Shock *Heating*?

I shock heated my engines again on Sunday... This is ~ 5,800 times on the
left engine and 6,400 times on the right engine that the metal has been
taken from ambient temperature (a balmy 28f degrees sunday) to some
1200-1300 degrees F internally in ~10 milliseconds... I watched with
incredulous eyes as neither engine had a jug fly off, nor seized up, nor
started a death rattle, nor immediately dropped compressions into the
40's...

Then upon landing I reduced the throttle and watched as the EGT took some
5,000 milliseconds to to begin to decrease and the CHT's barely dropped
until I was half way back to the hangar on the taxiway... I obviously shock
cooled it into oblivion...

denny - straight from hades...

"Jay Honeck" wrote Until you can prove
conclusively that shock cooling
does
not exist, baby the engine.

That's good advice -- with any engine.
--

denny - straight from hades...

Thanks, Denny -- I couldn't have said it better myself.

I personally don't believe in either shock cooling *or* shock heating -- but
an awful lot of mechanics do.

So, I treat my engine like it's made out of glass.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Not that it's gospel but....

http://www.lycoming.textron.com/supp...enCooling.html

"And finally, power-off let downs should be avoided. This is especially
applicable to cold weather operations when shock cooling of the cylinder
heads is likely. It is recommended that cylinder head temperature change not
exceed 50oF. per minute. Plan ahead, reduce power gradually and maintain
some power throughout the descent. Also keep the fuel/air mixture leaned out
during the descent. If an exhaust gas temperature gage is installed with a
normally aspirated engine, keep it peaked to insure the greatest possible
engine heat for the power setting selected; for a turbocharged installation,
lean to peak during descent unless otherwise specified in the Pilot's
Operating Handbook, or under conditions where the limiting Turbine Inlet
Temperature would be exceeded."


And from AvWeb....

http://www.avweb.com/news/maint/182883-1.html

"My own gut tells me that shock cooling-while bound to induce dimensional
changes in the engine-is not a great contributor to cylinder cracking. We
know it induces dimensional changes, because (for example) valve sticking
has been induced in some engines by sudden power reductions. (A Lycoming
Flyer article once stated: "Engineering tests have demonstrated that valves
will stick when a large amount of very cold air is directed over an engine
which has been quickly throttled back after operating at normal running
temperatures." See 101 Ways to Extend the Life of Your Engine, page 96.) But
it's a big jump to go from that to saying you can make a cylinder head crack
just by pulling the throttle back too quickly."


Given that cylinders are 1k each, I'll keep the temps up on decent when
possible. I mean how hard is it to pull back to 2,000 RPM instead of
idle??? Yeah, it's probably a waste of gas but I'm burning the cheap stuff
anyway.


Just my $.02



"Dennis O'Connor" wrote in message
...
I shock heated my engines again on Sunday... This is ~ 5,800 times on the
left engine and 6,400 times on the right engine that the metal has been
taken from ambient temperature (a balmy 28f degrees sunday) to some
1200-1300 degrees F internally in ~10 milliseconds... I watched with
incredulous eyes as neither engine had a jug fly off, nor seized up, nor
started a death rattle, nor immediately dropped compressions into the
40's...

Then upon landing I reduced the throttle and watched as the EGT took some
5,000 milliseconds to to begin to decrease and the CHT's barely dropped
until I was half way back to the hangar on the taxiway... I obviously
shock
cooled it into oblivion...

"G.R. Patterson III" wrote in message
...


C J Campbell wrote:

It is up to those that assert there is such a thing as damage from shock
cooling and shock heating to prove it.

With the cost of engines the way it is, I suggest that the situation is
exactly
the other way 'round. Until you can prove conclusively that shock cooling
does
not exist, baby the engine.

I plead guilty. Even though I do not believe in shock cooling, I admit that
I fly as if I did believe in it.

I have my limits as to how far I will go to accommodate myth and
superstition, though. I refuse to turn my cell phone off at the gas pump
even when Fred Meyer has a big sign ordering me to do it.

I disagree, as long as you allow yourself to think that droughts are a
product of sin or witches, then you will never learn about things like el
nino and its weather affects. Believing things without any evidence gave us
the dark ages.

Mike
MU-2


"G.R. Patterson III" wrote in message
...


C J Campbell wrote:

It is up to those that assert there is such a thing as damage from shock
cooling and shock heating to prove it.

With the cost of engines the way it is, I suggest that the situation is
exactly
the other way 'round. Until you can prove conclusively that shock cooling
does
not exist, baby the engine.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way
that
you look forward to the trip.

"Mike Rapoport" wrote in message
ink.net...
I disagree, as long as you allow yourself to think that droughts are a
product of sin or witches, then you will never learn about things like el
nino and its weather affects. Believing things without any evidence gave
us
the dark ages.


"I worry that, especially as the Millennium edges nearer, pseudo-science and
superstition will seem year by year more tempting, the siren song of
unreason more sonorous and attractive. Where have we heard it before?
Whenever our ethnic or national prejudices are aroused, in times of
scarcity, during challenges to national self-esteem or nerve, when we
agonize about our diminished cosmic place and purpose, or when fanaticism is
building up around us -- then, habits of thought familiar from ages past
reach for the controls.

"The candle flame gutters. Its little pool of light trembles. Darkness
gathers. The demons begin to stir." -- Carl Sagan "The Demon Haunted World,"
1995.

I read this prophetic passage in the light of 9/11, the xenophobic reaction
of the political right, the resulting attempt to grab power at all costs on
the part of the political left, the rise of New Age mysticism and violent
religious fundamentalism, the polarization of the country over abortion, the
environment, nuclear power, etc.; the incredible acceptance of junk science
in the court room, people fearful of little airplanes dropping nuclear
weapons on them....

Well, I have to wonder how long it will be before we sink into the long
night of another dark age.

"C J Campbell" wrote in message
...

"Mike Rapoport" wrote in message
ink.net...
I disagree, as long as you allow yourself to think that droughts are a
product of sin or witches, then you will never learn about things like
el
nino and its weather affects. Believing things without any evidence
gave
us
the dark ages.


"I worry that, especially as the Millennium edges nearer, pseudo-science
and
superstition will seem year by year more tempting, the siren song of
unreason more sonorous and attractive. Where have we heard it before?
Whenever our ethnic or national prejudices are aroused, in times of
scarcity, during challenges to national self-esteem or nerve, when we
agonize about our diminished cosmic place and purpose, or when fanaticism
is
building up around us -- then, habits of thought familiar from ages past
reach for the controls.

"The candle flame gutters. Its little pool of light trembles. Darkness
gathers. The demons begin to stir." -- Carl Sagan "The Demon Haunted
World,"
1995.

I read this prophetic passage in the light of 9/11, the xenophobic
reaction
of the political right, the resulting attempt to grab power at all costs
on
the part of the political left, the rise of New Age mysticism and violent
religious fundamentalism, the polarization of the country over abortion,
the
environment, nuclear power, etc.; the incredible acceptance of junk
science
in the court room, people fearful of little airplanes dropping nuclear
weapons on them....

Well, I have to wonder how long it will be before we sink into the long
night of another dark age.


In light of the rapid disappearance of science, math and technology from our
classrooms one can only wonder when not if the next dark age will be upon
us.

"C J Campbell" wrote:
"The candle flame gutters. Its little pool of light trembles.
Darkness gathers. The demons begin to stir."
-- Carl Sagan "The Demon Haunted World,"
1995.

I read this prophetic passage in the light of 9/11, the
xenophobic reaction of the political right, the resulting
attempt to grab power at all costs on the part of the
political left, the rise of New Age mysticism and violent
religious fundamentalism, the polarization of the country
over abortion, the environment, nuclear power, etc.; the
incredible acceptance of junk science in the court room,
people fearful of little airplanes dropping nuclear
weapons on them....

Well, I have to wonder how long it will be before we sink
into the long night of another dark age.

Amen. There seems to be no leadership for dispassionate critical
thinking. While Greenpeace et al. wail that the sky is falling, the Bush
administration deliberately ignores any scientific research that
conflicts with its policy objectives. Meanwhile, "Scientific
Creationism" becomes an idea seriously discussed by school boards and
textbook committees, polls reveal that most Americans believe in
astrology, "posperity preachers" attract throngs, and no conspiracy
theory is too bizarre to attract followers.

We smugly assume that our technically sophisticated information culture
somehow protects us from the follies of ignorance. In fact, it may be
overwhelming us with propaganda and superstition.
--
Dan
C172RG at BFM
(remove pants to reply by email)

"C J Campbell" wrote in message
...

"Mike Rapoport" wrote in message
ink.net...
I disagree, as long as you allow yourself to think that droughts are a
product of sin or witches, then you will never learn about things like
el
nino and its weather affects. Believing things without any evidence
gave
us
the dark ages.


"I worry that, especially as the Millennium edges nearer, pseudo-science
and
superstition will seem year by year more tempting, the siren song of
unreason more sonorous and attractive. Where have we heard it before?
Whenever our ethnic or national prejudices are aroused, in times of
scarcity, during challenges to national self-esteem or nerve, when we
agonize about our diminished cosmic place and purpose, or when fanaticism
is
building up around us -- then, habits of thought familiar from ages past
reach for the controls.

"The candle flame gutters. Its little pool of light trembles. Darkness
gathers. The demons begin to stir." -- Carl Sagan "The Demon Haunted
World,"
1995.

I read this prophetic passage in the light of 9/11, the xenophobic
reaction
of the political right, the resulting attempt to grab power at all costs
on
the part of the political left, the rise of New Age mysticism and violent
religious fundamentalism, the polarization of the country over abortion,
the
environment, nuclear power, etc.; the incredible acceptance of junk
science
in the court room, people fearful of little airplanes dropping nuclear
weapons on them....

Well, I have to wonder how long it will be before we sink into the long
night of another dark age.

One could say that we're well along that road, that a new form of primitive
tribalism is at our door. Whether some form of environmental "Back to the
Pleistocene", or mystical "Dark Ages", it's very real.

"C J Campbell" writes:

"Mike Rapoport" wrote in message
ink.net...
Believing things without any evidence gave us the dark ages.

"I worry that, especially as the Millennium edges nearer, pseudo-science and
superstition will seem year by year more tempting, the siren song of
unreason more sonorous and attractive. Where have we heard it before?
Whenever our ethnic or national prejudices are aroused, in times of
scarcity, during challenges to national self-esteem or nerve, when we
agonize about our diminished cosmic place and purpose, or when fanaticism is
building up around us -- then, habits of thought familiar from ages past
reach for the controls.

"The candle flame gutters. Its little pool of light trembles. Darkness
gathers. The demons begin to stir." -- Carl Sagan "The Demon Haunted World,"
1995.

Even Sagan himself was apparently not immune to the the dangers
he warns against:

(from http://www.crichton-official.com/spe...s_quote04.html)

A final media embarrassment came in 1991, when Carl Sagan
predicted on Nightline that Kuwaiti oil fires would produce a
nuclear winter effect, causing a "year without a summer," and
endangering crops around the world. Sagan stressed this outcome
was so likely that "it should affect the war plans." None of it
happened.

--
Matt Emerson