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Aviation History
1988
1988 - 0483.PDF
Facing page The MD-80 ultra-high- bypass demonstra tor has a General Electric unducted fan mounted on the port pylon. Above The MD-91 is a propfan-powered equivalent of the 114-seat MD-87. Left The MD-92 is a 165-seat derivative of the MD-82. Below The UDF is now flying with two rows of eight propulsor blades general manager Bruce Gordon. "We're protecting this schedule. If they can't sell the aircraft we'll delay. Obviously they have got to get a couple of airlines to order substantial quantities before we'll go ahead," he adds. The seven-stage, high-pressure com pressor on test at Snecma (which has a 35 per cent share in development of the engine) is running "extremely well", says Gordon, and will be mated to the rest of the all-new core later this year, and to the propulsor in late 1989, ready for the first production-configuration engine in early 1990. The same production engine will power both MD-90s, but will be derated by 3,0001b, to 22,0001b thrust, for the smaller MD-91. Certification testing of the airframes will be done first with two pre- production GE36-C25s. These will be replaced by production engines as they become available. Gordon says that more than 700 propulsor-blade configurations have been tested since March 1984. The decision on the number of blades on the production engine will be made "within a month," he says. Gordon hints that one row will probably have more than ten blades, the other less. The proof-of-concept engine is currently an 8 x 8 set-up, the 10 x 8 engine previously flight-tested being about to undergo icing tests at GE's Peebles outdoor test facility. Flight testing of the Pratt & Whitney/Allison 578DX geared propfan demonstrator will begin in May, at Edwards Air Force Base, California. The powerplant has been extensively tested at Allison's Indianapolis propeller test facility, and will occupy the same pylon that carries the GE36, with a modified mounting. McDonnell Douglas says it has had "no firm offer" from the PW/A team yet on an MD-90 engine. The Pratt & Whitney/Allison 578DX demonstrator propfan is too small to be developed for the MD-92, admits Tadry Domagala, P&W's vice-president commercial project management. During 1986-87 Pratt & Whitney/Allison encoun tered problems with its propfan, including an increase in the power needed to drive the MD-92 from 14,000 s.h.p. to 16,000 s.h.p. per engine. No P&W propfan could be ready for commercial service before 1993, Domagala says. A simultaneous MD-91 and MD-92 product launch this summer could commit McDonnell Douglas to a September 1992 certification date. The company does not yet know whether the MD-91 or MD-92 will be certificated first. "That will depend on the airline," says Still. The second version would be launched "three to six months behind the first," he adds. Development of the MD-90 airframe will cost "substantially less than $1 billion", says Still, who reckons that the $3 billion development cost of the propfan-powered 7J7 was the main reason Boeing pulled out of the project. "If you assess the potential for capturing a share of the market when each aircraft must bear an extra $4-5 million price tag because it is new, it turns out to be hard to -get," he says. Still would not reveal MD-90 prices, except to say that they will be "not lower than the MD-87". •. Douglas claims that the MD-90s will be the ' "quietest aircraft in the industry." Watching the demonstrator take-off with another load of airline executives aboard, just after a Boeing 727 and before an MD-80, one could see this prediction coming true—especially bearing in mind the continued development being applied to both airframe and engine. S3 FLIGHT INTERNATIONAL, 27 February 1988 31
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