Shock *Heating*?

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...

"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

Dan,

There seems to be no leadership for dispassionate critical
thinking.


there's an oxymoron if ever I saw one.

"Critical thinking" kind of goes against following any kind of
leadership blindly. And that's why "leaders" tend to want those being
led to not think critically. Dubya is a prime example.

--
Thomas Borchert (EDDH)

Tom,

The days of the dominant media having a monopoly on the dissemination
of "news" is over.


Huh? Have you watched Fox "News" lately? Or CNN? Have you checked the
numbers of people who use the internet or other halfway independent
sources versus "McNews" from Fox and CNN? The days of dominant media
have never been better.

--
Thomas Borchert (EDDH)

Tom,

It's called "faith".


Yes. And that still gave us the Dark Ages.

--
Thomas Borchert (EDDH)

"Thomas Borchert" wrote:
There seems to be no leadership for dispassionate critical
thinking.


there's an oxymoron if ever I saw one.

"Critical thinking" kind of goes against following any
kind of leadership blindly. And that's why "leaders"
tend to want those being led to not think critically.
Dubya is a prime example.

Hmm... Are you saying that it is impossible for a society of critical
thinkers to have a leader? Does having a leader always mean
"following...blindly?"
--
Dan
C172RG at BFM
(remove pants to reply by email)

Huh? Have you watched Fox "News" lately? Or CNN? Have you checked the
numbers of people who use the internet or other halfway independent
sources versus "McNews" from Fox and CNN? The days of dominant media
have never been better.

Where *is* this so-called "independent" news source on the internet?

Everywhere I look, I see someone with an axe to grind, or an agenda to put
forth.

At least the major news networks pretend that their mission is to provide
unbiased, dispassionate news.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Dan,

Hmm... Are you saying that it is impossible for a society of critical
thinkers to have a leader? Does having a leader always mean
"following...blindly?"


No. All I'm saying is that critical thinking requires a lot of
independence.

--
Thomas Borchert (EDDH)

"Thomas Borchert" wrote:

"Critical thinking" kind of goes against following any
kind of leadership blindly. And that's why "leaders"
tend to want those being led to not think critically.
Dubya is a prime example.


Let's see: He wants people to spend their own money, have choices for
schools, to behave responsibly...

Yup...really blind followers.

Of course, Americans used to be self-directed...

Note the top posting so it is easy to read with outhouse express and you
don't have to scroll down to read the reply:

This naturally depends on how much time you spend in inverted flight or
pulling negative g's!

Hope this helps all you morons understand thatI know whatI'm taking aboutand
that the spacebar is old from postingsomanytrolls AND YOU CAN ALL GO AND GET
STUFFED!

pETER

;)

"Ben Jackson" wrote in message
news:Nwt_b.45072$Xp.200197@attbi_s54...
In article eTn_b.385903$na.592869@attbi_s04,
Jay Honeck wrote:

So, I treat my engine like it's made out of glass.

Oh great, now there will be a big flamewar over whether after 100 years
of sitting your glass engine would be thicker on the bottom...

--
Ben Jackson

http://www.ben.com/