Simviation Forum

Jan 31^st, 2006 at 8:06pm

cheesegrater Ex Member

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?

Back to top

IP Logged

Reply #1 - Jan 31^st, 2006 at 10:22pm

Nexus Offline
Colonel
The greater of two evils...

Gender:
Posts: 3282

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% 8)

That may be the answer, will try to catch him tomorrow

Back to top

IP Logged

Reply #2 - Jan 31^st, 2006 at 11:15pm

Felix/FFDS Offline
Admin
FINALLY an official Granddad!
Orlando, FL

Gender:
Posts: 1000000627

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.

Felix/FFDS

Back to top

IP Logged

Reply #3 - Feb 1^st, 2006 at 2:35am

ozzy72 Offline
Global Moderator
Pretty scary huh?
Madsville

Gender:
Posts: 37122

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 Wink

There are two types of aeroplane, Spitfires and everything else that wishes it was a Spitfire!

Back to top

IP Logged

Reply #4 - Feb 1^st, 2006 at 8:09am

Nexus Offline
Colonel
The greater of two evils...

Gender:
Posts: 3282

Ah, thanks Ozzy

Never thought of that (I kinda see a pattern here Grin

)

Back to top

IP Logged

Reply #5 - Feb 1^st, 2006 at 11:01am

C Offline
Colonel
Earth

Posts: 13144

Quote:

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 Wink

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...

Back to top

IP Logged

Reply #6 - Feb 1^st, 2006 at 5:32pm

Nexus Offline
Colonel
The greater of two evils...

Gender:
Posts: 3282

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?

Back to top

IP Logged

Reply #7 - Feb 2^nd, 2006 at 11:38am

C Offline
Colonel
Earth

Posts: 13144

Quote:

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

Back to top

IP Logged

Reply #8 - Feb 13^th, 2006 at 6:29am

Ivan Offline
Colonel
No, I'm NOT Russian, I
only like Russian aircraft
The netherlands

Gender:
Posts: 6058

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

Wing on top = lower gear = more space inside

Russian planes: IL-76 (all standard length ones), Tu-154 and Il-62, Tu-134 and An-24RV&&&&AI flightplans and repaints can be found here

Back to top

IP Logged

Reply #9 - Feb 13^th, 2006 at 7:19am

ozzy72 Offline
Global Moderator
Pretty scary huh?
Madsville

Gender:
Posts: 37122

Ivan does that mean the C-17 is related to the Piper Cub? Grin

It matches the criteria..... Grin

There are two types of aeroplane, Spitfires and everything else that wishes it was a Spitfire!

Back to top

IP Logged

Reply #10 - Feb 17^th, 2006 at 11:32am

C Offline
Colonel
Earth

Posts: 13144

Quote:

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 Grin

.

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

Back to top

IP Logged

	Search the archive: