Adaptable Software At Heart Of Future Gripen

Gripen E
The Swedish Air Force plans to integrate standoff missiles, while Saab’s Electronic Attack Jammer Pod, pictured on the outer wing pylon, could bolster Gripen E survivability in hostile airspace.
Credit: Per Kustvik/Saab

With flight-test activities spanning two hemispheres, development of Saab’s next-generation Gripen is gaining momentum.

Four years after its first flight, the aircraft is expected to pass Swedish military certification hurdles, the Brazilian Air Force will take delivery of its first Gripen for development tasks in October, and both countries are planning for the type to reach the front line in the next two years.

  • New avionics approach reduces need to recertification, saving time and cost
  • Electronic warfare  system widens surveillance across electromagnetic spectrum
  • Brazil’s fighters will feature indigenous weapons, including a cruise missile

While the aircraft has been built around Sweden’s exacting national defense requirements, Saab is hoping that the new fighter’s attributes, including advanced avionics and electronic warfare suites, will have international appeal beyond the current foreign customer, Brazil.

Externally, the next-generation Gripen retains the distinctive canard planform of the earlier model, but it is a far stockier machine than its predecessor. Maximum takeoff weight for both the single-seat Gripen E and the two-seat Gripen F has increased to 16.5 metric tons, 2.5 tons heavier than the C/D model.

A new approach to blending the delta wing and fuselage developed through the Gripen Demo program—which had its first flight in 2008 and continues to support Gripen E/F flight testing—means the aircraft acts more like a lifting body and provides more room for fuel and extra weapon pylons.

The added weight drives a need for more power, so the Gripen E/F uses General Electric’s F414, providing 22,000 lb. of thrust—4,000 lb. more than the Volvo RM12, a derivative of the GE F404, that powers the Gripen C/D. 

But the biggest changes are under the skin. One impetus for keeping the Gripen’s existing planform was cost. Developing an entirely new fighter from scratch would have been a high cost for post-Cold War Sweden to bear, so investment has been focused on areas to ensure the aircraft can be kept relevant throughout its operational life, moving away from a program of expensive structured upgrades and midlife updates that require recertification every few years.

Saab’s new approach to avionics software, a step beyond the traditional federated and integrated modular systems on the current generation of aircraft is something to which other European future combat air systems developers are aspiring. The company often compares the avionics capabilities of the Gripen E with modern smartphones, whose hardware can be regularly updated with software that can take better advantage of existing hardware capabilities.

Upgrades to aircraft hardware, engines and hydraulics are “linear and predictable,” says Johan Segertoft, head of Gripen E/F program management at Saab. “You expect to have an upgrade cycle for such systems every 10-15 years.” 

But updates and upgrades to high-end features are increasingly being realized through software, which heightens complexity and demands greater computing power. 

Traditional federated aircraft systems have allowed manufacturers to “quickly tack on new features,” Segertoft says. But space and weight limitations mean that only so many features can be added. “If you want to combine data from different sensors, that can be very difficult to achieve,” he notes.

In wholly integrated modular systems, where the software for numerous aircraft systems are embedded in a central computer, even minor changes to the code could influence safety-critical functions.

This often requires recertification, even if only minor new functionalities are added, increasing the time and cost of the upgrade process.

Saab’s approach uses essentially three layers. The bottom layer is hardware with computers such as for flight management, tactical management or stores management, but that layer can also comprise Linux-based computers in a rig-installment or even a desktop station. The top layer is a strict software layer in which applications are separate components, akin to virtual machines. The novel engineering is between the two layers, the avionics platform. This could be compared to so-called middle-ware, but it goes beyond that and is a more complex ecosystem of code, automatic tests and tools. The top layer interacts with the platform, making it hardware--agnostic; upgrading the bottom layer does not concern the software components. 


“Even if you have millions of lines of code, and you want to add an application that is a few thousand lines of code, you don’t have to recertify those millions of lines again as you need to in traditional systems,” says Eddy de La Motte, head of Saab’s Gripen E/F business unit.

Segertoft says that in the 13 months between the first flights of prototypes 39-8 and 39-9, the company was able to introduce entirely new computer hardware with multicore processing units, and the software adapted to the to the new computers and ran stably.

Saab expects this approach will allow it to introduce new technologies to the aircraft, such as artificial intelligence and deep learning to assist the pilot. The company is working on a decision-support system that could help the pilot with high workload periods. For example, during an air-to-ground mission, the decision-support system would monitor the air threat and alert the pilot if it sensed an emerging threat. Adding new weapons is a slightly more complex process, especially as large bulky weapons can directly influence flight control stability.

To simplify the process, different types of weapons are classed into performance groups, with basic performance data supporting each group. If a new weapon can be classified within one of those performance groups, then the process of integration can be streamlined.

New functionality could be added to the aircraft “by individual nations or even individual squadrons, depending on the changing threat situation,” de La Motte says.

“We [Sweden] are a small country in a desolate part of the world, and we need to produce a solution that our air force can afford to use,” Segertoft says. “The big question[s are]: ‘How will our customers adapt to this capability, and what does this mean for our business models?’”  

Mikael Franzen, vice president and head of marketing and sales at Saab’s aeronautics business, says discussions are underway with Sweden about introducing the rapid upgrades, especially when it comes to approving those upgrades and training pilots to make the best of use of them.

“We have done the work to do this technically; then you need to also adapt the processes in the air force, which is of course also a challenge,” Franzen says.

While other manufacturers have focused on low-observability attributes in fighter designs, Saab’s view is that such advanced shapes could be beaten by the increasing proliferation of radars operating in low-frequency bandwidths.

To deal with the new and emerging range of threats such as the Russian S-400 ground-based air defense system or the Sukhoi Su-57 fighter aircraft, the Gripen E will rely on advanced electronic warfare capabilities, the influence of which can be seen externally.

The most obvious features are the enlarged wingtip missile rails—-referred to by engineers as canoes—and fin-top fairings, each containing active, electronically scanned array (AESA) quadrant receivers and transmitters. A fairing under the belly operates in very low bands to provide “early warning of ground radar sets,” says Jonas Gronberg, Saab’s head of marketing, sales and emerging products for fighter electronic warfare. 

“[For both] ground-based and airborne threats, adversaries are moving toward low-frequency operation. We can see on the Su-57 that there are sensor arrays out on the wing, constituting low-frequency radar [that will] operate against stealthy fighters,” adds Gronberg. 

At the roots of the canard foreplanes and the trailing edge of the main wing are missile-approach warning sensors using infrared sensors to look for the plume of an incoming weapon. All these sensors, along with Gripen’s Leonardo-developed Raven ES-05 AESA radar and the Skyward-G infrared search-and-track system, are fused. The Raven ES-05 features a roll-repositionable AESA antenna to provide a wider field of regard, allowing the radar to data-link to missiles as the aircraft turns away from the threat. 

Saab has also developed an electronic attack jammer pod, developed from the Gripen E’s onboard electronic warfare system, that could provide an escort jamming capability for a strike formation to enable the escort to get into standoff-weapon range of targets. For the ongoing Finnish campaign, the company is also proposing co-develop-ment with Finland of a lightweight air-launched decoy missile that would act as an extension of the Gripen electronic warfare system (AW&ST Sept. 14-27, 2020, p. 29)

Even with all this new technology, Sweden still demands that the aircraft operate according to the constraints of its dispersed wartime basing systems to be able to take off and land on road runways in the hinterlands and be turned around, rearmed and refueled by a team of conscripts.

Design features call for the rapid field removal and replacement of engines, the ability to access aircraft systems by ground crews wearing gloves in the coldest of winters and an auxiliary power unit that keeps aircraft systems and communications up and running during the turnaround process so that the aircrew can maintain situational awareness of the air battle above while they are still on the ground. De La Motte says there has been a particular focus on developing systems with high mean time between failures as well as low mean time to recovery.

The Gripen’s introduction should give Brazil the most modern combat aircraft in Latin America. Brazil has contracted to buy 36 Gripens and has a requirement for more to replace its current fighter fleet. The first Brazilian F-39—as the type will be locally designated—built in Sweden was transferred to Brazil at the end of 2020 to support the national flight-test program. As the Brazilian climate is virtually a polar opposite to that of Sweden, the flight-test program will have a particular focus on the aircraft’s climate control systems as well as unique elements of the configuration, including the Brazilian Air Force’s Link-BR2 data--link system and local armaments.

Saab plans to deliver the first of 36 F-39 Gripen E/F fighters to the Wing 2 base in Anapolis, Brazil, this October. In recent weeks, Brazilian Air Force pilots have been undertaking conversion courses with the Swedish Air Force, flying the two-seat Gripen D. Weapons planned for Brazil’s Gripens include the A-Darter missile, developed through a technology transfer with South Africa’s Denel Dynamics, as well as MBDA’s Meteor beyond--visual-range air-to-air missile and an indigenous cruise missile, the MICLA-BR (AW&ST Feb. 22-March 7, p. 46)

Brazil has also been talking with Ukraine about the development of weaponry that could be integrated onto the Gripen. Development of a wide-area display cockpit configuration by Brazil’s AEL-Sistemas has been adopted for use by the Swedish Air Force, too. The configuration also includes two small head-down displays and a new head-up display.

Development of the two-seat Gripen F is proceeding apace, with work shared jointly between Embraer and Saab. The addition of a second cockpit requires lengthening the fuselage by 65 cm (25 in.) and adjusting the electrical system to accommodate the additional avionics and oxygen system. The design of the ducting from the air intake to the engine is being redesigned, and the fuselage is being strengthened to deal with increased bending moment. The two-seat version is designed to be fully operational: Although it will lack the gun of the single-seat model, the two cockpits can be operated independently to enable the rear-seater to operate the electronic warfare system. First flight of a two-seat Gripen is expected in 2022.

The Swedish Air Force, which is buying only the single-seat Gripen E model, is preparing to introduce the type to the first frontline unit in 2023. But it is also beginning studies on how the aircraft will operate alongside the Gripen C/Ds, which will be retained until the 2030s as part of Sweden’s strengthened national defense plans.

One Gripen E is already being operated by the air force for testing and evaluation purposes from its own airbase at Malmen, close to Saab’s facilities in Linkoping, where the majority of the flight-test activity is taking place. Sweden’s Gripens will carry many of the same weapons that equip the Gripen C/D. But there are calls for the introduction of air-launched cruise missiles after 2025, likely the KEPD 350 Taurus missile developed jointly by Sweden and Germany.

The Gripen E/F is also competing for Finland’s HX fighter contest and will likely participate in other upcoming tenders, including in Colombia.

Tony Osborne

Based in London, Tony covers European defense programs. Prior to joining Aviation Week in November 2012, Tony was at Shephard Media Group where he was deputy editor for Rotorhub and Defence Helicopter magazines.