Happy-flier From Canada, joined Dec 1999, 299 posts, RR: 0 Posted (15 years 9 months 1 week 6 days 4 hours ago) and read 2806 times:
This is something that I have been dying to find out for ages now: is the P&W engine that powers the 737-200 a turboFAN or a turboJET?? I have had the opportunity to see the engine close up and while peering into the exhaust duct, I could see all the way to the turbine blades but could not see any bypass duct either within the main exhaust duct or surrounding it outside the nacelle. If this is a bypass engine, which I suspect it is, then where the heck does the bypass air meet the core jet exhaust stream?
May the wind be always at your back . . . except during takeoff & landing.
DLMD-11 From , joined Dec 1969, posts, RR:
Reply 1, posted (15 years 9 months 1 week 6 days 4 hours ago) and read 2729 times:
The 737-200 is powered by the JT8D Turbofan. It is just an old (1960s) fan with a ratio of only 3:1 (3 times as much air goes around the outside as thru the core turbojet) - whereas engines such as the PW4000 (747 etc.) have a ratio of about 11:1 (11 times as much air goes around the sides than thru the core) This is why older engines are louder and less efficient.
Jim From United States of America, joined Jul 1999, 455 posts, RR: 1
Reply 3, posted (15 years 9 months 1 week 5 days 9 hours ago) and read 2693 times:
The JT8D family is a bypass fan engine. As stated in the other posts, it is a low-bypass fan, where very little air is bypassed around the core.
The cold stream duct, where the bypass air flows around the core, is only about 4 - 5 inches wide on this engine. Compare that to the nearly two FEET width on the B777 Trent engine, and you'll understand why they are called HIGH bypass engines ;-)
Buzz From United States of America, joined Nov 1999, 697 posts, RR: 20
Reply 4, posted (15 years 9 months 1 week 5 days 9 hours ago) and read 2688 times:
Hi Everybody, Buzz here. All good answers. If you get the chance to look up an A320's tailpipe, they meet and mix just forward of the nozzle. Similar idea on the JT8D's.
Don't drop any igniter plugs when you change them, it's REALLY hard to fish out of the fan duct.
By the way...... The basic core was originally a 'disposable' engine for a 1950's cruise missle. Then Grumman, and Douglas wanted a lightweight turbojet engine. So the A4 Skyhawk and the A6 Intruder used them. Later Pratt and Whitney grafted a fan onto it, and got 14,000 lbs of thrust out of it. It took years to become reliable, but it's stood the test. g'day
NKP S2 From United States of America, joined Dec 1999, 1714 posts, RR: 5
Reply 5, posted (15 years 9 months 1 week 5 days 8 hours ago) and read 2685 times:
Hey Buzz,that igniter comment made me laugh. I still have gook all over a socket and extensions from the cargo pit tape that I use to tape the socket to the extensions and the extensions together. You didn't want to drop anything in there,much less something with your name vibro-peened on it!