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musang
Topic Author
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AA 707 Cabin Windows

Wed Mar 03, 2010 11:16 pm

Good Day All.

American ordered their 707-120s and/or 720s with larger than normal passenger windows.

Anyone know how much bigger they were, and whether any other customer went for this option?

Regards - musang
 
N49WA
Posts: 61
Joined: Mon Apr 07, 2008 11:06 pm

RE: AA 707 Cabin Windows

Fri Mar 05, 2010 12:26 pm

Hi,

Last week I looked at a piece of wall art made by MotoArt (Google them, great stuff)...it was a Boeing fuselage panel with 4 or 5 windows. The back, or inside surface clearly showed the structure and support pieces. It made me wonder how airlines could order different sized cabin windows since it seems that it would involve a lot of engineering and modification and would probably not be cost effective.
All this being said, I'm curious as to your source. The only window mods I have seen are on a SAHA 707 that has a elongated window in back, probably used when the airplane was a tanker to observe the refueling process.
I am a 707/720 nut-case so I am really curious about your statement. Where did you get your info?
Thanks


N49WA
If it's new and quiet, I don't want to fly it.
 
musang
Topic Author
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RE: AA 707 Cabin Windows

Fri Mar 05, 2010 12:41 pm

Hi N49WA.

"Boeing 707/720" by Jim Winchester (Airlife's Classic Airliners series, ISBN1-84037-311-3) page 25.

And I see it answers my own question about the size. 10 x 14 inches vs. the usual 9 x 12.5.

There's a photo which shows that the apertures in the over-wing exits are visibly smaller than the rest.

Regards - musang
 
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longhauler
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RE: AA 707 Cabin Windows

Fri Mar 05, 2010 3:54 pm

This is very interesting.

My first inclination was that it was incorrect, until I pulled out the reference you quoted, and looked at the picture you mentioned, and yes you are absolutely correct. It just goes to show you, it is a bad day one doesn't learn something!

On the same note, one thing I have noticed is that American appears to be the only carrier who has put windows in the forward lavs of their B707/720s. Are you aware of any other airline that has opted for this?
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
Viscount724
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RE: AA 707 Cabin Windows

Fri Mar 05, 2010 9:45 pm

Quoting longhauler (Reply 3):
one thing I have noticed is that American appears to be the only carrier who has put windows in the forward lavs of their B707/720s.
AA 707s were also among the very few with only 2 turbocompressors (like 720s). Look at photos of AA 707s and you will note that engine #4 has the same narrow pylon as engine #1, while virtually all other 707s built have the same turbocompressor pylon on engines 2/3/4. AA apparently decided that they didn't need the 3rd turbocompressor as they had no overwater routes when the 707s were ordered and in the event of a pressurization problem they would always be iin close proximity to a diversion airport. (The missing turbompressor on engine #4 is only obvious on -123Bs and -323B/Cs with JT3D turbofans. There wasn't any noticeable difference in the pylon shape on the turbojet JT3C-powered -123s before being re-engined, but #4 still lacks a turbocompressor).

[Edited 2010-03-05 13:51:19]

[Edited 2010-03-05 14:39:11]
 
Fly2HMO
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RE: AA 707 Cabin Windows

Fri Mar 05, 2010 10:01 pm

Quoting Viscount724 (Reply 4):
AA 707s were also among the very few with only 2 turbocompressors (like 720s). Look at photos of AA 707s and you will note that engine #4 has the same narrow pylon as engine #1, while virtually all other 707s built have the same turbocompressor pylon on engines 2/3/4.

Not to hijack the thread, but how did they work? Was there a shaft from the engine to the compressor or did they use exhaust gases like you would in a turbocharger?
 
Viscount724
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RE: AA 707 Cabin Windows

Fri Mar 05, 2010 10:53 pm

Quoting Fly2HMO (Reply 5):
Quoting Viscount724 (Reply 4):
AA 707s were also among the very few with only 2 turbocompressors (like 720s). Look at photos of AA 707s and you will note that engine #4 has the same narrow pylon as engine #1, while virtually all other 707s built have the same turbocompressor pylon on engines 2/3/4.

Not to hijack the thread, but how did they work? Was there a shaft from the engine to the compressor or did they use exhaust gases like you would in a turbocharger?

I can't help with the technical explanation. DC-8s also had turbocompressors (4 if memory correct) but they were in the nose and the air intakes on both sides behind the radome. They were removed on the -70 series DC-8s re-engined with CFM56s.


View Large View Medium
Click here for bigger photo!

Photo © Bruce Leibowitz



This thread has more explanation (also refers to the 707):
Question On Nose Intakes On Douglas DC-8 (by LTU932 Mar 28 2007 in Tech Ops)

[Edited 2010-03-05 14:54:39]
 
Viscount724
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Joined: Thu Oct 12, 2006 7:32 pm

RE: AA 707 Cabin Windows

Sat Mar 06, 2010 2:22 am

Quoting Musang (Reply 2):
There's a photo which shows that the apertures in the over-wing exits are visibly smaller than the rest.
Quoting longhauler (Reply 3):
My first inclination was that it was incorrect, until I pulled out the reference you quoted, and looked at the picture you mentioned, and yes you are absolutely correct. It just goes to show you, it is a bad day one doesn't learn something!

Be careful with that photo. Note the overwing exit windows lack the approximate 1 inch wide frame around the actual window area in the other windows. If you add that I don't think you would notice any significant difference in the actual glass area.

I also have that book and was very curious about the reference to the larger AA windows as I have never seen that mentioned anywhere else.

If corrrect, the 1-inch wider AA windows would mean that the structural metal gap between adjacent windows would have to be 2 inches narrower on AA 707s than on all other 707s, and when I look at 707 photos closely in p hotos I just can't see that difference which I think would be obvious to the naked eye. And if Boeing offered two different window size options on 707s, why didn't any of the many other carriers choose the larger windows? It would seem like an attractive option to me. Or why didn't Boeing make the larger windows standard to simplify construction and reduce the number of parts? And why didn't later Boeing models such as the 727/737 offer the larger window option, or did they? I can't recall ever seeing any references to AA 727s having larger than standard windows? Wouldn't AA have wanted to avoid two different replacement windows for 707s and 727s?

I hope one of the Boeing experts can confirm one way or the other whether the AA window reference in that book is correct.
 
113312
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RE: AA 707 Cabin Windows

Sat Mar 06, 2010 2:24 am

Turbocompressors use a small amount of engine bleed air through a small turbine to spin a compressor on the same shaft for use in cabin airconditioning and pressurization. The next generation of jet transports, the B727 and DC-9 etc. used engine bleed air directly for that purpose. With the first generation of jetliners, the engines had marginal thrust and using bleed air for pressurization would have taken too much power and efficiency. In addition, there was initial concern that bleed air, taken from the engine compressor, might carry contamination from lubrication oil and clean air taken in by the turbocompressor would less likely be contaminated and more easily isolated.
 
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jetmech
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RE: AA 707 Cabin Windows

Sat Mar 06, 2010 4:33 am

Quoting Fly2HMO (Reply 5):
Was there a shaft from the engine to the compressor or did they use exhaust gases like you would in a turbocharger?
Quoting 113312 (Reply 8):

As others have said, the turbo compressor was driven by gases bled off the main engine. It's been a very long time since I've seen a JT3D, but I suspect that the pipe circled in red in the following picture may be the turbo compressor bleed off take.


http://www.380aew.afcent.af.mil/shar...todb/photos/081217-F-2753C-070.jpg

Quoting 113312 (Reply 8):

Do you know the exact off take point for the turbo compressor bleed? Is it compressor discharge or combustion chamber discharge?

Quoting Viscount724 (Reply 7):
If corrrect, the 1-inch wider AA windows would mean that the structural metal gap between adjacent windows would have to be 2 inches narrower on AA 707s than on all other 707s,

I'd say the actual frame spacing was the same. I suspect Boeing my have used unique window frame forgings to accommodate the different window sizes. First I’ve heard of it too!

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
411A
Posts: 1788
Joined: Mon Nov 12, 2001 10:34 am

RE: AA 707 Cabin Windows

Sun Mar 07, 2010 2:02 am

Quoting jEtMeCh (Reply 9):
Is it compressor discharge or combustion chamber discharge?

Compressor bleed air...9th stage, if I recall correctly.
Keep in mind that many B707's also had direct compressor bleed air for cabin pressurization, as an option, in addition to turbocompressors.

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