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UA744
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Boeing 707 JT8D

Wed May 16, 2018 8:53 pm

First post here, I was wondering if anyone knows why Boeing did not develop a 707 with JT8D-17R engines as they are similar in size and power output as the TF33/JT3D the 707-320 used but are significantly more fuel efficient. The aircraft could have been in service by the early 1970s when 707 sales were still relatively common with civil operators, and could have been marketed as a re-engine program like Douglas did with the CFM-56. Were there any design studies or consideration of this idea?
 
Max Q
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Re: Boeing 707 JT8D

Wed May 16, 2018 9:47 pm

There was a 707 re-engine program with the CFM 56 but the airlines weren’t interested in it, despite the significant fuel burn reduction, so a JT8D fit would have been even less interesting to them


There were several brand new aircraft on the near horizon by then anyway, the 767 was a perfect 707 replacement with a quantum leap in efficiency



And for shorter routes the 757 and the 727 had plenty of life left in it as the 707 came to the end of its own
The best contribution to safety is a competent Pilot.
 
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lightsaber
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Re: Boeing 707 JT8D

Thu May 17, 2018 12:03 am

JSTARS has JT8Ds

GE was agressive with the KC-135. Pratt made a huge mistake with the JT10D program cancelation.

Lightsaber
You only have the first amendment with the 2nd. If you're not going to offend someone with what you say, you don't have the 1st.
 
FrmrKSEngr
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Re: Boeing 707 JT8D

Thu May 17, 2018 2:50 am

lightsaber wrote:
JSTARS has JT8Ds


Only 1 JSTARS was converted before the program was cancelled.

https://www.defenseindustrydaily.com/ju ... nes-05156/
 
crownvic
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Re: Boeing 707 JT8D

Thu May 17, 2018 4:22 am

You guys are forgetting about the bird sitting in Opa Locka.
 
KFLLCFII
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Re: Boeing 707 JT8D

Thu May 17, 2018 7:29 am

crownvic wrote:
You guys are forgetting about the bird sitting in Opa Locka.


N88ZL, JT3D within hushkit nacelles. We were both part of this same discussion almost 13 years ago. ;)

Clean 707.......what Kind Of Engines?
"About the only way to look at it, just a pity you are not POTUS KFLLCFII, seems as if we would all be better off."
 
LH707330
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Re: Boeing 707 JT8D

Thu May 17, 2018 4:10 pm

Does anyone have numbers showing the -17R was better? The Boeing materials I have show a 14% improvement for the CFM56-2s, the JT8D-200 plan was supposed to be about half that, so I doubt a -17R would do much, if anything. Recall that the JT8 was designed as a cruise missile engine at first, so I doubt it was well-optimized.
 
timz
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Re: Boeing 707 JT8D

Thu May 17, 2018 8:12 pm

Yeah, no indication the JT8D-17 had much better sfc than the JT3D. Think Jane's showed about the same cruise SFC for both -- around 0.81 pounds of fuel per hour per pound of thrust, wasn't it?
 
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CrimsonNL
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Re: Boeing 707 JT8D

Fri May 18, 2018 7:58 am

The government of Iran has a JT8D powered 707, I've no idea what kind of conversion this is



Martijn
Always comparing your flown types list with mine
 
LH707330
Posts: 1954
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Re: Boeing 707 JT8D

Fri May 18, 2018 6:30 pm

CrimsonNL wrote:
The government of Iran has a JT8D powered 707, I've no idea what kind of conversion this is



Martijn

That fan spinner looks like a JT3D3B, you sure that ain't the long-duct retrofit that N88ZL got?
 
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CrimsonNL
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Re: Boeing 707 JT8D

Fri May 18, 2018 6:49 pm

LH707330 wrote:
CrimsonNL wrote:
The government of Iran has a JT8D powered 707, I've no idea what kind of conversion this is



Martijn

That fan spinner looks like a JT3D3B, you sure that ain't the long-duct retrofit that N88ZL got?


Really? Hmm, I was sure I was told JT8D at some point, that's why I remembered it when reading this thread. But I suppose you could be right!

Martijn
Always comparing your flown types list with mine
 
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DL_Mech
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Re: Boeing 707 JT8D

Sat May 19, 2018 12:08 am

The JT8D-219 is a physically larger engine and no turbocompressors are installed.

This plane is built to withstand anything... except a bad pilot.

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