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Aviation History
1962
1962 - 1122.PDF
Type A£ 8010 constant-speed drive, used in the Viekers VCIO, under test in a 200 h.p. dynamometer at Bradford English Electrics A RANGE OF NEW PRODUCTS FROM BRADFORD EIGHT years ago the English Electric Company formed an Aircraft Equipment Division from a section which was already manufacturing electrical equipment for aircraft and guided weapons. Since that time the AED has expanded con siderably, in the face of steadily increasing competition. Much of their success is due to the fact that in 1957 the company spent some £500,000 on a series of test laboratories in Bradford, Yorkshire, which we recently visited. The laboratories have stood the AED in good stead over a period of exceptional technical progress, and they have required very little extension. One recent addition is a new analogue computer, and the only laboratory that has really required enlargement is that for control gear. It was here that our visit began, and one at once acquired the impression of being in a factory making electronics rather than in one concerned with power engineering. Practically all the control equipment now in production is of the static type, invariably transistorized and employing printed circuits. The occasional magnetic amplifier could be seen, but there were no carbon-pile regulators or potentiometers at all. Reliability has been much easier to achieve since the elimination of calibrated relays. Perhaps the most important new electrical system coming into production at Bradford is that for the Blackburn Buccaneer S.2, and the Type AE 7017 control and protection unit for this ap plication weighs only 13 Jib, compared with nearly 281b foi earlier units serving the same function. The alternators for this aircraft deliver three-phase current at 200v. Pausing at an Airmec tape-control machine governing a Newall jig borer, which is employed on production runs not long enough to warrant elaborate tooling, we came to the high-altitude laboratory which is probably the most impressive part of the facility. The largest chamber is a cylinder 9ft in diameter and 9ft long, capable of simulating flight at altitudes up to 90,000ft and with blast air available at from —65 to 200CC. This sort of equipment is essential for the development of an electrical system for any future super sonic transport, and at the time of our visit contained one of the FLIGHT International, 12 July 196: company's new solid-rotor generators running an endurance test ai high inlet temperatures. Solid-rotor (homopolar) machines ma; sometimes be only superficially the right answer, but in some cast- careful assessment has shown them to be the optimum solution. Next on the list came the control laboratory, where fascinatin. work is being done in the direct conversion of d.c. to a.c. and a.c. to d.c, and the achievement of constant frequency by purely electrics means. English Electric have spent over £100,000 of their own money in the development of brushless d.c. generators. Even a: relatively low altitudes conventional machines normally have to be replaced every 700hr or so, but the new generators from Bradford will be guaranteed for 3,000hr. Further advantages of the brushless machines are that they generally weigh only about 60 per cent as much as corresponding conventional generators, and that—since lint contactors are no longer needed—they enable a completely static system to be designed. At the time of our visit a 12kW design was on efficiency testing, and similar units are flying from Hucknall in the Rolls-Royce Tyne-Ambassador. In a period of a few minutes it is not possible to take in a compre hensive picture of the work of the material laboratories, but the main emphasis is on the development of components suitable for super sonic aircraft with ambient temperatures greater than 150°C. A wide range of new insulants has been investigated, and two machines were actually running on top of Bunsen-burner flames—admitted ly with their shaft bearings in a cooler environment. Since their purchase of the license for the Sundstrand equipment shortly after the formation of the division, one of the major activities of AED has been the development and manufacture of hydromec- hanical constant-speed drives. Taking advantage of the operational experience gained by the American company, drives essentialh similar to Sundstrand designs are in production at the company's works at Netherton, Liverpool, while new types of drive are being designed and qualified at Bradford. English Electric drives are used in the Boeing 707-420 fleets of BOAC and Air-India. Driven by Rolls-Royce Conway engines, these units are now cleared for 2,500hr between overhauls, a longer period than that authorized for any other drive in service. The Type AE 8010, now in production for the VC10 and Super VC10, is slightly modified in order to achieve maximum life at a higher rating. Although nominally a 40kVA unit, like that of the 707, the actual electrical loadings will be much higher in the VC10. The 8010 is fully qualified at 600hr. and the company is confident that it will reach the same overhaul life as that of the 707 drive. At the time of our visit an example was running in an environment simulating that measured during test on the first VC10. Systems for the Services In the military field RAF Bomber Command depend heavily upon the company's electrical systems, which are fitted to both the Vulcan B.2 and Victor B.2. The latter has a paralleled a.c. system employing 50kVA oil-cooled brushless generators. Work on such machines began at Bradford in 1957 on the company's own initiative, and the complete Victor unit was on final type-test when we saw it. The company also supply generating systems for Canberras. Javelins and Lightnings, the latter having a 12,000 r.p.m. alternator driven by an air-turbine. English Electric has responsibility for the electrical system of the Buccaneer S.2. With typical ingenuity they have taken the cylinder block from the constant-speed drive of the Victor, the governor from the 707 and the charger pump and gears from other drives. and put these well-proved parts together in a very neat package tailored to the RB.168 (military Spey). The drive and its associated brushless generator were only wooden mock-ups at the SBAC Show last year, but deliveries are now being made. This tight schedule has been possible only by the trouble-free behaviour of the new unit, which will be offered at 2,500hr and appears to be of a size well suited to numerous civil and military applications. The tour ended with a brief demonstration of one of the neat transistorized PACE analogue computers produced by Electronic Associates, which Bradford use as a tool for system design engineers With a Variplotter, it has been found ideal for devising stabilizing networks for alternator control loops. The PACE is small enough to be taken to an actual system, but its chief function is in achieving optimum damping characteristics under all system conditions before new control and protection units have even been built. Such a procedure is critically dependent upon the accuracy with which the analogue simulation approximates to what will actually happen in practice.
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