Shock *Heating*?

[Jay Honeck]

In another thread (about cold starting) it was mentioned that Alaskan bush
pilots routinely drain their oil, take it inside, and heat it on the stove
before starting in the morning.

While this guarantees a warm(er) engine, wouldn't this risk damage to the
engine from shock heating (assuming there is such a thing), by suddenly
introducing boiling hot (or nearly so) oil to a cold-soaked engine?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[john smith]

Jay Honeck wrote:
> In another thread (about cold starting) it was mentioned that Alaskan bush
> pilots routinely drain their oil, take it inside, and heat it on the stove
> before starting in the morning.
> While this guarantees a warm(er) engine, wouldn't this risk damage to the
> engine from shock heating (assuming there is such a thing), by suddenly
> introducing boiling hot (or nearly so) oil to a cold-soaked engine?

Your engine operates at what temperature?
Think about the operating temperature of the oil. I doubt someone
knowledgeable would heat their oil up to the full operating temperature
and risk breaking down the oil. There is sufficient mass in the engine
to absorb the "warm" oil without damaging the case. I suspect that the
temperature of the oil by the time it has all been added will have
dropped many degrees.

[Ben Jackson]

In article <QdQZb.376650$na.567800@attbi_s04>,
Jay Honeck > wrote:
>While this guarantees a warm(er) engine, wouldn't this risk damage to the
>engine from shock heating

Look at a graph from one of those data-capturing engine monitors some
time. The steepest lines on the graph will always be at takeoff. Even
pulling power and diving can't cool the engine as fast as the takeoff
roll can heat it up.

--
Ben Jackson
>
http://www.ben.com/

[Jay Honeck]

> Look at a graph from one of those data-capturing engine monitors some
> time. The steepest lines on the graph will always be at takeoff. Even
> pulling power and diving can't cool the engine as fast as the takeoff
> roll can heat it up.

So would this be proof that damage from "shock cooling" is a myth?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[G.R. Patterson III]

john smith wrote:
>
> I suspect that the
> temperature of the oil by the time it has all been added will have
> dropped many degrees.

It will have dropped many degrees just carrying the can out to the plane.

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.

[C J Campbell]

It is up to those that assert there is such a thing as damage from shock
cooling and shock heating to prove it. So far all anyone has ever offered is
a small amount of anecdotal evidence: "I knew a pilot once who did this and,
sure enough, his engine quit, although it was for some other reason."

[Tony Cox]

"Gene Kearns" > wrote in message
...
> On Sun, 22 Feb 2004 02:18:40 GMT, "Jay Honeck"
> > wrote:
>
> >> Look at a graph from one of those data-capturing engine monitors some
> >> time. The steepest lines on the graph will always be at takeoff. Even
> >> pulling power and diving can't cool the engine as fast as the takeoff
> >> roll can heat it up.
> >
> >So would this be proof that damage from "shock cooling" is a myth?
>
> No. The offender is thermal shock... heating or cooling.....
>

It's not clear to me that the stresses in shock heating should be
the same as for shock cooling. Just because people don't
(apparently) suffer from the effects of shock heating doesn't
by itself preclude the possibility of shock cooling.

On take-off, the equilibrium is disturbed by heat being applied
uniformly around the cylinder bores. Any distortions result in
forces being applied to metals at low temperature. Speed is low,
so cooling (and hence cooling distortions) are minimal.

In cruise and at least the initial part of the descent, metal temperatures
are higher. Whether this makes metals more or less susceptible to
cracking, I've no idea - but if shock cooling is a fact and shock
heating isn't, we should expect metal to be more fragile at higher
temperatures. Also, since the initial airspeed is higher, changes in
cooling (speed-up during descent, closing cowl flaps) will alter
temperatures (and introduce differentials) on the 'cooling' side which
are far less uniform than during the initial climbout.

In summary, take-off -- low metal temps, less cooling, similar
'outer surface' temperatures, faster temperature change, descent --
high metal temps, more cooling, distorted 'outer surface'
temperatures, slower temperature change. Quite different
régimes.

[Tony Cox]

"Gene Kearns" > wrote in message
...
> On Sun, 22 Feb 2004 17:31:16 GMT, "Tony Cox" > wrote:
> >
> >It's not clear to me that the stresses in shock heating should be
> >the same as for shock cooling. Just because people don't
> >(apparently) suffer from the effects of shock heating doesn't
> >by itself preclude the possibility of shock cooling.
> >
>
> Agreed, but I think the point not to lose sight of is that it is the
> rapid *change* in temperature that causes the problem...
> high-low...low-high... does it really matter?

The problem is induced stress, caused by different temperatures
at different locations in the metal of the engine. Temperature rate
of change observed on (say) the cylinder head is just one factor
which might predict the temperature variations throughout the engine;
my point is that there are other factors too. These factors are
different on take-off and landing. So even if the temperature rate
of change in one régime is higher than in another, this doesn't
necessarily indicate that the maximum stress in the engine is
higher. So no, I don't agree that rapid change (as measured by
some CHT) is the cause of the problem.

High-low and low-high *do* matter if the stress limit of metal
is a function of temperature, even if the internal stress fields are
similar for shock heating and cooling. Assuming that maximum
stress occurs at the instant that take-off power is applied (or
when power is reduced during descent) one would expect the
engine materials to be subject to this stress when they were
relatively cool (or hot, in descent). Stress limits of metals at
different temperatures are probably different.

> {snip}
> >Whether this makes metals more or less susceptible to
> >cracking, I've no idea - but if shock cooling is a fact and shock
> >heating isn't, we should expect metal to be more fragile at higher
> >temperatures.
>
> The word "fragile" is not used much in reference to metallurgy and
> doesn't convey a lot of meaning to me. Remember, we are talking about
> the forces involved in incidents akin to pouring a cool liquid into a
> warm punch bowl.... not a pretty sight.... and is common to all
> crystalline substances (amorphous or not).

OK, more likely to crack then. (and if you're keen to be pedantic,
crystals are never amorphous).

>
> >Also, since the initial airspeed is higher, changes in
> >cooling (speed-up during descent, closing cowl flaps) will alter
> >temperatures (and introduce differentials) on the 'cooling' side which
> >are far less uniform than during the initial climbout.
> >
>
> No, remember here, this is about transfer of (heat) energy. There is
> more capacity of rushing (relatively cooler) air at descent, thus the
> greater energy is cooling..... just the opposite is true at climb,
> where the combustion process holds the upper hand and can cause
> temperatures to soar in non-uniform ways.

You'd really have to do a finite element analysis to verify this.
But you can reasonably assume that if the airspeed is higher, then
the *variation* of the airspeed over different parts of the engine
is higher too. This means that substantially different amounts of heat
are being transferred away from different parts of the engine, which
(other things being equal), will mean that there'll be a temperature
variation over the surface which could itself lead to cracks.

The point is not to quantify this one way or the other - as I've said,
you need to do some complex modelling to be sure - rather, it is
to show that you can't predict the stresses in different modes of
flight by simply looking at the CHT rate of change.

[G.R. Patterson III]

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.

[Jay Honeck]

> 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.

That's good advice -- with any engine.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[C J Campbell]

"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.

[Dennis O'Connor]

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.
> --

[Jay Honeck]

> 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"

[Mike Rapoport]

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.

[C J Campbell]

"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.

[Malcolm Teas]

"Jay Honeck" > wrote in message news:<QdQZb.376650$na.567800@attbi_s04>...
> In another thread (about cold starting) it was mentioned that Alaskan bush
> pilots routinely drain their oil, take it inside, and heat it on the stove
> before starting in the morning.
>
> While this guarantees a warm(er) engine, wouldn't this risk damage to the
> engine from shock heating (assuming there is such a thing), by suddenly
> introducing boiling hot (or nearly so) oil to a cold-soaked engine?

Oh great! A new Old Wive's Tale <grin> When this gets around the
only safe thing to do with your engine is to run it at idle. And
you'll need to do that once a week to prevent rusting too.

Of course, this dovetails into the TFR stuff too. With all the
security TFRs, and the TFR-in-chief starting his campaign shortly, and
the wannabe TFR-in-chiefs all doing their campaigns... Well, the only
thing we'll be able to do is idle the engines and taxi around the
airport anyway.

Malcolm Teas
JYO

[Thomas Borchert]

Jay,

> So would this be proof that damage from "shock cooling" is a myth?
>

At least it would be some support for that opinion.

--
Thomas Borchert (EDDH)

[Tony Cox]

"Thomas Borchert" > wrote in message
...
> Jay,
>
> > So would this be proof that damage from "shock cooling" is a myth?
> >
>
> At least it would be some support for that opinion.
>

FWIW, "Light plane maintenance" doesn't believe in shock cooling
either, but they do recommend babying the engine for other
reasons (unspecified). Risk of detuning engine?

[Ben Jackson]

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/

[G.R. Patterson III]

Mike Rapoport wrote:
>
> 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.

Well, when I get that farm in NC a few years from now, I'm gonna paint a hex sign
on the barn. Can't hurt.

As they said in Brigadoon, we still have witches; we just pronounce it differently
these days.

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.

[Dave Stadt]

"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.

[G.R. Patterson III]

Dave Stadt wrote:
>
> 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.

No fear. The Chinese schools still teach these subjects.

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.

[Dan Luke]

"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)

[G.R. Patterson III]

Dan Luke wrote:
>
> In fact, it may be overwhelming us with propaganda and superstition.

How many times do we calmly accept a label like "television" when "magic" would
be much more appropriate?

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.

[Tom Sixkiller]

"Jay Honeck" > wrote in message
news:eTn_b.385903$na.592869@attbi_s04...
> > 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.

"Shock heating" I can understand. When you start your car on a cold morning,
you don't rev the engine to 4000 RPM, do you? Same thing when you start your
airplane's engine; you don't go immediately to full throttle.

Now, spraying cold water onto your engine as soon as you taxi in would be my
idea of "shock cooling".

[Tom Sixkiller]

"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.

It's called "faith".

[Tom Sixkiller]

"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.

[Tom Sixkiller]

"G.R. Patterson III" > wrote in message
...
>
>
> Dave Stadt wrote:
> >
> > 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.
>
> No fear. The Chinese schools still teach these subjects.

Don't confuse "technology" with "science". The Chinese (and most other
nations schools) teach "technology", not "science". Note how technology
abounds in many of the cultures of the fundamentalist Middle East: the
"barbarian with a nuke".

[Tom Sixkiller]

"Dan Luke" > wrote in message
...
> 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.

That's been the political game for a couple generations -- Bush is nothing
new in that realm.

> 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.

Sounds like the environmental movement.


> 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.

And our technology can keep such follies at bay by way of the information
age. The days of the dominant media having a monopoly on the dissemination
of "news" is over. OTOH, if people cannot (by lack of training and PROPER
education) sort through information, reason, think critically, etc., then,
yes, we are doomed.

[Tom Sixkiller]

"G.R. Patterson III" > wrote in message
...
>
>
> Dan Luke wrote:
> >
> > In fact, it may be overwhelming us with propaganda and superstition.
>
> How many times do we calmly accept a label like "television" when "magic"
would
> be much more appropriate?

And when, academia through the schools of philosophy (the schools of liberal
arts) teaches us that television (or anything else) doesn't really
exist...then propaganda and superstition are institutionalized.

[Brian Sponcil]

Not that it's gospel but....

http://www.lycoming.textron.com/support/publications/keyReprints/operation/avoidSuddenCooling.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...

[Matt Emerson]

"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/speeches/speeches_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

[Thomas Borchert]

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)

[Thomas Borchert]

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)

[Thomas Borchert]

Tom,

> It's called "faith".
>

Yes. And that still gave us the Dark Ages.

--
Thomas Borchert (EDDH)

[Dan Luke]

"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)

[Jay Honeck]

> 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"

[Thomas Borchert]

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)

[Tom Sixkiller]

"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...

[Bushy]

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/

[Aaron Coolidge]

:> 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.

: That about sums up my feelings, too.

: We can't prove that it exists, but the very threat of a cracked cylinder
: head due to shock cooling is enough to make us fear it, and fly like it's
: real.

Don't forget another pilot-induced mechanism to lead to rapid cylinder
head cooling: pushing the mxture full rich at the top of descent, while
simultaneously reducing the throttle a modest amount. At this point, the
pilot could probably lean the mixture more, or leave it leaned for cruise,
until time to add power to level out.

--
Aaron Coolidge (N9376J)

[Ray Andraka]

For descents, I just pull back my MP about 4" for 500 fpm. Don't touch the
mixture until leveling back off, don't touch the throttle, don't touch the
trim. Most times, this won't register as shock cooling on my JPI, and the
times it does it just over the 50 deg/min alarm limit. This technique keeps
your airspeed constant, and makes for a minimum pilot load, and cools the
cylinders gently. PIC taught me the technique in one of my instrument
refreshers.

Aaron Coolidge wrote:

> :> 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.
>
> : That about sums up my feelings, too.
>
> : We can't prove that it exists, but the very threat of a cracked cylinder
> : head due to shock cooling is enough to make us fear it, and fly like it's
> : real.
>
> Don't forget another pilot-induced mechanism to lead to rapid cylinder
> head cooling: pushing the mxture full rich at the top of descent, while
> simultaneously reducing the throttle a modest amount. At this point, the
> pilot could probably lean the mixture more, or leave it leaned for cruise,
> until time to add power to level out.
>
> --
> Aaron Coolidge (N9376J)

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

[Bill Hale]

(Malcolm Teas) wrote in message >...
> "Jay Honeck" > wrote in message news:<QdQZb.376650$na.567800@attbi_s04>...
> > In another thread (about cold starting) it was mentioned that Alaskan bush
> > pilots routinely drain their oil, take it inside, and heat it on the stove
> > before starting in the morning.

Getting back to the subject, one might surmise that by
far the worst temperature shock happens to the engine
when the key is turned on.

One should avoid this action.

Bill Hale

[Ray Andraka]

On mine, all turning the key does is unground the p-leads on the mags (I need to push the starter button to
get the prop to turn). How does turning the key on induce 'the worst temperature shock'? ;-)

Bill Hale wrote:

> (Malcolm Teas) wrote in message >...
> > "Jay Honeck" > wrote in message news:<QdQZb.376650$na.567800@attbi_s04>...
> > > In another thread (about cold starting) it was mentioned that Alaskan bush
> > > pilots routinely drain their oil, take it inside, and heat it on the stove
> > > before starting in the morning.
>
> Getting back to the subject, one might surmise that by
> far the worst temperature shock happens to the engine
> when the key is turned on.
>
> One should avoid this action.
>
> Bill Hale

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

[Newps]

If you don't have a slippery plane why pull the power at all for
descents? In my 182 I close the cowl flaps if they aren't already and
simply roll in two swipes of nose down trim. Leave power as is, which
for me is almost always top if the green throttle and prop or the max it
will give me. Bingo, 500 fpm down. Don't even get into the yellow.



Ray Andraka wrote:
> For descents, I just pull back my MP about 4" for 500 fpm. Don't touch the
> mixture until leveling back off, don't touch the throttle, don't touch the
> trim. Most times, this won't register as shock cooling on my JPI, and the
> times it does it just over the 50 deg/min alarm limit. This technique keeps
> your airspeed constant, and makes for a minimum pilot load, and cools the
> cylinders gently. PIC taught me the technique in one of my instrument
> refreshers.
>
> Aaron Coolidge wrote:
>
>
>>:> 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.
>>
>>: That about sums up my feelings, too.
>>
>>: We can't prove that it exists, but the very threat of a cracked cylinder
>>: head due to shock cooling is enough to make us fear it, and fly like it's
>>: real.
>>
>>Don't forget another pilot-induced mechanism to lead to rapid cylinder
>>head cooling: pushing the mxture full rich at the top of descent, while
>>simultaneously reducing the throttle a modest amount. At this point, the
>>pilot could probably lean the mixture more, or leave it leaned for cruise,
>>until time to add power to level out.
>>
>>--
>>Aaron Coolidge (N9376J)
>
>
> --
> --Ray Andraka, P.E.
> President, the Andraka Consulting Group, Inc.
> 401/884-7930 Fax 401/884-7950
> email
> http://www.andraka.com
>
> "They that give up essential liberty to obtain a little
> temporary safety deserve neither liberty nor safety."
> -Benjamin Franklin, 1759
>
>

[Ray Andraka]

That is how i used to do it, but the pulling 4" off turns out to be less of a
workload, which makes a difference in IFR conditions especially in the terminal
environment.

The difference is that using power to control the descent, you get a primary
instrument to maintain the descent (MP/RPM), where controlling it with trim you
have to rely on secondary instruments (VSI). Using power to control it, you set
the power to the target setting, wait for the descent to become established, cross
check the rate on the VSI, and then if necessary tweak the power a fraction of an
inch. On mine a 4" reduction gets me a 500 fpm descent regardless of the
configuration (flaps, trim). Once established, maintaining a constant rate
descent is just a matter of moving the throttle to keep the MP pegged (it will
creep up as you descend into denser air). As long as the MP is constant, the rate
of descent is too. Note that the trim sets the airspeed, and in this case you
maintain a constant airspeed throughout the maneuver. Since the power is reduced,
there is no harm in leaving the mixture at the leaned for cruise setting until you
increase power at the end of the descent (in fact it helps to keep the engine
warm). I have only one lever to move throughout my descent, one mixture
adjustment as I level off, and one gauge to look at to immediately see the result
of my moving that lever.

If you use the trim to control your descent, you have no indicator to directly
show the control setting, instead you have to rely on the VSI and the AI for
secondary info. Additionally, you need to adjust the trim as you pick up speed in
the descent to keep the descent rate up. You'll pick up speed both because of the
change in the trim, as well as from the gradual increase in power as you descend
into denser air. Since there is no primary instrument to use in maintaining the
trim, you have to rely on the secondary instruments to adjust the trim based on
the end result. This is a feedback loop and is prone to getting you into a
chasing the needle situation. This method also requires you to monitor and
continuously adjust the mixture because at full power you will need mixture
enrichment as you descend into lower altitudes to keep from running in an
overleaned high power configuration, which is bad for the engine. Also, the
amount of trim required to achieve a given descent rate varies considerably with
airspeed, so you have multiple settings to memorize to fit all the flight
configurations you use. You also need to keep close tabs on the airspeed unless
your airplane is a brick. I have a Cherokee Six, which is by no means a slippery
airplane. Using your technique will put me into the yellow arc in a descent from
cruise, which can be a problem if the air down there is bumpy as it often is.

Newps wrote:

> If you don't have a slippery plane why pull the power at all for
> descents? In my 182 I close the cowl flaps if they aren't already and
> simply roll in two swipes of nose down trim. Leave power as is, which
> for me is almost always top if the green throttle and prop or the max it
> will give me. Bingo, 500 fpm down. Don't even get into the yellow.

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

[Dave Stadt]

"Bill Hale" > wrote in message
om...
> (Malcolm Teas) wrote in message
>...
> > "Jay Honeck" > wrote in message
news:<QdQZb.376650$na.567800@attbi_s04>...
> > > In another thread (about cold starting) it was mentioned that Alaskan
bush
> > > pilots routinely drain their oil, take it inside, and heat it on the
stove
> > > before starting in the morning.
>
> Getting back to the subject, one might surmise that by
> far the worst temperature shock happens to the engine
> when the key is turned on.
>
> One should avoid this action.
>
> Bill Hale

So if my plane does not have a key the engine will last forever?

[G.R. Patterson III]

Bill Hale wrote:
>
> Getting back to the subject, one might surmise that by
> far the worst temperature shock happens to the engine
> when the key is turned on.
>
> One should avoid this action.

Wilco. I'm gonna start leaving the ignition on all the time and propping it.

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.

[Tom Sixkiller]

"Bushy" > blathered...

Boyfriend not putting out?

> ;<)
>
> "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/
>
>