hemispheres
Posts: 86
Joined: Thu May 20, 2004 10:42 am

707 Engine Pylons

Sat Jan 22, 2005 7:41 am

I've always wondered this but was too dumb to ask. Why is the engine pylon for the #1 engine different than the rest. It's missing the distinctive hump toward the front of the engine. Anyone know the purpose? (enlarge the first pic, you can see what I mean better)

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Photo © Stefan Welsch

"I have to put in my two cents, but I only get a penny for my thoughts. - Someone is making money"
 
BR715-A1-30
Posts: 6525
Joined: Thu May 30, 2002 9:30 am

RE: 707 Engine Pylons

Sat Jan 22, 2005 7:53 am

Didn't it have something to do with RAM-AIR or BLEED-AIR or some AIR thing in order to start the engines. 4-3-2-1... In either way, 1 was the last to be started at any given time.

Send an email to John Travolta  Big grin
Puhdiddle
 
jetstar
Posts: 1380
Joined: Mon May 19, 2003 2:16 am

RE: 707 Engine Pylons

Sat Jan 22, 2005 7:55 am

The foward part of the engine pylons for #2, 3 & 4 have the turbo compressors needed for the aircraft cabin pressurization system, Engine #1 did not have the compressor.

In the early jet airplane days, the FAA did not allow engine bleed air to be used for cabin pressurization, they had to use outside air. The turbo compressors used engine bleed air to drive a pump the compressed the outside air and pumped it into the cabin.

Nowadays engine bleed air is now used for direct cabin pressurization.
 
SATL382G
Posts: 2679
Joined: Sat Aug 14, 2004 12:02 am

RE: 707 Engine Pylons

Sat Jan 22, 2005 7:57 am

Ah yes, the weekly what is that thing on top of the 707 pylon thread.

It's a turbocompressor. Essential for aircraft pressurization.

If you look at the entire Boeing/KC135 series you'll see a variety of diffent configurations. Some have 3 turbocompressors, some 2, others 1, etc.

regards
"There’s nothing quite as exhilarating as being shot at and missed" --Winston Churchill
 
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bully707
Posts: 1014
Joined: Wed Jan 19, 2005 7:29 pm

RE: 707 Engine Pylons

Sat Jan 22, 2005 10:22 am

And the TF33 powered AWACS have none....  Big grin

Bully
"That's the good thing about the 707...it can do anything, but read!" Joe Patroni, Airport '70
 
andz
Posts: 7623
Joined: Mon Feb 16, 2004 7:49 pm

RE: 707 Engine Pylons

Sat Jan 22, 2005 8:29 pm

Ah yes, the weekly what is that thing on top of the 707 pylon thread.

First time I've seen it, the poster learned something and so did I. That's what the forum is for.

After Monday and Tuesday even the calendar says WTF...
 
bucky707
Posts: 955
Joined: Sat Aug 19, 2000 2:01 am

RE: 707 Engine Pylons

Sat Jan 22, 2005 11:13 pm

"And the TF33 powered AWACS have none....

Bully"


Are you an AWACS driver?

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