the seven prototypes were assigned different roles, although the initial aircraft were focused on supporting the development of the initial production variant, the AJ37. In 1967, the Swedish Government concluded that the in-development AJ 37 Viggen would be both cheaper and superior to the McDonnell Douglas F-4 Phantom II. In April 1968, the Swedish government formally issued the authorization for manufacturing of the Viggen to proceed, issuing an order for 175 Viggens that year. Also in 1968, Saab began work on the Viggen’s maritime reconnaissance and photo reconnaissance variants. In May 1969, the Viggen made its first public appearance outside of Sweden at the Paris Air Show. On 23rd February 1971, the first production aircraft, an AJ37 model, conducted its first flight. In July 1971, the first production aircraft was delivered to the Swedish Air Force.
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 21st 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, thus, 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 4th 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 performed to the Viggen since its introduction had “doubled the effectiveness of the overall system”.
A weapons load of up to 7,000 kg could be accommodated on nine hardpoints: 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 wet pylon and was usually occupied by an external fuel tank. A pair of air-to-air missiles were intended to be placed on the outboard wing pylons, which were more lightweight than the other attachment points. The pylons behind the landing gear were not used until the JA 37D modification when BOY countermeasure dispensers were fitted to them. Ground crew would enter the munitions fitted into the aircraft’s central computer using a load-selector panel, which would automatically choose the correct values for fire control, fuel consumption, and other calculations.
The AJ 37 was typically equipped with a total of seven hardpoints, three underneath the fuselage and two under each wing, a further two wing-mounted hardpoints could be optionally fitted but this facility was rarely used. Various munitions could be carried, such as several types of rockets: the 135 mm M56GP 4 kg armour-piercing, the M56B with 6.9 kg of HE, and the M70 with a 4.7 kg HEAT warhead.
The AJ 37 was designed to carry two RB 04E anti-ship missiles on the inboard wing pylons with an optional third missile on the centreline pylon. The RB-04 was a relatively simple cruise missile which was further developed to become the more capable RBS-15, also integrated on the Viggen. An optional load consisted of two RB 05 air-to-surface missiles on the fuselage pylons. The RB 05 was later replaced by AGM-65 Maverick (Swedish designation “RB 75”) TV-guided missiles. In a ground-attack role, a combination of unguided 135 mm rockets in sextuple pods and 120 kg fragmentation bombs on quadruple-mounts could be used. Other armaments include explosive mines, and 30 mm ADEN cannon pods with 150 rounds of ammunition on the inboard wing pylons.
Self-defence measures included various electronic countermeasures (ECM) systems, as well as either the AIM-4 Falcon (Swedish designation “RB 28”) or AIM-9 Sidewinder (Swedish designation “RB 24”) air-to-air missiles. At one point, the AJ 37 Viggen was under consideration as a carrier of both a Swedish nuclear weapon and chemical weapons, although no nuclear or chemical weapons were ultimately adopted by Sweden.
The JA 37 fighter interceptor, introduced in 1979, featured the Ericsson PS 46/A radar, which was capable of guiding the medium-range semi-active radar homing RB 71 Skyflash air-to-air missiles. Both the RB 71 and the PS 46/A radar were designed to provide the Viggen with a look-down/shoot-down capability and to engage targets at beyond visual range distances. The JA 37 could carry up to two RB 71s on the fuselage pylons; in a typical air defense loadout, these would typically had been combined with four RB 24J/RB 24J air-to-air missiles, a more capable and newer version of the Sidewinder missile than employed on earlier Viggen variants.
Following the evaluation of several alternative cannons, including the British ADEN cannon, the American M61 Vulcan, and French DEFA cannon, an Oerlikon KCA 30mm cannon was selected for the JA 37. The KCA was carried, along with 126 rounds of ammunition, in a conformal pod under the fuselage. The firing rate of the cannon was selectable at 22 or 11 rounds. It reportedly fired 50% heavier shells at a higher velocity than the ADEN cannon, resulting in six and a half times the kinetic energy on impact, and was effective up to 2,000 meters. This, in conjunction with the fire control system, allowed air-to-air engagements at longer range than other fighters.
In July 1971, the first production AJ 37 Viggen was delivered to the Swedish Air Force. F 7 Såtenäs became the first wing to receive deliveries of both the single-seat AJ 37 attack model and the twin-seat SK 37 training model of the Viggen, where upon the type began to replace their existing Lansen aircraft. Conversion training to pilot the Viggen involved a minimum of 450 flight hours performed on an initial mixture of the Saab 105, the Lansen, and finally the Viggen itself; dedicated Viggen simulators were also used, the latter of which was seen as a decisive factor in the ease of conversion to the type.
In October 1973, F 7 Såtenäs was reportedly close to achieving full operational effectiveness; by May 1974, the Swedish Air Force had two operational squadrons using the Viggen along with a third squadron in the final process of achieving that status. By 1974, the safety and reliability levels of the Viggen were reportedly above expectations, despite the overall complexity and relative newness of the aircraft. In practice, one of the most significant issued encountered with the Viggen during low-level flight, as extensively performed during a typical attack mission profile, was the threat posed by birds; as such, the Swedish Air Force paid close attention to their migratory patterns.
During the later half of the 1970s and into the 1980s, the introduction of various variants of the Viggen proceeded; these included the SK 37, a two-seat operational-conversion trainer, introduced in 1972, the SF 37, an overland reconnaissance model, introduced in 1977, and the SH 37, a maritime reconnaissance version, introduced in 1975. By September 1980s, the JA 37 fighter-interceptor model of the Viggen was introduced, F 13 Norrköping being the first wing of the Swedish Air Force to convert to the new type. The Viggen went on to become Sweden’s primary air defense platform for many years.
When operated from austere bases and improvised landing strips such as public roads, an intended function of the type, a single Viggen could be maintained by a team of five conscripts under the supervision of a single chief mechanic. During such operations, a standard turnaround, including refueling and rearming, took less than ten minutes to perform; while an engine replacement took four hours. Over the long term, the Viggen required 22 man hours per flight hour of maintenance work at the depot level, and nine man hours per flight hour at the front line.
By the mid-1980s, Swedish Viggen fighter pilots, using the predictable patterns of Lockheed SR-71 Blackbird routine flights over the Baltic Sea, had managed to achieve missile lock-on with radar on the SR-71 on numerous occasions. Despite heavy jamming from the SR-71, target illumination was maintained by feeding target location from ground-based radars to the fire-control computer in the Viggen. The most common site for the lock-on to occur was the thin stretch of international airspace between Öland and Gotland that the SR-71 used on the return flight. The Viggen is the only aircraft to get an acknowledged radar lock on the SR-71.
By 1994, the replacement of the Viggen by the later and more advanced Saab JAS 39 Gripen was in progress, the type being progressively phased out as greater numbers of Gripen aircraft were delivered. In November 2005, the last front line Viggen was formally retired by the Swedish Air Force. A few aircraft were kept in an operational condition for electronic warfare training against the Gripen at F 17M in Linköping; the last of these Viggen flights took place in June 2007.
Although the Viggen was offered by Saab for sale worldwide, and was the subject of a heavy marketing campaign in both European and developing countries during the 1970s, ultimately no export sales were made.
During the 1970s, Saab proposed a new variant of the Viggen, designated the Saab 37E Eurofighter (unrelated to the later Eurofighter Typhoon), for the United States Air Force’s Air Combat Fighter competition to find a replacement for the Lockheed F-104 Starfighter. The 37E Eurofighter competed against Dassault-Breguet’s proposed Mirage F1M-53, the SEPECAT Jaguar, Northrop’s P-530 Cobra (based on the Northrop YF-17), and General Dynamics’s YF-16; on 13th January 1975, Secretary of the Air Force John L. McLucas announced the YF-16 had been selected as the winner of the ACF competition.
In 1978, the United States blocked a major prospective sale to India, which would have involved selling a number of Swedish-built Viggens in addition to a licensed production agreement under which the Viggen would also have been built in India, by not issuing an export license for the RM8/JT8D engine and other American technologies used. India later opted to procure the SEPECAT Jaguar in its place. According to leaked US diplomatic cables, India’s interest in the Viggen was reported to be entirely due to Rajiv Gandhi’s influence, and had alleged have been without any input from the Indian Air Force. According to author Chris Smith, the Viggen had been the favoured candidate for the Indian Air Force prior to the deal being blocked by the US.
By 1994, the replacement of the Viggen by the later and more advanced Saab JAS 39 Gripen was in progress, the type being progressively phased out as greater numbers of Gripen aircraft were delivered. In November 2005, the last front line Viggen was formally retired by the Swedish Air Force. A few aircraft were kept in an operational condition for electronic warfare training against the Gripen at F 17M in Linköping; the last of these Viggen flights took place in June 2007.
An AJS 37 Viggen (s/n 37098) with the code F 7–52 has been retained and went through a long period of restoration and maintenance to be airworthy again. This Viggen was built in 1977 and served all its active duty in F 15 Wing at Söderhamn. It was transferred into civil registry with the registration number SE-DXN. It undertook its maiden flight after having been approved by the authorities on 27th March 2012 from the F 7 Wing at Såtenäs. The Viggen is unpainted to represent the first delivered Viggens as they looked in the early 1970s.
Aviation 72 1/72nd scale Viggens available from Flying Tigers.
Aviation 72 have produced some great 1/72nd scale Viggens and the latest arrival at Flying Tigers has been “flying off the shelves” as soon as it arrived. Sold out this week on first delivery , more have arrived today to meet the demand. There are more models in the series and these are availble to order from stock or pre-order now.
Aviation 72 1/72nd scale Arrivals at Flying Tigers this week.
The following models have just arrived at Flying Tigers. Pre-orders are being dispatched this week and those of you that have pre-ordered these models will be receiving them shortly, if you have not already received them.
I have small quantities on the shelf available to order for immediate dispatch if you have not already ordered.
Please click on the individual images to go straight to the model of your choice or CLICK HERE to see the full range of Aviation 72 Range available to order.
Many of these models are made with very small Limited Editions, so if you want one, order early to avoid missing out.
That’s all for this week.
Thank you for reading this week’s Newsletter.
Richard.
Flying Tigers.