Mark Ayton details Saab’s Gripen E fighter
Comparing a Gripen C to the brandnew Gripen E model on the flight line at Linköping, it’s clear Saab has made some significant physical design changes to its new fighter.
The E-model is a major change to the Gripen aircraft, capable of carrying 40% more fuel with a 16,500kg (36,375lb) max take-off weight.
Gripen E comes with a new engine, two additional weapon pylons, an active electronically-scanned array radar, an infrared search and track sensor (IRST), a new electronic warfare system, avionics architecture, and changes to the airframe.
Gripen E’s forward fuselage is distinguishable from earlier models by the turret ball located forward of the windshield housing the IRST and IFF. Each air intake is fitted with a sensor housing for the distributed missile warning system.
The main landing gear is positioned outward from the position on a Gripen C, which makes the wing shorter with a different shape on its bottom side. The new wing’s wing roots are further out from the fuselage centreline to accommodate additional fuel tanks to increase the fuel payload by 40%.
Gripen E’s wing tip stations are different in form to those used on the Gripen C variant housing an array of antennas for the electronic warfare system.
The fin houses a new intake for the secondary environmental control system at its base, and stands higher than the Gripen C to accommodate the integrated fuel tanks and the new engine.
Saab engineers have lengthened the fuselage by 370mm (14.5 inches) aft of the wing to help manage the aircraft’s centre of gravity because of new loads and changes to weight distribution.
Gripen E retains the central weapon station as per the Gripen C but has two additional missile stations on each outer side of the fuselage.
Lars Ydreskog, Head of Aero Operations said the weight of the structure compared to the maximum take-off weight has been reduced by 3%: “So the structure is more optimised than the Gripen C to enable carriage of more fuel and payload. Approximately 20% of the maximum take-off weight is structure weight, which is amazing. We use aluminium-lithium alloys for some of the structural components to reduce weight.”
Saab uses model-based definition comprising 3D models and associated metadata within 3D computer aided design software to define and provide specifications for individual components and product assemblies. This methodology has allowed Saab to test and verify complex aircraft systems in a virtual environment using simulation tools and digital engineering, resulting in a 60% reduction in the number of hours required to build the first Gripen E aircraft 39-8 not least because all of the parts, components, tubes and harnesses fitted first time.
Saab first used the GE Aviation F414G engine for its Gripen NG demonstrator 39-7, a modified Gripen D. The American F414 is big brother to the F404, the Gripen’s original engine built under license by GKN Aerospace
Engine Systems and marketed as the RM12.
Rated at 22,000lb (97.86kN), the F414G generates an additional 20% of thrust (4,000lb/17.79kN) compared to the RM12, and the primary reason why Gripen E should achieve super cruise flight: the ability to fly supersonically without the need for afterburner.
GE’s F414 is the power plant of the twinengine F/A-18 Super Hornet, the battle proven work horse of the US Navy fleet.
To meet system safety requirements with single-engine operation and to enable super cruise flight, GE Aviation and Saab has made adaptions to the FADEC (full authority digital engine control) software. The need for super cruise was driven by the Svenska Flygvapnet to have high speed performance for transiting to an area of operation caused largely by the reduction of the Flygvapnet’s fleet and the number of bases.
Gripen E’s primary sensor is the Leonardo Raven ES-05 active electronically scanned array radar. The ES-05 antenna is fitted to a repositionable swashplate with one thousand transmit-receive modules coupled to a full digital multi-channel exciter/receiver and processor, to provide a full 100° field of regard either side of the nose centreline. According to Leonardo this allows a Gripen E to turn away after missile launch while maintaining datalink connection to the missile. A Gripen E pilot can be in zero Doppler, perpendicular to the threat and still have good situational awareness from his or her own radar, looking perpendicular to their flight path. Like any other radar, the ES-05 is limited by the antenna’s sight, but the computing power available to the radar allows the beam to instantly switch direction to track outside of the radar’s search volume.
ES-05 has four primary operating modes; air-to-air; air combat; air-to-surface and interleaved, meaning it can conduct air and surface searches simultaneously. Each primary mode has a sub-set. Air-to-air has search while track and single target track. Air combat offers head-up display search, vertical scan, slewable scan and boresight.
The largest sub-set comes with the air-tosurface mode which features real beam ground map, Doppler beam sharpening, sea surface search and track, ground moving target indication and track, spotlight and strip map synthetic aperture radar, inverse synthetic aperture radar imaging and air-tosurface ranging.
Infrared search and track
As passive sensors go, the Leonardo SkyWard G infrared search and track is fully integrated into the target acquisition solution, the radar and other sensors, giving Gripen E a silent engagement capability; information is only fed from passive sensors. The SkyWard G system comprises a sensor head unit and a processor unit and is defined by Leonardo as a passive long-range detection and identification system, with a detection range out to beyond-visual-range air-to-air missile engagement range. Its main features are:
• Passive operations immune to electronic detection and RF countermeasures
• Mid or long waveform infrared detection
• Long range detection
• Scan volume of 160° x 60°
• Field proven search track while scan (S-TWS) modes; air-to-air; air-to-ground; air-to-surface; multiple (MTT) and single track targeting
• Detection and tracking of up to 200 targets
• Selectable fields of view; wide 30° x 24° (imaging); medium 16° x 12.8° (S-TWS and MTT); and narrow 8° x 6.4° (S-TWS and MTT)
• Open architecture
• Air cooled
• Software algorithms for low false alarm rate
Saab developed the Arexis electronic warfare (EW) suite to meet the requirements of the Svenska Flygvapnet based on the threats already being encountered and for front line operations from 2025 onward. Specifically, the Gripen E system, dubbed MFS-EW, was developed to handle current and future complex signal environments and provide increased coverage and frequency waveform detection, greater threat geolocation accuracy, and increased electronic and passive jamming.
An ultra-wide digital radar warning receiver is at the heart of the system providing spherical coverage around the aircraft with high probability of intercept and robust positioning capabilities even during high G manoeuvres. The system uses digital radio frequency memory devices, gallium nitride solid-state active electronically scanned array jammer transmitters, and interferometric direction finding systems to provide high-powered electronic countermeasures and electronic attack functions.
Equipped with these capabilities should allow Gripen E to conduct suppression of enemy air defences, and precise simultaneous jamming of enemy fighters and airborne early warning radars.
When Saab rolled-out aircraft 39-8 a company spokesperson coined the term e-stealth to describe Gripen E capability.
Given it’s difficult to understand how an aircraft can be electronically stealthy, AIR International asked Saab whether the new EW system is linked to the term e-stealth: Lars Ydreskog responded by explaining that one component of the term is the Gripen E system’s ability to use radio silence with the IRST and passive radar modes. The other component is use of powerful on board jammers to nullify enemy radars: “We can put jamming on many different targets at the same time to protect us from being detected in some aspects. Gripen Es operating in a multi-ship can also support each other with jamming from different platforms, a tactic known as synchronised jamming.”
According to Lars one of Gripen E’s strengths will be its ability to operate in swarms, and not as a single ship attacking a target with a single weapon: “Multiple fighters attacking at the same time using multiple missiles, with each aircraft able to support all the missiles going to the target, will make it very difficult for an enemy to keep track of the situation.”
The EW suite will be further enhanced with a missile warning and awareness system.
Datalink and self-protection system
Saab has always highlighted the Gripen’s ability to integrate any type of datalink into the jet to make the aircraft compatible and interoperable with other air forces and their assets. The datalink fitted to Gripen E has improved bandwidth and capacity; the communication element is customisable for any future customer so linking in with coalition partners and other friendly forces is possible. Saab successfully did this for the Royal Thai Air Force and will follow with Brazil. Saab’s chief test pilot Hans Einerth explained: “With Gripen E, we can use it to fuse information in much better ways so we are not only exchanging locations of targets, we exchange a lot of sensor information between platforms to provide more complete situational awareness for the pilot. One aircraft in a flight of four, might fuse information it’s gathering from the battle space and datalink the fused picture to other aircraft in the flight.
Each aircraft can also control each other’s sensors, so if more information is required from a certain area the pilot can send a request to his or her wingmen via the datalink to place their sensors on the area, and then receive more information about each target.” Gripen E will carry an increased payload of chaff and flares, new dispensers and have the ability to deploy the Leonardo BriteCloud expendable active decoy.
Leonardo describes BriteCloud as a selfcontained digital radio frequency memory jammer designed to protect a fighter jet from threats such as RF-guided missiles and fire-control radars. After manual or automatic ejection from a dispenser, BriteCloud detects RF emissions and cross-references them against its preprogrammed threat library. Once a match is found, the decoy applies advanced algorithms and emits a deception signal to defeat the threat radar and incoming missile.