BAe 146

[cheesegrater]

I find it very unusual for such a small aircraft to have 4 engines. Isn't it easier to maintain 2 engines instead of 4? Why was this aircraft designed with 4 engines?

[Nexus]

I can get that answer for you tomorrow, since I know a guy who used to work as a mechanic on the Avroliner (146-200 derative)

But this is what I think. The Bae146 was designed as a regional jet which operates into short fields (often surrounded by terrain)
And the climb gradient after an engine loss is much better in a 4 engined plane compared to a 2 engine. So if you lose an engine...it's better to have 75% of them still working, than just 50%

[Felix/FFDS]

I was thinking also that (possbly) at the time the available small jets weren't powerful enough for the projected loads, and two  larger jets would have been too big.

[ozzy72]

Nexus is sort of right. My best friend used to build 146s at Hatfield! Okay so there are two reasons;
1) as Nexus stated the short airfield capability
2) noise restrictions, 4 small not straining engines make a lot less noise than two big ones going for it. This was an important consideration as the 146 is often used in built-up areas

[Nexus]

Ah, thanks Ozzy  :)
Never thought of that (I kinda see a pattern here  ;D)

[C]

2) noise restrictions, 4 small not straining engines make a lot less noise than two big ones going for it. This was an important consideration as the 146 is often used in built-up areas

Hence being known as the "Whisperjet", and one of the few jets able to used airports such as London City.

As Felix points out, the current generation engines used on todays regional jets were not available, and Hawker Siddeley, later BAe, used an engine which has very close relations to that of the Chinook helicopter...

[Nexus]

MY buddy the MX....also told that the aircraft also used a turbine similar to what was being used in tanks at the time.

Any credentials on that one?
Also heard that those engines cannot surge since those are centrifugal flow vs axial-flow used on most modern jets?

[C]

MY buddy the MX....also told that the aircraft also used a turbine similar to what was being used in tanks at the time.

Any credentials on that one?
Also heard that those engines cannot surge since those are centrifugal flow vs axial-flow used on most modern jets?

Mmm, don't know of Tank connections, but as I said it has its origins as a Avco-Lycoming/Allied Signal/Honeywell Turboshaft (T55) engine so it may be so, which leads be to the second point...

It has a centrifugal compressor behind a 6 or 7 stage axial compressor (very high bypass ratio too)...

http://www.globalturbine.com/components.html

[Ivan]

Nobody can ignore that it looks like a C17 that was washed too hot...

Wing on top = lower gear = more space inside

[ozzy72]

Ivan does that mean the C-17 is related to the Piper Cub? It matches the criteria.....

[C]

Nobody can ignore that it looks like a C17 that was washed too hot...

Wing on top = lower gear = more space inside

Predates the C-17 though . Maybe MD scaled up the 146 .

Very valid second point, hence the fact that most military transports are high wing.