View source for Saab 37 Viggen

{{Short description|1967 Swedish fighter aircraft family}}
{{Redirect2 |Viggen|Saab Viggen|the car|Saab 9-3#Saab 9-3 Viggen}}
{{Use dmy dates|date=October 2019}}
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{{Infobox aircraft
| name = Saab 37 Viggen
| image = Viggen (52526298757).jpg
| image_caption = A SK 37 Viggen in flight
| aircraft_type = [[Multirole combat aircraft]]<ref name= "saab.com">{{cite web |title= Viggen - ryggraden i det svenska flygvapnet under tre decennier |url= https://www.saab.com/sv/markets/sweden/stories/2021/saab-37-viggen | language = sv | website= Saab |publisher=Saab AB |access-date= 2023-03-08}}</ref>
*AJ 37: [[Fighter bomber]]
*SF 37: [[Reconnaissance aircraft|Photo reconnaissance]]
*SH 37: [[Maritime patrol aircraft|Maritime patrol]]
*JA 37: [[Strike fighter]]
*SK 37: [[Trainer aircraft]]
| manufacturer = [[Saab AB]]
| national_origin = Sweden
| first_flight = 8 February 1967
| introduction = 21 June 1971 (AJ 37)
| retired = 26 June 2007 (SK 37E)
| primary_user = [[Swedish Air Force]]
| produced = 1970–1990<ref name = "bomber 247">Gunston and Gilchrist 1993, p. 247.</ref>
| number_built = 329<ref name = "bomber 247" />
| variants = 
}}
The '''Saab 37 Viggen''' (''The [[Tufted Duck]]'', ambiguous with ''The [[Thunderbolt]]'')<ref name=fmv>{{Cite web |last=Nilsson |first=Axel |url= https://www.fmv.se/en/Projects/JAS-39-Gripen/Milestones/ |title=JAS 39 Gripen − Milestones |work=Projects |publisher=Swedish Defence Materiel Administration |date=13 January 2012 |access-date=12 February 2014 |quote=Swedish naming of aircraft |url-status=dead |archive-url=https://web.archive.org/web/20140222071158/https://www.fmv.se/en/Projects/JAS-39-Gripen/Milestones/ |archive-date=22 February 2014 |df=dmy-all}}</ref> is a single-seat, single-engine [[multirole combat aircraft]] designed and produced by the Swedish aircraft manufacturer [[Saab AB|Saab]].<ref name= "saab.com"/> It was the first [[Canard (aeronautics)|canard]]-equipped aircraft to be produced in quantity<ref name="fred 279">Fredriksen 2001, p. 279.</ref> and the first to carry an airborne [[Computer#Digital computers|digital central computer]] with [[integrated circuit]]s for its avionics, arguably making it the most modern/advanced [[combat aircraft]] in Europe at the time of introduction. The digital central computer was the first of its kind in the world, automating and taking over tasks previously requiring a navigator/copilot, facilitating handling in tactical situations where, among other things, high speeds and short decision times determined whether attacks would be successful or not, a system not surpassed until the introduction of the [[Panavia Tornado]] into operational service in 1981.<ref>{{Citation |date=8 May 2016 |first=Mario H. |last= Zorro |url=https://www.plane-encyclopedia.com/cold-war/sweden-cold-war/saab-s37-viggen/ |title=Saab S37 Viggen |encyclopedia=Plane Encyclopedia}}.</ref>

Development work begun during the early 1950s to develop a successor to the [[Saab 32 Lansen]] in the attack role, as well as to the [[Saab 35 Draken]] as a fighter. Saab's design team opted for a relatively radical [[delta wing]] configuration, and operation as an integrated weapon system in conjunction with Sweden's [[STRIL]]-60 national electronic air defense system. It was also designed to be operated from runways as short as 500 meters. Development work was aided by the "[[Sweden–United States relations#Military relations|37-annex]]" under which Sweden could access advanced U.S. [[Aeronautics|aeronautical]] technology to accelerate both design and production.<ref name= "SDRA"/> The aircraft's aerodynamic design was finalised in 1963. The prototype performed its [[maiden flight]] on 8 February 1967 and the following year the Swedish government ordered an initial batch of 175 Viggens. The first of these entered service with the [[Swedish Air Force]] on 21 June 1971.

Even as the initial AJ 37 model entered service, Saab was working on further variants of the Viggen. Several distinct variants of the Viggen would be produced to perform the roles of [[fighter bomber]]/[[strike fighter]] (AJ 37), [[aerial reconnaissance]] (SF 37), [[maritime patrol aircraft|maritime patrol]]/[[Anti-surface warfare|anti-surface]] (SH 37) and a [[Trainer aircraft|two-seat trainer]] (Sk 37). During the late 1970s, the all-weather [[interceptor aircraft|interceptor]]/[[strike fighter]] JA 37 variant was introduced. Attempts to [[export]] the Viggen to other nations were made, but ultimately proved unsuccessful. In November 2005, the last Viggens were withdrawn from service by the Swedish Air Force, its only operator; by this point, it had been replaced by the newer and more advanced [[Saab JAS 39 Gripen]].

== Name ==
''Viggen'' is the [[definiteness|definite form]] of the [[Swedish language|Swedish]] word ''vigg'', which has two meanings. According to Saab, the aircraft's name alluded to both.

The first meaning refers to the Swedish name for the [[tufted duck]], a small [[diving duck]] common in Sweden. In this sense, it serves as a reference to the aircraft's [[Canard (aeronautics)|canard]] configuration, as "canard" is French for duck.

''Vigg'' is also ''åskvigg'', or "thunderbolt" (thunder wedge), stemming from the [[Thunderstone (folklore)|thunderstones]] of [[Nordic folklore]], called "åskviggar", said to come from the lightning strikes of [[Norse mythology|Norse god]] [[Thor]] when he hunted [[Giants (Norse mythology)|giants]] with his [[war hammer]], [[Mjölnir]].<ref>{{Cite web|date=2020-10-13|title=Saab history, Saab 37 Viggen|url=https://history.saab.com/teman/svensk-sakerhet/saab-37-viggen/|website=history.saab.com|access-date=13 October 2020|archive-date=24 September 2020|archive-url=https://web.archive.org/web/20200924153454/https://history.saab.com/teman/svensk-sakerhet/saab-37-viggen/|url-status=dead}}</ref>

== Development ==
=== Origins ===
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.<ref name= "Karling">{{Citation |last= Karling |first= Krister |language= sv |title= Saab 37 Viggen – utvecklingen av ett Nytt Enhetsflygplan för det Svenska Flygvapnet 1952–1971: Sett ur en Aerodynamikers Perspektiv |isbn= 91-631-2395-9 |place= Stockholm |publisher= Svenska mekanisters riksfören |series= Småskrift | issn = 1652-3563 | number = 2 |trans-title= Saab 37 Viggen – Development of a New Unitary aircraft for the Swedish Air Force 1952–1971: From an Aerodynamicist's View |year= 2002}}</ref><ref name= "saab 60" /> 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 earlier than the middle of the next decade.<ref name= "bomber 243">Gunston and Gilchrist 1993, p. 243.</ref><ref name= "field 707">Field 1974, p. 707.</ref> 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 [[Delta wing#double delta|double delta]] wings, and [[Canard (aeronautics)|canard wings]]. Even [[VTOL]] designs were considered, with separate lift engines, but were soon identified as being unacceptable.<ref name= "Karling" /><ref name= "field 707" /><ref name= "warwick 1260" />

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.<ref name= "bomber 243" /> Other requirements included [[Supersonic speed|supersonic]] ability at low level, [[Mach number|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.<ref>{{Citation | first1 = Anders | last1 = Nowotny | first2 = Sten | last2 = Ekedahl | url = http://www.aircraftresourcecenter.com/AWA1/101-200/walk200_viggen/walk200.htm | title = Viggen walkaround | publisher = Aircraft resource center | access-date = 23 April 2007 | archive-date = 20 February 2007 | archive-url = https://web.archive.org/web/20070220110308/http://www.aircraftresourcecenter.com/AWA1/101-200/walk200_viggen/walk200.htm | url-status = dead }}</ref><ref>Bitzinger 1991, p. 18.</ref>

One radical requirement of the proposed aircraft was the ability for it to be operated from relatively short runways only 500 meters long; this was part of the [[Bas 60]] air base system that had been introduced by the Swedish Air Force in the late 1950s. Bas 60 revolved around [[force dispersal]] of aircraft across many wartime air bases, including [[Highway strip|road runways]] acting as backup runways.<ref>{{Cite web | place = NU |url= http://www.fht.nu/Dokument/Flygvapnet/flyg_publ_dok_flygbassystemet_bas_60.pdf |archive-url=https://web.archive.org/web/20150924012245/http://www.fht.nu/Dokument/Flygvapnet/flyg_publ_dok_flygbassystemet_bas_60.pdf |archive-date=2015-09-24 |url-status=live|title= Flygbassystem 60 |last= Rystedt|first= Jörgen |date= 1 October 2005 | work = FHT}}</ref><ref>{{Cite web | place = [[Sweden|SE]] |url= https://www.forsvarsmakten.se/siteassets/5-information-och-fakta/historia/vagbaserna/fortv-2007-1.pdf |archive-url=https://web.archive.org/web/20170603214913/http://www.forsvarsmakten.se/siteassets/5-information-och-fakta/historia/vagbaserna/fortv-2007-1.pdf |archive-date=2017-06-03 |url-status=live |title= Svenska militära flygbaser|last=Törnell |first= Bernt |date= 5 February 2007 | work = Forsvarsmakten}}</ref><ref>{{Cite web | place = SE |url= https://www.forsvarsmakten.se/siteassets/5-information-och-fakta/historia/vagbaserna/fortv_rapport_2006.1.pdf |archive-url=https://web.archive.org/web/20170604001219/http://www.forsvarsmakten.se/siteassets/5-information-och-fakta/historia/vagbaserna/fortv_rapport_2006.1.pdf |archive-date= 2017-06-04 |url-status=live |title= Svenska reservvägbaser|last= Andersson |first= Lennart |date= 23 November 2006 | work = Forsvarsmakten}}</ref> Utilizing partially destroyed runways was another factor that motivated STOL capability. Bas 60 was developed into [[Bas 90]] in the 1970s and 1980s, and included short runways only 800 meters in length.<ref>{{Cite web | place = NU |url= http://www.fht.nu/Dokument/Flygvapnet/flyg_publ_dok_flygbassystem_90.pdf |archive-url=https://web.archive.org/web/20160514115339/http://fht.nu/Dokument/Flygvapnet/flyg_publ_dok_flygbassystem_90.pdf |archive-date=2016-05-14 |url-status=live |title= Flygbassystem 90 |last= Rystedt | first= Jörgen |date= 20 April 2009 | work = FHT}}</ref> Enabling such operations 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.<ref name= "bomber 243" />

In 1960, the U.S. [[United States National Security Council|National Security Council]], led by President [[Dwight D. Eisenhower|Eisenhower]], formulated a security guarantee for Sweden, promising U.S. military help in the event of a Soviet attack against Sweden; both countries signed a military-technology agreement. In what was known as the "[[Sweden–United States relations#Military relations|37-annex]]", Sweden was allowed access to advanced U.S. [[Aeronautics|aeronautical]] technology that made it possible to design and produce the Viggen much faster and more cheaply than would otherwise have been possible.<ref name= "SDRA">{{Citation |language= sv | place = SE |url= http://www.foi.se/Global/Våra%20tjänster/Rapporter/Tidningen%20Framsyn/Framsyn%202005/Framsyn%20Nr%201%202005.pdf |title= Hemliga atomubåtar gav Sverige säkerhetsgaranti |trans-title= Secret nuclear submarines gave Sweden security guarantee |newspaper= Framsyn |year= 2005 |number= 1 |publisher= The Swedish Defence Research Agency}} {{Dead link |date= March 2018 |bot= InternetArchiveBot |fix-attempted= yes}}</ref> According to research by [[Nils Bruzelius]] at the [[Swedish Defence University|Swedish National Defence College]], the reason for this officially unexplained U.S. support was to protect U.S. [[UGM-27 Polaris|Polaris]] submarines deployed just outside the Swedish east coast against the threat of Soviet anti-submarine aircraft.<ref name= "SDRA" /> However, Bruzelius' theory has been discredited by Simon Moores and Jerker Widén.<ref name="KKrVAHT nr 4 2007">{{Citation |language= sv |url= http://www.kkrva.se/wp-content/uploads/Artiklar/074/kkrvaht_4_2007_9.pdf |archive-url=https://web.archive.org/web/20120321195606/http://www.kkrva.se/wp-content/uploads/Artiklar/074/kkrvaht_4_2007_9.pdf |archive-date=2012-03-21 |url-status=live |title= En djärv tes utan empiriskt stöd |trans-title= A bold claim without empirical support |journal= KKrVAHT |number= 4 |year= 2007 |place= SE}}</ref> 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.{{Citation needed |date= March 2016}}

=== Project launch ===
In December 1961, the Swedish government gave its approval for the development of ''Aircraft System 37'', which would ultimately become the Viggen.<ref name="saab 60">[http://saabgroup.com/about-company/history/1960s/ "1960s."] ''Company History'', Saab. Retrieved 6 March 2016.</ref> 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.<ref name="bomber 243" /> In February 1962, approval of the overall configuration was given and was followed by a development contract in October 1962.<ref name="field 707" /> According to aviation authors [[Bill Gunston]] and Peter Gilchrist, the project was "by far the largest industrial development task ever attempted in Sweden".<ref>Gunston and Gilchrist 1993, pp. 243–44.</ref> During the 1960s, the Viggen accounted for 10 percent of all Swedish R&D funding.<ref>Larsson, Letell and Thörn 2012, p. 47.</ref>

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 [[Flap (aeronautics)|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.<ref name="saab 60" /><ref name="bomber 244">Gunston and Gilchrist 1993, p. 244.</ref> 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.<ref name= "warwick 1260" /><ref>Roskam 2002, p. 206.</ref> Further aerodynamic refinements during the later stage of development included the addition of [[Leading-edge extension#Dogtooth extension|dog-tooth]] patterns upon the main wing to generate [[Vortex|vortices]], allowing for the elimination of [[blown flap]]s from the canard. The use of a [[thrust reversal|thrust reverser]] enabled the sought short landing performance.<ref name= "bomber 244" /><ref>Roskam 2002, p. 376.</ref>

[[File:AJ37 Viggen Aircraft.jpg|thumb|left|AJS 37 Viggen on display at the [[Swedish Air Force Museum]], [[Linköping]]]]
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 [[Hawker Siddeley Trident|de Havilland Trident]], being downsized during development.<ref name="bomber 244" /> 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.<ref name="bomber 244" />

During 1964, construction of the first [[prototype]] aircraft commenced; on 8 February 1967, the first of an eventual seven prototypes conducted its [[maiden flight]], which had occurred as per the established development schedule.<ref name="Donald Military">Donald 1996, p. 366.</ref><ref name= "proto first" /><ref>Eliasson 2010, pp. 81–82.</ref> 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…"<ref name="proto first">[https://www.flightglobal.com/pdfarchive/view/1967/1967%20-%200272.html "The Viggen Airborne."] ''Flight International'', 16 February 1967, p. 270.</ref>

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.<ref name = "bomber 245">Gunston and Gilchrist 1993, p. 245.</ref> In 1967, the Swedish Government concluded that the in-development AJ 37 Viggen would be both cheaper than and superior to the [[McDonnell Douglas F-4 Phantom II]].<ref name="warwick 1261" /> 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.<ref name="saab 70s" /><ref name= "ford 617">Ford 1973, p. 617.</ref> Also in 1968, Saab began work on the Viggen's maritime reconnaissance and photo reconnaissance variants.<ref name= "ford 617" /> In May 1969, the Viggen made its first public appearance outside of Sweden at the [[Paris Air Show]].<ref>[https://www.flightglobal.com/pdfarchive/view/1969/1969%20-%200974.html "Paris Airshow..."] ''Flight International'', 29 May 1969, p. 880.</ref> On 23 February 1971, the first production aircraft, an AJ37 model, conducted its first flight.<ref name="bomber 247" /> In July 1971, the first production aircraft was delivered to the Swedish Air Force.<ref name="saab 70s">[http://saabgroup.com/about-company/history/1970s/ "1970s."] ''Company history'', Saab. Retrieved 6 March 2016.</ref><ref name = "Eliasson 87">Eliasson 2010, p. 87.</ref>

=== Further development ===
[[File:Saab SF 37 Viggen 37951 F 13 Bråvalla 001.jpg|thumb|An SF 37 Viggen in flight, 1977]]
As the initial AJ 37 Viggen was being introduced to service, further variants of the Viggen proceeded to complete development and enter production.<ref name = "wagner 125">Wagner 2009, p. 125.</ref> 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.<ref name = "fred 279" /><ref name="ford 616">Ford 1973. p. 616.</ref> 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.<ref>Wagner 2009, pp. 125–26.</ref>

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.<ref name="warwick 1261" /> 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.<ref name="ford 617" /> 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.<ref name="warwick 1261" /> 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.<ref name="warwick 1261" />

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 principal externally visible changes from most earlier variants were a taller tailfin and the underfuselage gunpack arrangement.<ref name = "fred 279" /><ref name="warwick 1260" /><ref>Chant 2014, pp. 458–59.</ref> 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.<ref name="warwick 1261" /><ref name="chant 458" /> In November 1977, the first production JA 37 Viggen conducted its maiden flight.<ref name="chant 459" /> 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.<ref name="chant 459">Chant 2014, p. 459.</ref><ref name= "warwick 1265" /> According to [[Flight International]], at the time of the JA 37's introduction, it was the most advanced European fighter then in service.<ref name="warwick 1260" />

[[File:Saab JA37C Viggen, Sweden - Air Force AN1117367.jpg|thumb|left|JA 37 Viggen at the [[Royal International Air Tattoo]] 1993]]
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.<ref>[https://www.flightglobal.com/pdfarchive/view/1964/1964%20-%201127.html "World News: Over 800 Viggens."] ''Flight International'', 23 April 1964, p. 630.</ref> However, a combination of [[inflation]] and other factors eventually reduced the total number of aircraft manufactured to 329.<ref name="bomber 247" /> 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.<ref name= "warwick 1260" /> 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.<ref>Eliasson 2010, pp. 87, 229.</ref> In 1990, production of the Viggen ceased and the final aircraft was delivered.<ref>Forsberg 1994, p. 220.</ref><ref name = "Eliasson 82">Eliasson 2010, p. 82.</ref>

In May 1991, a [[Swedish krona|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.<ref name="bomber 247" /> Specifically, the implementation of a new stores management system and [[MIL-STD-1553]] [[serial communication|serial]] [[bus (computing)|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.<ref name="upgrade flies" />

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".<ref name="upgrade flies">Jeziorski, Andrzej. [https://www.flightglobal.com/news/articles/saab-flies-upgraded-viggen-fighter-12677/ "Saab flies upgraded Viggen fighter."] ''Flight International'', 19 June 1996.</ref>

== Design ==
=== Propulsion ===
[[File:Viggen cockpit.jpg|thumb|Closeup view of the cockpit and air intake of a JA 37 Viggen]]
The Viggen was powered by a single [[Volvo RM8]] turbofan. This was essentially a heavily modified [[Licensed production|licence-built]] variant of the [[Pratt & Whitney JT8D]] engine that powered commercial airliners of the 1960s, with an afterburner added for the Viggen. The airframe also incorporated a thrust reverser to use during landings and land manoeuvres, which, combined with the aircraft having flight capabilities approaching a limited STOL-like performance, enabled operations from 500&nbsp;m airstrips with minimal support.<ref name = "bomber 244" /> The thrust reverser could be pre-selected in the air to engage when the nose-wheel strut was compressed after touchdown via a [[Pneumatics|pneumatic]] trigger.<ref name = "warwick 1261">Warwick 1980, p. 1261.</ref><ref>Ahren, B. "Viggen Thrust Reverser", ''AIAA Journal of Aircraft'', vol. 18, no. 5, 1981.</ref>

The requirements from the Swedish Air Force dictated Mach 2 capability at high altitude and Mach 1 at low altitude. At the same time, short-field take-off and landing performance was also required. Since the Viggen was developed initially as an attack aircraft instead of an interceptor (the [[Saab 35 Draken]] fulfilled this role), some emphasis was given to low fuel consumption at high subsonic speeds at low level for good range. With turbofan engines just emerging and indicating better fuel economy for cruise than [[turbojet]] engines, the former was favoured, since the latter were mainly limited by metallurgy development resulting from limitations in [[Turbojet#Cycle improvements|turbine temperature]].{{Citation needed|date= January 2013}} Mechanical simplicity was also favoured, so the air intakes were simple D-section types with boundary layer [[Splitter plate (aeronautics)|splitter plates]], while the fixed inlet had no [[Inlet cone#Alternative shapes|adjustable geometry]] for improved pressure recovery. The disadvantage was that the required engine would be very large.<ref name = "bomber 244" /> In fact, at the time of introduction, it was the second-largest fighter engine, with a length of 6.1&nbsp;m and 1.35&nbsp;m diameter; only the [[Tumansky R-15]] was bigger.{{Citation needed|date = January 2013}}

[[File:Goteborg Volvo Museum 09 RM8.jpg|thumb|left|Volvo RM8 on display, 2014]]
Saab had originally wanted the [[Rolls-Royce Medway]] as the Viggen's powerplant.<ref name = "bomber 244" /> Owing to the cancellation of the Medway, the JT8D was instead chosen as the basis for modification. The RM8 became the second operational afterburning turbofan in the world, and also the first equipped with a thrust reverser. According to aviation author Christopher Chant, the RM8 has the distinction of being the first engine to be fitted with both an afterburner and a thrust reverser.<ref name = "chant 458">Chant 2014, p. 458.</ref> It had a bypass ratio of around 1.07:1 in the RM8A, which reduced to 0.97:1 in the RM8B.<ref name="Nativi">Nativi 1993</ref>{{Page needed | date = January 2014}} The RM8A was the most powerful fighter engine in the late 1960s.<ref name = "warwick 1260" />

The AJ, SF, SH and SK 37 models of the Viggen had the first version of the RM8A engine with uprated internal components from the JT8D that it was based on. Thrust was 65.6&nbsp;kN dry and 115.6&nbsp;kN with afterburner.<ref name = "Janes88-89 p 702" /> For the JA 37, the RM8A was developed into the RM8B, achieved by adding a third low-pressure compressor stage over the preceding model, increasing the turbine inlet temperature and fuel diffusion within the combustion chamber.<ref name="auto">Warwick 1980, p. 1264.</ref> Thrust is 72.1&nbsp;kN dry and 125.0&nbsp;kN with afterburner.<ref name="Janes88-89 p 702">Taylor 1988, p. 702.</ref> Owing to the increased length and weight of the RM8B engine over its predecessor, the airframe of the JA 37 was stretched in order to accommodate it.<ref name="auto" /> Onboard electrical power was provided by a 60 [[Volt-ampere|kVA]] generator. In the event of an in-flight engine failure, emergency power was provided by an automatically deploying [[ram air turbine]] (RAT), capable of generating 6 kVA.<ref name = "bomber 245" />

=== Avionics ===
[[File:LA2-Datasaab-CK37-full.jpg|thumb|upright|The CK 37 computer]]
In the early 1960s, it was decided that the Viggen should be a single seat aircraft, Saab having recognized that advanced avionics such as a [[Computer#Digital computers|digital central computer]] and a [[head-up display]] could perform the workload of a human navigator and entirely replace the need for a second crew member.<ref name = "bomber 244" /> The use of a digital computer would reduce or entirely replace [[Analogue electronics|analogue]] systems, which had proven to be expensive to maintain and alter, as had been the case of the earlier Draken, in addition to accuracy issues.<ref name = "data saab" /> The computer, called ''{{ill|CK 37|sv|Centralkalkylator 37}}'' (short for ''Centralkalkylator 37'', "central calculator 37"), was the world's first airborne computer to use [[integrated circuit]]s. Developed by [[Datasaab]], the CK 37 was the integrating unit for all electronic equipment to support the pilot, performing functions such as navigation, flight control, and weapon-aiming calculations.<ref name = "bomber 245" /><ref name="data saab">{{Citation|title=Central Computer for aircraft Saab 37, Viggen|url=http://www.datasaab.se/Papers/Articles/Viggenck37.pdf|place=Sweden|publisher=Data Saab|language=EN|trans-title=ViggenCK37 with photos|access-date=1 December 2007|archive-url=https://web.archive.org/web/20081030040312/http://www.datasaab.se/Papers/Articles/Viggenck37.pdf|archive-date=30 October 2008 |url-status=dead}}</ref><ref>[https://www.flightglobal.com/pdfarchive/view/1969/1969%20-%201463.html "INDUSTRY International."] ''Flight International'', 13 February 1969. p. 262.</ref> In practice, the CK 37 proved to be more reliable than predicted.<ref name = "data saab" />

On later variants of the Viggen, from the JA37 onwards, it was decided to adopt a newer and more powerful [[Kearfott Guidance & Navigation|Singer-Kearfott]] SKC-2037 digital central processor, license-manufactured and further developed by Saab as the CD 107.<ref name = "data saab" /><ref name= Goebel>{{Cite web |last=Goebel |first=Greg |url=https://www.airvectors.net/avvig.html |title=SAAB 37 Viggen |date=1 December 2021|quote="The rest of the JA 37's avionics suite included...[a] more powerful Singer-Kearfott SKC-2037 digital central processor, built by SAAB as the CD 107." |access-date= 26 June 2023}}</ref><ref name=globalaircraft>{{Cite web |url=https://www.globalaircraft.org/planes/saab_37_viggen.pl | quote="The avionics suite of the JA was a major improvement over the other variants designed a decade earlier. The onboard computer was a Singer-Kearfott SKC-2037 built under license by Saab as CD 107...." |publisher=Global Aircraft|title=Saab 37 Viggen |access-date=26 June 2023}}</ref> The computing techniques and concepts, such as [[distributed computing]], went beyond use of the Viggen, in addition to civil-orientated derivatives, it directly contributed to the computers used on board the Viggen's replacement, the Saab JAS 39 Gripen.<ref name = "data saab" /><ref name = "Eliasson 38">Eliasson 2010, p. 38.</ref> Various [[electronic countermeasure]]s (ECM) were installed upon the Viggen, these were typically provided by Satt Elektronik.<ref name = "bomber 245" /> The ECM systems consisted of a Satt Elektronik [[radar warning receiver]] system in the wings and the tail,<ref>{{Citation | title = ECM contract for MSDS | format = PDF | url = http://www.flightglobal.com/pdfarchive/view/1973/1973%20-%202723.html?search=Satt%20Elektronik | newspaper = Flight International | date = 1 November 1973 | publisher = Flight global | page = 762 | quote = Satt Elektronik in Sweden provides active and passive equipment for the Saab 105XT, Viggen and Lansen.}}</ref> an optional Ericsson Erijammer pod and [[BOZ counter-measures pod|BOZ-100]] [[Chaff (countermeasure)|chaff]]/[[Flare (countermeasure)|flare]] pod. [[Missile approach warning system#Infrared-based MAW|Infrared warning receivers]] were also later installed. In total, the electronics weighed 600&nbsp;kg, a substantial amount for a single-engine fighter of the era.<ref name = "bomber 245" />

The aircraft's principal sensor was an [[Ericsson]] PS 37 X-band [[monopulse radar]], which used a mechanically steered [[parabolic reflector]] housed in a [[radome]].<ref name = "bomber 245" /> This radar performed several functions, including air-to-ground and air-to-air [[telemetry]], [[radar configurations and types#Search|search]], [[Radar configurations and types#Targeting radars|track]], [[Terrain-following radar|terrain-avoidance]] and [[cartography]].<ref name = "ford 617" /> On the JA 37 fighter-interceptor model, the PS 37 radar was replaced by the more capable Ericsson PS 46 X-band [[pulse-doppler radar]], which had an all-weather [[look-down/shoot-down]] capability reportedly in excess of 50 kilometers and [[Semi-active radar homing#Continuous-wave|continuous-wave]] illumination for the [[Skyflash]] missiles as well as the [[Track while scan|ability to track two targets while scanning]].<ref name = "warwick 1261" /> According to Ericsson, it had a 50 percent chance of spotting a low-flying [[McDonnell Douglas F-4 Phantom II]] within a single scan and possessed a high level of resistance to interference from ECM.<ref name = "warwick 1261" />

Saab and [[Honeywell]] co-developed an automatic digital [[Aircraft flight control system|flight control system]] for the JA 37 Viggen, which has been claimed to be the first such system in a production aircraft.<ref name = "warwick 1261" /> To assist low altitude flight, a Honeywell [[radar altimeter]] with transmitter and receiver in the canard wings was used.<ref name = "bomber 245" /> The aircraft was also fitted with a Decca Type 72 [[Doppler radar#navigation|Doppler navigation radar]]. TILS (Tactical [[Instrument landing system|Instrument Landing System]]), a landing-aid system made by Cutler-Hammer AIL, improved landing accuracy to 30&nbsp;m from the threshold on the short highway airbase system.<ref>Battle, EH et al. "Some Early Achievements in Landing Guidance using Mechanically Scanned Pulse-encoded Beams", ''IEEE Transactions on Aerospace and Electronic Systems'', Vol. 25, no. 5, 1989, pp. 775–81.</ref> In order to effectively enforce Sweden's air space, the Viggen was integrated with [[STRIL|STRIL 60]] national defence system.<ref name = "bomber 243" /> The JA 37 Viggen was also equipped with a [[Garrett AiResearch]] digital [[Central Air Data Computer]], modified from the unit used upon the [[Grumman F-14 Tomcat]].<ref name = "warwick 1261" />

Initially, only a single reconnaissance (S) variant was considered, but fitting cameras as well as a radar proved to be impossible. The SH 37 maritime strike and reconnaissance variant was very similar to the AJ 37 and differed mainly in a maritime-optimized PS 371/A radar with longer range, a cockpit air-data camera and tape recorder for mission analysis. "Red Baron" and a SKa 24D 600&nbsp;mm LOROP camera pods were usually carried on the fuselage pylons.<ref name = "chant 458" /> The centreline fuel tank was converted for a short period of time to a camera pod with two Recon/Optical CA-200 1676&nbsp;mm cameras. In addition to the reconnaissance equipment, the SH 37 could also use all weapons for the AJ 37.{{Citation needed |date= January 2013}} For the photographic SF version, the radar in the nose was omitted in favour of four SKa 24C 120&nbsp;mm and two SKa 31 570&nbsp;mm photographic cameras as well as one 57&nbsp;mm VKa 702 [[Thermographic camera|Infrared linescan camera]] and air-data camera; all of which were integrated with and controlled by the aircraft's central computer.<ref name = "chant 458" /> Additional equipment, such as more camera pods, fuel tanks, ECM pods, and self-defense air-to-air missiles could also be carried upon the fuselage pylons.<ref name = "chant 458" />

The fighter-interceptor version of the Viggen, the JA 37, featured various avionics changes, including the extensive use of digital electronics alongside mechanical technology.<ref name = "Eliasson 115">Eliasson 2010, p. 115.</ref> In 1985, the "fighter link" entered service, permitting encrypted data communication between up to four fighters; this enabled one fighter to "paint" an airborne enemy with guidance radar for the [[Skyflash]] missiles of the three other fighters in a group while they had their own search and guidance radars switched off. This system was operational ten years before any other country's.<ref>{{Citation | date = April 2001 | url = http://www.militartekniska.se/mtt/include/archive/200104/MTT401_Viggen.pdf | title = Viggen | place = [[Sweden|SE]] | publisher = Militar tekniska | url-status=dead | archive-url = https://web.archive.org/web/20070926193720/http://www.militartekniska.se/mtt/include/archive/200104/MTT401_Viggen.pdf | archive-date = 26 September 2007 | df = dmy-all}}</ref> The autopilot was also slaved to the radar control to obtain better precision firing the cannon.<ref>Forsling, G. and Järmark, B. "Optimal Fuselage Aiming." ''AIAA Paper 85-1961''.</ref> Once in service, the Viggen's [[software]] was regularly updated every 18 months.<ref name = "Eliasson 125">Eliasson 2010, p. 125.</ref> In 1983, the [[mean time between failures]] (MTBF) was reported as 100 hours, a very high reliability level for the generation of avionics systems involved.<ref>Gunston, Bill ''Modern Combat Aircraft: From Fighters to Battlefield Helicopters''. Hong Kong: Hennerwood Publications, 1983. {{ISBN|978-0-86273-074-1}}.</ref>

=== Cockpit ===
[[File:Viggen 2008-03-01-35.jpg|thumb|Cockpit of an AJSF 37 Viggen]]
The displays in the original cockpit were all of the traditional analogue/mechanical type with the exception of an electronic [[head-up display]] (HUD), which Saab has claimed makes the Viggen easier to fly, especially at low altitudes during air-to-ground strike missions.<ref>[http://saab.com/globalassets/commercial/air/avionics-systems/aviguide-helicopter/saabs-history-hud.pdf "Head-Up Displays and Optical Systems."] {{Webarchive |url=https://web.archive.org/web/20160307043046/http://saab.com/globalassets/commercial/air/avionics-systems/aviguide-helicopter/saabs-history-hud.pdf |date=7 March 2016 }} ''Saab'', September 2014.</ref> Unusually for a 1970s fighter, the JA 37 variant of the Viggen featured three multi-purpose [[cathode-ray tube]] (CRT) display screens fitted within the cockpit, in a system called AP-12, developed by Saab and Ericsson.<ref name="Nativi" /> These displays would be used to display processed radar information, computer-generated maps, flight and weapons data, along with steering cues during precision landings.<ref name = "warwick 1265" />

[[File:Viggen skolversion.jpg|thumb|left|A two-seat SK 37 Viggen on display]]
Between 1989 and 1992, the AP-12 display system was subject to a substantial upgrade. In 1999, a new tactical [[liquid-crystal display]] (LCD) system derived from the Saab JAS 39 Gripen, which replaced the CRT-based AP-12 system, began flight tests with the Swedish Air Force.<ref>[https://www.flightglobal.com/news/articles/sweden-tests-viggen-upgrade-49475/ "Sweden tests Viggen upgrade."] ''Flight International'', 24 March 1999.</ref> On the twin-seat SK 37 trainer, the rear cockpit used by the instructor is only fitted with conventional instrumentation and lacks a HUD, computer controls and other features.<ref>Field 1974, pp. 709–10.</ref>

The ejection seat was the Raketstol 37 (literally; Rocket chair 37) and was the last Saab designed seat in service. A derivative of the [[Saab 105]] trainer seat, the seat was optimized for low altitude, high speed ejections.<ref name = "bomber 245" /> Once activated by the pilot via triggers built into the armrests (on twin-seat models, the occupant of the forward cockpit position is able to initiate the ejection of both seats), the ejection sequence is automated, including the removal of the canopy; in the event of a malfunction, a reserve trigger can be activated.<ref name = "field 708" /> A combined parachute and seat harness is used, which features a barometric interlock to appropriately release the occupant and harness from the seat during the ejection sequence, a manual override handle is also provided for this function.<ref name = "field 708" />

There were dedicated warning caption panels on each side of the pilot's legs. On the right console panel were numerous dedicated controls and indicators, including weapons and missile controls, nav panel, oxygen on/off, windshield de-fogging, [[Identification friend or foe|IFF]] control, lighting controls. Situated on the left console panel were radar controls, canopy handle, landing gear handle, radio controls and the cabin pressure indicator.<ref name = "field 709">Field 1974, p. 709.</ref><ref>Warwick 1980, pp. 1262–63.</ref> As per then-standard practice within the Swedish Air Force, all cockpit instrumentation and labeling were in Swedish.<ref name = "field 708">Field 1974, p. 708.</ref><ref>Detailed schematic diagram of the original cockpit layout in Coombs 2005.</ref><ref>{{Citation |last=Toll |first=Jörgen |year=2012 |chapter-url=http://www.aircraftresourcecenter.com/AWA1/501-600/walk519_Viggen_Toll/walk519.htm |title=Saab Viggen Walk Around |chapter=part 1 |publisher=Aircraft resource center |access-date=23 June 2012 |archive-date=3 March 2016 |archive-url=https://web.archive.org/web/20160303231227/http://www.aircraftresourcecenter.com/AWA1/501-600/walk519_Viggen_Toll/walk519.htm |url-status=dead }}</ref>

=== Wings and airframe ===
With the performance requirements to a large extent dictating the choice of the engine, the airframe turned out to be quite bulky compared to contemporary slimmer designs with turbojet engines. The first prototypes had a straight midsection [[fuselage]] that was later improved with a "hump" on the dorsal spine for reduced drag according to the [[area rule]].<ref name="Vectorsite">{{Citation | url = http://www.vectorsite.net/avvig.html | title = The Saab 37 Viggen | publisher = Vector site | access-date = 15 September 2007 | archive-url = https://web.archive.org/web/20071013164709/http://www.vectorsite.net/avvig.html | archive-date = 13 October 2007 | url-status=usurped | df = dmy-all}}</ref> The wing had the shape of a double delta with a dogtooth added to improve longitudinal stability at high incidence angles.<ref>Riebe, J. and William C. "Low-Speed Stability Characteristics of a Cambered-Delta-Wing Model", ''NACA RM-L55L21a'', 1956.</ref>{{Page needed |date=April 2016}}

[[File:JA 37D tail.jpg|thumb|Vertical stabilizer]]
A consequence of a tailless delta design, such as in the Viggen, is that the elevons, which replace more conventional control surfaces, operate with a small effective [[torque|moment arm]]; their use adds substantial weight to the aircraft at takeoff and landing. Hinged leading edge surfaces can help counteract this, but an even more effective tool is the canard. The canard surfaces were positioned behind the inlets and placed slightly higher than the main wing, with a higher stall angle than the wing, and were equipped with flaps. The lifting canard surfaces act as a vortex generator for the main wing and therefore provide more lift. An added benefit was that they also improved roll stability in the transonic region.<ref>Peake, D. and Tobak M. "Three-Dimensional Interactions and Vortical Flows with Emphasis on High-Speed Vehicles", ''AGARD AG-252'', 1980.</ref> The canard flaps were deployed in conjunction with the landing gear to provide even more lift for takeoff and landing.{{Sfn | Gunston | Spick | 1983 | pp = 22–23, 244}}

To withstand the stresses of no-flare landings, Saab made extensive use of [[aluminium]] in the airframe of the Viggen, which was constructed using a bonded metal [[honeycomb structure]]; the entire rear section of the fuselage, downstream of the engine nozzle, formed a heat-resistant ring composed of [[titanium]].{{Sfn | Gunston |Spick | 1983 | p = 245}}<ref>Warwick 1980, pp. 1260–61.</ref> The main landing gear, manufactured by Motala Verkstad, was highly strengthened as well; each leg held two small wheels fitted with [[anti-lock braking system|anti-skid brake]]s placed in a tandem arrangement. The design requirements imposed by the large anti-ship missiles employed upon the Viggen necessitated that both the undercarriage and [[vertical stabilizer]] be quite tall.<ref name = "warwick 1261" /> To accommodate this, and to allow the main landing gear to be stowed outside of the wing root, the undercarriage legs shortened during retraction.{{Sfn | Gunston | Spick | 1983 | p = 245}}  The [[vertical stabilizer]] could also be folded via an [[actuator]] in order that the aircraft could be stored in smaller hangars, [[hardened aircraft shelter]]s, and [[underground hangar]]s, the latter of which were employed by the Swedish military to limit the damage of preemptive attacks.{{Sfn | Gunston | Spick | 1983 | p = 245}}

The six tanks in the fuselage and wings held approximately 5,000 litres of fuel with an additional 1,500 litres in an external drop tank. The specific fuel consumption was only 0.63 for cruise speeds{{Sfn | Gunston | Spick | 1983 | p = 245}}<ref name="Nativi" />{{Page needed | date = January 2014}} (fuel consumption was rated 18&nbsp;mg/Ns dry and 71 with afterburner).<ref name = "Nativi" />{{Page needed | date = January 2014}} The Viggen's consumption was around 15&nbsp;kg/s at maximum afterburner.<ref name = "Nativi" />{{Page needed | date = January 2014}} A pair of inlets placed alongside the cockpit feed air to the engine; simple fixed-geometry inlets were adopted, similar to the Draken, except for being larger and standing clear of the fuselage.{{Sfn | Gunston | Spick | 1983 | pp = 244–45}}

=== Armament ===
[[File:Saab viggen underside.jpg|thumb|Underside of a Viggen, 1985. The empty weapons pylons are visible.]]
A weapons load of up to 7,000&nbsp;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 pylon plumbed for carrying an external fuel tank, and was usually so occupied.  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.<ref name = "ford 618">Ford 1973. p. 618.</ref> The pylons behind the landing gear were not used until the JA 37D modification when BOL countermeasure dispensers were fitted to them.<ref>{{Citation | title = Viggen | first = Sven | last = Stridsberg | page = 156}}</ref> 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.<ref name = "ford 618" />

==== AJ 37 ====
The AJ 37 was typically equipped with a total of seven [[hardpoint]]s, 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&nbsp;mm M56GP 4&nbsp;kg armour-piercing, the M56B with 6.9&nbsp;kg of [[Explosive#High explosives|high explosives]], and the M70 with a 4.7&nbsp;kg [[High-explosive anti-tank|HEAT]] warhead.<ref name="Nativi" />{{Page needed | date = January 2014}}{{Sfn | Gunston | Gilchrist | 1993 | pp = 245–47}}

The AJ 37 was designed to carry two [[RB 04]]E [[anti-ship missile]]s on the inboard wing pylons with an optional third missile on the centreline pylon.<ref>Ford 1973. pp. 618–19.</ref> The RB-04 was a relatively simple [[cruise missile]] that was further developed to become the more capable [[RBS-15]], also integrated on the Viggen.{{Sfn | Gunston | Gilchrist | 1993 | p = 247}}  An optional load consisted of two [[Rb 05]] [[air-to-surface missile]]s on the fuselage pylons. The RB 05 was later replaced by [[AGM-65 Maverick]] (Swedish designation "RB 75") [[Missile guidance#Passive homing|television-guided]] missiles. In a ground-attack role, a combination of unguided 135&nbsp;mm rockets in sextuple pods and 120&nbsp;kg fragmentation bombs on quadruple-mounts could be used. Other armaments include [[explosive mine]]s, and 30&nbsp;mm [[ADEN cannon]] pods<ref name="Andersson150">Andersson 1989, p. 150.</ref> with 150 rounds of ammunition on the inboard wing pylons.{{Sfn | Gunston | Gilchrist | 1993 | p = 247}}<ref name="Jacksonp59">Jackson 1993, p. 59.</ref>

Self-defence measures included various 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.{{Sfn | Gunston | Gilchrist | 1993 | p = 247}}  At one point, the AJ 37 Viggen was under consideration as a carrier of both [[Swedish nuclear weapons program|a Swedish nuclear weapon]] and [[chemical weapon]]s, although no nuclear or chemical weapons were ultimately adopted by Sweden.<ref>{{Cite book| last = Agrell | first = Wilhelm | author-link = Wilhelm Agrell | title = Svenska Förintelsevapen – Utveckling av kemiska och nukleära stridsmedel 1928–70 |trans-title= Swedish Holocaust Weapons – Development of chemical and nuclear weapons 1928–70 | year = 2002 | publisher = Historiska Media | location = Falun | language = sv | isbn = 91-89442-49-0}}</ref>

====JA 37====
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 missile|beyond visual range]] distances.<ref name="auto" /> The JA 37 could carry up to two RB 71s on the inner wing pylons; in a typical air defense loadout, these would typically have been combined with four [[AIM-9 Sidewinder|RB 24J]] air-to-air missiles, a more capable and newer version of the Sidewinder missile than employed on earlier Viggen variants.<ref name= "auto" />

Following the evaluation of several alternative cannons, including the British [[ADEN cannon]], the American [[M61 Vulcan]], and French [[DEFA cannon]], an [[Rheinmetall Air Defence|Oerlikon]] [[Oerlikon KCA|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.<ref name= "auto" /> The firing rate of the cannon was selectable at 22 or 11 rounds per second.  It fired the same cartridge as the [[GAU-8]], reportedly 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.<ref name="Jackson p76-77">Jackson 1993, pp. 76–77.</ref><ref>Warwick 1980, pp. 1264–65.</ref> This, in conjunction with the fire control system, allowed air-to-air engagements at longer range than other fighters.<ref name = "warwick 1265">Warwick 1980, p. 1265.</ref><ref name="williams p57">Williams and Gustin 2004, p. 57.</ref>

Perhaps the most important improvement was the expanded [[STRIL]] datalink which entered service in 1982–85. It allowed not only ground control-aircraft communication, but also between up to four aircraft simultaneously regardless if airborne or on the ground. Datalink information was displayed on the Horizontal Situation Display and a tactical display, the latter using link symbology that could be overlaid with an electronic map on a multifunction display.<ref>Dario Leone, [https://theaviationgeekclub.com/viggen-vs-blackbird-swedish-air-force-ja-37-fighter-pilots-able-achieve-radar-lock-legendary-sr-71-mach-3-spy-plane/  Viggen vs Blackbird: how Swedish Air force JA-37 fighter pilot were able to achieve radar lock on the legendary SR-71 Mach 3 spy plane], The aviation geek club, 9th of January 2018.</ref><ref>"In 1985, the fighter-to-fighter data link became operational, allowing the aircraft to share targeting and weapon information. Improvements continued into the 1990s, with a multi-target tracking capability becoming operational in 1990 and automatic gun aiming being introduced to the aircraft in 1992." Putnikov, M. 2013. Saab 37 Viggen Walk Around. Carrollton, TX: Squadron Signal Publications. p. 60</ref>

== Operational history ==
[[File:Saab 37 Viggen flygvapenmusèum.JPG|thumb|The first production JA 37 Viggen at the Swedish Air Force Museum]]
[[File:SAAB J-37 Viggen special red version.jpg|thumb|This AJS 37 was painted red in 1999 for the last years of Viggen sorties at F 10 Ängelholm.]]

In July 1971, the first production AJ 37 Viggen was delivered to the Swedish Air Force.<ref name = "saab 70s" /> The [[Skaraborg Wing]] (F 7) became the first [[wing (military aviation unit)|wing]] to receive deliveries of both the single-seat AJ 37 attack model and the twin-seat SK 37 training model of the Viggen, whereupon the type began to replace their existing Lansen aircraft.{{Sfn | Gunston | Gilchrist | 1993 | p = 246}} 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.<ref name = "field 707" /><ref>Ford 1973. pp. 616–17.</ref>

In October 1973, Skaraborg Wing was reportedly close to achieving full operational effectiveness;<ref name= "ford 616" /> 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.<ref name = "field 707" /> By 1974, the safety and reliability levels of the Viggen were reportedly above expectations, despite the overall complexity and relative newness of the aircraft.<ref name = "field 712">Field 1974, p. 712.</ref>  In practice, one of the most significant issues encountered with the Viggen during low-level flight, as extensively performed during a typical attack mission profile, was the threat posed by birds; thus, the Swedish Air Force paid close attention to their migratory patterns.<ref name = "field 710">Field 1974, p. 710.</ref>

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.<ref name = "fred 279" /><ref name = "chant 458" />  By September 1980, the JA 37 fighter-interceptor model of the Viggen was introduced, [[Bråvalla Wing]] (F 13) being the first wing of the Swedish Air Force to convert to the new type.<ref name = "warwick 1260">Warwick 1980, p. 1260.</ref> The Viggen went on to become Sweden's primary air defense platform for many years.<ref name = "boyne 548">Boyne 2002, p. 548.</ref>

The Viggen was designed to be simple to maintain, even by conscripted flight line mechanics with limited technical training.<ref name= ":0">{{Cite web |url= http://www.flyghistoria.org/images/publications/FR/_37-bok.pdf|title=System 37 Viggen|date=2009}} {{Dead link|date=April 2020 |bot= InternetArchiveBot |fix-attempted=yes }}</ref> A single Viggen could be maintained by a team of five conscripts under the supervision of a single chief mechanic.<ref name = "warwick 1265" /><ref name = "boyne 610">Boyne 2002, p. 610.</ref> 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.<ref name = "warwick 1265" />

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 [[radar 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.<ref>''Mach 14'', vol 4, no 3, 1983, p. 5. {{ISSN|0280-8498}}.</ref><ref>''Mach 25'', vol 7, no 2, 1986, pp. 28–29. {{ISSN|0280-8498}}.</ref><ref>Darwal 2004, pp. 151–56.</ref> The Viggen is the only aircraft to get an acknowledged radar lock on the SR-71.<ref name = "I&F6/05">{{Citation | title = Insats & Försvar | trans-title = Military Intervention & Defence | volume = 6 | year = 2005 | publisher = Försvarsmakten (Swedish Armed Forces)}}</ref>

===Retirement===
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.<ref name = "fred 279" /><ref>Forsberg 1994, pp. 222–23.</ref> On 25 November 2005, the last front line Viggen was formally retired by the Swedish Air Force.<ref name=":0" /> A few aircraft were kept in an operational condition for electronic warfare training against the Gripen at [[Östgöta Wing|F 17M]] in [[Linköping]]; the last of these Viggen flights took place in June 2007.<ref>{{Citation | language = sv | url = http://www.sff.n.se/aktuellt_arkiv_2007.htm | publisher = Svensk Flyghistorisk Förening [Swedish Aviation Historical Society] | title = Sista Viggarna lämnar Malmen | trans-title = Last Tufted Duck must submit ore | date = 1 July 2007 |archive-url= https://web.archive.org/web/20080324022354/http://www.sff.n.se/aktuellt_arkiv_2007.htm |archive-date=24 March 2008}}</ref>

=== Overseas sales efforts ===
Although Saab offered the Viggen for sale worldwide, and was the subject of a heavy marketing campaign in both European and [[developing country|developing countries]] during the 1970s, ultimately no export sales were made.<ref>Forsberg 1994, p. 236.</ref>

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]] [[Lightweight Fighter program|Air Combat Fighter competition]] to find a replacement for the [[Lockheed F-104 Starfighter]]. The 37E Eurofighter competed against [[Dassault Aviation|Dassault-Breguet's]] proposed [[Dassault Mirage F1|Mirage F1M-53]], the [[SEPECAT Jaguar]], [[Northrop Corporation|Northrop]]'s P-530 Cobra (on which the [[Northrop YF-17|YF-17]] was based), and [[General Dynamics]]'s [[General Dynamics F-16 Fighting Falcon|YF-16]];<ref>Coram 2002, p. 305.</ref><ref>Dörfer, Ingemar. [http://www.foreignaffairs.com/articles/37508/andrew-j-pierre/arms-deal-the-selling-of-the-f-16 "The Selling of the F-16."] ''Foreign affairs,'' 1983. Retrieved 23 April 2011.</ref> on 13 January 1975, [[United States Secretary of the Air Force]] [[John L. McLucas]] announced the YF-16 had been selected as the winner of the ACF competition.<ref>Peacock 1997, pp. 13–16.</ref>

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.<ref name = "calbe rajiv" /><ref>Snyder and Brown 1997, p. 150.</ref> India later opted to procure the [[SEPECAT Jaguar]] in its place.<ref>"Nuclear Stability and Arms Sales to India: Implications for US Policy", ''Arms Control Today'', vol. 27, no. 5, 1997.</ref> According to [[United States diplomatic cables leak|leaked United States 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.<ref name = "calbe rajiv">Krishnaswamy, Murali N. [http://www.thehindu.com/news/national/rajiv-gandhi-was-entrepreneur-for-swedish-jet-us-cable-says/article4592091.ece "Rajiv Gandhi was 'entrepreneur' for Swedish jet, U.S. cable says."] ''The Hindu'', 8 April 2013.</ref><ref>{{Citation | url = http://www.livemint.com/Politics/HCyNt9yd7GFhk3QVE6Ai4L/WikiLeaks-to-release-more-US-diplomatic-records.html | title = WikiLeaks' Rajiv Gandhi report may lead to another Parliament logjam | newspaper = Live mint| date = 8 April 2013 }}</ref> 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.<ref>Smith 1994, p. 99.</ref>

== Variants ==
{{More citations needed|date=May 2016}}
;AJ 37: Primarily a single-seat ground-attack fighter aircraft (AJ: Attack-Jakt), with a secondary fighter role.<ref name="Jackson p57">Jackson 1993, p. 57.</ref> RM8A powerplant. PS 37A radar.<ref name="Jackson p63-6">Jackson 1993, pp. 63–66.</ref> First delivery in mid-1971,<ref name= "Andersson148">Andersson 1989, p. 148.</ref> 108 built, with serial numbers 37001-37108.<ref name="Jackson p82">Jackson 1993, p. 82.</ref> 48 airframes upgraded to AJS 37.<ref name="wapj22 p31">Hewson 1995, p. 31.</ref> Partially decommissioned in 1998.
;SK 37: Two-seat trainer aircraft (Sk: Skol) with no radar and reduced fuel.<ref name="Jackson p70-1">Jackson 1993, pp. 70–71.</ref> First flight on 2 July 1970.<ref name="Andersson155">Andersson 1989, p. 155.</ref> 17 built, with delivery from June 1972, serial numbers 37801-37817.<ref name= "Jackson p82" /> Decommissioned in 2003, 10 airframes converted to SK 37E.
;SF 37: Single-seat photographic reconnaissance aircraft (SF: Spaning Foto), with radar replaced by battery of cameras in nose, with provision for additional reconnaissance pods.<ref name="Jackson p59,70">Jackson 1993, pp. 59, 70.</ref> It made its first flight on 21 May 1973.<ref name= "Andersson152">Andersson 1989, p. 152.</ref> 28 built, with deliveries from April 1977, serial numbers 37950-37977.<ref name="Jackson p82" /> 25 airframes upgraded to AJSF 37.<ref name="wapj22 p31" /> Partially decommissioned in 1998.
;SH 37: (SH- Spaning Hav, reconnaissance sea) Single-seat maritime reconnaissance and strike aircraft,<ref name="Andersson152" /> equipped with PS-371A radar.<ref name="Jackson p70">Jackson 1993, p. 70.</ref> 27 built, with delivery from June 1975, serial numbers 37901-37927.<ref name= "Jackson p82" /> 25 airframes upgraded to AJSH 37.<ref name="wapj22 p31" /> Partially decommissioned in 1998.
;Saab 37E Eurofighter: Proposed NATO replacement of F-104 Starfighter in 1975, none built.<ref name="Jackson p78">Jackson 1993, p. 78.</ref>
;Saab 37X: Proposed export version offered to Norway in 1967–68, none built.<ref name="Jackson p78,0">Jackson 1993, pp. 78, 80.</ref>
;JA 37: Primarily a single-seat all-weather interceptor fighter, with a secondary attack role. Its first flight was on 27 September 1974<ref name= "Andersson162">Andersson 1989, p. 162.</ref> with the first deliveries starting in 1979,<ref name="Andersson162" /> serial numbers 37301-37449. A {{Convert |10|cm|0|abbr=on}} stretch in the shape of a wedge wider at the bottom than on the top of AJ 37 fuselage between canard and main wing. PS 46A LD/SD radar. Partially decommissioned in 1998, some upgraded to JA 37D.
;AJS/AJSF/AJSH 37: Upgrade of some AJ/SF/SH 37 between 1993 and 1998. Avionics and software upgrade. 48 AJ 37 airframes modified. 25 SH 37 airframes modified. 25 SF 37 airframes modified. Decommissioned in 2005.
;JA 37C: Upgrade of older JA 37, avionics and software upgrade as well as the integration of countermeasures.
;JA 37D: Upgrade of older JA 37 between 1993 and 1998, avionics and software upgrade. Rb99 air-to-air missile (AIM-120 in Swedish service) integrated. 35 airframes modified.
;JA 37DI: JA 37D with avionics and software modified for international duties. Instruments labeled in English and feet/knots instead of meter/kmh. 20 airframes modified.
;SK 37E: Electronic warfare trainer, conversion of 10 obsolete SK 37 trainers from 1998 to 2000, serial numbers 37807-37811 & 37813-37817, decommissioned in 2007.
;37AU: Proposed Australian export variant with AIM-54 Phoenix missiles.<ref>Air Enthusiast, January 1973</ref><ref>Air Enthusiast, Vol.9/No.3, September 1975</ref><ref>{{cite book | url=https://libris.kb.se/bib/20912411 | title=Aircraft Saab 37AU : Specification. / D. 1 | date=1972 | publisher=Saab-Scania, Aerospace }}</ref><ref>{{cite book | url=https://libris.kb.se/bib/20912374 | title=Aircraft Saab 37AU : Specification. / D. 2 | date=1972 | publisher=Saab-Scania, Aerospace }}</ref> Cancelled in favour of F/A-18 Hornet.<ref>Modern Combat Aircraft 21, Robert F. Dorr, Ian Allan Ltd., 1985</ref>

==Operators==
[[File:Saab 37 Viggen klargöring 1982 001.jpg|thumb|Saab 37 Viggen being serviced on the ground, April 1982]]
[[File:SE-DXN SAAB Viggen "Gustav 52" (21366952562).jpg|thumb|Viggen landing at [[Prestwick]], [[Scotland]], 2015]]
{{External media |topic= |width=20% |float=right |video1=[https://www.youtube.com/watch?v=pAPteuBsRGg Swedish documentary on the Viggen] |video2=[https://www.youtube.com/watch?v=c6Utwdv_pAo Viggen display flight at an air show] |video3=[https://www.youtube.com/watch?v=pRSVHxT-ziM Multiple Viggens performing a mock dogfight]}}
; {{SWE}}
* [[Swedish Air Force]]

=== Operational units ===
* [[Jämtland Wing|F 4 Frösön]]
** 2 squadrons JA 37 1983–2003
** 1 squadron SK 37 1999–2003
** 1 squadron SK 37E 1999–2003
* [[Västgöta Wing|F 6 Karlsborg]]
** 2 squadrons AJ 37 1978–1993
* [[Skaraborg Wing|F 7 Såtenäs]]
** 3 squadrons AJ 37 1972–1998
** 1 squadron SK 37 1972–1974
* [[Scania Wing|F 10 Ängelholm]]
** 1 squadron AJ/SF/SH 37 (combined) 1993–2001
* [[Bråvalla Wing|F 13 Norrköping]]
** 1 squadron SF/SH 37 (combined) 1977–1993
** 1 squadron JA 37 1980–1993
* [[Hälsinge Wing|F 15 Söderhamn]]
** 2 squadrons AJ 37 1974–1998
** 1 squadron SK 37 1974–1998
* [[Uppland Wing|F 16 Uppsala]]
** 2 squadrons JA 37 1986–2003
* [[Blekinge Wing|F 17 Kallinge]]
** 1 squadron JA 37 1981–2002
** 1 squadron SF/SH 37 (combined) 1979–1993
** 1 squadron JA 37 1993–2002
* [[Norrbotten Wing|F 21 Luleå]]
** 2 squadrons JA 37 1983–2004
** 1 squadron SF/SH 37 1979–2002
** 1 squadron SK 37E (combined) 2003–2007

== Accident and incidents ==
Very little is publicized about Sweden's military air accidents and incidents, however, an incident resulting in a fatality of a Saab 37 pilot during a reconnaissance fly-by of Russian nuclear-powered [[Russian battlecruiser Pyotr Velikiy|battlecruiser ''Pyotr Velikiy'']] occurred on 16 October 1996,<ref>{{Cite web |title=Swedish Military Jet Crashes Scouting Ship |url= https://www.spokesman.com/stories/1996/oct/17/swedish-military-jet-crashes-scouting-ship/ |access-date= 2022-08-16 |website= The Spokesman-Review|date= 17 October 1996 }}</ref> and is the last known operational fatality of 19 total known fatalities (in over 50 accidents) involving the Saab 37 Viggen in its almost 40 years of operational history.<ref>{{Cite web |last= Ranter |first=Harro |title= WikiBase results |url= https://aviation-safety.net/wikibase/type/SB37 |access-date= 2022-08-16 |website= Aviation safety}}</ref>

== Surviving aircraft ==
[[File:Septemberleucharsviggen.jpg|thumb|Viggen 37098 landing after displaying at Leuchars, 2013]]
* 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 27 March 2012 from the F 7 Wing at Såtenäs.<ref>{{Citation | language = sv | url = http://www.swafhf.se/ | title= SE-DXN far stor uppmarkksamhet langt utanfor Sverige | trans-title = SE-DXN Far big up ground operations far outside Sweden |work= Swedish Air Force Historic Flight | place= [[Sweden|SE]] | access-date = 23 June 2012}}</ref> The Viggen is unpainted to represent the first delivered Viggens as they looked in the early 1970s.<ref>{{Citation | url = https://sle-p.transportstyrelsen.se/extweb/sv-se/sokluftfartyg | title = Sök luftfartyg | trans-title = Search aircraft | language = sv | place = SE | publisher = Transportstyrelsen [Transport Board] | access-date = 9 April 2019 | archive-date = 1 May 2019 | archive-url = https://web.archive.org/web/20190501140500/https://sle-p.transportstyrelsen.se/extweb/sv-se/sokluftfartyg | url-status = dead }}</ref>
* An SK 37 Viggen (two seat trainer) (s/n 37809) with the code F 15-61 has been retained and went through a period of restoration and maintenance to be airworthy again.  This Viggen was built in 1973 and served its first activities in F 7 Wing at Såtenäs, later in F 15 Wing at Söderhamn and finally in FMV Prov at Linköping until 2007. It was transferred into civil registry with the registration number SE-DXO. It undertook its maiden flight 15 May 2018 from the F 7 Wing at Såtenäs after having been approved by the authorities on 21 March 2018<ref>{{Citation | url = https://blogg.forsvarsmakten.se/flygvapenbloggen/2018/06/26/sk-37-viggen-flyger-igen/ | title = Sk 37 Viggen flyger igen! | trans-title = Sk 37 Viggen is flying again! | work = Swedish Airforce | language = sv | place = SE | publisher = Transportstyrelsen [Transport Board] | access-date = 9 April 2019 | archive-date = 19 December 2019 | archive-url = https://web.archive.org/web/20191219182046/https://blogg.forsvarsmakten.se/flygvapenbloggen/2018/06/26/sk-37-viggen-flyger-igen/ | url-status = dead }}</ref> The Viggen is painted in the unique four colour camouflage as all Viggens were painted from the late 1970s.
* An SK 37E Viggen (s/n 37898) is preserved at the [[Musée de l’air et de l’espace]] located at the former [[Paris–Le Bourget Airport]] in France.<ref>{{Citation | title = Saab SK 37E Viggen | url = http://www.museeairespace.fr/c/m/saab-sk-37e-viggen/presentation/ | publisher = Musée de l'Air | language = fr}}</ref>
* A JA 37 Viggen (sn: 37429) is preserved at the [[Estonian Aviation Museum]] near Tartu, Estonia. The aircraft was obtained from Swedish Air Force Museum, and flew from Sweden to Tartu in 2004.<ref>{{Citation | place = [[Estonia|EE]] | title = Lennundus muuseum | url = http://www.lennundusmuuseum.ee/index.php?lang=2}}</ref>
* An AJSF 37 Viggen (s/n 37954) is on display at the [[Polish Aviation Museum]] in [[Kraków]].<ref>{{Citation | language = pl | url = http://www.aviationmuseum.eu/World/Europe/Poland/Krakow/Muzeum_Lotnictwa_Polskiego.htm | title = Muzeum Lotnictwa Polskiego w Krakowie | publisher = Aviation museum | place = [[European Union|EU]] | access-date = 6 March 2016}}</ref>
* Two Viggens as well as the nose parts of some JA-37s can be found at the [[Göta Wing|Aeroseum]] near [[Gothenburg]]. An AJ-37 (s/n 37094/57) and an AJSH-37 (s/n 37911/55).<ref>{{Citation |title = Aircraft at the Aeroseum |publisher = Aeroseum |url = http://www.aeroseum.se/english/aircraft.html |url-status=dead |archive-url = https://web.archive.org/web/20150405031205/http://www.aeroseum.se/english/aircraft.html |archive-date = 5 April 2015 |df = dmy-all}}</ref>
* Two Viggens can be found at Söderhamn Aviation Museum at the former F 15 wing in Söderhamn, Sweden. One is an AJS 37 and the other is an SK 37 trainer aircraft.<ref>{{Citation |title = Museet Verksamhetsutställning |publisher = Söderhamn Flygmuseum |url= http://www.soderhamnflygmuseum.se/museet.html}}</ref>
* An AJ 37 Viggen is on display at the Västerås Aviation Museum in Västerås, Sweden.<ref>{{Citation |title = Saab 37 Viggen |publisher = Västerås Flygmuseum |url = http://www.flygmuseum.com/Flygplan/saab-37-viggen |access-date = 6 March 2016 |archive-url = https://web.archive.org/web/20160328114555/http://www.flygmuseum.com/Flygplan/saab-37-viggen |archive-date = 28 March 2016 |url-status = dead }}</ref>
* An AJS 37 Viggen is on display at the Swedish Airforce Museum in Linköping, Sweden.<ref>{{Citation |title = Saab 37 Viggen |publisher = Flygvapenmuseum |url = http://www.flygvapenmuseum.se/Samlingar/Foremal/Flygplan/Utstallda-flygplan/Flygplan-fran-tiden-for-kalla-kriget/Saab-37-Viggen/ |access-date = 17 July 2015 |archive-url = https://web.archive.org/web/20150721150919/http://www.flygvapenmuseum.se/Samlingar/Foremal/Flygplan/Utstallda-flygplan/Flygplan-fran-tiden-for-kalla-kriget/Saab-37-Viggen/ |archive-date = 21 July 2015 |url-status= dead |df = dmy-all}}</ref>
* An AJSH 37 Viggen (s/n 373918) is on display at [[Newark Air Museum]], Newark, Nottinghamshire, UK.
* The front section of an SF 37 Viggen is on display at the Swedish Aerial Reconnaissance Museum located at the old F 11 wing in Nyköping, Sweden.<ref>{{Citation |title = Flygplanhallen |publisher = F 11 Museum |url= http://www.f11museum.se/utstallning.html}}</ref>
* An AJSF 37 Viggen is on display at Prague Aviation Museum, Kbely, Czech Republic. s/n 37957 c/n 56-21.
* An AJSH 37 Viggen (s/n 37901) is on display at the [[Aviodrome]] museum at [[Lelystad]] Airport in the [[Netherlands]].
* An AJSF 37 Viggen (s/n 374974) is on display at the [[Flugausstellung Hermeskeil]] museum in [[Hermeskeil]], [[Germany]].
* Five Ja 37 Viggens, of which one is JA37Di standard preserved at Jämtlands Flyg och Lottamuseum, Jämtland, Sweden.<ref name="flygolotta.se" />
* One AJ 37 Viggen preserved at Jämtlands Flyg och Lottamuseum, Jämtland, Sweden.<ref name="flygolotta.se"/>
*Front half of one AJS 37 Viggen preserved at Jämtlands Flyg och Lottamuseum, Jämtland, Sweden.<ref name="flygolotta.se">{{Citation|title= Våra flygplan och övriga föremål|url=http://flygolotta.se/vara%20flygplan.htm|publisher=Jämtlands Flyg och Lottamuseum|access-date=24 May 2019 |archive-date= 3 September 2018|archive-url=https://web.archive.org/web/20180903231859/http://flygolotta.se/vara%20flygplan.htm|url-status=dead}}</ref>
*One SK 37 Viggen preserved at Jämtlands Flyg och Lottamuseum, Jämtland, Sweden.<ref name="flygolotta.se"/>
*One AJ 37 Viggen is on display in Luleå, Norrbotten, Sweden.<ref>{{Citation|title=Flygplan på väg| newspaper= Sveriges Radio | date= 24 February 2009 |url= https://sverigesradio.se/artikel/2658047|publisher=SR P4|access-date=7 Jan 2021}}</ref>
* One AJS 37 Viggen (s/n 37074) is on display at the [[Museum of Aeronautics and Astronautics (Madrid)]] museum in [[Madrid, Cuatro Vientos]], [[Spain]].

== Specifications (JA 37 Viggen) ==
[[File:Saab J 37 Viggen 3-view.svg|thumb|Saab JA 37 Viggen 3-view drawings]]
{{Aircraft specs
| ref= Combat Aircraft since 1945<ref>Wilson 2000, p.&nbsp;123.</ref>
|prime units?=met
<!--
        General characteristics
-->
|crew=1
|length m=16.4
|length note=
|span m=10.6
|span note=
|height m=5.9
|height note=
|wing area sqm=46
|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil=
|empty weight kg=9500
|empty weight note=
|gross weight kg=16439
|gross weight note= ('''AJ37''' {{cvt|17000|kg|0}}){{Sfn | Gunston | Spick | 1998 | p = 148}}
|max takeoff weight kg=19274
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
        Powerplant
-->
|eng1 number=1
|eng1 name=[[Volvo RM8B]]
|eng1 type=afterburning [[turbofan]]
|eng1 kw=<!-- prop engines -->
|eng1 hp=<!-- prop engines -->
|eng1 shp=<!-- prop engines -->
|eng1 kn=72.1
|eng1 lbf=<!-- jet/rocket engines -->
|eng1 note=
|power original=
|thrust original=
|eng1 kn-ab=125
<!--
        Performance
-->
|max speed kmh=2231
|max speed note=at {{Cvt|36100|ft|0}}
|max speed mach=2.1
|cruise speed kmh=
|cruise speed note=
|stall speed kmh=
|stall speed note=
|never exceed speed kmh=
|never exceed speed note=
|range km=
|range note=
|combat range km=
|combat range note=
|ferry range km=1820
|ferry range note=internal fuel only
|endurance=<!-- if range unknown -->
|ceiling m=18000
|ceiling note=
|g limits=<!-- aerobatic -->
|roll rate=<!-- aerobatic -->
|climb rate ms=203
|climb rate note={{Sfn | Gunston | Spick | 1998 | p = 148}}

|time to altitude=
|wing loading kg/m2=
|wing loading note=
|fuel consumption kg/km=
|thrust/weight=

|more performance=
<!--
        Armament
-->
|guns = 1 × 30&nbsp;mm [[Oerlikon KCA]] cannon with 125 rounds <ref>FPL JA37 1983, ch.1, sec. 18, p. 17</ref>
|hardpoints=9 (three hardpoints under fuselage and three under each wing)
|hardpoint capacity={{convert|7000|kg|lb|abbr=on}} 
|hardpoint missiles = <nowiki/>
***4 x RB99 [[AIM-120 AMRAAM|AMRAAM]] (JA 37D), 
***2 x RB71 [[Skyflash]] (only JA37), 
***6 x [[AIM-9 Sidewinder]]
***4 rocket pods (135&nbsp;mm, 5.4&nbsp;in).
***U95 ECM pod (JA 37D)
***2 x [[RB 04]]
***2 x [[RBS 15]]
***2 x [[Rb 05]]
|avionics=
}}

== See also ==
{{Portal|Aviation|Sweden}}
{{Aircontent|
| related=
| similar aircraft=
* [[Dassault Mirage F1]]
* [[McDonnell Douglas F-4 Phantom II]]
* [[Mikoyan-Gurevich MiG-23]]
* [[Mikoyan MiG-27]]
* [[SEPECAT Jaguar]]
* [[Shenyang J-8]]
* [[Vought XF8U-3 Crusader III]]
| lists=
* [[List of fighter aircraft]]
* [[List of military aircraft of Sweden]]
| see also=
* [[Saab 9-3#Viggen|Saab 9-3 Viggen automobile]]
}}

== Notes ==
{{Reflist|group=Nb}}

=== References ===
{{Reflist|30em}}

=== Bibliography ===
* {{cite book |last=Andersson |first=Hans G. |title=Saab Aircraft Since 1937 |publisher=Smithsonian Institution Press |year=1989 |isbn=0-8747-4314-1}}
* {{cite book |last=Bitzinger |first=Richard |title=Facing the Future: The Swedish Air Force, 1990–2005 |publisher=Rand Corporation |year=1991 |isbn=0-8330-1103-0}}
* {{cite book |last=Boyne |first=Walter J. |title=Air Warfare: An International Encyclopedia, Volume 1 |publisher=ABC-CLIO |year=2002 |isbn=1-5760-7345-9}}
* {{cite book |last=Chant |first=Christopher |title=A Compendium of Armaments and Military Hardware |publisher=Routledge |location=London |year=2014 |isbn=1-1346-4668-2}}
* {{cite book |last=Coombes |first=L.F.E. |title=Control in the Sky – The Evolution and History of the Aircraft Cockpit |publisher=Pen and Sword Books/Leo Cooper |location=Barnsley, South Yorkshire, UK |year=2005 |isbn=1-84415-148-4}}
* {{cite book |last=Coram |first=Robert |title=Boyd: The Fighter Pilot Who Changed the Art of War |publisher=Little, Brown, and Co. |location=New York |year=2002 |isbn=0-316-88146-5}}
* {{cite book |last=Crickmore |first=Paul F. |title=Lockheed Blackbird: Beyond the Secret Missions |url=https://books.google.com/books?id=xwPFC3GtcL8C |publisher=Osprey Publishing |location=Oxford, UK |year=2004 |isbn=1-84176-694-1}}
* {{cite book |editor1-last=Donald |editor1-first=David |editor2-last=Lake |editor2-first=Jon |title=Encyclopedia of World Military Aircraft (single volume ed.) |publisher=Aerospace Publishing |location=London |year=1996 |isbn=1-874023-95-6}}
* {{cite book |last=Eliasson |first=Gunnar |title=Advanced Public Procurement as Industrial Policy: The Aircraft Industry as a Technical University |publisher=Springer Science & Business Media |year=2010 |isbn=1-4419-5849-5}}
* {{cite magazine |last=Field |first=Hughes |title=Saab Viggen: In The Air |magazine=Flight International |date=30 May 1974 |pages=707–712 |url=https://www.flightglobal.com/pdfarchive/view/1974/1974%20-%200833.html}}
* {{cite magazine |last=Ford |first=T.E. |title=The Viggen in Service |magazine=Flight International |date=11 October 1973 |pages=616–619 |url=https://www.flightglobal.com/pdfarchive/view/1973/1973%20-%202567.html}}
* {{cite book |last=Fredriksen |first=John C. |title=International Warbirds: An Illustrated Guide to World Military Aircraft, 1914–2000 |publisher=ABC-CLIO |year=2001 |isbn=1-5760-7364-5}}
* {{cite book |title=Speciell Förarinstruktion FPL JA37 (A/C JA37 Flight Manual) |publisher=Försvarets Materielverk |year=1983 |location=Sweden |id=M5800-370051}}
* {{cite book |last=Erichs |first=Rolph |title=The Saab-Scania Story |publisher=Streiffert & Co. |location=Stockholm |year=1988 |isbn=91-7886-014-8}}
* {{Citation | last = Forsberg | first = Randall | title = The Arms Production Dilemma: Contraction and Restraint in the World Combat Aircraft Industry | publisher = MIT Press | year = 1994 | isbn = 0-2625-6085-2}}.
* {{Citation | last1 = Gunston | first1 = William ‘Bill’ | first2 = Michael ‘Mike’ | last2 = Spick | title = Modern Air Combat: The Aircraft, Tactics and Weapons Employed in Aerial Warfare Today | place = New York | publisher = Crescent Books | year = 1983 | isbn = 0-517-41265-9}}.
* {{Citation | last1 = Gunston | first1 = William ‘Bill’ | author-mask = 3 | first2 = Michael ‘Mike’ | last2 = Spick | author2-mask = 3 | title = Moderne Kampfflugzeuge. Technik, Taktik und Bewaffnung | trans-title = Modern combat aircraft. Technique, tactics and armament | language = de | place = Tyskland, [[Germany|DE]] | publisher = Stocker-Schmid | year = 1998 | isbn = 978-3-7276-7062-6}}.
* {{Citation | last1 = Gunston | first1 = William ‘Bill’ | author-mask = 3 | first2 = Michael ‘Mike’ | last2 = Spick | author2-mask = 3 | title = Moderne Kampfflugzeuge | trans-title = Modern combat aircraft | language = de | place = Tyskland, [[Germany|DE]] | publisher = Stocker-Schmid | year = 2001 | isbn = 978-3-613-01926-3}}.
* {{Citation | last1 = Gunston | first1 = William ‘Bill’ | author-mask = 3 | first2 = Peter | last2 = Gilchrist | title = Jet Bombers: From the Messerschmitt Me 262 to the Stealth B-2 | publisher = Osprey | year = 1993 | isbn = 1-85532-258-7}}.
* {{cite magazine |last=Hewson |first=Robert |title=Briefing: Saab AJS 37 Viggen: The Flygvapen's new 'Thunderbolt' |magazine=World Air Power Journal |volume=22 |date=Autumn 1995 |pages=30–31 |publisher=Aerospace Publishing |location=London |isbn=1-874023-62-X |issn=0959-7050}}
* {{cite book |last1=Larsson |first1=Bengt |last2=Letell |first2=Martin |last3=Thörn |first3=Håkan |title=Transformations of the Swedish Welfare State: From Social Engineering to Governance? |publisher=Springer |year=2012 |isbn=0-2303-6395-4}}
* {{cite magazine |last=Jackson |first=Paul |title=Saab 37 Viggen |magazine=World Air Power Journal |volume=13 |date=Summer 1993 |pages=46–89 |publisher=Aerospace Publishing |location=London |isbn=1-874023-17-4}}
* {{cite magazine |last=Nativi |first=Andrea |title=Viggen, Il Caccia Venuto dal Freddo [Viggen, The Hunting Came from the Cold] |magazine=RID magazine |date=June 1993 |pages=20–36 |language=Italian}}
* {{cite book |last=Peacock |first=Lindsay |title=On Falcon Wings: The F-16 Story |publisher=The Royal Air Force Benevolent Fund Enterprises |location=RAF Fairford, United Kingdom |year=1997 |isbn=1-899808-01-9}}
* {{cite book |last=Roskam |first=Jan |title=Airplane Design: Layout Design of Cockpit, Fuselage, Wing and Empennage : Cutaways and Inboard Profiles |publisher=DARcorporation |year=2002 |isbn=1-8848-8556-X}}
* {{cite book |last=Smith |first=Chris |title=India's Ad Hoc Arsenal: Direction Or Drift in Defence Policy? |publisher=Oxford University Press |year=1994 |isbn=0-1982-9168-X}}
* {{cite book |last1=Snyder |first1=William P. |last2=Brown |first2=James |title=Defense Policy in the Reagan Administration |publisher=DIANE Publishing |year=1997 |isbn=0-7881-4146-5}}
* {{cite book |last=Taylor |first=John W.R. |chapter=SAAB 37 Viggen (Thunderbolt) |title=Jane's All the World's Aircraft 1980–81 |publisher=Jane's |location=London |year=1981 |isbn=0-531-03953-6}}
* {{cite book |editor-last=Taylor |editor-first=John W.R. |title=Jane's All the World's Aircraft, 1988–1989 |publisher=Jane's |location=London |year=1988 |isbn=0-7106-0867-5}}
* {{cite book |title=This Happens in the Swedish Air Force (brochure) |publisher=Information Department of the Air Staff, Flygstabens informationsavdelning, Swedish Air Force |location=Stockholm |year=1983}}
* {{cite book |last=Wagner |first=Paul J. |title=Air Force Tac Recce Aircraft: NATO and Non-aligned Western European Air Force Tactical Reconnaissance Aircraft of the Cold War |publisher=Dorrance Publishing |year=2009 |isbn=1-4349-9458-9}}
* {{cite magazine |last=Warwick |first=Graham |title=Interceptor Viggen |magazine=Flight International |date=27 September 1980 |pages=1260–65 |url=https://web.archive.org/web/20160313203725/https://www.flightglobal.com/pdfarchive/view/1980/1980%20-%202917.html}}
* {{cite book |last1=Williams |first1=Antony G. |last2=Gustin |first2=Emmanuel |title=Flying Guns, The Modern Era |publisher=The Crowood Press |location=Marlborough, Wiltshire, UK |year=2004 |isbn=1-86126-655-3}}
* {{cite book |last=Wilson |first=Stewart |title=Combat Aircraft since 1945 |publisher=Aerospace Publications |location=Fyshwick, AU |year=2000 |isbn=1-875671-50-1}}
* {{cite book |editor-last=Winchester |editor-first=Jim |title=Saab AJ/SF/SH Viggen |chapter=Military Aircraft of the Cold War (The Aviation Factfile) |publisher=Grange Books |location=London |year=2006 |isbn=1-84013-929-3}}

== External links ==
{{Commons category|Saab 37 Viggen}}
* {{Citation | url = http://www.milavia.net/specials/iv_viggen/ | title = Interview with Viggen pilot | publisher = Milavia}}.
* {{usurped|1=[https://web.archive.org/web/20020802062717/http://hem.passagen.se/weasle/ Saab 37 Viggen]}}, SE: Passagen.
* [http://www.canit.se/~griffon/aviation/text/37viggen.htm Saab 37 Viggen], SE: Canit.
* {{Citation | url = http://www.aircraftresourcecenter.com/AWA1/501-600/walk519_Viggen_Toll/walk519.htm | title = Viggen | publisher = Aircraft resource center | access-date = 8 August 2005 | archive-date = 3 March 2016 | archive-url = https://web.archive.org/web/20160303231227/http://www.aircraftresourcecenter.com/AWA1/501-600/walk519_Viggen_Toll/walk519.htm | url-status = dead }}.
* {{Citation | url = http://www.vectorsite.net/avvig.html | title = Viggen | publisher = Vector site | access-date = 15 September 2007 | archive-url = https://web.archive.org/web/20071013164709/http://www.vectorsite.net/avvig.html | archive-date = 13 October 2007 | url-status=usurped | df = dmy-all}}.
* [http://members.chello.nl/~f.vanvoorst/ Saab 37 Viggen webpage] {{Webarchive|url=https://web.archive.org/web/20030416222119/http://members.chello.nl/~f.vanvoorst/ |date=16 April 2003 }} (in Dutch)
* [https://web.archive.org/web/20071004171102/http://www.flug-revue.rotor.com/FRHeft7X/FRHeft75/FRH7502/FR7502a.htm Flug Revue test flight report] (in German)

{{Saab aircraft}}
{{Swedish military aircraft designations}}
{{Authority control}}

{{DEFAULTSORT:Saab 37 Viggen}}
[[Category:Delta-wing aircraft]]
[[Category:Saab aircraft|37]]
[[Category:1960s Swedish fighter aircraft]]
[[Category:Canard aircraft]]
[[Category:Single-engined jet aircraft]]
[[Category:Nuclear weapons program of Sweden]]
[[Category:Aircraft first flown in 1967]]
[[Category:1967 establishments in Sweden]]
[[Category:Third-generation jet fighters]]
[[Category:Aircraft with retractable tricycle landing gear]]
[[Category:Low-wing aircraft]]
[[Category:Swedish Culture Canon]]