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Boeing KC-135R A/C Generators  
User currently offlineEffedia41 From Italy, joined Feb 2008, 1 posts, RR: 0
Posted (6 years 5 months 3 weeks 7 hours ago) and read 4103 times:

Looking at the overhead panel of the KC-135R (with CFM-56 turbofan) I noticed that there are only three A/C generators. Which engine lacks it?

12 replies: All unread, jump to last
 
User currently offlineDeltaGuy From , joined Dec 1969, posts, RR:
Reply 1, posted (6 years 5 months 3 weeks 7 hours ago) and read 4105 times:

It's the #1 engine. The 707 has always had 3, and the #1 motor has always lacked that extra fairing. Take a look back at some old JT3 equipped frames, especially the FE panel, and you'll see it as well.

DeltaGuy


User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2543 posts, RR: 24
Reply 2, posted (6 years 5 months 3 weeks 3 hours ago) and read 4036 times:



Quoting DeltaGuy (Reply 1):
It's the #1 engine. The 707 has always had 3, and the #1 motor has always lacked that extra fairing. Take a look back at some old JT3 equipped frames, especially the FE panel, and you'll see it as well.

I think the question maybe referring to AC electrical generators rather than air conditioning turbo-compressors. From the way the panel is laid out, most likely the answer is the same though (engine 1).



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineBoeingFixer From Canada, joined Jul 2005, 529 posts, RR: 0
Reply 3, posted (6 years 5 months 3 weeks ago) and read 4013 times:



Quoting DeltaGuy (Reply 1):
It's the #1 engine. The 707 has always had 3, and the #1 motor has always lacked that extra fairing. Take a look back at some old JT3 equipped frames, especially the FE panel, and you'll see it as well.

DeltaGuy

Actually, the B707 always had 4 AC Generators. Generator control panel at top left has controls for 4 AC generators


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Photo © Stuart mitchell



Also remember that the KC-135 and B707 are very different aircraft. The KC-135 has more in common with the Boeing Dash 80 than the B707.

As for only three AC generators on the KC-135, I can only guess that the power consumption is less on the KC-135 than the B707(galleys etc...) and thus it only requires 3 generators.

Cheers,

John



Cheers, John YYC
User currently offlineEx52tech From United States of America, joined Dec 2006, 559 posts, RR: 1
Reply 4, posted (6 years 5 months 2 weeks 5 days 18 hours ago) and read 3941 times:

Ahhh....... the KC135A did not have a generator on #4 engine. So my guess is that they would have had to accomplish a major modification of the electrical system on the R model to have more than three, and with the removal of the water injection system, there would be less demand on the electrical system. As far as I know all of the R models are converted A models.

Quoting DeltaGuy (Reply 1):
It's the #1 engine. The 707 has always had 3, and the #1 motor has always lacked that extra fairing.

I wonder if you are thinking about the turbo compressor inlets on the pylon above the engine inlet. If that is what you are talking about, remember that some of the 720s had only two turbo compressors on the #2 and #3 engines.



"Saddest thing I ever witnessed....an airplane being scrapped"
User currently offlineDeltaGuy From , joined Dec 1969, posts, RR:
Reply 5, posted (6 years 5 months 2 weeks 5 days 1 hour ago) and read 3892 times:



Quoting Ex52tech (Reply 4):
I wonder if you are thinking about the turbo compressor inlets on the pylon above the engine inlet. If that is what you are talking about, remember that some of the 720s had only two turbo compressors on the #2 and #3 engines.

That was it!! It's been a long time since I jumpseated on that Omega Tanker, but I did remember seeing how there was only 3 of certain things...only 3 TR's as well.

Good thread! This is the kind of tech/ops questions that we need more of!

DeltaGuy


User currently offlineEx52tech From United States of America, joined Dec 2006, 559 posts, RR: 1
Reply 6, posted (6 years 5 months 2 weeks 3 days 19 hours ago) and read 3816 times:

Another little bit of trivia.....The KC135A did not have turbo compressors at all. The aircraft employed freon airconditioning pacs..

All that smoke in water injection, and all the holes in the ozone.  Wow!



"Saddest thing I ever witnessed....an airplane being scrapped"
User currently offlineMoose135 From United States of America, joined Oct 2004, 2301 posts, RR: 10
Reply 7, posted (6 years 5 months 2 weeks 1 day 1 hour ago) and read 3759 times:

All this talk about AC generators got me to thinking...the A-model had another generator, powered by a pump on the right-hand hydraulic system, that powered the copilot's flight instruments. I got out just as the R-models were coming on board and never got to fly them, but I'm assuming was this retained with the R-model conversion. Am I correct in that assumption?


KC-135 - Passing gas and taking names!
User currently offlineRSBJ From United States of America, joined Jan 2006, 152 posts, RR: 0
Reply 8, posted (6 years 5 months 1 week 4 days 18 hours ago) and read 3675 times:

Not just the R's retained the Co-pilot

Quoting Moose135 (Reply 7):
All this talk about AC generators got me to thinking...the A-model had another generator, powered by a pump on the right-hand hydraulic system, that powered the copilot's flight instruments. I got out just as the R-models were coming on board and never got to fly them, but I'm assuming was this retained with the R-model conversion. Am I correct in that assumption?

Yes, the R model has it. Also, our E model's had this neat, and very redundant, feature.



I fly really fast and take a lot of chances.
User currently offlineVenus6971 From United States of America, joined Dec 2004, 1440 posts, RR: 0
Reply 9, posted (6 years 5 months 1 week 3 days 7 hours ago) and read 3606 times:



Quoting Ex52tech (Reply 6):
Another little bit of trivia.....The KC135A did not have turbo compressors at all. The aircraft employed freon air conditioning packs..

The KC-135 uses bleed air or ram air for air conditioning, if you notice the ac pack is in the left keel beam, the USAF had some C-18's which were old American Airline 707-320s that used freon packs since these initially bought from Boeing for short haul routes and needed something to cool the acft down quick, in a KC-135 you are either freezing or roasting, there was temp controller in the cabin on the fwd bulkhead near the lavatory which I think was there just for looks. Also the C-18's only had 2 turbo-compressors which is the AA ordered them, the TC's gave you clean air to pressurize the cabin instead of using bleed air which sometimes gave the cabin an oily smell if you also had nose cowl anti ice turned on and the seal on the #1 bearing seal leaked especially on the TF-33(Jt-3D)
I remember coming back from Greenville Texas in my C-137B(707-153B) dead heading to ADW we had it up at 41,000 ft and had to supplement the TC's with engine bleed air to keep the acft pressurized at 8.6 psi due to the thin air. Plus also to insure the pax o2 masks would not drop.



I would help you but it is not in the contract
User currently offlineViscount724 From Switzerland, joined Oct 2006, 24891 posts, RR: 22
Reply 10, posted (6 years 5 months 1 week 2 days 23 hours ago) and read 3586 times:



Quoting Ex52tech (Reply 4):
Quoting DeltaGuy (Reply 1):
It's the #1 engine. The 707 has always had 3, and the #1 motor has always lacked that extra fairing.

I wonder if you are thinking about the turbo compressor inlets on the pylon above the engine inlet. If that is what you are talking about, remember that some of the 720s had only two turbo compressors on the #2 and #3 engines.

Not all 707s had 3 turbocompressors. AA's (both -123/-123B and -323B/C) only had 2 turbocompressors on engines 2 and 3, like the 720/720B. Note the narrow engine pylon on #4 in photos below (same as #1). I recall reading that AA decided they only needed 2 since their routes were domestic only when they ordered their 707s and they would never be far from an alternate airport in the event of a pressurization failure.


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Photo © Art Brett - Photovation Images
View Large View Medium
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Photo © Richard Silagi



If memory correct a few other 707s, including Air India's early R-R Conway-powered 707-420s, also only had 2 turbocompressors although you can't see that visually on the AI -420s since their pylons are the same for all engines (as on JT3C and JT4A 707s), unlike those on JT3D-powered 707s (and 720s) where the pylons on engines without turbocompressors are much .


User currently offlineVenus6971 From United States of America, joined Dec 2004, 1440 posts, RR: 0
Reply 11, posted (6 years 5 months 1 week 2 days 21 hours ago) and read 3582 times:



Quoting Viscount724 (Reply 10):
Not all 707s had 3 turbocompressors. AA's (both -123/-123B and -323B/C) only had 2 turbocompressors on engines 2 and 3, like the 720/720B. Note the narrow engine pylon on #4 in photos below (same as #1). I recall reading that AA decided they only needed 2 since their routes were domestic only when they ordered their 707s and they would never be far from an alternate airport in the event of a pressurization failure.

in the event of a TC failure it you could select bleed air tto pressurize



I would help you but it is not in the contract
User currently offlineEx52tech From United States of America, joined Dec 2006, 559 posts, RR: 1
Reply 12, posted (6 years 5 months 1 week 2 days 19 hours ago) and read 3570 times:



Quoting Venus6971 (Reply 9):
clean air to pressurize the cabin instead of using bleed air which sometimes gave the cabin an oily smell if you also had nose cowl anti ice turned on and the seal on the #1 bearing seal leaked especially on the TF-33(Jt-3D)

The oily smell with anti-ice on with the J-57, and the TF-33, was because the hydraulic resevoirs were pressurized by a line that fed off the anti-ice duct. When the check valve stuck open in that line hydraulic fluid would drain back into that anti-ice duct, turn on the anti-ice and you got smoke or oily smell in the airplane.

I was standing just off of the inlet of a J57-59W one morning, a little closer than I should have been, the inlet was icing, and I told the guy running the engines to snap on the anti-ice. The engine injested a large quantity of hydraulic fluid that was in the duct. The engine had a massive compressor stall, which sent me heading for the hills, we figured that the fluid probably ignited in the compressor before it even got to the combustion chamber.

The J-57 was known for breathing anyway, and they would loose oil past the bearing carbon seals and smoke the cabin, so that was another way to get the oily smell in the cabin.



"Saddest thing I ever witnessed....an airplane being scrapped"
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