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Aviation History
1989
1989 - 0364.PDF
SIGHT UNSEEN Among its research programmes, the Royal Aerospace Establishment is developing new technologies to overcome the limitations of night-vision sensors and to improve the accuracy of air-to-air missiles. Eric Beech reports from Farnborough. The Royal Aerospace Establishment's Mission Management Department is developing obstacle cueing and perspective displays to overcome the limitations of forward-looking infrared (FLIR) imagery superimposed on a ground- attack pilot's headup display. This continues a development process which has seen the use of radar progress from nightfighter inter cepts at altitude to ground-attack aircraft flying at high speed and low level using auto matic terrain-following radar to find their targets at night or in poor visibility. From 1979 the Royal Aircraft Establish ment (as it was then known) has researched the use of passive electro-optic sensors as aids to pilots in poor light conditions. Low-light television and, later, forward-looking infrared (FLIR) systems teamed with night- vision goggles and compatible cockpit light ing, can enhance a pilot's natural vision, as well as improving the operational effec tiveness of ground-attack aircraft by up to 40 per cent. The passive systems avoid the disadvantages of active terrain-following radar, which reveal the aircraft's position, are expensive, lack flexibility, and are susceptible to jamming. Passive systems, however, have their own disadvantages. Ridgelines cannot always be distinguished in poor conditions. Power cables and masts are not always seen in sufficient time. Heavy precipitation degrades the image, and the sensors cannot provide any forward vision through cloud. Solution Farnborough is working with Ferranti to overcome these shortcomings by developing Penetrate, which provides obstacle cueing and perspective displays. The current fixed- field-of-view FLIR imagery superimposed on a raster headup display is augmented by selected outputs from a digital map and a terrain-reference navigation system (TRNS). Penetrate's database contains the surveyed height of the terrain at each point on a regu- . lar lattice alongside the data on obstructions. Power cables, ridgelines, and chimneys stored in the system can overlay the FLIR image and be presented in the HUD in true pers pective (Fig. 1). Obstructions ahead can, therefore, be identified in advance of their acquisition by the FLIR. In heavy precipi tation or cloud, the pilot can use these obsta cle and ridgeline displays until conditions allow the full FLIR image to be restored. RAE Farnborough operates this BAe Harrier T.4, dubbed "The Night Bird", to research pilot night vision systems combining forward-looking infrared and night vision goggles Following RAE's mission Management Department's successful trials of Penetrate in racked form on the Establishment's BAe Andover C.l flying laboratory, the system is undergoing trials on Farnborough's BAe Hunter T7. Operating parameters will now be 400-500kt at 200ft. According to the superintendent combat mission systems, Maurice Gates, "the trials will last at least until next year as part of an ongoing programme". Ferranti has installed the Penetrate system on the Hunter in pod form. This makes the package more marketable and the production engineer's job easier. Penetrate can reduce pilot workload as well as increasing an aircraft's operational effectiveness. In addition to terrain and obstacle clearance, the system permits tacti cal mass data storage and management. It also provides tactical map overlays and the option of tactical routeing. These aids to mission planning and execution will save time and dispense with low-tech kneepads. Penetrate's terrain-reference navigation system is linked to the aircraft's radio altime ter and inertial navigation system, and is updated periodically by Satellite navigation. Farnborough is confident that sufficient satellite information exists to service the system over Eastern Europe. The Mission Management Department sees excellent 34 FLIGHT INTERNATIONAL, 11 February 1989
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