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Aviation History
1976
1976 - 0018.PDF
18 FIRE POWER the radar can begin to compute the range rate (the rate at which the separation from the target is changing). At about 80 miles the equipment can calculate the individual range rates of more than 20 targets. In the case of a number of targets appearing on the screen with different ranges and closing rates, a weapon computer in the radar computes which targets should have priority because of range or closing speed. Several search patterns can be selected, depending on where the target is situated. For example, during a fighter escort mission the F-14 can use data-link information from the bomber force (usually Intruders), with its greater scanning range, to point its own radar in the direction from which defending fighters have been detected. AWG-9 reliability and capacity will improve when the CDC 5400B computer is replaced by the C model, which is almost half the size, operates twice as fast and is cheaper. McDonnell Douglas F-15 Eagle The F-15's Hughes APG-63 X-band pulse-Doppler air-to-air radar has a detection range about 15 per cent less than that of the F-14's AWG-9 and it is not designed to track as many targets simultaneously. The Eagle emphasises the performance needed for closer combat, involving the detection and tracking of targets— particularly at low levels—coming from all directions. The APG-63 uses both medium and high pulse-repetition fre quencies (PRFs), for detection of receding and high-speed approaching targets respectively. In its primary search mode the planar-array dish scans a volume 60° on either side of the aircraft centreline and + 10° in pitch about a pilot-chosen datum, out to about 150 miles. When the radar has acquired a target the pilot directs the equipment to lock on and track it, and the display then shows attack information such as target range, differential altitude, steering information, closing speeds and weapon- release limits. As the target comes within range the pilot can elect to attack using the vertical situation display, or he may decide to go in visually and transfer his attention to the McDonnell Douglas Electronics head-up display. This provides aiming points and maximum and minimum launch ranges for the missiles. A useful long-range mode is velocity search, in which the radar displays only target velocities. A return showing a speed of Mach 3, for example, is a reasonably sure guide to the presence of a Foxbat. At the other end of the scale a target flying at 80kt or so could be a troop-carrying helicopter. A novel mode is known as supersearch, in which the radar scans the field of view of the head-up display between 500ft and 10 n.m. and automatically locks on to the nearest target found therein. The pilot interrogates it, and if it is friendly the radar is unlocked to continue its search at longer range. When a "hostile" has been detected the absence of an IFF return causes a rectangle to appear in the head-up display, enclosing the target, which at that time may be invisible to the pilot. General Dynamics F-16 Westinghouse has been selected to supply the F-16 radar after a fly-off against a Hughes contender. The entirely solid-state self-testing equipment is based on the company's private-venture WX-200 series and consists of six modular line-replaceable units. Operation is entirely digital, with the exception of the initial signal- amplification stage. A development of Westinghouse's general-purpose minicomputer is employed. The entire radar is expected to weigh about 2601b and will, excluding the 23in aerial and controls, fit into 4 cu ft. Target production cost is $250,000. Basic modes are air-to-air look-up and look-down, auto matic acquisition in dogfight and air-to-ground ranging. Search angle in the air-to-air role is ±60° in both azimuth and elevation. Fire-control functions are shared by the central Delco M362F computer and the Marconi-Elliott FLIGHT International, w/c 3 ]anuary 1976 Hudsight. The latter consists of a pilot's display system with a 5in optical system, digital electronics unit pro grammed for display and gunsight computation, and a rate- gyro sensor for the gunsight. The equipment is based on the Type 664 Hudwac, itself derived from the HUDs supplied for A-7Ds and A-7Es. Singer-Kearfott supplies the inertia! system and Kaiser the joint radar/electro-optical display. McDonnell Douglas/Northrop F-18 The US Navy is expected to run a new competition to select the F-18 radar supplier rather than adopting the Westinghouse F-16 equip ment. The radar will be used to direct attacks with Sparrow air-to-air missiles and will provide the pilot with steering information for Sidewinder operations and air-to-ground weapon delivery. An air-to-air range of 45 n.m. is the goal, with 30 n.m. as threshold, and snap-up and snap-down missile operation will be required. A 28in antenna is to be used. General Dynamics F-lll The basic radars are General Electric's forward-looking APQ-114 and an APQ-113 for mapping. The Westinghouse EAR (see B-l entry) may be retrospectively fitted in FB-llls. The Pave Tack pod (see F-4 entry) will also be installed on F-lllE/Fs. The trials of the Westinghouse F-16 radar, winner of the fly-off against the Hughes system, were carried out in an F-4 Phantom
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