smoke from B-52 exhaust
Scott (Davis) Strang
One consistent thing I have noticed on B-52's is that they always have very
thick, black exhaust plumes. I thought they burned JP-4 (same as Jet-A?).
If that is so, why do they always produce so much smoke. The trails I see
from airliners and other military craft pale by comparison.
Personally, I love that thick smoke, but was just curious as to why it's like
that.
thanks
Scott
Massa
I remember reading somewhere that it has to do with water-injection
Scott (Davis) Strang <y106fm...@iamerica.net> wrote in article
<y106fmnospam...@iamerica.net>...
Corsair
>One consistent thing I have noticed on B-52's is that they always have very
>thick, black exhaust plumes. I thought they burned JP-4 (same as Jet-A?).
>If that is so, why do they always produce so much smoke. The trails I see
>from airliners and other military craft pale by comparison.
If I recall, water is injected into the engine output. The purpose for this is
to increase the density of the thrust, thus helping to get the aircraft and
its payload aloft. It really is quite a site.
Corsair
* Web CAG of "The Jolly Rogers": Past & Present
http://www.interlog.com/~vf84
* If at first you don't succeed, skydiving is not for you.
*** edit REMOVE out of my email ***
vic
Scott (Davis) Strang wrote:
>
> One consistent thing I have noticed on B-52's is that they always have very
> thick, black exhaust plumes. I thought they burned JP-4 (same as Jet-A?).
> If that is so, why do they always produce so much smoke. The trails I see
> from airliners and other military craft pale by comparison.
>
> that.
>
> thanks
> Scott
>
JP-4 is Jet-B and JP-5 is Jet-A. JP-4/Jet-B is closer to gasoline than
to kerosine and JP-5/Jet-A is closer to kerosine than gasoline.
As to the smoke byproduct, the cause is much like that in an F-4, lack
of combustion. Burn the fuel longer and/or hotter and you achieve a
cleaner exhaust with a corresponding decrease in engine life. Notice
how much longer a cool burning diesel engine lasts compared to a hot
burning gasoline engine. Now stand by for some engineer to give you the
real answer, I'm just an old test pilot who used to refuel my own ship
while the crew chief went inside to get some more parts. -vic
Joe Hyde
> Not your scientific answer but;
>
> JP-4 is Jet-B and JP-5 is Jet-A. JP-4/Jet-B is closer to gasoline than
> to kerosine and JP-5/Jet-A is closer to kerosine than gasoline.
>
> As to the smoke byproduct, the cause is much like that in an F-4, lack
> of combustion. Burn the fuel longer and/or hotter and you achieve a
> cleaner exhaust with a corresponding decrease in engine life. Notice
> how much longer a cool burning diesel engine lasts compared to a hot
> burning gasoline engine. Now stand by for some engineer to give you the
> real answer, I'm just an old test pilot who used to refuel my own ship
> while the crew chief went inside to get some more parts. -vic
Here's the skinny on B-52 smoke:
The B-52G (all retired now) smoked more than the B-52H (90 something in
service). The G model used water injection to boost takeoff thrust (13,500
lbs of thrust per engine augmented with water, 8000 lbs or so without
water. Water was used ONLY for takeoffs. There were 1200 lbs of water to
"burn", and it took about 1+15 minutes to use all the water. Water usually
ran out about 2000 feet in the middle of flap retraction. That's why
G-models always seemed to level off just after taeoff. I'm no engineer, but
here's how the water worked: the water was misted through injectors in
front of each engine nacelle. Supposedly, this thickened the air density
around each engine which in turn yeilded more thrust. The G model used P&W
J57 turbojet engines--the same as the KC-135A. More trivia: the KC-135A had
four less engines than the G-model yet made losts more noise. the reason
was the G-model engines had "sonic thrust suppressors" installed in each
engine's exhaust which broke up the airflow and denied the airflow from
going near supersonic. The TOAD did not.
The H-model uses P&W TF-33-P-3 fans. Each engine yields about 17,000 lbs of
thrust. there is no water injection. Although the fans produced less smoke
than the G-model's J57s, it still smokes. As of 1994, all the B-52s
converted to JP-8 fuel. JP-8 is supposedly safer because is has a much
higher flash point than JP-4 (the flash point of JP-4 is around 246 degrees
C. Not sure about JP-8). Somehow, the JP-8 makes the H model smoke like a
G-model used to. I guess it has to do with the burn temperature of the new
fuel.
Remember, even the TF-33s are 1960's technology. So when comparing engine
smoke, it's probably better to compare the Buff to 707s and DC-8s
unmodified with the hush kits.
There is a proposal out there to re-engine the Buff, but alas there is no
money...
Joe
________________________________________________________
http://www.flyboys.com
________________________________________________________
>>>>>>PROFESSIONAL GEAR FOR PROFESSIONAL AVIATORS<<<<<<<
Walter Witherspoon
Scott (Davis) Strang wrote:
>
>
> One consistent thing I have noticed on B-52's is that they always have very
> thick, black exhaust plumes. I thought they burned JP-4 (same as Jet-A?).
> If that is so, why do they always produce so much smoke. The trails I see
> from airliners and other military craft pale by comparison.
>
> Personally, I love that thick smoke, but was just curious as to why it's like
> that.
>
> thanks
> Scott
B-52Gs use J-57 Jurbojets, B-52Hs use TF-33s (essentially a J-57
adapted as a low bypass fanjet). The core design of both engines dates
from the late 40's. Generally you see the most smoke on takeoff, where
these engines are using water injection to increase thrust. By using
water they can burn more fuel, and because they don't burn the fuel
efficiently, a lot of it becomes soot, hence the black smoke. Basically
the same as an older car with a stuck choke... Newer engines run
turbine temps the old engines never could, and thus can burn fuel with a
lot less unburned residue (soot). There was some chatter here some time
ago about "optimal stoichiometric ratios" and I'm sure the enginners
will give you the real scoop, but hey, I'm just an avionics toad...
Walt W.
Doodda McGee
vic wrote:
>
> Scott (Davis) Strang wrote:
> >
> > One consistent thing I have noticed on B-52's is that they always have very
> > thick, black exhaust plumes. I thought they burned JP-4 (same as Jet-A?).
> > If that is so, why do they always produce so much smoke. The trails I see
> > from airliners and other military craft pale by comparison.
> >
> > Personally, I love that thick smoke, but was just curious as to why it's like
> > that.
> >
> > thanks
> > Scott
> >
>
> JP-4 is Jet-B and JP-5 is Jet-A. JP-4/Jet-B is closer to gasoline than
> to kerosine and JP-5/Jet-A is closer to kerosine than gasoline.
>
> As to the smoke byproduct, the cause is much like that in an F-4, lack
> of combustion. Burn the fuel longer and/or hotter and you achieve a
> cleaner exhaust with a corresponding decrease in engine life. Notice
> how much longer a cool burning diesel engine lasts compared to a hot
> burning gasoline engine. Now stand by for some engineer to give you the
> real answer, I'm just an old test pilot who used to refuel my own ship
> while the crew chief went inside to get some more parts. -vic
low EGT's (exhaust gas temps) Most engine's of that era did. Both P & W
and GE. They have learned much since then, in as much as producing a
better burn and the metalurgy is much more advanced now. So, we have
higher EGT's and a lot less smoke. a simple answer...
Burkhard Domke
On Wed, 24 Sep 1997 15:44:10 -0500, jh...@delrio.com (Joe Hyde) wrote:
>Here's the skinny on B-52 smoke:
>
>The B-52G (all retired now) smoked more than the B-52H (90 something in
>service). The G model used water injection to boost takeoff thrust (13,500
>lbs of thrust per engine augmented with water, 8000 lbs or so without
>water. Water was used ONLY for takeoffs. There were 1200 lbs of water to
>"burn", and it took about 1+15 minutes to use all the water. Water usually
>ran out about 2000 feet in the middle of flap retraction. That's why
>G-models always seemed to level off just after taeoff. I'm no engineer, but
>here's how the water worked: the water was misted through injectors in
>front of each engine nacelle. Supposedly, this thickened the air density
>around each engine which in turn yeilded more thrust. The G model used P&W
>J57 turbojet engines--the same as the KC-135A. More trivia: the KC-135A had
>four less engines than the G-model yet made losts more noise. the reason
>was the G-model engines had "sonic thrust suppressors" installed in each
>engine's exhaust which broke up the airflow and denied the airflow from
>going near supersonic. The TOAD did not.
>
>Joe
The purpose of water injection is to cool the compressor stages (and
evrything downstream), so the whole engine can be run at a higher RPM
(pressure ratio) without exceeding structural temperature limits,
corresponding to a higher thrust. The effect of injected water itself
on mass flow is negligible (note that air density decreases with
humidity, as H2O has less molecular weight than Nitrogene and
Oxygene).
Water injection has a detrimental effect on combustion and aggravates
turbine blade corrosion, as the humidity combines into acids with
combustion by-products.
Burkhard
Paul Tomblin
In a previous article, Dan Ford <d...@christa.unh.edu> said:
>> One consistent thing I have noticed on B-52's is that they always have very
>> thick, black exhaust plumes. I thought they burned JP-4 (same as Jet-A?).
>> If that is so, why do they always produce so much smoke. The trails I see
>> from airliners and other military craft pale by comparison.
>
>clips of its first takeoff at Northrop Field in Hawthorne CA, it's
>followed by these incredible black smudges. - Dan
>
Old engines weren't as efficient. As technology has progressed, we have
better high temperature materials, and we understand the combustion process
better, so jet engines run hotter and with closer to complete combustion
than in the past.
The reason B-52s seem smokey compared to other military aircraft is that
their engines are very old-tech.
--
Paul Tomblin (ptom...@xcski.com) I don't buy from spammers.
"Once you have flown, you will walk the earth with your eyes turned skyward,
for there you have been, there you long to return." -- Leonardo da Vinci.
Scott (Davis) Strang
>Old engines weren't as efficient. As technology has progressed, we have
>better high temperature materials, and we understand the combustion process
>better, so jet engines run hotter and with closer to complete combustion
>than in the past.
>The reason B-52s seem smokey compared to other military aircraft is that
>their engines are very old-tech.
But I must say that I love that black trail. It just looks like power.
Since all of the H models are now retired, I suppose the possibility of seeing
that black smoke again at the Barksdale AFB air show in Shreveport LA is not
possible. It was around the mid to late 70's when I saw it last. I was too
young at the time to really appreciate it. Now I would probably wet my
drawers ;-)
Once again, I fully appreciate everyone's response to my question. Your
answers were very much appreciated.
Now back to being radio dreck.
cheers,
Scott
David Lesher
vic <vl...@worldnet.att.net> writes:
>JP-4 is Jet-B and JP-5 is Jet-A. JP-4/Jet-B is closer to gasoline than
>to kerosine and JP-5/Jet-A is closer to kerosine than gasoline.
JetA *is* Kerosene. 100% pure kerosene.
AFAIK, JP-4 is JetA+naphtha+toluene+other nasties.
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
Scott (Davis) Strang
> I'm just an avionics toad...
Hey; at least you're an avionics toad. I'm just a plain ole radio toad.
Warts and all.
Thanks to all who have responded.
Scott
Tarver Engineering
On Wed, 24 Sep 1997 23:35:13 -0700, Walter Witherspoon
<wal...@av.qnet.com> wrote:
<snip>
> B-52Gs use J-57 Jurbojets, B-52Hs use TF-33s (essentially a J-57
>adapted as a low bypass fanjet). The core design of both engines dates
>from the late 40's. Generally you see the most smoke on takeoff, where
>these engines are using water injection to increase thrust. By using
>water they can burn more fuel, and because they don't burn the fuel
>efficintly, a lot of it becomes soot, hence the black smoke.
<snip>
J-57 equipped B-52s smoked a lot worse before they got their smokless
burner cans. What smoke?
John
William Finch
David Lesher wrote:
> JetA *is* Kerosene. 100% pure kerosene.
Well now I'm confused. I thought that Jet A is #2 Fuel Oil, also the
same as Diesel, but with a spec on Vanadium. I got this impression by
reading the ASTM spec. Any real fuel experts out there ... what is
correct?
David Lesher
William Finch <ali...@ix.netcom.com> writes:
>David Lesher wrote:
I'm an EE, not a fuel's chemist; but I worked at a refined-product
pipeline terminal. We fed about half a million gallons a day of
Jet-A to the a/p via a 6" line.
The jet arrived in a tender [batch] and was sent to storage.
After sitting for ?24 hours, top bottom and maybe middle samples
were sent to the lab. They tested about 24 factors. If the batch
flunked any, and the customer airline [one carrier bought 4x all the
rest; and thus ruled to roost in such] decided not to waive the
result; then all that JetA was transfer-pumped into the #1 Kero tank
and sold as same. The big buyer of #1 was ConRail/CSX.
If it DID pass, it was transferred to the smaller demand tanks that
held 2 days supply. There it was pumped as needed to the A/P
storage.
[ps: #2 FO is NOT the same as #2 Diesel -- the Centane ratings
differ greatly, for one thing...]
BUFDRVR
>But I must say that I love that black trail. It just looks like power.
Yeah you and the fighter pukes we go against during Flag exercises :)
>Since all of the H models are now retired
G models are now being cut up for scrap, not the H models. At least I
hope there not......geeze you go on leave for a few weeks and they retire
your aircraft :)
BUFDRVR
vic
> >vic <vl...@worldnet.att.net> writes:
>
> >JP-4 is Jet-B and JP-5 is Jet-A. JP-4/Jet-B is closer to gasoline than
> >to kerosine and JP-5/Jet-A is closer to kerosine than gasoline.
>
>
> JetA *is* Kerosene. 100% pure kerosene.
>
agree that Jet-A is kerosine. The "almost like" pairs as I remember
being taught were JP-4 and Jet-B (about 80% gasoline); the other being
JP-5 and Jet-A (about as close to kerosine as a non-chemist can
understand). I remember watching a match being thrown into a small pool
or JP-5 and it went out. When thrown into a small pool of JP-4 it
flamed up nicely. Parents, do not let your children try this at home!
There's bound to be a fuel salesman from one of them big ole refinery
companies who can correct my perception if it is wrong. -vic
John Weiss
BUFDRVR wrote:
>
> G models are now being cut up for scrap, not the H models. At least I
> hope there not......geeze you go on leave for a few weeks and they retire
> your aircraft :)
Better the aircraft than you... ;-)
--
john.r...@boeing.com (Notice: *NOSPAM*. in reply address)
737/757 Scientific Computing Development
Boeing Commercial Airplane Group
Ray Crenshaw
>> One consistent thing I have noticed on B-52's is that they always have
>very thick, black exhaust plumes. I thought they burned JP-4 (same as
>Jet-A?).
>> If that is so, why do they always produce so much smoke. The trails I
>see from airliners and other military craft pale by comparison.
i always attributed it to the old low(no?)-bypass engines the 52 uses. don't
they date from late 1940's?
ray in sc, usa
Tarver Engineering
The J-57 is the same engine as an F-86, it does not smoke so bad. Add
water injection and maximum load, you get smoke.
John
Darrell Schmidt
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> BUFDRVR wrote:
> >
> > G models are now being cut up for scrap, not the H models. At least I
> > hope there not......geeze you go on leave for a few weeks and they retire
> > your aircraft :)
>
> Better the aircraft than you... ;-)
>
How's this for dating myself? I flew the B-52H when it was BRAND NEW. Right
off the assembly line. Still had the "new car smell". Matter of fact, up in
Minot, N.D. we failed our first ORI because (they found later) the compass
systems in the wing tips were shock mounted but still bolted down for ......
whatever. Made our heading system very unreliable. To the point that on bomb
run heading the gunner was supposed to use the sextant to get a heading check
to manually set it. You can imagine what a heading error would do for targets
that could only be "seen" with offset aiming points. Got to Minot in the Fall
of '61 and left in '66. UGH! :( --
My Home Page: http://home.pacbell.net/schmidt/ (B-58 "Hustler")
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Scott (Davis) Strang
>JetA *is* Kerosene. 100% pure kerosene.
>AFAIK, JP-4 is JetA+naphtha+toluene+other nasties.
Scott
Scott (Davis) Strang
In article <19970926020...@ladder02.news.aol.com> buf...@aol.com (BUFDRVR) writes:
>From: buf...@aol.com (BUFDRVR)
>Subject: Re: smoke from B-52 exhaust
>Date: 26 Sep 1997 02:00:10 GMT
>Yeah you and the fighter pukes
^^^^^^^^^^^^^^^
What is that?
BUFDRVR
Darrell Schmidt wrote :
> I flew the B-52H when it was BRAND NEW. Right
>off the assembly line. Still had the "new car smell".
I flew 61-0013 a little over two weeks ago before I started leave, it got
13879.7 hours on it now and that "new car" smell has been replaced by an
oily, burned lunch, spilled coffee smell. Whats worse is I kind of like
the smell in a sick sort of way :)
> To the point that on bomb run heading the gunner was supposed to use the
sextant to get a heading check
Whats a gunner ?......Whats a sextant ? :)
> Got to Minot in the Fall of '61 and left in '66.
My God man 6 winters ??!! 3 was too many for me !
BUFDRVR
BUFDRVR
>>Yeah you and the fighter pukes
> ^^^^^^^^^^^^^^^
>What is that?
A fighter puke is a fighter pilot trying to simulate my death :)
A fighter guy would be the guy(or gal) that comes to my rescue to get the
fighter puke off me. Its all very technical... :)
BUFDRVR
Scott (Davis) Strang
>A fighter puke is a fighter pilot trying to simulate my death :)
>A fighter guy would be the guy(or gal) that comes to my rescue to get the
>fighter puke off me. Its all very technical... :)
Ahhh. Okay. Now that makes sense.
Scott
Darrell Schmidt
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BUFDRVR wrote:
Darrell Schmidt wrote :
> I flew the B-52H when it was BRAND NEW. Right
>off the assembly line. Still had the "new car smell".
> I flew 61-0013 a little over two weeks ago before I started leave, it got
> 13879.7 hours on it now and that "new car" smell has been replaced by an
> oily, burned lunch, spilled coffee smell. Whats worse is I kind of like
> the smell in a sick sort of way :)
Worst thing I did in the B-47 was to put my bite size steak in aluminum
wrapping on top of the amplifier rack to warm it up. Later I had smoke in the
cockpit, declared an emergency, threw out the drag gear and made an emergency
landing. Maintenance later found the smoke was from the steak juice leaking
from my lunch onto the hot amplifiers. WHOOPS! :)
Of course I was just a 25 year old Ist Lt Aircraft Commander who wasn't
SUPPOSED to know much. I just didn't need to PROVE it so publicly. :( They
punished me by promoting me to B-52s!
> > To the point that on bomb run heading the gunner was supposed to use the
> sextant to get a heading check
>
> Whats a gunner ?......Whats a sextant ? :)
Mine was a Master Sergeant who was the world's greatest "dog robber". All I
had to do was think out loud about wanting "something" and ... VOILA!, it
showed up. They were all GREAT guys.
> > Got to Minot in the Fall of '61 and left in '66.
>
> My God man 6 winters ??!! 3 was too many for me !
You're probably the world's greatest PILOT but missing a few cogs in MATH!
'61 to '66 is 5 years. It sureseemed like 6, though. But you didn't SAY
"years" did you? You said WINTERS. And maybe THAT is a valid comparison.
Guess I really went through six WINTERS in Minot since summer lasted only 24
hours!!!!! :)--
My Home Page: http://home.pacbell.net/schmidt/ (B-58 "Hustler")
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Mike Kopack
All the BUFF's flying today are H's with Turbofan engines, alas, very
little smoke. If you compare the old B-52 smoke to the airliners of it's
era (early 707 / KC-135) the smoke is about the same.
Mike