From: h andrew chuang <firstname.lastname@example.org> Date: 06 Jan 94 01:54:00 PST References: 1 2 Followups: 1 2
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Karl Swartz wrote: | >what happened to unducted fans? | | The biggest appeal to the UDF was fuel economy. When fuel prices | retreated a bit, so did the appeal of the UDF. Compounding this | was the risk/cost of the new technology, noise and vibation problems, | and potential image problems of what some might view as a "prop" | plane. Just to clear up some terminologies. UDF is a registered trademark of GE. The engine, GE36, had the counter-rotating fans. (Coincidentally, in Cincinnati, where the GE Aircraft Engines headquarters is, there is a chain of convenient stores called UDF---United Dairy Farmers. I wonder if the store name inspired GE's naming scheme! :-) If I remember correctly, Pratt's counterpart was a single-stage, gear-driven propfans that did not really had a special name like the UDF. Garrett was a partner and its main function was designing the gearbox. Pratt's current Advanced Ducted Prop (ADP) also uses gear-driven fans. Pratt is currently working on an ADP application for the growth A340. Few years back, Lufthansa was very disappointed when Airbus decided not to offer the A340 with a proposed UHB (ultra high by-pass) V2500. | Delta's MD-90 launch order actually included the option to convert | some of the orders to a UDF version, but everyone else lost interest. Correct me if I'm wrong. Both GE and Pratt practically halted their propfan efforts after the cancellation of the 150-seat B7J7 program. I seem to remember that the current V2500-powered MD-90 was launched after the B7J7 cancellation. Therefore, I seriously doubt that Delta's order included options for a UDF version. It was proposed to put the UDF on the MD twins, but I don't recall an actual offer of MD90/UDF to any customers. | >I seem to recall that somebody even bolted a prototype onto one side | >of a DC-9 and flew it around. | | The prototype MD-80, actually. I once saw it at Mojave, with an | extra-long pylon but no #1 engine at that point. Boeing did the | same thing with a 727. Seems to me the MD-80 had a GE engine while | the 727 had a Pratt, but I wouldn't bet on it. I believe Karl is right.