BR715-A1-30 From , joined Dec 1969, posts, RR: Reply 1, posted (9 years 9 months 6 days 1 hour ago) and read 2038 times:
There are many threads that answer your question, but I will answer it again to the best of my knowledge.
During the high fuel cost era of the 1980s, GE developed the GE-36 Ultra-High Bypass Un-ducted fan. Basically it was a Jet engine, but only 20% of the power came from the core, and the rest was generated by the fan blades in the rear. It was supposed to be ultra quiet, but by the time it was completed, fuel prices were dropping, and it turned out to be quite loud.
FBU 4EVER! From Norway, joined Jan 2001, 998 posts, RR: 7 Reply 2, posted (9 years 9 months 1 day 17 hours ago) and read 1893 times:
Furthermore,the FAA insisted that the engine be certified to turboprop standards regarding shedding of blades during operation and this made the whole project (both projects,there were two designs) rather more complicated and expensive.
LMP737 From , joined Dec 1969, posts, RR: Reply 3, posted (9 years 9 months 1 day 3 hours ago) and read 1820 times:
Several of my former co-workers at Boeing Flight Test-Long Beach worked on that program. While it was good on gas there were issues with the UDF that made it unfeasible at the time. One problem was it produced large cloulds of blue smoke on start up. Not very reassuring to passengers. Secondly the interior noise and vibration levels were just to high for comfortable travel.