The Saab 37 Viggen is a retired Swedish single-seat, single-engine, short-medium range combat aircraft.
Development work on the type was initiated at Saab in 1952 and, following the selection of a radical delta wing configuration, the resulting aircraft performed its first flight on 8 February 1967 and entered service on 21 June 1971.
It was the first canard design produced in quantity.
The Viggen was also the most advanced fighter jet in Europe until the introduction of the Panavia Tornado into operational service in 1981.
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 earlier 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 defence 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 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 war time air bases, including road runways acting as backup runways.
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.
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.
In 1960, the U.S. National Security Council, led by President 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 “37-annex”, Sweden was allowed access to advanced U.S. aeronautical technology that 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.
Variants
AJ 37
Primarily a single-seat ground-attack fighter aircraft, with a secondary fighter role.
RM8A powerplant.
PS 37A radar.
First delivery in mid-1971,108 built.
48 airframes upgraded to AJS 37.
Partially decommissioned in 1998.
SK 37
Two-seat trainer aircraft with no radar and reduced fuel.
First flight on 2 July 1970.
17 built, with delivery from June 1972.
Decommissioned in 2003, 10 airframes converted to SK 37E.
SF 37
Single-seat photographic reconnaissance aircraft, with radar replaced by battery of cameras in nose, with provision for additional reconnaissance pods.
It made its first flight on 21 May 1973. 28 built, with deliveries from April 1977.
25 airframes upgraded to AJSF 37.
Partially decommissioned in 1998.
SH 37
Single-seat maritime reconnaissance and strike aircraft, equipped with PS-371A radar.
27 built, with delivery from June 1975.
25 airframes upgraded to AJSH 37.
Partially decommissioned in 1998.
Saab 37E Eurofighter
Proposed NATO replacement of F-104 Starfighter in 1975, none built.
Saab 37X
Proposed export version offered to Norway in 1967–68, none built.
JA 37
Primarily a single-seat all-weather interceptor fighter, with a secondary attack role.
Its first flight was on 27 September 1974 with the first deliveries starting in 1979.
A 10 cm (4 in) 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.
JA 37D
Upgrade of older JA 37 between 1993 and 1998, avionics and software upgrade. 35 airframes modified.
JA 37DI
JA 37D with avionics and software modified for international duties.
Instruments labelled 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, decommissioned in 2007.
Specifications
Crew
1
Length
16.4 m (53 ft 10 in)
Wingspan
10.6 m (34 ft 9 in)
Height
5.9 m (19 ft 4 in)
Wing area
46 m2 (500 sq ft)
Empty weight
9,500 kg (20,944 lb)
Gross weight
16,439 kg (36,242 lb) (AJ37 17,000 kg (37,479 lb))
