December 9 / Saab JAS 39 Gripen first flight
Saab JAS 39 Gripen
Swedish Air Force Gripen at the Zigermeet 2019 in Mollis
The Saab JAS 39 Gripen is a light single-engine multi-role fighter aircraft manufactured by the Swedish aerospace and defence company Saab AB. The Gripen has a delta wing and canard configuration with a relaxed stability design and fly-by-wire flight controls. Later aircraft are fully NATO interoperable.
In 1979, the Swedish government began development studies for an aircraft for fighter, attack, and reconnaissance to replace the Saab 35 Draken and 37 Viggen in the Swedish Air Force. A new design from Saab was selected and developed as the JAS 39. The first flight occurred in 1988, with the delivery of the first serial production airplane in 1993. It entered service with the Swedish Air Force in 1996. Upgraded variants, featuring more advanced avionics and adaptations for longer mission times, began entering service in 2003.
To market the aircraft internationally, Saab formed partnerships and collaborative efforts with overseas aerospace companies. On the export market, early models of the Gripen achieved moderate success, with sales to nations in Central Europe, South Africa, and Southeast Asia. Bribery was suspected in some of these procurements, but Swedish authorities closed the investigation in 2009.
A major redesign of the Gripen series, previously referred to as Gripen NG (Next Generation) or Super JAS, now designated JAS 39E/F Gripen began deliveries to the Swedish and Brazilian Air Forces in 2019. Changes from the JAS C to JAS E include a larger fuselage, a more powerful engine, an increased weapons payload capability, and a new cockpit, avionics architecture, electronic warfare system and other improvements.
Czech Air Force Gripen at the Nato & Czech Air Force Days 2018
Design
Overview
The Gripen is a multirole fighter aircraft, intended as a lightweight and agile aerial platform with advanced, highly adaptable avionics. It has canard control surfaces that contribute a positive lift force at all speeds, while the generous lift from the delta wing compensates for the rear stabiliser producing negative lift at high speeds, increasing induced drag. Being intentionally unstable and employing digital fly-by-wire flight controls to maintain stability removes many flight restrictions, improves manoeuvrability, and reduces drag. The Gripen also has good short takeoff performance, being able to maintain a high sink rate and strengthened to withstand the stresses of short landings. A pair of air brakes are located on the sides of the rear fuselage; the canards also angle downward to act as air brakes and decrease landing distance. It is capable of flying at a 70–80 degrees angle of attack.
To enable the Gripen to have a long service life, roughly 50 years, Saab designed it to have low maintenance requirements. Major systems such as the RM12 engine and PS-05/A radar are modular to reduce operating costs and increase reliability. The Gripen was designed to be flexible, so that newly developed sensors, computers, and armaments could be integrated as technology advances. The aircraft was estimated to be roughly 67% sourced from Swedish or European suppliers and 33% from the US.
One key aspect of the Gripen programme that Saab has been keen to emphasize has been technology-transfer agreements and industrial partnerships with export customers. The Gripen is typically customized to customer requirements, enabling the routine inclusion of local suppliers in the manufacturing and support processes. A number of South African firms provide components and systems – including the communications suite and electronic warfare systems – for the Gripens operated by the South African Air Force. Operators also have access to Gripen's source code and technical documentation, allowing for upgrades and new equipment to be independently integrated. Some export customers intend to domestically assemble the Gripen; it has been proposed that Brazilian aerospace manufacturer Embraer may produce Gripens for other export customers as well.
Close up with the Swedish Gripen at Försvarsmaktens flygdag 2022
Pair of Swedish Gripens enroute to RIAT 2022
Avionics and sensor
All of Gripen's avionics are fully integrated using five MIL-STD-1553B digital data buses, in what is described as "sensor fusion". The total integration of the avionics makes the Gripen a "programmable" aircraft, allowing software updates to be introduced over time to increase performance and allow for additional operational roles and equipment. The Ada programming language was adopted for the Gripen and is used for the primary flight controls on the final prototypes from 1996 onwards and all subsequent production aircraft. Gripen's software is continuously being improved to add new capabilities, as compared to the preceding Viggen, which was updated only in an 18-month schedule.
Much of the data generated from the onboard sensors and by cockpit activity is digitally recorded throughout the length of an entire mission. This information can be replayed in the cockpit or easily extracted for detailed post-mission analysis using a data transfer unit that can also be used to insert mission data into the aircraft. The Gripen, like the Viggen, was designed to operate as one component of a networked national defence system, which allows for the automatic exchange of information in real-time between Gripen aircraft and ground facilities. According to Saab, the Gripen features "the world's most highly developed data link". The Gripen's Ternav tactical navigation system combines information from multiple onboard systems such as the air data computer, radar altimeter, and GPS to continuously calculate the Gripen's location.
The Gripen entered service using the PS-05/A pulse-Doppler X band multi-mode radar, developed by Ericsson and GEC-Marconi, which is based on the latter's advanced Blue Vixen radar for the Sea Harrier that also served as the basis for the Eurofighter's CAPTOR radar. The all-weather radar is capable of locating and identifying targets 120 km (74 mi) away and automatically tracking multiple targets in the upper and lower spheres, on the ground and sea or in the air. It can guide several beyond-visual-range air-to-air missiles to multiple targets simultaneously. Saab stated the PS-05/A is able to handle all types of air defence, air-to-surface, and reconnaissance missions, and is developing a Mark 4 upgrade to it. The Mark 4 version has a 150% increase in high-altitude air-to-air detection ranges, detection and tracking of smaller targets at current ranges, 140% improvement in air-to-air mode at low altitude, and full integration of modern weapons such as the AIM-120C-7 AMRAAM, AIM-9X Sidewinder, and MBDA Meteor missiles.
The future Gripen E/F use a new Active Electronically Scanned Array (AESA) radar, Raven ES-05, based on the Vixen AESA radar family from Selex ES. Among other improvements, the new radar is capable of scanning over a greatly increased field of view and improved range. In addition, the new Gripen integrates the Skyward-G Infra-red search and track (IRST) sensor, which is capable of passively detecting thermal emissions from air and ground targets in the aircraft's vicinity. The sensors of the Gripen E are claimed to be able to detect low radar cross-section (RCS) targets beyond visual range. Targets are tracked by a "best sensor dominates" system, either by onboard sensors or through the Transmitter Auxiliary Unit (TAU) data link function of the radar.
Hungarian Gripen dumping and burning fuel at the Nato Days 2020
Swedish Air Force JAS 39D Gripen at RIAT 2017
Cockpit
The primary flight controls are compatible with the Hands On Throttle-And-Stick (HOTAS) control principle – the centrally mounted stick, in addition to flying the aircraft, also controls the cockpit displays and weapon systems. A triplex, digital fly-by-wire system is employed on the Gripen's flight controls, with a mechanical backup for the throttle. Additional functions, such as communications, navigational and decision support data, can be accessed via the Up Front Control Panel, directly above the central cockpit display. The Gripen includes the EP-17 cockpit display system, developed by Saab to provide pilots with a high level of situational awareness and reduces pilot workload through intelligent information management. The Gripen features a sensor fusion capability, information from onboard sensors and databases is combined, automatically analysed, and useful data is presented to the pilot via a wide field-of-view Head-Up Display, three large multi-function colour displays, and optionally a Helmet Mounted Display System (HMDS).
Of the three multi-function displays (MFD), the central display is for navigational and mission data, the display to the left of the centre shows aircraft status and electronic warfare information, and the display to the right of the centre has sensory and fire control information. In two-seat variants, the rear seat's displays can be operated independently of the pilot's own display arrangement in the forward seat. Saab has promoted this capability as being useful during electronic warfare and reconnaissance missions, and while carrying out command and control activities. In May 2010, Sweden began equipping their Gripens with additional onboard computer systems and new displays. The MFDs are interchangeable and designed for redundancy in the event of failure, flight information can be presented on any of the displays.
Saab and BAE developed the Cobra HMDS for use in the Gripen, based on the Striker HMDS used on the Eurofighter. By 2008, the Cobra HMDS was fully integrated into operational aircraft, and is available as an option for export customers; it has been retrofitted into older Swedish and South African Gripens. The HMDS provides control and information on target cueing, sensor data, and flight parameters, and is optionally equipped for nighttime operations and with chemical/biological filtration. All connections between the HMDS and the cockpit were designed for rapid detachment, for the safe use of the ejection system.
Trio of Czech, Swedish and Hungarian Gripens at the Nato Days 2020
Czech Air Force Gripen at the Radom Airshow 2018
Engine
All in-service Gripens as of January 2014 are powered by a Volvo RM12 turbofan engine (now GKN Aerospace Engine Systems), a licence-manufactured derivative of General Electric F404, fed by a Y-duct with splitter plates; changes include increased performance and improved reliability to meet single engine use safety criteria, as well as greater resistance to bird strike incidents. Several subsystems and components were also redesigned to reduce maintenance demands. By November 2010, the Gripen had accumulated over 143,000 flight hours without a single engine-related failure or incident; Rune Hyrefeldt, head of Military Program management at Volvo Aero, stated: "I think this must be a hard record to beat for a single-engine application".
Like the Gripen, test models of the Dassault Rafale used F404 engines until replaced by the SNECMA M88-2 engine on production aircraft. A JAS 39C variant powered by a new 80–93 kN (8,200–9,500 kgf; 18,000–21,000 lbf) thrust SNECMA M88-3 engine was proposed. The M88-3 variant would have a new low-pressure compressor (LPC) with a new variable stator vane stage and an increased mass flow of 73.4 kg/s (9,710 lb/min).
The JAS 39E and F variants under development are to adopt the F414G powerplant, a variant of the General Electric F414. The F414G can produce 20% greater thrust than the current RM12 engine, enabling the Gripen to supercruise (fly at supersonic speed without the use of afterburners) at a speed of Mach 1.1 while carrying an air-to-air combat payload. In 2010, Volvo Aero stated it was capable of further developing its RM12 engine to better match the performance of the F414G, and claimed that developing the RM12 would be a less expensive option. Prior to Saab's selection of the F414G, the Eurojet EJ200 had also been under consideration for the Gripen; proposed implementations included the use of thrust vectoring.
Czech Gripen at the Belgian Air Force Days 2018
Equipment and armaments
The Gripen is compatible with a number of different armaments, beyond the aircraft's single 27 mm Mauser BK-27 cannon (omitted on the two-seat variants), including air-to-air missiles such as the AIM-9 Sidewinder, air-to-ground missiles such as the AGM-65 Maverick, and anti-ship missiles such as the RBS-15. In 2010, the Swedish Air Force's Gripen fleet completed the MS19 upgrade process, enabling compatibility with a range of weapons, including the long-range MBDA Meteor missile, the short-range IRIS-T missile and the GBU-49 laser-guided bomb. Speaking on the Gripen's selection of armaments, Saab's campaign director for India Edvard de la Motte stated that: "If you buy Gripen, select where you want your weapons from. Israel, Sweden, Europe, US… South America. It's up to the customer".
In flight, the Gripen is typically capable of carrying up to 6,500 kg (14,330 lb) of assorted armaments and equipment. Equipment includes external sensor pods for reconnaissance and target designation, such as Rafael's LITENING targeting pod, Saab's Modular Reconnaissance Pod System, or Thales' Digital Joint Reconnaissance Pod. The Gripen has an advanced and integrated electronic warfare suite, capable of operating in an undetectable passive mode or actively jamming hostile radar; a missile approach warning system passively detects and tracks incoming missiles. In November 2013, it was announced that Saab will be the first to offer the BriteCloud expendable Active jammer developed by Selex ES. In June 2014, the Enhanced Survivability Technology Modular Self-Protection Pod, a defensive missile countermeasure pod, performed its first flight on the Gripen.
Saab describes the Gripen as a "swing-role aircraft", stating that it is capable of "instantly switching between roles at the push of a button". The human/machine interface changes when switching between roles, being optimized by the computer in response to new situations and threats. The Gripen is also equipped to use a number of different communications standards and systems, including SATURN secure radio, Link-16, ROVER, and satellite uplinks. Equipment for performing long-range missions, such as an air-to-air refuelling probe and Onboard Oxygen Generation System (OBOGS), was integrated into the Gripen C/D.
Hungarian Air Force Gripen at the Sanicole Sunset Airshow 2021
Usability and maintenance
During the Cold War, the Swedish Armed Forces were to be ready to defend against a possible invasion. This scenario required defensive force dispersal of combat aircraft in the Bas 90 system to maintain an air defence capacity. Thus, a key design goal during the Gripen's development was the ability to operate from snow-covered landing strips of only 500 metres (1,600 ft); furthermore, a short-turnaround time of just ten minutes (attack mission preparations is double that time), during which a team composed of a technician and five conscripts would be able to re-arm, refuel, and perform routine inspections and servicing inside that time window before returning to flight for air-to-air missions. For air-to-ground missions, this turnaround time using the same resource is slightly longer at twenty minutes.
During the design process, great priority was placed on facilitating and minimizing aircraft maintenance; in addition to a maintenance-friendly layout, many subsystems and components require little or no maintenance at all. Aircraft are fitted with a Health and Usage Monitoring System (HUMS) that monitors the performance of various systems and provides information to technicians to assist in servicing them. Saab operates a continuous improvement programme; information from the HUMS and other systems can be submitted for analysis. According to Saab, Gripen provides "50% lower operating costs than its best competitor".
A 2012 Jane's Aerospace and Defense Consulting study compared the operational costs of a number of modern combat aircraft, concluding that Gripen had the lowest cost per flight hour (CPFH) when fuel used, pre-flight preparation and repair, and scheduled airfield-level maintenance together with associated personnel costs were combined. The Gripen had an estimated CPFH of US$4,700 whereas the next lowest, the F-16 Block 40/50, had a 49% higher CPFH at $7,000.
Pair of Swedish Gripens enroute to RIAT 2022