smartt1982 From United Kingdom, joined Nov 2007, 225 posts, RR: 0 Posted (2 years 9 months 2 weeks 6 days 17 hours ago) and read 5554 times:
Anytime I see some of the older jets take off e.g. older MD 80 series etc. I notice a fiar amount of what I would describe as a very smokey oily exhaust trail.
Now I realise that the aircraft and engines are probably not the newest but is this just the way the engines are, even with the necessary and required maintenance these older engines will allows produce more a s smokey oily exhaust trail?
Polot From United States of America, joined Jul 2011, 3624 posts, RR: 1
Reply 1, posted (2 years 9 months 2 weeks 6 days 16 hours ago) and read 5538 times:
Quoting smartt1982 (Thread starter): Now I realise that the aircraft and engines are probably not the newest but is this just the way the engines are, even with the necessary and required maintenance these older engines will allows produce more a s smokey oily exhaust trail?
Yes- because the smokey trails stem from design, not maintenance. They just don't burn as cleanly as newer engine designs, and no amount of maintenance can fix that.
Early jet engines at times required water injection in order to product the needed thrust for takeoff. As technology improved, the need for water injection was lessened as engines were able to produce the necessary thrust without having to use water injection.
The MD-80s are really the last of the "smoky" airliners as the engine tech has improved even further. The engines on the MD-80 are updated versions of the same engine they used on the DC-9 as well as the 727 and the 737-100 and 737-200.
jetstar From United States of America, joined May 2003, 1715 posts, RR: 11
Reply 6, posted (2 years 9 months 2 weeks 4 days 10 hours ago) and read 4853 times:
The black smoke you see coming from the exhaust of jet engines in carbon. One of the effects of these carbon particles was erosion of the turbine blades. The jet engine manufacturers redesigned the combustion chambers to burn up the carbon internally instead of it coming out of the exhaust and this basically eliminated exhaust blade erosion.
Many years ago when I was working on the turboprop Grumman Gulfstream 1, the RR Dart engines would build up a clump of carbon within the combustion chamber and when it grew large enough, it would let go and come out the exhaust pipe, you would see these on takeoff as a puff of black smoke. I believe the term RR used was clingers and it was causing erosion problems on the turbine blades, RR redesigned the combustion chamber and it solved the problem.
When I was flying the JetStar and ATC called out traffic and if the visibility was clear enough you could spot the airplane by the black smoke, especially if they were climbing out on takeoff.
It was in the late 1970’s or so when due to FAA, I believe under pressure from the EPA the engine manufacturers redesigned the combustion chambers and they had to be installed whenever the engine was overhauled.