McDonnell Douglas opens UHB flight tests

With a sound that is a curious mix of old and new, the McDonnell Douglas MD-80/Ultra High Bypass Demonstrator powered by the General Electric Unducted Fan (UDF) took to wing here, signaling the start of an extensive flight test program. Direct goal of this program is the production of two propfan-powered MD-80 derivatives, plus gaining the capability to retrofit existing MD-80s to propfan power.

Jim Worsham, McDonnell Douglas corporate VP-aerospace group, said the start of the flight test program puts the company on track to have the first UHB-powered airliner in service. That aircraft will be the MD-91X, a shortened-body version of the MD-80 seating about 115 in mixed-class configuration, planned for first deliveries in late 1991 or early 1992. Following closely, probably in late 1992, will be the MD-92X, seating 155 passengers. Decision to launch these projects may be made by the end of 1987, Worsham said. McDonnell Douglas' ability to adapt existing designs to propfan power "gives us a fine technology leap-frog program.'

Walter Orlowski, UHB program manager for McDonnell Douglas, said flight tests with the UDF will last three to four months, with a target of 60-80 hours accumulated in up to 35 flights. First half of the UDF test series will use the same UDF demonstrator engine flown on the Boeing 727 testbed, with eight blades in each propulsor fan section. A second generation demonstrator with two additional blades in the front fan, giving it a 10 8 configuration, will be substituted halfway through the program.

The PW/Allison Engines' 578-DX geared contra-rotating propfan will be fitted in November to the MD-80/UHB Demonstrator for another series of flight tests running into early 1988.

McDonnell Douglas wants to be able to offer either engine on the MD-91X or the MD-92X, Louis Harrington, McDonnell Douglas vice president-commercial products, told ATW. "It is our policy to give airlines the opportunity to select engines. But with the possibility that a high degree of airframe tuning will be needed,' matching the airframe to each engine's particular noise characteristics, "we may be able to offer only one engine.' If this is the case, McDonnell Douglas will use the same engine on both aircraft, added Worsham.

Worsham refused to characterize the back-to-back flight...