flyerboyek From United States of America, joined Aug 2005, 72 posts, RR: 0 Posted (5 years 2 months 2 weeks 1 day 21 hours ago) and read 4920 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?
RJSampson From United States of America, joined Jul 2010, 64 posts, RR: 0
Reply 1, posted (5 years 2 months 2 weeks 1 day 21 hours ago) and read 4898 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..
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.
tb727 From United States of America, joined Jun 2005, 1936 posts, RR: 12
Reply 6, posted (5 years 2 months 4 days 23 hours ago) and read 3816 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.
113312 From United States of America, joined Apr 2005, 603 posts, RR: 1
Reply 7, posted (5 years 2 months 3 days 6 hours ago) and read 3535 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.