smartt1982
Topic Author
Posts: 226
Joined: Sat Nov 24, 2007 11:17 pm

Dirty Exhaust From Engines, Just Old?

Sat Feb 09, 2013 3:03 pm

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?
 
User avatar
Polot
Posts: 4933
Joined: Thu Jul 28, 2011 3:01 pm

RE: Dirty Exhaust From Engines, Just Old?

Sat Feb 09, 2013 3:50 pm

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.
 
rcair1
Crew
Posts: 1139
Joined: Wed Oct 28, 2009 8:39 pm

RE: Dirty Exhaust From Engines, Just Old?

Sat Feb 09, 2013 4:55 pm

It is amazing how we have changed. I remember I used to like those trails - but now they look very dirty.
rcair1
 
srbmod
Posts: 15446
Joined: Tue Mar 20, 2001 1:32 pm

RE: Dirty Exhaust From Engines, Just Old?

Sat Feb 09, 2013 6:10 pm

Quoting Polot (Reply 1):
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.

Case in point:


View Large View Medium
Click here for bigger photo!

Photo © Charlie Atterbury



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.
 
User avatar
HAWK21M
Posts: 29867
Joined: Fri Jan 05, 2001 10:05 pm

RE: Dirty Exhaust From Engines, Just Old?

Sat Feb 09, 2013 6:48 pm

Amazing Improvement with regards to sound and pollution.
From the turbojet age to the low bybass turbofan to the current high bypass turbofan.
I may not win often, but I damn well never lose!!! ;)
 
fuelfool
Posts: 87
Joined: Wed Feb 16, 2011 4:41 am

RE: Dirty Exhaust From Engines, Just Old?

Sat Feb 09, 2013 9:39 pm

Between the nasty exhaust of the huffer and the engines on the DC8, I used to feel like I could feel cancer cells forming in my body every time we fired one up.
I love the smell of jet fuel in the morning...Smells like victory!
 
jetstar
Posts: 1370
Joined: Mon May 19, 2003 2:16 am

RE: Dirty Exhaust From Engines, Just Old?

Mon Feb 11, 2013 9:30 pm

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.

JetStar
 
User avatar
Aaron747
Posts: 8557
Joined: Thu Aug 07, 2003 2:07 am

RE: Dirty Exhaust From Engines, Just Old?

Tue Feb 12, 2013 4:17 am

Gotta love it. There just isn't enough smoke these days. For awhile longer we can enjoy these over on this side of the Pacific:


View Large View Medium
Click here for bigger photo!

Photo © Ryotaro Shinozaki

If you need someone to blame / throw a rock in the air / you'll hit someone guilty
 
bluejuice
Posts: 319
Joined: Sun Jun 20, 2010 5:55 am

RE: Dirty Exhaust From Engines, Just Old?

Wed Feb 13, 2013 6:53 am

 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Dirty Exhaust From Engines, Just Old?

Wed Feb 13, 2013 7:05 am

Under certain conditions, the IAE V2500 gives off a little bit of smoke trail, guess it is the Pratt & Whitney heritage of the combustor showing through  
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
LH707330
Posts: 1510
Joined: Fri Jun 15, 2012 11:27 pm

RE: Dirty Exhaust From Engines, Just Old?

Thu Feb 14, 2013 6:14 am

Quoting KELPkid (Reply 9):
Under certain conditions, the IAE V2500 gives off a little bit of smoke trail, guess it is the Pratt & Whitney heritage of the combustor showing through

Often that's due to dirt in the combustor, I've seen CFM56s and other new engines do this as well.
 
bhill
Posts: 1314
Joined: Thu Sep 13, 2001 8:28 am

RE: Dirty Exhaust From Engines, Just Old?

Thu Feb 14, 2013 7:14 pm

Wow....wonder if pilots had to change regimes from VFR to IFR being behind a few of those birds after takeoff....  
Carpe Pices

Who is online

Users browsing this forum: longhauler, Starlionblue and 6 guests