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Aviation History
1974
1974 - 0019.PDF
FLIGHT International, 3 January 1974 Avionics 19 By HUGH W. COWIN Integrated electronic displays DURING THE latter half of the 1960s ample, to use one display as a hori-there was considerable interest zontal situation indicator while the in the United Kingdom in the develop- other read out fuel remaining against ment of fully integrated electronic dis- distance-to-go along with the direc- plays. The idea was to develop a sub- tion of an alternative airfield. (Before system for two-seat strike aircraft too many strike pilots rush to point which would replace conventional in- out that such a, surfeit of information strumentation in the front cockpit could well prove an embarrassment with a head-up display and three during, say, the attack approach, they head-down cathode ray tube displays may like to reflect on its value. Suppose on which the pilot could call up all battle damage has just incapacitated the data he required. Three British the navigator and possibly severed companies, Ferranti, Marconi-Elliott one or more of the main fuel feed Avionics and Smiths Industries are lines?) Under less arduous conditions known to have carried out indepen- it would be the navigator's task to dent studies which were completed at monitor the aircraft systems and the end of 1968. navigate with the aid of his two head- Essentially, the aim of the studies down displays and a separate moving was to explore the possibility of bring- map. The pilot would be free to con ing together all flight data, systems centrate on flying the aircraft home, monitoring and electronic sensor in puts. The crew would be able to call up all the information they required on the special displays. A significant design requirement was that the dis- i 1 play of flight data had to be fail-safe !___':?? with automatic reselection of the ap- j "** propriate processing channel and/or r"r~ display in the event of a failure. J Presentations of data considered to ! """** be non-essential were left to be pirz": manually reselected by push button I after failure. ""*" The simplified block schematic is uzzzr based on a typical solution proposed | by Ferranti. It shows that the overall j TV sub-system was virtually invulnerable Li—r to any single failure. Nothing within T the sub-system's basic data input and ! «"••-«* processing channel blocks was left un- I duplicated. Much of the system for 1 the multi-function displays, particu- I systems larly in the pilot position, was multi- L^!f™_j plexed to a much higher level of failure survival. The sub-system promised a big im provement to crew efficiency over the Throughout the design of the sub- TSR.2—which at that time was the system, emphasis was laid on the most advanced design in Europe. For ability to make instantaneous changes the first time, the system designer was to the information on display. Data given the freedom of bringing the drawn from a dozen or more sensors pilot fully into the display loop by could be called up at the touch of a providing him with a completely inte- button, while fail-safe functions were grated system which included the maintained by automatic switching of head-up display and three head-down displays and processing channels. For displays. These displays all but instance, should one of the two wave- eliminated conventional instrumenta- form generators fail, the remaining tion from the front cockpit. Vital flight element was capable of either driving data could be presented to the pilot all the displays at a reduced data re- on the head-up display and the central fresh rate, or maintaining the original head-down display. During critical data rate to fewer displays—the flight phases the pilot was left to choice was left to the crew. choose the data to be presented on Although production cost estimates the remaining two head-down dis- were not published, it is of interest to plays. It would be possible, for ex- note that the consensus within in dustry put it at about £30,000 over a large-scale production run. While this figure neglects non-recurrent develop ment costs, it nonetheless provides a useful comparison with the estimate of £20,000 for a comparable non- integrated electronic display sub system for the same type of aircraft. In the 1960s the concept of a fully integrated electronic display was pushing the state of the art in several areas. Subsequent work by Marconi- Elliott in fibre optics and by Ferranti with its Contrastive (cursive on-TV raster) display has largely solved these problems. Ironically the greatest single problem that prevented the studies progressing lay in the system's flexibility of presentation. In effect, the proposal offered a large-capacity CroistaHt Aulo-swi Idling L^ Multiplexed System Selection electronic blackboard on which all kinds of information could be written. Decisions on equipment for military aircraft fall within the province of both the Ministry of Defence and industry. As a consequence there must have been considerable discussion be tween operational requirement staff (some of whom are pilots and others navigators), not to mention the system designers, on what should or should not be displayed. Certainly, the more conservative approach adapted for the MRCA front cockpit, which in cludes discreet head-up and terrain- following displays, tends to bear out the conclusion that improved system flexibility may carry its own philo sophical pitfalls.
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