LockstockNL777
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Bleedless Engines On KC-135/707?

Wed Apr 16, 2008 12:28 pm

Hey all,

forgive me if this is a stupid question  Wink But looking at the picture below..


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Photo © Bruce Leibowitz



.. and looking specificly to engines #3 and #4 it seems they are bleedless right? But I seem to remember that on the 707 only the #1 engine was bleedless, like in this picture;


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Photo © Ondrej Smrtka




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Photo © Jason McDowell



So what's up here? Does the KC-135 have different engines? And if so, where does the bleedair for the airco and other things come from?

Thanks in advance!

Joost
 
AFC_Ajax00
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RE: Bleedless Engines On KC-135/707?

Wed Apr 16, 2008 2:33 pm

Those 3 pictures all feature different engines! Those are J57s on the KC-135, early turbojets, if memory serves, they have small "lip" inlets on all 4 engines. The 2nd pictures the fairly common JT3D on a 707, with 3 out of the 4 engines having a supercompressor inlet. The 3rd picture is of a 707 with RR Conway engines, don't know what the inlet situation is there!
Once you have tasted flight, you will walk the earth with your eyes turned skyward; for there you long to return
 
LockstockNL777
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RE: Bleedless Engines On KC-135/707?

Wed Apr 16, 2008 2:43 pm

Ok, thanks man! I had a feeling it would be something like that. Indeed not the most intelligent question  Wink Anyway, glad to see there are some Ajax supporters in the States  Smile Greetings from Amsterdam!
 
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Starlionblue
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RE: Bleedless Engines On KC-135/707?

Wed Apr 16, 2008 2:52 pm

AFAIK they're not bleedless. They're just missing the compressor and the related inlet.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
AFC_Ajax00
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RE: Bleedless Engines On KC-135/707?

Wed Apr 16, 2008 3:11 pm



Quoting LockstockNL777 (Reply 2):
Anyway, glad to see there are some Ajax supporters in the States

The flag is a tad deceiving, I'm actually Dutch!
Once you have tasted flight, you will walk the earth with your eyes turned skyward; for there you long to return
 
KELPkid
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RE: Bleedless Engines On KC-135/707?

Wed Apr 16, 2008 5:49 pm

The 707's were almost, but not quite, bleedless. The "supercompressor" was driven by bleed air, as the CAA (predecessor to the modern FAA) didn't like the idea of feeding bleed air (engine air in the minds of the certification folks) to the cabin...so bleed air was indirectly used in this instance  Smile The 707/KC135's also used bleed air for ice protection, as I recall...
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
DashTrash
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RE: Bleedless Engines On KC-135/707?

Wed Apr 16, 2008 6:05 pm

"Bleedless" is a bit of a misnomer. Almost all, if not all turbine engines have bleed air taken out for stall / surge protection if nothing else.

If memory serves, the CJ-610 has 4 stages of bleed, but only 1 of them is used for environmental and anti-ice. 8th stage is the one that gets used, 3rd, 4th, and 5th stages bleed overboard.
 
Blackbird
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RE: Bleedless Engines On KC-135/707?

Wed Apr 16, 2008 6:09 pm

Well... there are small lip inlets under each engine. Also on the left side of the plane is an intake under the wing-root. The C-135's which carry people have one on each side (What are those for?)


Andrea Kent
 
Viscount724
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RE: Bleedless Engines On KC-135/707?

Thu Apr 17, 2008 12:54 am



Quoting AFC_Ajax00 (Reply 1):
The 2nd pictures the fairly common JT3D on a 707, with 3 out of the 4 engines having a supercompressor inlet.

AA's 707s only had 2 turbocompressors on #2 and #3. Look at any AA 707-123B or -323B/C photos and you'll note the narrow engine pylon on engines #1 and #4 (like the 720B). Since AA had no long overwater routes when those aircraft were acquired they apparently considered they would be close enough to a diversion airport to make the 3rd turbocompressor unnecessary in the event of a pressurization problem.

Quoting AFC_Ajax00 (Reply 1):
The 3rd picture is of a 707 with RR Conway engines, don't know what the inlet situation is there!

As far as I know the 707-420 had the usual 3 turbocompressors but engine #1 without the turbocompressor had the same pylon design (like the non-turbofan P&W 707-120/220/320) so the lack of a turbocompressor wasn't obvious as it is with JT3Ds. I recall reading that Air India's 707-420s only had 2 turbocompressors.
 
Blackbird
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RE: Bleedless Engines On KC-135/707?

Thu Apr 17, 2008 3:01 am

From what I remember the B-707-420 did actually have four turbocompressors...

Andrea Kent
 
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RE: Bleedless Engines On KC-135/707?

Fri Apr 18, 2008 4:29 am



Quoting Blackbird (Reply 9):
From what I remember the B-707-420 did actually have four turbocompressors...

The ones I personally flew only had three TC's installed, but 4 was a customer option.

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