flyerboyek
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JT8D Question

Mon Sep 13, 2010 2:59 am

What's the difference between the JT8Ds that flew on the 737-100 and -200, 727s and DC-9s and the ones still flying all over the U.S. today on AA's MD-80s and DL's MD-88s? Are they quieter? Do they get better fuel economy?
 
rjsampson
Posts: 81
Joined: Sat Jul 31, 2010 12:00 am

RE: JT8D Question

Mon Sep 13, 2010 3:30 am

Yes, yes, and I think you're referring to the JT8D-200 series (the ones on the MDs). I believe they have higher bypass ratios, and use a single fan stage whereas the earlier generation JT8Ds have two fan stages.

DL is flying the DC-9 for a few more weeks as well..
 
josekmlb
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RE: JT8D Question

Fri Sep 17, 2010 4:08 am

I know that the J-STAR 707 in KMLB has the JT8D's on their bird now as well. I don't know if all 707's have them though
 
CanadianNorth
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RE: JT8D Question

Fri Sep 17, 2010 8:11 pm

Quoting josekmlb (Reply 3):
I don't know if all 707's have them though


Standard engines on the 707:
-120: JT3C
-120B: JT3D
-220: JT4A
-320: JT4A
-320B: JT3D
-420: Rolls-Royce Conways

A few re-engines were tried, one using JT8Ds, and the other using CFM56s.

As for the original question, the MD-80s are quieter because they are JT8D-200s, which are much improved for both noise and efficiency over the original JT8Ds.



Edited for more info.

CanadianNorth

[Edited 2010-09-17 13:22:40]
What could possibly go wrong?
 
TheSonntag
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RE: JT8D Question

Sat Sep 18, 2010 12:51 am

Quoting flyerboyek (Thread starter):

The main difference is the fan size. The original JT-8D had a bypass ratio of around 1.0. The JT-8D 200 has a ratio of 1.7, so that 1.7 times as much air passes around the core than through the core. Compared to other engines like the CFM 56 this is still low, which is why the JT8D200 still is louder than the A320s, 737s.
 
MSPNWA
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RE: JT8D Question

Sat Sep 18, 2010 2:33 am

Just for a quick, fun fact, NW DC-9s had at least five different versions of the JT8D. I've got the formerly large DC-9 fleet with:

JT8D-7B
JT8D-9A
JT8D-11 - DC-94
JT8D-15
JT8D-17 - DC-95

And I don't even know what the DC-9-10 had. The JT8D evolved heavily in its lifetime. More power, better efficiency, less noise, etc.

Quoting CanadianNorth (Reply 4):
As for the original question, the MD-80s are quieter because they are JT8D-200s, which are much improved for both noise and efficiency over the original JT8Ds.

Yep, and it's not hard to tell the difference in noise levels. The MDs sound loud until a DC-9 spools up. Deafening . . . and fun!
 
tb727
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RE: JT8D Question

Fri Sep 24, 2010 1:57 am

Quoting MSPNWA (Reply 6):
And I don't even know what the DC-9-10 had. The JT8D evolved heavily in its lifetime. More power, better efficiency, less noise, etc.

I think the one we operate has a -7 and a -9 derated to the -7 numbers.

I like the -15 on the 727, we have a couple with them and a couple with the -9's which are lead sleds when you compare the 2. You could even operate the -7's on the 727-200. Problem was that you had to leave them at such high thrust settings to climb and cruise to get what should be normal performance out of them, you ended up just working them too hard and wearing them out quicker. You can even inter-mix different engines on the 727, I think -7 and -9's were common pairings.
Too lazy to work, too scared to steal!
 
113312
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RE: JT8D Question

Sat Sep 25, 2010 6:45 pm

Like all engines, they evolve over time with improvements in materials to produce greater thrust, improved efficiency, reduced emissions and noise. The original JT8D-1 was introduced on the DC-9 and Boeing 727 with 14,000 lbs. thrust. These were soon upgraded to -7 still producing 14,000 lbs thrust but better performance. By this time, most turbine engines had standardized on flat rating engines to 30 degrees Celsius at sea level pressure.

By the late 1970s, the popular engine was used on various models of DC-9, Boeing 727 and Boeing 737 with -7B, -9, -15, and -17 variants. Mixing of variants on a single aircraft were allowed in some cases.

The JT8d-200 series had fan stages of greater diameter and produced still greater thrust and lower noise and was introduced on the DC9-80 (MD-80) series of aircraft as well as being used for replacement for the outboard engines on some Valsan modified Boeing 727s.
 
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CrimsonNL
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RE: JT8D Question

Thu Sep 30, 2010 10:28 am

Is the JT8D still being produced? Or are there so many examples left there is no need for new ones?

Martijn
Always comparing your flown types list with mine
 
tdscanuck
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RE: JT8D Question

Thu Sep 30, 2010 2:07 pm

Quoting CrimsonNL (Reply 8):
Is the JT8D still being produced?

The JT8D-219 (and related derivatives) is still in production.

Tom.

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