Matt

I'll use your post to stick my 2 cents in.

Long before my retirement from the USAF, I was told that the smoke
trail out of the US engines was caused by the engine design where an
internal bearing was oiled by a spray and that that oil migrated back
and was burned and made the smoke trail.

Used to see and take my Fighter off behind B-52's and their heavy
smoke all the time at SAC bases.

Also the smoke trail worked against the F-86. It was much easier to
spot the F-86 with their smoke trail then the Russian MIG which didn't
have a smoke trail.

Amy one out there want to take this up and add to this technical
issue?

Seem to remember that the B-52(s) that flew non stop around the world
(used air to air refueling) had extra oil tanks installed so there
would be enough oil for the trip????

Long time ago in a land far away................

Big John
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On Tue, 25 May 2004 22:03:12 -0700, matt weber
wrote:

On Tue, 25 May 2004 00:11:32 -0400, "Scott M. Kozel"
wrote:

"Ralph Nesbitt" wrote:

"matt weber" wrote

Early jet engines often had multiple small combustion chambers, the
volume to surface ratio prevented the temperatures from getting high
enough in parts of the chamber to burn the fuel effectively and some
even had an exhaut pipe for each chamber. As the materials improved,
a switch to a single combustion chamber, with a much more favorable
surface to volume ratio and higher combustion chamber temperatures
produced more complete combustion, and the black exhaust plume started
to disappear. By the early 1970's such plumes had become rare on
commercial jets in the USA.

As a boy growing up in the mid 50's we lived near a SAC Base. An "Alert
Scramble/Launch" was a sight to see.

The above Pic is from a single 707. Consider the smoke put off by a dozen
B-52's followed by a dozen KC-135's using "Powder Charges" to start the
engines. It would take ~ 30 minuets for all the B-52's & KC-135's to get
airborne.

If there was little/no wind the smoke would hang over the base for hours.

What has been done to make the B-52s less smoky? There was talk about
15 years ago of re-engining them with 4 large turbofans to replace the 8
original Jet engines, but that was not done.

The current inventory I believe is all H models, and H's have ended up
with TF33PW-103's engines, which is the miltary version of a late
model JT4, in otherwords a turbofan without water injection.All prior
model B52's used the J57, which is a turbojet, not a turbofan, and no
doubt water injected...

In short, replace the cans with larger burner, get rid of the water
injection, add a turbofan and a better designed combustion chamber,
and most of the smoke disappears...


The civilian vesion of the J57 is a JT3 (turobjet), used on early
707's, the civilian version of the TF33 is the JT4, used on later
707's. J57 is a 12,000-13000 pound thrust engines, most of the TF33's
are 17,000-18,000 pounds.