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Aviation History
1958
1958 - 0230.PDF
240 FLIGHT FIGHTER DESIGN PHILOSOPHY . . . except that provided at launch by the airborne radar, or by visual sighting. The first stage can still be recognized as a modern form offighter. At the present time it must still have sufficient per- formance and manoeuvrability to get into position to use unguidedarmaments, such as guns and rockets, or guided armaments like those now entering service. As soon as we can rely on moreadvanced guided missiles for the second stage the fighter will degenerate into a guided-missile platform, carrying precisionairborne radar. The mobility of this platform in terms of inter- ception distance, reinforcement, airfield diversion, patrol endur-ance and ability to get into position to use airborne radar and launch weapons will be of great importance; but developmentsin airborne radar and missiles will make it less necessary to compete with further improvements in the performance of thebomber. TYPICAL INTERCEPTIONS. As broad statements ofphilosophy are best illustrated by examples, let us assume that modern fighters are stationed ready to intercept an attack by dayor night. It should be possible to base these fighters on widely spaced airfields in countries where cities and other targets arewell scattered. The ability of the fighter to move from one airfield to another enables the defences to be switched or reinforced inaccordance with the tactical situation. This flexibility avoids the danger of a Maginot Line type of defence which can bepunctured, turned or even avoided altogether. The value of more-static defences is to defend key targets, and this is whereground-launched guided weapons play a vital role. A simple diagrammatic picture of the situation is given in Fig. 2. Early Warning Radar is required with any defensive system togive the maximum possible warning of attack and while the bombers are still at a sufficient distance from their targets. Unlikepresent forms of ground-launched weapons, fighters have suffi- cient endurance and long-range guidance to be despatched as soonas the threat has been confirmed. In a confused battle with many attacks, and even with jammed ground radar as well, the fightercan deal with the situation from the air. It is possible for the enemy to jam a number of ground radar stations, but virtuallyimpossible for him to deal with a whole series of fighters each carrying its own radar "station." Proper airborne radar can reduce the task of the ground radarmerely to approximate positioning of the fighter on initial compass headings or course corrections. This is most important, as groundradar is notoriously easy to jam and gives far less accurate results than precision radar which is airborne nearer the target. The fighter can take off and climb up to its cruising altitude intwo or three minutes. Directions from the ground radar may be in the form of an elaborate radio link with the controls of theaircraft, but the fighter pilot always retains the ability to fall back on simple voice communication as he did so effectively in the last war. This system is imperative in confused situations whereany part of the automatic system has broken down or has been interfered with.While the fighter is many miles from its target, its own radar scanner is searching to and fro over a large area of sky. Informa-tion is presented on the pilot's screen and this increases his effective vision by very many times. Even with chanceencounters a proper airborne radar should enable the pilot to locate a target whilst he still has sufficient distance to manoeuvreinto position to use his weapons. With the rate of climb and dive of our modem fighter, this is true even if the target is at a verydifferent altitude from the fighter. The Turn to Attack can begin as soon as the pilot identifies atarget on the radar screen. The radar instrumentation is arranged to supply information on the course to steer so as to reach thebest position for launching the weapons against the target. There are a number of ways of doing this, of which the most sophisticatedis to stop the radar scanner from wagging and leave it pointing directly at the target. A servo system is then used to "lock" thescanner so as to follow the direction of the target. The angular positions of the scanner, and possibly range information fromthe radar, are then fed into a computer which provides the course to steer, either through the pilot's instruments or possibly throughthe autopilot as well. To be successful, the system should take account of any limita-tions on performance or manoeuvrability of the fighter, together with possible evasive action on the part of the target. Extremelycomplicated mathematical equations can be derived for the opti- mum course, but it is usually better to approximate this course soas to simplify the computer and instrumentation. It must end at a position from which the weapons can be fired successfully,taking account of any limitation on performance or manoeuvra- bility of the missile. Weapon aiming with unguided shells or rockets must obviouslybe accurate, pointing ahead of the target with just sufficient "lead" angle to collide with it. This computing is at presentcarried out in the highly ingenious but simple mechanism of the gyro gun-sight. Less accurate aim should be necessary with guided missiles,because they can manoeuvre and guide themselves. They can thus be designed for less complicated computing than is required forfiring guns and unguided rockets. There is, however, a temptation to make use of modern electronics to the extent that, once thepilot has carried out his essential function of identifying and marking the target, he can sit back and let the autopilot fly thefighter into the optimum position from which the weapons are fired automatically. However near one approaches completeautomation, full use is not being made of the man in the aircraft unless the design of the system is such that its partial or evencomplete failure would not prevent the pilot from completing his mission on simple instruments or even visual sighting. With a beam-riding weapon, it is necessary for the fighter toaim accurately at the target right up to detonation of the warhead. Fig. 2. This illustration portrays the major elements in a hypothetical target-defence situation, with missile-firing fighters engaging piloted bomber aircraft: A, intended guided-weopon target for main bomber attack; B, rocket-boosted fighter; C, intended release-point of powered bomb; D, bombers detected by ground radar over own territory; E, tighter airfield; F, fighters' cruise-out under approximate ground guidance; G, identification of bomber force by airborne radar; H, long-range reinforcement fighters.
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