BabyJumbo-SP From Hong Kong, joined May 2001, 28 posts, RR: 0 Posted (13 years 7 months 2 weeks 6 days ago) and read 2067 times:
Does anyone know if the four "little" engines on BAe146 are turbofan? Is the layout a typical turbine engine (i.e. Fan-LP compressor-HP compressor-Combustion-HP turbine-LP turbine)? In my mind, they seem too small for a turbofan system to be efficient. What's the concept behind it, using 4 small engines instead of 2 "normal" size turbofan?
It would be great anyone has the engine's cross-section diagram.
Rmm From Australia, joined Feb 2001, 525 posts, RR: 1
Reply 1, posted (13 years 7 months 2 weeks 5 days 23 hours ago) and read 2040 times:
These engines are turbofans. They are similar to your describtion but have a reverse flow combustor and a reduction gear set for the fan. I don't have a cut away handy but if you search around you should be able to find one.
I consider these to be the most unreliable engines that I have ever worked on, especially the early ones.
GDB From United Kingdom, joined May 2001, 13457 posts, RR: 77
Reply 2, posted (13 years 7 months 2 weeks 5 days 15 hours ago) and read 2022 times:
The BAe-146 was originally the HS-146, designed in 1973. The oil crisis suspended the programme until 1978.
At that time, the only engine suitable for the aircraft's perceived role - operating quietly in and out of city-centre small airports, was a turbofan version of the turoshaft used on the CH-47 helicopter!
Not a perfect choice, but the only game in town.
BAe missed the opportunity to upgrade the aircraft with two modern engines in the 1990's.
But the Avro, as it was then called, was a low priority.
Just as the RJ market took off! Typical.
Prebennorholm From Denmark, joined Mar 2000, 6841 posts, RR: 54
Reply 3, posted (13 years 7 months 2 weeks 5 days 15 hours ago) and read 2012 times:
Dear BabyJumbo-SP, the concept behind four engines instead of two is to be able to operate from shorter runways.
Since every airliner must have runway to spare to tolerate one engine quit at V1, then maintaining 75% power instead of 50% calls for a substantial shorter runway.
That could be compensated by installing more power.
But then the 146 was also designed to be the world's most quiet jet airliner. More power and everything else equal would spell more noise too.
So the concept was clever enough. Except for that fact that it didn't last and has now been discontinued. Cheaper procurement and maintenance prices of twins won in the long run.
The demise of the 146/ARJ/RJX line shows us that there is no money in low noise levels. Planes must obey to stage 3 rules. But apart from that nobody wants to pay one cent for noise levels considerably lower than that.
Regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs