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Aviation History
1995
1995 - 1251.PDF
MIL! more than 35°C. Towards the end of the third quarter of 1995, the joint Allison/GE team will design the hardware for the Phase II variable-cycle Advanced Technology Engine Gas Generator (ATEGG) and JTDE. GE's future in advanced fighter engines is considered to be tied to variable-cycle tech nology (VCE), particularly since its develop ment of the YF120, an operational VCE which was competed against P&Ws YF119 for the ATF competition. As part of its drive for VCE supremacy, GE is concentrating on core-driven fan engines. In these powerplants a secondary fan, driven from the core as an extended high-pressure (HP) compressor first stage, helps supercharge the air travelling down the bypass duct. The secondary fan improves the fuel effi ciency of a VCE. Maclin says that the Allison/GE team hopes to complete "..the component demonstration of its variable- cycle-core-drive fan stage" in the fourth quar ter of 1995. Earlier work to test a GE-developed core- driven fan and compressor was recently com pleted at the US Air Force's Wright Laboratories at Wright Patterson AFB, Ohio. The components under test incorporated new materials which helped prevent twisting of the extended fan blades, a common problem of earlier core-driven-fan concepts. During the third quarter of 1995, Allison and GE will demonstrate an advanced high- pressure ratio swept-fan design, just as the first demonstrations are due to begin of the core engine technology in an ATEGG test. The Allison/GE team and P&W each won new ATEGG contracts from the US govern ment under recently announced IHPTET awards. Maclin stresses that these tests will be of the Allison/GE core in its fixed-cycle mode. Full VCE tests are not scheduled until "late 1996, or early 1997." Tests of a full core- driven fan JTDE could follow in late 1997. As a result of the Allison/GE tie-up, some existing arrangements for GE's JTDE con tract needed to be changed. "We have been informed by the USAF that we should move ahead witii our JTDE design effort under the current contractual arrangement, while nego tiations proceed to assure that the Phase II goals will be demonstrated before the end of 1997," says Maclin. P&W meanwhile, with the broad experi ence of P&WXTE-65 under its belt, is press ing ahead with preparations for testing its successor, P&W XTE-66. The first Phase II core tests began in April, says Jimmy Reed, manager of P&W Government and Space Propulsion business Advanced Engineering Propulsion Center. "Testing will continue for at least three to four months at Wilgoos Test Center near East Hartford [Connecticut]. Being a core engine (without a low-pressure system), it needs an altitude chamber to duplicate the correct conditions," says Reed. Work on the XTE-66 ATEGG will even tually lead to "...running that core in 1998 with full Phase II capability. Before that we will have initiated Phase III work", Reed says. P&W is concentrating on inserting new tech nology in the Phase II engine. "The primary new technology associated with XTE-66 is the super-cooling turbine." The advanced casting process used to produce in-built cooling will be tested on "blades, vanes and outer air-seals. We will be testing the next generation of super-cooling," says Reed. MMCs also make a re-appearance in the core, having first appeared in quantity in the XTC-65 when it used a first-stage compres sor made from a composite of titanium C alloy matrix and silicon-carbide fibres. "In that engine we used it at the front of the core, around the first stage of the HP compressor. In this core it will be used in the second and third stages are MMC," Reed adds. HAIL CAESAR Caesar (component and engine structural- assessment research) "...is a collective effort between P&W, Wright Laboratories and the F-22 System Program Office," says Reed. "It was put together to do high-endurance test ing on advanced technology which usually runs for only 30 to 200h. In this case, we'll run it for several thousand hours." The high technology can be exposed to CAESAR to see if it stands up to the typical rigours of opera tional life. If it does, the technology could be incorporated in new-production engines, or retrofitted to older ones. Advanced features will be inserted into a basic Fl 19 "shell" made up of a HP compres sor, HP turbine and combustor. "Probably one of the most interesting aspects of the Caesar project is the compressor which will be fitted with blades made by Allison, GE, P&W and Rolls-Royce," says Reed. Each company is supplying lightweight blades made from varying mixes of gamma- titanium-aluminide alloy. "They all have high Large-scale aerodynamic and propulsion in> and Vertical Landing concept undergoing g Palm Beach factory GE F414 Afterburner, showing composite panel strength, but very different blends. Using Caesar we will make an evaluation of their strength," says Reed. Some earlier development problems with the Fl 19 HP turbine caused P&W to "stand- down" the turbine section of CAESAR until the Fl 19 was solidified. The problems were resolved and "...that program is on track and going full-speed ahead," he says. By early April seven Fl 19 test engines had accumulated 4,300h, some l,830h of which were made during endurance testing and a further further hours were amassed during afterburner trials. COMPARATIVELY SMOOTH Development of the Eurojet's EJ200 has so far gone relatively smoothly, at least in compari son to some other elements of the Eurofighter EF2000 programme. Daimler-Benz Aerospace (DASA) sub- sidary MTU experienced problems in com pressor design, and integration of the full-authority digital engine-control (FADEC) system was not trouble-free. The engine's performance envelope for the first year of test flights in the DA3, which will ensure the FADEC powerplant interaction is as predicted has now been cleared. For all four Eurojet partners — Italy's FiatAvio, Spain's ITP, MTU and the UK's Rolls-Royce — the success of the programme 24 FLIGHT INTERNATIONAL 3 - 9 May 1995
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