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Saab JA37 Viggen (Thunderbolt)

Supersonic Strike Fighter / Interceptor Aircraft

Sweden | 1968

"After 34 years of faithful service to the nation of Sweden, the Saab JA37 Viggen supersonic fighter was replaced by the advanced Saab JAS Gripen multi-role performer in 2005."

Authored By: Staff Writer | Last Edited: 07/23/2021 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site; No A.I. was used in the generation of this content.
The Swedish Saab JA 37 "Viggen" ("Thunderbolt") was yet another milestone aircraft design for the Scandinavian nation strictly adhering to a policy of indigenous design, development, and production of its various frontline military weapons. The aircraft - a true multirole fighter for its time- was designed from the outset to be as "battlefield friendly" as possible, capable of utilizing the Swedish network of highways as emergency runways and could further be serviced (refueled and rearmed) by a team of just seven - even with six being conscript-level personnel. To this battlefield survivability was added an advanced onboard computer that negated the need for a second crewman onboard to act as a dedicated radar operator, allowing internal volume to be used on fuel and avionics. Rounding out the requirements was a folding vertical tail fin which decreased the aircraft's side profile and allowed it to be housed in the various underground hangars positioned strategically about the country. If the Soviet Union was to invade, Sweden would have been ready.

The Viggen appeared per a Swedish Air Force requirement to succeed the Saab "Draken" as frontline interceptor/fighter with the inherent strike capabilities of the outgoing Saab 32 "Lansen" series. Work on what would become the Viggen was actually started as early as 1952 and evolved throughout the decade before being approved during December of 1961 by the government. The initial guise was to encompass a strike platform and this model was to be followed by a reconnaissance-minded variant and then an all-weather fighter/interceptor offering with exceptional performance and handling. A prototype first flew on February 8th, 1967 and proved the rather unorthodox design highly sound. The following April, serial production was ordered under the "Viggen" name and introduction occurred on June 21st, 1971.

Like the Saab Draken before it (detailed elsewhere on this site) the Viggen was required to operate from short runways. To help generate the needed lift in short order, the aircraft was given a large-area "canard delta" design wing planform with forward mounted canard foreplanes located to either side of the intake openings. While fixed in place, the canards featured trailing edge flaps and aided both lift and high-speed agility. To this was added a single powerful afterburning turbofan engine - the American Pratt & Whitney JT8D-22 series which powered Boeing 737s. The engine was license-built locally by Volvo Flygmotor as the "RM8" though the afterburner component was of an all-Swedish development. Additionally, the aircraft could be outfitted with rockets for power-assisted take-offs allowing the aircraft to get airborne quickly. Landings were shortened by way of a thrust reverser feature in the engine mated to the nose landing gear leg to work at slowing the aircraft down. The HUD (Head-Up Display) not only served to report pertinent mission details and weapon settings but also assisted the pilot during landings. The undercarriage was reinforced for the abuses of unprepared airstrips with the main legs featuring unique tandem wheels while the nose leg fitted a dual-wheel arrangement - something of a rarity for non-carrier, non-naval fighter aircraft.

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The large-area wing surface served to provide six underwing/under fuselage hardpoints for the carrying of air-to-air and air-to-surface ordnance. A single 30mm Oerlikon KCA cannon was fitted for close-in work and allotted 150 rounds of ammunition. A typical weapons load became 2 x RB71 "Skyflash" short-range air-to-air missiles and 4 x AIM-120 AMRAAM medium-range air-to-air missiles.

The RM8 engine outputted at 16,200lbf on dry thrust and 28,110lbf with afterburning. This provided the aircraft with a maximum speed of Mach 2.1 - or 1,385 miles per hour - when running at an altitude of 36,100 feet. Range was out to 1,245 miles and the aircraft sported a service ceiling of 59,100 feet. Rate-of-climb was an impressive 40,025 feet per minute - a good quality for an interceptor-minded airframe.

The initial production version of the Viggen was the AJ 37 which served in the single-seat ground attack role while retaining fighter capabilities. The aircraft were delivered from 1971 onwards and fitted the RM8A engine with Ericsson PS-37/A series radar in the nose. Saab provided the navigation/attack computer hardware and software for this model as well as the HUD system. The SK 37 served as a two-seat trainer and appeared from 1973 onwards while lacking the radar seen in the AJ 37 mount. The SF 37 was a single-seater and used in the photographic-reconnaissance role which saw the radar system in the nose replaced by a battery of cameras. The SH 37 was used for the maritime patrol role with over-water strike capabilities built in. These aircraft appeared from 1975 onwards.

The JA 37 became the definitive (and final) Viggen production form. These were single-seat interceptors retaining their strike capabilities and first appeared in 1979. The model carried the Ericsson PS-46/A "Look Down/Shoot Down" Doppler multimode radar suite supporting missile armament. The RM8B engine was an uprated design and there proved a slight revision of the canard foreplanes. The last of these was delivered during 1990. The JA 37C were JA 37 models upgraded with new flight software and avionics for multirole service. Similarly, the JA 37D, numbering 35 aircraft, were JA 37s upgraded with new avionics and software and some 20 JA 37Ds followed, upgraded to the JA 37DI standard featuring more modern PS-46/A radar systems and AIM-120 missile support. The AJS model line were earlier upgraded (AJ 37, SF 37, and SH 37) Viggens to a new standard that introduced modern avionics and software. The modernization took place from 1993 to 1998 and numbered 86 existing airframes.

There also proved some lesser-known models of the Viggen including the SK 37E which served as an Electronic Warfare Aircraft (EWA) trainer platform. This stock was made up of 10 outgoing SK 37 trainer types and were modified from 1998 into 2000. The Saab 37X was to become an export-minded variant of the mainline JA 37 but the initiative fell to naught. The Saab 37E "Eurofighter" was a proposed interceptor competitor for NATO intended to replace outgoing stocks of Lockheed F-104 Starfighters then in service. This project was not furthered into anything tangible.

Total production of Viggens numbered 329 aircraft, a far cry from the original 800+ once envisioned. Production spanned from 1970 to 1990 and the type gave excellent service that spanned some 34 years of the critical and tumultuous Cold War decades. The product was never exported due to strict exportation rules followed by Sweden but the Saab aircraft served 25 total Swedish Air Force squadrons internally during its long, storied tenure. The line was eventually retired on November 25th, 2005 and succeeded directly by the new Saab "Gripen" multirole, lightweight fighter detailed elsewhere on this site.

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Power & Performance
Those special qualities that separate one aircraft design from another. Performance specifications presented assume optimal operating conditions for the Saab JA37 Viggen (Thunderbolt) Supersonic Strike Fighter / Interceptor Aircraft.
1 x Volvo Flygmotor RM8B afterburning turbofan developing 28,110 lb of thrust.
1,320 mph
2,125 kph | 1,147 kts
Max Speed
60,007 ft
18,290 m | 11 miles
Service Ceiling
1,243 miles
2,000 km | 1,080 nm
Operational Range
32,000 ft/min
9,754 m/min
City-to-City Ranges
Operational range when compared to distances between major cities (in KM).
The nose-to-tail, wingtip-to-wingtip physical qualities of the Saab JA37 Viggen (Thunderbolt) Supersonic Strike Fighter / Interceptor Aircraft.
51.1 ft
15.58 m
O/A Length
34.8 ft
(10.60 m)
O/A Width
19.4 ft
(5.90 m)
O/A Height
33,069 lb
(15,000 kg)
Empty Weight
37,479 lb
(17,000 kg)
Design Balance
The three qualities reflected below are altitude, speed, and range. The more full the box, the more balanced the design.
Available supported armament and special-mission equipment featured in the design of the Saab JA37 Viggen (Thunderbolt) Supersonic Strike Fighter / Interceptor Aircraft provided across 7 hardpoints.
1 x 30mm Oerlikon KCA internal automatic cannon.

Additional mission-specific ordnance across six hardpoints for:

Rb-74 "Sidewinder", Rb-71 "Sky Flash", or AIM-120 AMRAAM Air-to-air Missiles (AAMs), rocket pods, and / or conventional drop bombs.

Hardpoints Key:

Not Used
Notable series variants as part of the Saab JA37 Viggen (Thunderbolt) family line.
"Aircraft System 37" - Initial Developmental Project Model Designation.
AJ 37 - Basic Attack Platform Designation.
S 37 - Reconnaissance Variant Designation.
JA 37 - All-Weather Fighter Model Designation.
Global customers who have evaluated and/or operated the Saab JA37 Viggen (Thunderbolt). Nations are displayed by flag, each linked to their respective national aircraft listing.

Total Production: 329 Units

Contractor(s): Saab - Sweden
National flag of Sweden

[ Sweden (retired) ]
Relative Max Speed
Hi: 1400mph
Lo: 700mph
Aircraft Max Listed Speed (1,320mph).

Graph Average of 1,050 MPH.
Era Crossover
Pie graph section
Showcasing Aircraft Era Crossover (if any)
Max Alt Visualization
Small airplane graphic
Production Comparison
Entry compared against Ilyushin IL-2 (military) and Cessna 172 (civilian) total production.
MACH Regime (Sonic)
RANGES (MPH) Subsonic: <614mph | Transonic: 614-921 | Supersonic: 921-3836 | Hypersonic: 3836-7673 | Hi-Hypersonic: 7673-19180 | Reentry: >19030
Aviation Timeline
1 / 1
Image of the Saab JA37 Viggen (Thunderbolt)
Image from the United States Department of Defense imagery database.

Mission Roles
Some designs are single-minded in their approach while others offer a more versatile solution to airborne requirements.
Some designs stand the test of time while others are doomed to never advance beyond the drawing board; let history be their judge.
Going Further...
The Saab JA37 Viggen (Thunderbolt) Supersonic Strike Fighter / Interceptor Aircraft appears in the following collections:
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