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Aviation History
1995
1995 - 1252.PDF
MJLlTARY AVIATION odd of Lockheed's X-32 Advanced Short Takeoff" round engine run at Pratt & Whitney's West Eurojet EJ200 undergoing accelerated simulated mission endurance testing is critical. So far, the signs arc relative ly auspicious. The two-spool turbofan has a three-stage low-pressure compressor and a five-stage high- pressure compressor which is driven by an HP turbine fitted with single crystal blades. Total running hours for the engine are around the 5,000h mark, including one engine some 600h of simulated service opera tion on one engine. While technically the EJ200 is progressing relatively smoothly, there are potential problems concerning workshare. Because of the continuing changes in the numbers of aircraft which some of the Eurofighter nations intend to take, engine and airframe workshare will have to be re allocated. UK production work will almost certainly have to be taken from Germany and Spain, a move which could cause political problems. Europe's competing powerplant is France's Snecma M88. With delivery of the first pro duction M88 for the Rafale fighter due at the end of 1996, Snecma is focussing on what must follow if it is to retain its long-estab lished military engine capability. Snecma is looking to the Saab JAS39 Gripen as the potential launch airframe for a more powerful derivative of the M88. A com petition which Eurojet is also addressing with the EJ2000. The M88-3, as it is called, is initially aimed at Sweden's need for a more powerful engine for the JAS39, now equipped with the General Electric/Volvo Flygmotor RM-12, a derivative of the GEF404. One option is that this engine may be retained and given a "throttle boost", increas ing thrust by 5%. Sweden may, however, demand a more potent solution to future Gripen needs, and will be able to choose between a more advanced F404, the GE F414, the Eurojet 200, or the M88-3. Either of the latter three would confer a 20% thrust increase over the RM-12, for vir tually no increase in weight. Massot considers the Snecma solution the best: "The M88 fits very well into the same engine bay, and by the time of the decision at the end of 1996, the core will have built up significantly more run ning time. It is the best, lowest-risk solution". It is hoped that the prospects of a Gripen contract will drive the decision to go ahead with the M88-3, which would then be offered to the French air force for future, heavier, ver sions of the Rafale. "One thing is certain", says Snecma's military engines vice-president Alain Habrard, "the Rafale will get heavier, and the air force will demand more power". He stresses that while the current M88-2 is "good enough for all perceived require- Vectoring in vogue Thrust-vecotoring technology is close to becoming a deployable reality. Russia's Sukhoi design bureau is working on a pre-pro duction model of its Su-35 derivative of the Su-27 Flanker, equipped with two-dimension al thrust vectoring nozzles, while in die USA several programmes are under way. Exactly how capable the Su-35 thrust- vectoring system is remains to be seen, as does the extent to which it is fully integrated with the aircraft's flight control system. In Europe, the four Eurofighter nations are also looking at the possibility of intro ducing thrust vectoring as part of a mid-life update for the Eurofighter EF2000. Ger many had intially considered pushing for thrust vectoring, but the technology was not considered mature enough. Following the succesful Rockwell/ Daimler Benz Aerospace X-31 programme, the latter company is looking to draw upon this work for inclusion on the EF2000. Pratt & Whitney's pitch/yaw balanced beam nozzle (PYBBN) will be flown fitted to a McDonnell Douglas F-15 in May as part of the advanced control technology for inte grated vehicles (ACTIVE) programme. While the Lockheed F-22 will be the first US Air Force combat aircraft to be deployed, with thrust vectoring, retrofitting some of the USAF's current inventory also remains a possibility. Lockheed and General Electric, partners in the multi-axis thrust vectoring (MATV) project, see the potential for retrofitting. Their argument is that thrust vectoring will provide the aircraft with: "A lot more bang for the buck." FLIGHT INTERNATIONAL 3 - 9 May 1995
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