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JT8D Question  
User currently offlineflyerboyek From United States of America, joined Aug 2005, 72 posts, RR: 0
Posted (4 years 1 month 1 week 5 days 6 hours ago) and read 4400 times:

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?

9 replies: All unread, jump to last
 
User currently offlineRJSampson From United States of America, joined Jul 2010, 35 posts, RR: 0
Reply 1, posted (4 years 1 month 1 week 5 days 5 hours ago) and read 4378 times:

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..


User currently offlinejosekmlb From United States of America, joined May 2008, 493 posts, RR: 0
Reply 2, posted (4 years 1 month 1 week 1 day 4 hours ago) and read 3936 times:

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

User currently offlineCanadianNorth From Canada, joined Aug 2002, 3390 posts, RR: 9
Reply 3, posted (4 years 1 month 1 week 12 hours ago) and read 3771 times:

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?
User currently onlineTheSonntag From Germany, joined Jun 2005, 3631 posts, RR: 29
Reply 4, posted (4 years 1 month 1 week 8 hours ago) and read 3685 times:

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.


User currently offlineMSPNWA From United States of America, joined Apr 2009, 1969 posts, RR: 2
Reply 5, posted (4 years 1 month 1 week 6 hours ago) and read 3668 times:

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!


User currently offlinetb727 From United States of America, joined Jun 2005, 1615 posts, RR: 9
Reply 6, posted (4 years 1 month 1 day 7 hours ago) and read 3296 times:

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!
User currently offline113312 From United States of America, joined Apr 2005, 573 posts, RR: 1
Reply 7, posted (4 years 4 weeks 1 day 14 hours ago) and read 3015 times:

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.


User currently offlineCrimsonNL From Netherlands, joined Dec 2007, 1887 posts, RR: 42
Reply 8, posted (4 years 3 weeks 3 days 22 hours ago) and read 2728 times:
AIRLINERS.NET CREW
CHAT OPERATOR

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

Martijn



Nothing's worse then flying the same registration twice, except flying it 4 times..
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 9, posted (4 years 3 weeks 3 days 18 hours ago) and read 2689 times:

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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