The SAAB JAS-39 Gripen

v1.0.0 / 01 jun 02 / greg goebel / public domain

* Since World War II, the Swedish SAAB aircraft firm has maintained a tradition of building cutting-edge fighter aircraft for the defense of Sweden. The latest of this series of aircraft, the SAAB "JAS-39 Gripen (Griffin)", is now in operational service.

The Gripen is a state of the art multirole combat aircraft, arguably the first "fourth-generation" fighter to reach service. It maintains the tradition of excellence in Swedish fighter design, but departs from tradition in proving a very competitive item for export sales. This document provides a short history of the Gripen.



* In the 1970s, the "SAAB 37 Viggen" began to go into service with the Flygvapnet (Swedish Air Force) as the nation's first-line combat aircraft. Swedish military planners then began to look down the road for a next-generation fighter to follow the Viggen. While US-made aircraft such as the F-16 or F/A-18 were considered, the Swedes had proven capable of building their own first-class fighter aircraft, tailored precisely to their specifications, and besides, modifying a foreign aircraft to fit into the tightly-linked Swedish defense network system would have been troublesome.

In 1980, the Swedish Defense Materiel Administration (FMV) issued a requirement to Swedish manufacturers for a next-generation combat aircraft, then known as the "JAS (Jakt, Attack, & Spaning / Fighter, Attack, & Reconnaissance)".

As the name implied, it was to be a multirole combat aircraft, with excellent performance and high agility to counter new Soviet fighters then going into service. It was to be simpler and cheaper to maintain than the Viggen, and easy to turn around quickly to ensure a high combat sortie rate. Long range was not a requirement, as the Flygvapnet's focus is on the defense of Sweden, not power projection.

A consortium named "IndustrieGruppen JAS" was formed between SAAB-Scania, Volvo Flygmotor, Ericsson, and Foerenade Fabriksverken (now FFV Aerotech). The group's proposal, with the company designation "SAAB 2110", was accepted in the spring of 1982, with a contract signed in June for five prototypes with some modifications from the original proposal, plus an initial production batch of 30 aircraft and an option for 110 more.

* Work on the prototypes began in 1984, with a full-size mockup completed in early 1986. The program ran into technical problems, cost increases, and schedule slips, leading to lobbying for its cancellation and purchase of a foreign aircraft. However, the first single-seat "JAS-39A Gripen (Griffin)" prototype flew on 9 December 1988, with test pilot Stig Holstrom at the controls, and the controversy faded. Design work on the "JAS-39B" two-seat version for operational conversion training began in 1989.

Unfortunately, the first JAS-39A prototype, the "39-1", was lost on 2 February 1989 due to a software glitch in the flight-control system. The aircraft veered off the runway on takeoff and cartwheeled, with the pilot, Lars Radestroem, suffering a broken arm. Work on cleaning up the software and fixing engine problems led to additional schedule slips.

The problems were resolved, and the second prototype, "39-2", took to the air on 4 May 1990. The third prototype to fly, which was actually designated "39-4" and featured operational avionics but no radar, performed its initial flight on 20 December 1990. The next prototype, the "39-3", was fitted with radar and flew on 25 March 1991; followed by the last of the five prototypes, "39-5", which was close to production spec, and flew on 23 October 1991.

By this time, the bugs had been largely ironed out. The Flygvapnet decided the Gripen had been worth the wait and trouble, as it handily exceeded many of its design specifications. In June 1992, SAAB got the go-ahead for building the two-seat JAS-39B, and the government formally signed off on the option for 110 more Gripens, which were to be built to an improved "Batch 2" standard. The new order included 96 JAS-39As and 14 JAS-39Bs.

The first production Gripen performed its maiden flight on 4 March 1993, with Radestroem at the controls. The second production item was the first to be handed over formally to the Flygvapnet, with delivery on 8 June 1993. However, the first production machine crashed during a flight demonstration in Stockholm on 18 August 1993, Radestroem ejecting without serious injury. Once again, the problem turned out to be a glitch in the flight control system software. All the Gripens were grounded until the bug was traced down and fixed.

The first JAS-39B was rolled out on 29 September 1995. It was actually a production-line modification of one of the 30 Batch-1 JAS-39As. The JAS-39A reached initial operational status in 1995 and full operational status in 1997. The first Batch 2 machine was delivered in December 1996, the same month that an order for 64 improved "Batch 3" was placed, including 50 JAS-39As and 14 JAS-39Bs.



* The Gripen is a true lightweight fighter by modern standards. It has 78% of the empty weight of an F-16C, and is about half the empty weight of the Viggen, the F/A-18E/F Super Hornet, or the Dassault Rafale. The Gripen's airframe features extensive use of composite components to reduce weight. The modest size reduces purchase cost to a degree and definitely reduces operating cost, makes the machine easier to handle on the ground, and gives it a lower radar signature.

The Gripen is a canard configuration aircraft, with a cropped delta wing with a sweep of 45 degrees, and all-moving canard forewings with a sweep of 45 degrees and dihedral. The wings are midbody-mounted to provide clearance for underwing stores, and each has a leading-edge flap and two trailing-edge drooping "elevons" to improve short-field performance, as well as maneuverability. There are two tiny strakes on the nose to generate vortices to improve flight control at high angles of attack.

The Gripen is powered by a Volvo Aero "RM-12" turbofan engine with afterburner. The RM-12 was developed in cooperation with General Electric and is derived from the GE F404J turbofan used on the Boeing F/A-18 Hornet. The F404J was selected due to its growth potential and reliability.

The Swedish version of the engine features a larger fan to provide more airflow and greater power; greater resistance to birdstrikes; and a Swedish-designed afterburner. The RM-12 provides 8,350 kilograms (18,400 pounds) of thrust in afterburner. 60% of the engine's components are built by GE, and shipped to Sweden where they are assembled along with the Swedish-built components.

Unlike the Viggen, the Gripen does not have a thrust reverser. The canard foreplanes can be tilted almost 90 degrees to act as airbrakes on landing. There are carbon brakes on all the wheels of the tricycle landing gear to reduce landing roll. The landing gear has an antiskid system. The two-wheel nose gear retracts backward, while the single-wheel main gear retract at a forward angle.

   _____________________   _________________   ___________________
   spec                    metric              english
   _____________________   _________________   ___________________

   wingspan                8 meters            26 feet 3 inches
   length                  14.1 meters         46 feet 3 inches
   height                  4.7 meters          15 feet 5 inches

   empty weight            6,620 kilograms     14,600 pounds
   max loaded weight       12,470 kilograms    27,500 pounds
   maximum speed           Mach 2 at altitude
   _____________________   _________________   ___________________

Swedish defense plans include a concept known as "BAS 90", which envisions dispersal of aircraft in groups of four to six to "road bases" defined around specially reinforced lengths of highway with associated dispersal areas. This scheme dictates the Gripen's short-field capabilities. The Gripen can take off and land in less than 600 meters (2,000 feet).

Once deployed to a road base, the Gripens are serviced by a team of six, including one highly trained specialist and five minimally trained conscripts. A service team can refuel and rearm a Gripen in ten minutes. The Gripen features an auxiliary power unit (APU) to reduce its dependence on ground systems, and the fighter's onboard digital systems include "built-in self-test" capabilities that can download diagnostic data to a tech's laptop computer. Service doors to critical systems are at head level or lower, allowing easy access by technicians. Flygvapnet experience shows that the Gripen requires 40% less maintenance work-hours and only half the fuel of the Viggen.

The Gripen cockpit layout contains three multifunction displays (MFD), plus a wide-angle head-up display (HUD) with a 28 by 22 degree field of view. The left MFD contains flight data and reflects HUD information; the lower MFD contains a tactical image in a "horizontal situation display" format; and the right MFD provides imagery from the radar, and potentially FLIR or an optical reconnaissance pod. Batch 1 and 2 machines use monochrome (green) MFDs.

The pilot flies the machine with an "hands on throttle and stick (HOTAS)" controls, including a center-mounted short-throw "ministick", and a throttle control that also operates as a joystick to make selections on the MFDs. The cockpit is climate-conditioned and pressurized, and fitted with a Martin-Baker Mark S10L zero-zero (zero altitude, zero speed) rocket propelled ejection seat. The Gripen is the first Swedish fighter not to use a SAAB-built ejection seat, and in fact the machine has considerable foreign content. The canopy hinges open sideways to the left.

The aircraft is controlled by a digital fly-by-wire (FBW) system with triple redundancy and an analog backup. The analog backup system provides a simple, reliable capability, and is automatically activated if two of the three digital FBW systems go down. The pilot can also activate the analog system with the push of a button.

The Gripen was designed from the outset to use the FBW system, which was evaluated on a modified Viggen. The FBW system compensates automatically for the degree of instability built into the Gripen to increase its maneuverability. The FBW system also allows the aircraft to adapt to combat damage, for example using differential control of the canards to fly the aircraft if the ailerons are disabled.

The Gripen's Ferranti-Ericsson PS-05/A X-band pulse Doppler radar has three times the processing power of the Viggen's PS-46/A radar but only 60% of its volume and weight. The PS-05/A has all-altitude look down capability, resistance to jamming, and provides a number of operating modes, including:

   air to air:

      long range search and track
      multiple target (up to ten) track while scan
      short range, wide angle search and track
      automatic gun and missile fire control

   air to ground:

      search and track
      ground and sea target track while scan
      high resolution mapping
      air to surface ranging
A mission computer alerts the pilot to priority threats. The Gripen has a ring-laser inertial navigation system (INS), and a suite of electronic warfare (EW) aids. The initial EW suite was built around the CelsiusTech (now Saab Avionics) AR830 radar-warning receiver (RWR), with receiving antennas on the front and back of the wingtip missile launch rails.

The EW system controls a set of chaff-flare dispensers, all built by Saab Avionics. BOL dispensers are built into the end of the missile launch rails and have a total capacity of 160 chaff packs or flares. BOP/C dispensers are built into the fuselage, while BOP/B dispensers are built into the end of the wing pylons. The BOP/B dispenser can trail a "BO2D" towed repeater RF decoy, which can be towed at supersonic speed and programmed to operate in several different modes.

Avionics are linked by three MILSTD 1553B data buses, one for basic aircraft and flight data; one for cockpit displays and data; and one for tactical and weapons data.

* The Flygvapnet was a pioneer in the development and deployment of datalinked combat systems, secretly fielding an initial version of a national defense datalink network with the SAAB 35 Draken fighter in the mid-1960s. They have continued to refine the network.

The Gripen is fitted with the "Tactical Information Datalink System (TIDLS)", which gives the fighter four high-bandwidth, two-way datalinks with a range of about 500 kilometers and very high resistance to jamming. The datalinks allow the Gripen to engage in combat using another aircraft's sensors or from targeting data provided by other defense systems. Data acquired from remote sources is fused and displayed on the fighter's main MFD. The link is fully operational when the aircraft is on the ground, allowing a pilot on standby to have high situational awareness of the battle environment.

One Gripen can provide radar sensing for four of its colleagues, allowing a single fighter to track a target, while the others use the data for a stealthy attack. TIDLS also permits multiple fighters to quickly and accurately lock onto a target's track through triangulation from several radars; or allows one fighter to jam a target while another tracks it; or allows multiple fighters to use different radar frequencies collaboratively to "burn through" jamming transmissions.

TIDLS also gives the Gripen transparent access to the SAAB-Ericsson 340B Erieye "mini-AWACs" aircraft, as well as the overall ground command and control system. This system provides Sweden with an impressive defensive capability at a cost that, though still high, is less than that of comparable systems elsewhere.

* The Gripen's built-in armament consists of a single Mauser BK-27 27 millimeter cannon, housed in a fairing on the aircraft's belly, offset to left to the rear of the engine intake. The aircraft's design philosophy dictated that it would generally carry guided weapons to ensure maximum combat effectiveness, given the aircraft's small size and limited warload. Possible external stores include:

The Gripen's rapid turnaround time will help increase its combat effectiveness, allowing to be rapidly rearmed and sent on consecutive missions.

* The two-seat JAS-39B Gripen is 67 centimeters (2 feet 2 inches) longer than the single-seat version. Fuel capacity is the same for both aircraft. There is no HUD for the back-seater in the two-seat version, though HUD and other video information can be linked into the back-seat display system. The JAS-39B has twin clamshell canopies. One of the interesting features of the machine is an airbag to protect the back seater from flying shards from a front-seat ejection. The airbag pops full in an instant, and then just as rapidly deflates to allow the back-seater to eject.

The JAS-39B is not really intended for flight training as such, since the Gripen is a very docile aircraft. Its primary purpose is tactical training, and except for the lack of a built-in cannon, it is fully combat capable.

Flight training for the Gripen is supplemented by four "Multi-Mission Trainer (MMT)" simulators built by Loral. Each MMT contains three wide-screen displays and a Gripen cockpit with a head-up display. The MMTs can be linked with dome simulators and other MMTs to provide interactive combat training.

* The Flygvapnet is currently taking deliveries of Batch 2 Gripens, which feature a new Sundstrand APU, replacing the older Microturbo APU, which was too noisy and not reliable enough; a new Lockheed Martin flight control system computer, replacing a Lear-Siegler unit; a Kaiser HUD, replacing the Hughes-built HUD; and a new display processor. The Sundstrand APU will be retrofitted to Batch 1 Gripens, as well as early Batch 2 aircraft that had an interim improved Microturbo APU.

Production is now shifting to the Batch 3 machines, which feature:

The last 20 Batch 2 aircraft will include some Batch 3 features, such as the color MFDs, CDL 39, and the five data buses. Deliveries are expected to shift from Batch 2 to Batch 3 in 2003.

The changes in Batch 3 give the new version a substantial increase in capability. They are sometimes referred to as "Super Gripens", with the single-seater Batch 3 machine sometimes informally referred to as the "JAS-39C" and the two-seater the "JAS-39D".

The Flygvapnet plans to obtain 204 Gripens by 2004, including 175 JAS-39As and 29 JAS-39Bs, for use in eight squadrons, replacing the Viggen. This represents a considerable downsizing of the air force, as in the late 1980s the country had 425 combat aircraft in 26 squadrons, and the original plan had been to obtain 350 Gripens.



* Although the Swedes have traditionally been reluctant to export weapons, the end of the Cold War seems to have led to some change in this policy, and in June 1995 SAAB formed a partnership with BAE Systems named "Gripen International" to sell the Gripen on the world market. SAAB was forced to seek international sales for the Gripen, as the Swedish government contract for the fighter was so tight-fisted that Gripen International's president, Hans Kruger, once said he'd "lost his shirt, tie, and jacket on the Batch 1 deal."

The arrangement allowed SAAB to leverage off the British firm's international marketing clout. BAE Systems felt that the Gripen would neatly fit in their product line, between the Hawk and the Eurofighter Typhoon. Three years later, BAE Systems obtained a 35% share in Saab.

There was skepticism in the aircraft industry that the Gripen could meet the competition from American and French manufacturers, but events have proven the skeptics wrong. The first export success for the Gripen occurred in 1999, when South Africa has ordered 28, with initial deliveries scheduled for 2006.

The South African deal wasn't heavily contested, but late in 2001, Hungary committed to a ten-year lease for 14 Gripens from the Flygvapnet, with an option to buy. The Hungarian Gripens are scheduled to go into service in 2004. Immediately after this win, the Czech Republic announced a preliminary agreement to buy 24 Gripens, including 18 JAS-39As and 6 JAS-39Bs, with initial service in 2005.

The success of the Gripen in Hungary and the Czech Republic was a real surprise, as there had been strong competition from US and French offerings. It gives the Gripen a step up for several other fighter competitions, going up against the F-16 and Mirage 2000:

Export Gripens will be Batch 3 standard aircraft. The British ASRAAM and Israeli Rafael Python 4 short-range heat-seeking AAMs, and the Rafael "Litening" targeting and navigation pod are being qualified for the Gripen to support export sales. The Thales "Vicon 70" reconnaissance pod will be qualified for export Gripens, though the Flygvapnet will use a pod being developed by Saab.

BAE Systems is working to integrate the NATO-standard "Link 16" datalink system with export Gripens, which is desired by potential customers though it isn't as capable as the TDLS datalink used by Flygvapnet Gripens.

* Features under development for future Gripens include:

The Gripen's digital architecture makes software upgrades straightforward, at least as such things go. Possible software improvements include new radar and datalink modes; a new terrain-referenced navigation system; and a fully autonomous precision landing-guidance system.

In the long term, SAAB is looking at a new engine, such as the General Electric F414 or a thrust-vectoring version of the EJ200 engine used on the Eurofighter; conformal fuel tanks or a fuselage stretch for greater range; a wide-angle HUD; a binocular helmet-mounted display; a direct voice-command system; and an advanced missions support system.

The Flygvapnet is also contemplating the the use of the two-seat JAS-39B for missions such as command and control of strike packages or maritime operations; suppression of enemy air defenses; as a "mini-AWACS" platform; or as a controller for unmanned aerial vehicles (UAVs).



* The aggressive sales promotion of the Gripen has led to a few odd statements, apparently the products of overactive minds in the marketing department. Some sources have stated that it was specifically designed to only use smart weapons, which leads to the puzzle of why the ability to carry dumb bombs would be designed out. In fact, there are plenty of pictures of Gripens carrying dumb bombs and unguided rocket pods.

Another even more puzzling statement in one source was that the Gripen was a "swing-role" aircraft, capable of changing operational roles in flight, as opposed to a "multi-role" machine, which was configured for a specific mission before takeoff.

This leads to wondering why anybody would normally want to fit an aircraft with a mix of stores, including long-range AAMs, air-to-surface weapons, and a reconnaissance pod, instead of fitting it with the weapons required for a specified mission; and on the other side of the coin, should there be a reason to fit such a mix, exactly what was special about the Gripen in permitting such a combination.

It appears the "swing-role" concept is based on the fact that the Gripen's datalink capabilities allow new mission programming to be uploaded to it in flight. A neat trick, but the marketese is still a bit overblown.

* Sources include:

* Revision history:

   v1.0.0 / 01 jun 02 / gvg