Air Transport World

Debate on next generation of powerplants intensified at Paris.

Debate on next generation of powerplants intensified at Paris

The 36th aviation salon here will be remembered as the air show where the attitudes among world aerospace manufacturers hardened considerably as to what type of propulsion system will power the next generation of commercial transports.

The battle lines for and against the propfan which began to emerge at the Farnborough air show last fall were very firmly established this time, with Rolls-Royce, Pratt & Whitney and Airbus Industrie expressing considerable reservations, and with General Electric, SNECMA, McDonnell Douglas and Boeing coming out in favor.

Joseph F. Sutter, exec. VP-Boeing Commercial Aircraft Co., envisioned a Boeing 747 powered by ultra-bypass engines (as Boeing calls propfans) by the year 2000, commenting, "We are on the threshold of a major change in engine cycles. Engines like the CF6-80C represent the third development cycle (after propellers and turbojets), and there is not much more manufacturers can do in the high-bypass ratio business.'

But for the moment, most of the controversy continues at the smaller end of the transport market, the short-haul, 150-seat transport, where the initial applications of propfan are expected.

G.E. most active

Among the engine-makers, G.E. has been the most active in pursuing this new area of engine technology, unveiling its turbine drive unducted fan (UDF) concept at the last Farnborough (ATW, 9/84). G.E. displayed another full-scale model of its UDF at Paris, with its rear-mounted contrarotating fans driven by a contra-rotating turbine that eliminates a gearbox.

G.E. intensified its commitment to the UDF further at Paris with a joint announcement with SNECMA, its CFM International partner in the CFM56 engine family, that SNECMA and G.E. have signed a memorandum of understanding making the French engine company a 35% partner in the UDF development program. The agreement includes SNECMA participation in component design and testing.

In a further development, G.E. and McDonnell Douglas announced that a UDF full scale test engine will be delivered to the Long Beach airplane builder to be mounted on the left side of an MD-80 for flight tests in 1987. G.E. made an earlier agreement with Boeing to flight test its UDF on a 727-100 in 1986. The UDF is to be mounted on the right side of the 727. These initial UDFs will be in the 25,000-ib. thrust class driven by a G.E. F404 gas generator.

Brian Rowe, G.E.'s sr. VP and group executive for the engine group, reported in Paris that the UDF program is on schedule, and the results thus far have been very encouraging. He said that tests have shown that the UDF can meet FAR Part 36 noise standards, a major concern at the Farnborough unveiling. He said five sets of blades have been tested thus far, exploring sweep and various configurations. He said that speeds up to Mach .83 have been simulated.

The first full-scale UDF is to be groundtested at the G.E. Peebles, Ohio, facility next year. Rowe said in Paris that a production UDF could be available in the early 1990s; certification target is still 1991. He said development costs for such an engine would run from $600-$800 million. Rowe is still estimating that a UDF can produce fuel saviags of up to 60% over current engines.

Others at the salon took a far less upbeat view. Ralph Robins, managing director of Rolls-Royce, while describing the propfan as, "an absolutely irresistible device, if it could really be made to work, and if it could give 10% better operating costs,' said that there were a lot of technical problems to be resolved.

Countering G.E.'s UDF concept, Robins said he believed that such a powerplant must have a gearbox, and doubted that it could be ready by 1992. …

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