Engine out practice

On Oct 14, 6:59 am, Matt Whiting wrote:

Yes, I'm well aware of thermal expansion and its affects. When an
engine is pulled to idle, the cylinders and heads are getting cooled
from both sides, the outside via airflow and the inside via airflow
through the engine.

Except that, with the throttle closed, there is almost no
airflow through the engine.

Dan

Stefan,

Which are those companies and where do I find those data?


One is: http://www.gami.com

See:
http://www.gami.com/gamitcmdefault.html
http://www.avweb.com/news/pelican/182544-1.html
http://www.engineteststand.com/
http://www.advancedpilot.com/

--
Thomas Borchert (EDDH)

"Newps" wrote in message
. ..
Stefan wrote:
Matt Barrow schrieb:

Thomas offers data and evidence, Lycoming offers anecdote and legend.

Lycoming offers running engines. Thomas offers words.


Lycoming and Continental offer no science whatsoever to back up their
recommendations. There are several companies that can show you hard
scientific data to disprove what the engine manufacturers claim.

Somewhere in John Deakins' "Engine Series" articles on AvWeb, there's a
nice graph that Deakins captured from his engine analyzer that duplicates
the conditions that manufacturers' claim to produce "Shock Cooling". It
pretty well debunks the claim. IIRC, he produced both total and immediate
shutdown of the engine as well as gradual power reduction.

IMONSHO, the manufacturers are covering their asses for poor design and
components.
--
Matt Barrow
Performance Homes, LLC.
Cheyenne, WY

Mxsmanic wrote in
:

Stefan writes:

Interesting point of view. Please explain.

There is a potential conflict of interest in that an engine that lasts
a long time delays a replacement sale. However, other factors come
into play, such as liability, reputation and customer goodwill, and so
on, so it's not clear that a manufacturer wouldn't provide good
advice.


You have no idea what you're talking about,

You don't fly and you never will.


Bertie

On Oct 14, 4:13 am, Bertie the Bunyip wrote:
Matt Whiting wrote in news:foeQi.309$2n4.18956
@news1.epix.net:







Stefan wrote:
Matt Whiting schrieb:

And Lycoming benefits if your engine lasts fewer hours.

So avoiding shock cooling actually lowers its life span? Wow.

You have no evidence that following Lycoming's recommendations avoids
the mythical shock cooling demon or that it lengthens engine life. My
experience is that the engines that are run the hardest also last the
longest. I'm basing this on everything from chainsaws to lawnmowers
to
motorcycles to cars to trucks to off-road heavy equipment (dozers,
skidders, etc.) to airplanes (trainers, air taxi operations, cargo).

I'm personally not convinced that Lycoming's recommendations lengthen
engine life.

Matt

Shock cooling isn't mythical. It's a fact. It's a physical law.

Any component subject to heating is subject to this law. If you take a
piece of metal and heat it rapidly on one side, that side will expand
more rapidly than the other. This gradient of temp will cause a
difference in physical size one side to the other. The elastic stress
induced by this is cyclically compounded and the resultant locked stress
points that build up in the material, particularly if it's a brittle
material like cast iron, will eventually fail, given time.
The speed at which these stresses are imposed are critical. Speed
because if you introduce the heat gradually (decrease the speed of the
overall temp change), it's given a chance to get to the other side and
expand the other side at a rate not quite so dramatically different as
the side the heat is applied to. Simple eh?
The quicker you insert heat on one side of the material, the greater the
load on the opposite side and the more likely minor damage events
(cracks on a near molecular leve) are occuring. These tiny bits of
damage will become stress risers for the next time th ematerial is
loaded and the cracks will continue to expand until a failure of the
component occurs.

I think Lycoming probably figured most of this out in the 1920s,
Continental even earlier.

However, if it's anectodal evidence that is required...
I've worked for recip operators where this was a daily problem. In
glider tugs, for instance, jug failures were common. Operations had to
be tailered to minimise the strain, and these adopted procedures worked.
I've also flown big recips and they also required careful management to
avoid blowing the top of a jug off. The emphasis is always on minimising
the speed at which th etemps change.
Jets are no different. Blades ae subject ot enoromous thermal stresses,
and all of the procedures laid down by the manufacturers are designed to
extend engine life as much as possible. Everything from engine startup,
through warmup times to takeoff (admittedly not all manufacturers have
done this over the years and there are other reasons for this) to
reduced power for climb to care in reduction of power at top of descent
are all used to this end.

Other bugbears of the punished engine are micro-seizures and excessive
friction due to reduced or even sometimes increased, clearances due to
rapid temp changes.

If the aircraft is being manuevered violently along with rapid power
changes, you can add precession to the damage being caused.In
aerobatics, obviously.
That is why, even though the pilot must be prompt with his power
changes to maintain control of his speed, it is accepted that it is best
practice to make these changes as smoothly and deliberately as possible
whilst still meeting the demands of aircraft control.
But even relatively mild manuevering combined with rapid throttle
changes will induce the same stresses to a lesser degree and are
therefore undesirable.

None of this is new info , of course. I have engine operating manuals
from the 1930s that address all of these issues and modern manuals
remain pretty much the same. These principles were understood long
before that. Interestingly though, I have a workshop manual for a 1933
Le Blond that talks about corrosion on the inside of a hollow crank,
it's causes and prevention, all of which could directly apply to that
debacle with lycomings. Seems some lessons have been forgotten!
The manufaturers have no interest in misleading anyone into screwing
their engines up to increase their profits. They rely on their
reputations as builders of reliable engines to increase their sales.
An engine that never makes it to TBO would be a liability to them..
Want to increase your engine life and reliability? Don't bash your
throttle around.

For real improvement in addition to these suggestions, install a pre-
oiler and oil heater. Your bottom end will last forever and the top will
be much improved as well. If you're operating on condition you might get
double the TBO overall or more! A really good filter is essential for
longevity as well.Get an STC for one if there's not one readily
available for your airplane..

Bertie- Hide quoted text -

- Show quoted text -

In this instance I agree with Bertie the Bunyip except for the simple
fact that,,,, If Lycoming and Continental and the FAA knew that a pre-
oiler and and oil heater would extent the life and safety of an
internal combustion engine as much as you claim it will, all of them
would have been made them mandatory 59 years ago. As a former racer I
totally agree to the idea of a pre-oiler and warm oil at start up, to
the idea the bottom end will last " forever", well, good luck on that.
Thank god my aircraft engine is water cooled.. No chance of shock
cooling for me.... As a post note Fall flying here in Jackson Hole Wy.
is spectacular. 27f sittin on the ramp, 18f at altitude, leaf colors,
breathtaking... Snow up high, Almost better then sex..I love the
mountains. !!!!!!!!!!!!!!!!!!!!!!


Ben
www.haaspowerair.com

" wrote in
ps.com:

On Oct 14, 4:13 am, Bertie the Bunyip wrote:
Matt Whiting wrote in news:foeQi.309$2n4.18956
@news1.epix.net:







Stefan wrote:
Matt Whiting schrieb:

And Lycoming benefits if your engine lasts fewer hours.

So avoiding shock cooling actually lowers its life span? Wow.

You have no evidence that following Lycoming's recommendations
avoids
the mythical shock cooling demon or that it lengthens engine life.
My
experience is that the engines that are run the hardest also last
the
longest. I'm basing this on everything from chainsaws to
lawnmowers
to
motorcycles to cars to trucks to off-road heavy equipment (dozers,
skidders, etc.) to airplanes (trainers, air taxi operations,
cargo).

I'm personally not convinced that Lycoming's recommendations
lengthen
engine life.

Matt

Shock cooling isn't mythical. It's a fact. It's a physical law.

Any component subject to heating is subject to this law. If you take
a
piece of metal and heat it rapidly on one side, that side will expand
more rapidly than the other. This gradient of temp will cause a
difference in physical size one side to the other. The elastic stress
induced by this is cyclically compounded and the resultant locked
stress
points that build up in the material, particularly if it's a brittle
material like cast iron, will eventually fail, given time.
The speed at which these stresses are imposed are critical. Speed
because if you introduce the heat gradually (decrease the speed of
the
overall temp change), it's given a chance to get to the other side
and
expand the other side at a rate not quite so dramatically different
as
the side the heat is applied to. Simple eh?
The quicker you insert heat on one side of the material, the greater
the
load on the opposite side and the more likely minor damage events
(cracks on a near molecular leve) are occuring. These tiny bits of
damage will become stress risers for the next time th ematerial is
loaded and the cracks will continue to expand until a failure of the
component occurs.

I think Lycoming probably figured most of this out in the 1920s,
Continental even earlier.

However, if it's anectodal evidence that is required...
I've worked for recip operators where this was a daily problem. In
glider tugs, for instance, jug failures were common. Operations had
to
be tailered to minimise the strain, and these adopted procedures
worked.
I've also flown big recips and they also required careful management
to
avoid blowing the top of a jug off. The emphasis is always on
minimising
the speed at which th etemps change.
Jets are no different. Blades ae subject ot enoromous thermal
stresses,
and all of the procedures laid down by the manufacturers are designed
to
extend engine life as much as possible. Everything from engine
startup,
through warmup times to takeoff (admittedly not all manufacturers
have
done this over the years and there are other reasons for this) to
reduced power for climb to care in reduction of power at top of
descent
are all used to this end.

Other bugbears of the punished engine are micro-seizures and
excessive
friction due to reduced or even sometimes increased, clearances due
to
rapid temp changes.

If the aircraft is being manuevered violently along with rapid power
changes, you can add precession to the damage being caused.In
aerobatics, obviously.
That is why, even though the pilot must be prompt with his power
changes to maintain control of his speed, it is accepted that it is
best
practice to make these changes as smoothly and deliberately as
possible
whilst still meeting the demands of aircraft control.
But even relatively mild manuevering combined with rapid throttle
changes will induce the same stresses to a lesser degree and are
therefore undesirable.

None of this is new info , of course. I have engine operating manuals
from the 1930s that address all of these issues and modern manuals
remain pretty much the same. These principles were understood long
before that. Interestingly though, I have a workshop manual for a
1933
Le Blond that talks about corrosion on the inside of a hollow crank,
it's causes and prevention, all of which could directly apply to that
debacle with lycomings. Seems some lessons have been forgotten!
The manufaturers have no interest in misleading anyone into screwing
their engines up to increase their profits. They rely on their
reputations as builders of reliable engines to increase their sales.
An engine that never makes it to TBO would be a liability to them..
Want to increase your engine life and reliability? Don't bash your
throttle around.

For real improvement in addition to these suggestions, install a pre-
oiler and oil heater. Your bottom end will last forever and the top
will
be much improved as well. If you're operating on condition you might
get
double the TBO overall or more! A really good filter is essential for
longevity as well.Get an STC for one if there's not one readily
available for your airplane..

Bertie- Hide quoted text -

- Show quoted text -

In this instance I agree with Bertie the Bunyip except for the simple
fact that,,,, If Lycoming and Continental and the FAA knew that a pre-
oiler and and oil heater would extent the life and safety of an
internal combustion engine as much as you claim it will, all of them
would have been made them mandatory 59 years ago. As a former racer I
totally agree to the idea of a pre-oiler and warm oil at start up, to
the idea the bottom end will last " forever", well, good luck on that.


just a flippant remark. didn't think anyone would take it seriously!


Seriously, though, they will increase engine life considerably.

Bertie

Stefan wrote:
Newps schrieb:

The engine manufacturers are about the last place I'd look for engine
management techniques.

Interesting point of view. Please explain.


Lean of peak. In the face of overwhelming evidence both engine
manufacturers flat out state that LOP is harmful to your engine.
Continental has slightly relented as they publish some LOP settings for
their 550 engines. But try and engage anyone in that company in
meaningful discourse on LOP ops and you get blank stares. They
absolutely refuse. LOP not only saves gas but is tremendously easier on
the engine.

On Oct 14, 3:22 pm, " wrote:

In this instance I agree with Bertie the Bunyip except for the simple
fact that,,,, If Lycoming and Continental and the FAA knew that a pre-
oiler and and oil heater would extent the life and safety of an
internal combustion engine as much as you claim it will, all of them
would have been made them mandatory 59 years ago.


They could extend the life, but won't make the engine fail-
proof. They add weight and complexity and further fail points.

I have a homebuilt with an old A-65. These old engines and their
brethren (A-75, A-80, C-75, C-85, C-90) all had a reputation for
losing oil pump prime when left sitting for long periods. The oil pump
is machined into the accessory cover and has an aluminum plate bolted
down over it, with minimal clearance over the pump gears. This plate
is supposed to seal tightly against the machined case surface, and I
always used a little sealant on it to discourage the leakage of all
the oil out of it when sitting, but most do leak, even with sealant,
and if the pump is dry enough the pressure won't come up or it'll be
delayed. The crankshaft and its bearings suffer accordingly, and this
spring I had to take mine apart and have the crank ground. The front
rod journal gets it the worst, being narrow, heavily loaded and
farthest from the pump.
I used to do what some other small Continental operators have
to do: take the temp probe out of the filter screen and pump some oil
into the filter, where it would fall into the pump and prime it. It
got so I didn't even bother starting the thing first to see if
pressure would build. Too chancy.
I finally got fed up and machined a little manual preoiler pump
from aluminum, a few fittings, O-rings, small springs and bearing
balls, and installed it. Homebuilts are wonderful that way. Now I open
a small valve, pump the preoiler about 20 strokes, close the valve and
start the engine. The oil pressure comes up instantly. The 20 strokes
fills the entire oil system and primes the pump, too. I expect that
crank to last awhile, now.

Dan

Bertie the Bunyip wrote:
Matt Whiting wrote in
:

Bertie the Bunyip wrote:
Matt Whiting wrote in news:foeQi.309$2n4.18956
@news1.epix.net:

Stefan wrote:
Matt Whiting schrieb:

And Lycoming benefits if your engine lasts fewer hours.
So avoiding shock cooling actually lowers its life span? Wow.
You have no evidence that following Lycoming's recommendations
avoids the mythical shock cooling demon or that it lengthens engine
life. My experience is that the engines that are run the hardest
also last the longest. I'm basing this on everything from chainsaws
to lawnmowers
to
motorcycles to cars to trucks to off-road heavy equipment (dozers,
skidders, etc.) to airplanes (trainers, air taxi operations, cargo).

I'm personally not convinced that Lycoming's recommendations
lengthen engine life.

Matt


Shock cooling isn't mythical. It's a fact. It's a physical law.
A physical law, eh? I've had 8 years of engineering school and
haven't seen this law. Can you provide a reference to the law of
shock cooling?
I searched for the "law of shock cooling" in Google and came up
empty...


Any component subject to heating is subject to this law. If you take
a piece of metal and heat it rapidly on one side, that side will
expand more rapidly than the other. This gradient of temp will cause
a difference in physical size one side to the other. The elastic
stress induced by this is cyclically compounded and the resultant
locked stress points that build up in the material, particularly if
it's a brittle material like cast iron, will eventually fail, given
time. The speed at which these stresses are imposed are critical.
Speed because if you introduce the heat gradually (decrease the speed
of the overall temp change), it's given a chance to get to the other
side and expand the other side at a rate not quite so dramatically
different as the side the heat is applied to. Simple eh?
The quicker you insert heat on one side of the material, the greater
the load on the opposite side and the more likely minor damage events
(cracks on a near molecular leve) are occuring. These tiny bits of
damage will become stress risers for the next time th ematerial is
loaded and the cracks will continue to expand until a failure of the
component occurs.
Yes, I'm well aware of thermal expansion and its affects. When an
engine is pulled to idle, the cylinders and heads are getting cooled
from both sides, the outside via airflow and the inside via airflow
through the engine. The far greater differential is under full
throttle during the first take-off when the engine has not yet reached
thermal equilibrium and you are heating it intensely on the inside and
cooling it on the outside.

If people wanted to talk about shock heating, then I'd be much more
willing to believe them and this fits the physics a lot better in my
opinion. Shock cooling is much less an issue from both a physics
perspective and an experience perspective.


It's the same either way. Cooling and heating are two sides of th esame
coin. It takes time to disapate heat and it's not so much the passage of
heat from one area to another (or the disappation, it's irrelevant) but
the speed at which the cooling or heating is taking place and thus the
gradient across the material.
In short, you take a frozen lump of metal and apply a torch to one side
you have a problem.
Take a cherry red pice of metal and put some ice on side and you have
the same problem (more or less, and disregading crystalisation)

It is the same if the same delta T is present, but my point is that it
is easier to heat something quickly than cool it quickly. Even at 250
C, you are only 523 degrees above absolute zero. So, this the absolute
largest delta T you can induce for cooling, and it is very hard to get
absolute zero, so you are more likely to have a cool temp closer to 0 C
yielding a delta T of only 250 degrees.

On the hot side things are more open-ended. It isn't too hard to get
450 C exhaust gas temperatures. For an engine that is started at say 20
C ambient temperature, you now have a delta T of 430 degrees which is
much greater than the 250 likely on the cooling side of the cycle.

That is one reason why I suspect that "shock heating" is more likely to
be an issue than "shock cooling." I suspect you can induce a higher
delta T during a full-throttle initial climb than you can during an idle
descent from a cruise power setting.

Matt

wrote:
On Oct 14, 6:59 am, Matt Whiting wrote:

Yes, I'm well aware of thermal expansion and its affects. When an
engine is pulled to idle, the cylinders and heads are getting cooled
from both sides, the outside via airflow and the inside via airflow
through the engine.

Except that, with the throttle closed, there is almost no
airflow through the engine.

Dan


True, but there is some and there is still some fuel going through which
is vaporized and removes heat as well.

Matt