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Aviation History
1979
1979 - 1114.PDF
1068 fUGHT International, 7 April 1979 It Q*. •- •"• <#s>m t§ • • Military airborne radars According to Erich Hartmann, top-scoring fighter "ace" of the Second World War, "the pilot who sees the other first already has half the victory." Airborne radar is for all practical purposes the long- range eyes of the modern military aircraft. The development of lasers or other sensors has done little to dent its supremacy. DOUG RICHARDSON has prepared this survey of the equipment in large-scale service with the world's air forces. THE PEOPLE and organisations involved in the develop ment and operation of the E-3A Sentry (Awacs) are proud of Nato's flying radar station. But at Westing- house the engineers walk that little bit taller than anywhere else. Boeing simply builds the aircraft, one company employee tells Flight, whereas Westinghouse builds the advanced APY-1 radar which converts the well known Boeing 707 into a flying early-warning station for the 1980s. Seattle would point out that there is more to building 707s than simply bending metal, as the 11-62 or Tu-154 sales records amply demonstrate. A modern military aircraft is a skillful blend of airframe, engine and avionics, but it is the last-mentioned which accounts for an ever-growing proportion of the fly-away price. Radar is still the primary long-range sensor, and the latest sets are as far removed from the crude "AI" (air borne interception) equipment of the 1940s as is the Bfl09 from Tornado. Now that aircraft performance has reached a Mach 2 plateau, the potential customer is likely to spend more time reading the avionics section of the brochure than any other before choosing a new mount for his air arm. But there are brochures and brochures, depending on the intended readership. F-18 literature being used as performance yardsticks by many Nato air staffs will leave little unsaid, but the air-show handouts make much lighter reading. The raw material for this survey was a pile of brochures, magazine articles, drawings and photographs more than a foot deep. Once these were "boiled down" to extract the hard data, a dozen sheets of paper could comfortably contain the end product. If aircraft effectiveness depends so heavily on radar performance, it is hardly surprising that detailed informa tion on such equipment remains classified. Paradoxically, and as a result of Nato "ferret" electronic-reconnaissance missions, more is often known about the characteristics of commonly used Soviet radars than of their Western counterparts. We make no apology for the greater-than-usual number of blanks and omissions which appear in the accompanying data tables. Subsequent revisions may help to fill these, but for the moment this Flight survey is by far the most comprehensive published by any magazine. More than 100 sets of equipment are listed, demanding some sort of categorisation. Since so many modern radars are multi-role, assignment of many to any particular section was difficult and in some cases rather arbitrary. For the benefit of readers not familiar with radar and its terminology, a few basic facts might be of help. The principles of airborne radar were explained in an article by Mike Hirst (Flight, September 3, 1977, page 695). To recap briefly, a radar unit emits short-duration pulses of electromagnetic energy at regular intervals. On striking a target they are reflected, producing an "echo" signal which the radar can subsequently detect. As soon as an individual pulse has been sent out, the radar switches over to listen for this echo. The more distant the target, the longer this echo takes to return and the weaker it is. By measuring the time interval between transmission and reception the radar can determine target range, since signal speed is constant. Radar antennas are designed to focus the emitted energy into a discrete beam and to receive signals only from the same direction. No antenna is perfect, so some off-axis response remains. These sidelobes plague the radar designer but are of great assistance to the other side's electronic-warfare specialists. Given range and antenna direction, a radar can compute the position of its target and so can tackle medium or high- altitude intruders. At low level, the problem is more complex. If the ground as well as the target is illuminated by the radar pulse, the relatively small target return will be hopelessly swamped by the large signal reflected by the
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