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Aviation History
1983
1983 - 0049.PDF
Range is "considerably longer" than the 'Sokm of the PS.46. *• When JAS 39 is used as a fighter, the .radar will perform search and multiple track-while-scan at long range, as well as wide-angle, quick scanning and lock-on at short range, plus missile and gun fire- control. In attack and reconnaissance mis sions, the radar will search against heavy ground and sea clutter. It will designate targets for the RBS15F and Sidewinder missiles, as well as the RBS15G glide- bomb. Both obstacle-avoidance and navi gation functions will be performed, and the radar will supply ground maps at nor mal and high resolution. Doppler beam- sharpening techniques are likely. Forward-looking infrared (Flir) is not yet specified for JAS 39, but Ericsson has flight-tested a prototype podded system and has a study contract for integrating any definitive Flir into the new aircraft. The JAS 39's 160kg pod would be moun ted on a front-fuselage hardpoint, and would use engine bleed-air cooling. Target designation would be provided on the Hud, and the standard navigation/ targeting field of view would be supple mented by a long-range mode. For day light use, the target information would still be provided on the Hud, but the Flir imagery would be relegated to the right- hand head-down display. Ericsson is making first-generation computer modules for the JAS 39's SDS- 80 standardised computer system, for de livery to SRA in mid-1983. These will be integrated into early display computers. Second-generation computer cards will start to appear in 1985 for delivery the following year. Only software differences will be allowed between these and the defi nitive systems. SDS-80 is a standard 32-bit computer and software package for the aircraft's radar, displays, electronic countermeasures pod, and systems com puter (which handles navigation and fire control). Use of the same components and software will reduce development, pro duction, and maintenance costs, as well as the cost and effort involved in devising modifications—the Ericsson-developed programming language is a high-level ver sion of Pascal. Bofors Aerotronics is supplying its AMR-345 radio for JAS 39, under a $25 million contract covering development, and production of 30 shipsets. The AMR- 345 is also being retrofitted into the Swedish Air Force's Sk 60 (Saab 105) trainer/light attack aircraft from 1984. The panel-mounted AMR-345 covers VHF and UHF, AM, and FM and can transmit data as well as voices. Secure speech and good electronic counter- countermeasures (ECCM) performance are claimed for the electromagnetic pulse-hardened radio. The micro processor control unit has access to 500 preset channels. FLIGHT International, 8 January 1983 TV guidance for glide bomb Selection of TV rather than laser guidance for the Saab-Bofors RBS15G glide bomb follows Swedish Air Force demands for 10km stand-off range against bridges and ships in harbour, even during heavy rain and snow which attenuate lasers appre ciably. The RBS15G is derived from the RBS15 sea-skimming anti-ship missile, which is available in ship, air, and ground- launched versions. Optimised for use by single-seat aircraft such as the AJ 37 attack Viggen and JAS 39, the LM Ericsson guidance system has been in full development since 1981, and includes a steerable, stabilised TV camera in the nose of the bomb and a spread- spectrum Ku band, pitch-steerable an tenna in its tail. Broad bandwidth for si multaneous video and command signals reduces susceptibility to jamming and minimises weather-induced fade. The 2 • 9m-long, 25cm-diameter, 65kg datalink pod (designed for the tough conditions on Viggen outer pylons) has a fixed antenna in the nose and a pitch/azimuth steerable antenna in the tail. Target location—either "blind" by INS position, or by radar or Flir—is followed by weapon release and an immediate 180° turn. The pilot has no picture during his turn, but the nav/attack system con tinuously computes aircraft position rela tive to the bomb and, once the aircraft is heading away from the target, the pod's rear antenna is steered by dead reckoning to the bomb's position. Only then is the datalink established and TV lock-on to target achieved via a joystick. This provides more operational freedom than systems which require pre-launch TV lock-on, but it demands accurate an tenna steering commands from the nav- attack system and fade-free picture trans mission to avoid overloading the pilot. Once the hairs are crossed, the guidance is essentially automatic, but the pilot may adjust the bomb's path to hit the most vul nerable section of the target. Infrared imaging may replace TV in later models, but the first hurdle is an im minent RSAF decision on whether to adopt the RBS15G or the Rockwell GBU- 15 with a Hughes datalink pod. Test firings of the ship-launched RBS15M are almost complete, and have been successful so far. About 20 Spica- class fast attack craft are to be equipped with four double RBS15M launchers, and Saab expects to deliver all the missiles on order within three years. The missile's front end is derived from that of the RB04 anti-ship missile in service on AJ 37 Vig- gens. A Microturbo air-breathing engine provides the motive power. Two strap-on booster rocket motors for canister launch ing detach, when spent, along with a pair of auxiliary aft stabilising fins. The RBS15M has a Philips frequency- agile radar seeker and radar altimeter. The Ku-band radar is fully digital and has extensive electronic counter- countermeasures facilities. The mag netron transmitter helps ECCM and re duces sea clutter by 6-8dB. Target dis crimination is likely to be good, for operation around Swedish archipelagos. The missile has a range of more than 70km, and cruises faster then Mach 0-8. The mission profile is in four parts—a ballistic-type initial segment is followed by high-level and low-level cruises before the final approach at sea-skimming height.The flight is pre-planned until mid way through the low-level cruise, when the seeker acquires the target. The RBS15M is 4 • 35m long and 0 • 5m in diameter; wing- span is 1 -4m. Weight is 598kg, plus 172kg for the boosters. The air-launched RBS15F is similar to the RBS15M, but there are no booster rockets and auxiliary fins. The guidance electronics are the same, but re- programmed, and a mounting for aircraft pylons is added. The Swedish Air Force has placed a SKr500 million (£41-7 mil lion) order for the RBS15F, with more production options, and the JAS 39 will carry two on underwing pylons. The coastal-defence version will be similar to the RBS15M. Flight understands that ex port versions of the missile are also planned, presumably with less electronics capability. The development, production, and mar keting of the RBS15 family is co-ordinated by the Saab-Bofors Missile Corporation, A Saab-Bofors RBS15M is test fired from the Pitea, a T-131 Spica-class fast patrol boat • JIN ilillfl 65
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