757man From United Kingdom, joined Feb 2001, 370 posts, RR: 1 Posted (14 years 3 hours ago) and read 1938 times:
I was just wondering if anybody remembered the proposed B7J7 prop-fan airliner which Boeing talked about in around 1989. I know McD actually built an MD-80 demonstrator with the new prop-fan technolgy at about the same time the 7J7 sketches were doing the rounds...So why were both abandoned? Were prop-fan powered aircraft not economical to operate or something?
GDB From United Kingdom, joined May 2001, 13416 posts, RR: 77
Reply 1, posted (14 years 3 hours ago) and read 1897 times:
l do remember the 7J7, and seeing the MD-80 demonstrator at Farnborough.
In an era of cheap fuel, propfans would have been more trouble than they were worth. Cruising speed would have dropped some too.
They won't be back, advances in engine technology since then have seen to that.
AA737-823 From United States of America, joined Mar 2000, 6112 posts, RR: 11
Reply 3, posted (13 years 12 months 4 days 21 hours ago) and read 1845 times:
The propfan (also known as UDF or Un-Ducted Fan) was also very noisy. Extremely noisy. Imagine a propeller spinning at near jet engine speeds, and now you have some idea of how noisy it was.
I recently talked to a docent at the Paul Garber facility in Washington DC (connected with the Smithsonian Air and Space) and he said that it only met the stage three requirements if you were standing in the next county. They have the engine at their facility, it's pretty interesting.