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Aviation History
1977
1977 - 0084.PDF
78 FLIGHT International, 8 January 1977 COMPONENT IMPROVEMENT AT SMITHS interface to clarify a problem we had been instinctively solving for years. And the complexity is always not so much in the central processor as in the interface—if you can get com patible units you get the reliability. For example, thermocouples have a response time, creating a problem on throttle slam. We know both ends of the problem—thermocouple and the amplifier—and we get the best match without knowing we are solving an interface problem. "Our industry owes a great deal to Rolls-Royce, who typify the British total-system, all-round approach. American engine companies have tended to follow the 'bare-engine' philosophy, even in some cases requir ing the airframe customer to select and fit his own accessories. Rolls- Royce deliver a complete powerplant, including the pod. This total approach to the product is reflected in a strong British control and accessory industry, and it is why I say we are more productive in design and why we can and do many things better than the Americans do." For example, when designing a digital engine-control system to apply to the Adour, Smiths uses the same central processor used by head- up display of the Tornado. Thus, says Hodges, "we can show the customer that the product is developed. The Americans tend to do something new S: fc "Basingstoke's proudest museum-piece is an amplifier taken from the wreckage of an A-7 shot down in Vietnam. Though buckled it still works" "For example, when designing a digital engine-control sys tem to apply to the Adour, Smiths uses the same central pro cessor used by the head-up display of the Tornado" each time—they have the dollars. We are always reading in the newspaper about the low productivity of the British but I can assure you that it does not apply in areas where we sell brains rather than brawn." Smiths Basingstoke's bread - and - butter comes mainly from three areas: engine equipment and controls; air frame equipment comprising fuel- gauging and radar altimeters; and igniters, spark-plugs and thermo couples. Roughly speaking the three sectors generate equal revenue, The bulk of R&D investment is private- venture and is heavily committed to the digital engine-control field. "We don't yet have an order for a digital engine-control system," says Hodges, "but this would be the biggest score we could make." SI Basingstoke's record in this field includes the selection of its analogue solid-state amplifier for the Allison TF41 of the US Navy's LTV A-7s. About 2,000 units have been produced of this rugged, hot - environment (125°C) system. Basingstoke's proudest museum-piece is an amplifier taken from the wreckage of an A-7 shot down in Vietnam. Though buckled it still works. Smiths will be making A-7 units into the 1990s. A Pakistan Air Force order for 50 aircraft is under negotiation. Hodges claims that in the analogue field Smiths has made more engine- control avionics than any European company. Now the firm's resources are going into digital systems appli cable to any of the projected or cur rent civil or military engines. A Smiths/Dowty digital control system designated DP197 is about to run at the National Gas Turbine Establishment at Pyestock. The com pany's "modular approach" leads Hodges to predict that DP197 elec tronics, duplicated for big tasks, could be linked with a new micro processor—possibly from Ferranti— for subsonic engines like the RB.211, the same microprocessor possibly being ideal for helicopter applications. "We believe in the building-brick principle because we can't afford new buildings for every purpose." On reliability, Hodges says that digital systems offer a great deal, though for integrity a duplicated or duplex is needed (aircraft flight- control systems may need multiplex systems). "A lot of prediction is based on educated guesswork in the absence of service data but the guess is that good digital equipment could achieve levels of reliability far above current standards even for single-channel systems like the new Smiths SEP10 autopilot." A controversial question at the present time is whether to go for long life or for what the Americans are beginning to call "availability." The ability to perform a mission the instant it is demanded is, according to Hodges, a very different engineer ing challenge from the requirement to run for 6,000hr without overhaul. In some ways it is an easier problem. Engine controls One reason why the British are ahead in electronic engine controls, according to Hodges, is historical. In the early days of the jet engine American manufacturers used ther mionic valves for their jet-pipe tem perature measuring systems — "an experience which swore them off engine electronics apparently for ever." The British used magnetic amplifiers, heavy but reliable, and these gave the confidence to go on with the electronic solutions. The British now have more than 20 years of production experience in this field. Smiths respects the long-standing competition from Ultra and more recently from Lucas and Hawker Siddeley Dynamics. On Concorde Smiths Basingstoke has 34 items, including fuel-flow indicators and pressure transmitters. Smiths' Cheltenham factory supplies an additional 58 items for Concorde, mainly for the flight deck. Concorde has been a substantial task, and has stimulated a high level of new tech nology. Smiths Industries of Basingstoke is bidding also for the F-18 fuel-gauging system, having spent about £40,000 on the bid. A special management team is beings formed and the division is determined to win. It is putting a lot of its Concorde technology into the system. n
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