SuperFan opponents dispute timing; UDF tests advance

The advanced engine development scene lately has become somewhat like a carnival sideshow, with new and unusual configurations displayed with a presentation more spicy than the usual combative stance taken by members of the engine manufacturing industry.

On one side we have General Electric, the senior figure in the group by virtue of its pioneering Unducted Fan (UDF) study and prototype development. On the other side we have International Aero Engines, a Johnny-come-lately to the battle, forging ahead with a new front end for its V2500 engine that gives it a new name--SuperFan. Standing aside the dust and mud flying about is Allison and Pratt & Whitney in their joint development of a geared, counter-rotating propfan engine.

IAE very quiet

With the entry of SuperFan into the race, the three basic configurations for advanced Ultra High Bypass (UHB) engines have been set. There will be other versions, but they will use elements of these three, be they geared drives as on SuperFan or the Allison/P&W effort, turbine drives as on the UDF, open fans or counter-rotating fans as on UDF and the Allison/P&W engine, or ducted variable pitch fans as on SuperFan.

Questions being posed to the SuperFan effort bear a similarity to those that surfaced several years ago when early research on advanced powerplant concepts showed such clear promise. The point is not will it work, but when. Also, what is the best application for a particular concept.

G.E. is saying that SuperFan cannot be made workable in the prescribed time, that is, for certification by April 1991 and delivery on the Airbus A340 or Boeing 7J7 by 1992. IAE is saying nothing. Now, the first of these two events is pretty much business and usual in the engine field: everyone else's engine either won't work or it isn't very good. One comes to expect these things. But the second stance, the one taken by IAE, is unusual.

General Electric finds itself in direct competition with SuperFan across the board. All announced engine selections on the McDonnell Douglas MD-11 have been G.E., and that aircraft is in direct competition with the Airbus A340 powered by SuperFan. Of course the alternate engine on the A340 is the CFM56-5S2, which is a partial G.E. product. And, in a surprising move, Boeing early this year said it is considering using the SuperFan on its 7J7 150-seater instead of UDF. The Allison /P&W effort has been dismissed due to insufficient power.

The pivotal roll to be played by the coming generation of UHB engines can be seen quite clearly in the way the addition of the International Aero Engines V2500 SuperFan to the Airbus A340 invigorated the program, turning it into a vibrant, competitive offering that has garnered a few airline commitments.

Airbus earlier agreed to use on the A340 the CFM International CFM56-5S2 producing about 28,600 lbs. thrust. Although adequate for the job, the engine/airplane combination won no raves or airline commitments. Airbus was encouraging...