Engine out practice

wrote in news:1192457661.189109.80330
@e34g2000pro.googlegroups.com:

On Oct 15, 6:20 am, Bertie the Bunyip wrote:

Standard practice in airplanes like that is to chop the power on
downwind opposite the touchdown point and regualte your approach by
varying the size of your pattern from that point. Now, with some
regard
towards rapid cooling we reduced to about 1200 rpm initially and then
chopped it a bit later.
Needless to say the students had very little trouble doing forced
landings when it came to that time in their training.
I've also taught just the same in Cherokees and Cessnas, although
teaching relatively recently within flying clubs I've had to go with
the
flow because somewhere some asshole back in the '70s got it in his
head
that since airliners do power stabilised approaches it;s a good idea
in
a lightplane as well. "Makes the whole trianing experience more
professional" you know.
Now there's a new thread!

That's what I was taught in the early '70s when I got my PPL.
When I went for the CPL in the '90s the whole syllabus had changed,
and so had the forced-approach proficiencies of the students and PPLs.
In the instructor refresher courses the forced approach comes up as
the most frequently failed item on both private and commercial flight
tests. The students simply don't know how to adjust glidepath using
nothing more than airspeed, with a slip thrown in if necessary. They
don't get the idea that they can glide farther if they drop the nose
and maintain best glide, drop it farther and go faster if they're
bucking a headwind, pull the nose up and sink if they're high, or get
into ground effect and skim along to the touchdown point if they're a
little short. If no fences are in the way, of course. I once did that
on an instructor checkride and the examiner told me that this was
acceptable. Your mileage may vary.


Sounds OK to me!
I ad the privelage of siting in the back of a cherokee while a guy ws
getting a currenc check recently. The instructor (also a desgnated
examiner) gave him a forced landing into a disused airfield. He didn't
do too good a job of it in the first try, so some instruction ensued.

The examiner wouldn't allow him to slip because he reckons they are
dangerous with the flaps out and that he should wiggle the ailerons back
and forth to lose height. He didn't even want him to slip clean.

Jesus wept.


This examiner had had a fright in a 172 (this was an archer anyway) and
did not alow anyone to slip with flaps out.
While I am firmly in the camp that says some cessnas can get a litle
fuzzy in pitch with full flaps, this is just stupidity incarnate.

As far as the preoiler, I made no drawings. I was always an
eyeball engineer, with a basic preliminary sketch if necessary. I made
my living designing, building, rebuilding and inventing stuff for 12
years and this comes easily enough. Maybe, when I get back from a trip
to Africa for the next three weeks, I'll draw something up and submit
it.


Good man!
I'll make one if you do!

Bertie

Matt: At least in my experience shock cooling did exist. I flew sky divers
in a Skylane and had taken over after another pilot who would climb hard and
chop the throttle and descend to the ground. There were frequent low hour
Top Over hauls, and cracked cylinders. When I began flying the bird the
owner asked me to be aware of cooling it down to fast. My method was to
climb to the drop and then close the cowl flaps, carry 15" MP and spiral
tightly down. It stopped the low hour top overhauls.
My descent rate could be pretty high and the engine was kept relatively
warm.

Stu Fields
Experimental Helo Magazine.
"Matt Whiting" wrote in message
...
Bertie the Bunyip wrote:
Matt Whiting wrote in

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.


Right, I'm with you now. yeah, I can buy that. Froma strictly clinical
viewpoint it absolutely makes sense. My experience with damage says
otherwise, though I can offer no explanation why that should be the case.
Years ago I towed gliders with Bird-dogs and we cracked a lot of
cylinders when we just closed the throttle after release. When we moved
to gradual reduction to ultimately 1500 RPM the problem disappeared
completely. Later, when I flew big pistons,the procedures for cooling
down the cylinders on the way down. You were almost gaurunteed a crack if
you yanked the taps closed. Can't see how we went from cold to hot any
more than you would just starting up and taking off. I've just bought an
aerobatic airplane with a Lycoming. We're not expecing to get to TBO with
the engine because we'll be doing aerobaics with it, but of course we're
prepared to live with that.
I suppose the point I'm making is that even if shick cooling is over-
rated, it certainly does no harm to observe trad practices as if it did.

I suspect, as with most "real world" problems, that there is more in play
than delta T induced stress. Probably geometry and other factors. Maybe
having the thin fins on the outside vs. thick metal on the inside is
making a big difference in the stress profile.

I've not had experience with the larger engines or with radials. However,
my experience with O-470 and smaller engines is that shock cooling just
isn't an issue and many folks are paranoid for nothing.

Operating the engine as if shock cooling was an issue is probably not a
problem in most cases, but if it causes you, as it has with Jay, to not
practice essential emergency procedures, then I disagree that it causes no
harm. This may be very harmful should Jay experience an engine failure
for real.

Matt

On Oct 15, 8:49 am, Bertie the Bunyip wrote:

The examiner wouldn't allow him to slip because he reckons they are
dangerous with the flaps out and that he should wiggle the ailerons back
and forth to lose height. He didn't even want him to slip clean.

Jesus wept.

This examiner had had a fright in a 172 (this was an archer anyway) and
did not alow anyone to slip with flaps out.
While I am firmly in the camp that says some cessnas can get a litle
fuzzy in pitch with full flaps, this is just stupidity incarnate.

Shoot. We do slips with full flaps all the time in 172s, have
done so for years, and never had a scare. I wonder if that "Avoid
Slips With Flaps Extended" applied to some earlier models? I'll have
to check the TCDS sometime.

Dan

In article .com,
wrote:

On Oct 15, 8:49 am, Bertie the Bunyip wrote:

The examiner wouldn't allow him to slip because he reckons they are
dangerous with the flaps out and that he should wiggle the ailerons back
and forth to lose height. He didn't even want him to slip clean.

Jesus wept.

This examiner had had a fright in a 172 (this was an archer anyway) and
did not alow anyone to slip with flaps out.
While I am firmly in the camp that says some cessnas can get a litle
fuzzy in pitch with full flaps, this is just stupidity incarnate.

Shoot. We do slips with full flaps all the time in 172s, have
done so for years, and never had a scare. I wonder if that "Avoid
Slips With Flaps Extended" applied to some earlier models? I'll have
to check the TCDS sometime.

It affected at least some 172s.

Back when dinosaurs still roamed the taxiways...well, around 1971, a
couple of the instructors who worked for the FBO for which I was a very
lowly minion were wondering why the sole 172 was placarded against slips
with full flaps. (We operated mostly Pipers, various Cherokees and a
Navajo, and this one slightly elderly 172, I don't recall which year it
was.)

So they went out one morning, got plenty of cushion between themselves
and the ground, set the 172 into a landing configuration with full
flaps, and slipped it.

It shook a bit and then went inverted on them. They recovered and came
back home.

It may have only done that in some specific CG configurations, but they
were satisfied, and didn't wonder any longer.

Didn't do it again, either.

wrote in news:1192492570.300275.289550
@i38g2000prf.googlegroups.com:

On Oct 15, 8:49 am, Bertie the Bunyip wrote:

The examiner wouldn't allow him to slip because he reckons they are
dangerous with the flaps out and that he should wiggle the ailerons back
and forth to lose height. He didn't even want him to slip clean.

Jesus wept.

This examiner had had a fright in a 172 (this was an archer anyway) and
did not alow anyone to slip with flaps out.
While I am firmly in the camp that says some cessnas can get a litle
fuzzy in pitch with full flaps, this is just stupidity incarnate.

Shoot. We do slips with full flaps all the time in 172s, have
done so for years, and never had a scare. I wonder if that "Avoid
Slips With Flaps Extended" applied to some earlier models? I'll have
to check the TCDS sometime.

Dan



Dunno. the manual in a 172 makes reference to a possibility of degraded
elevator control, but I think it's only a bit of a nod, really.
The Bird dog suffers from this ailment big time, though. it has,
essentially, the 172's wing, but the flaps go to 60 degrees. I can tell you
first hand that blanking of both the rudder and elevator are a very real
characteristic of that airplane if you slip it ith full flaps. I did it
once close to the ground and never even thought about it again..

Ernest Christley wrote in news:47142123$0$32479
:

Bertie the Bunyip wrote:

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.


With the heating, you only have the few hundred CFM of air passing
through the engine to heat it. With the cooling, you have all of the
great outdoors to do the trick. To tie it into your anology, you have a
butane lighter to heat the metal, and the Atlantic Ocean to cool it.


Kind of besides th point. you coudl say the same thing about an oxy
acetylene setup and we all know what that will do to a bit of metal.


Bertie

On Oct 16, 12:43 am, Bertie the Bunyip wrote:
wrote in news:1192492570.300275.289550
@i38g2000prf.googlegroups.com:



On Oct 15, 8:49 am, Bertie the Bunyip wrote:

The examiner wouldn't allow him to slip because he reckons they are
dangerous with the flaps out and that he should wiggle the ailerons back
and forth to lose height. He didn't even want him to slip clean.

Jesus wept.

This examiner had had a fright in a 172 (this was an archer anyway) and
did not alow anyone to slip with flaps out.
While I am firmly in the camp that says some cessnas can get a litle
fuzzy in pitch with full flaps, this is just stupidity incarnate.

Shoot. We do slips with full flaps all the time in 172s, have
done so for years, and never had a scare. I wonder if that "Avoid
Slips With Flaps Extended" applied to some earlier models? I'll have
to check the TCDS sometime.

Dan

Dunno. the manual in a 172 makes reference to a possibility of degraded
elevator control, but I think it's only a bit of a nod, really.
The Bird dog suffers from this ailment big time, though. it has,
essentially, the 172's wing, but the flaps go to 60 degrees. I can tell you
first hand that blanking of both the rudder and elevator are a very real
characteristic of that airplane if you slip it ith full flaps. I did it
once close to the ground and never even thought about it again..

Here's what the Type Certificate Data Sheet says:
.................................................. ...................................

D. On flap handle, Models 172 through 172E

(1) "Flaps - Pull to extend
Takeoff Retract 0°
1st notch 10°
Landing 0° - 40°

(2) "Avoid slips with flaps down."

E. Near flap indicator Models 172F (electric flaps) through 17271034,
excluding 17270050)

"Avoid slips with flaps extended."
.................................................. .........................................

The applicable models, 172 through 172F, were built between
1956 and 1964 ('65 model?). There's no mention of the slip with flaps
thing for later models. I wonder if the addition of the back window
changed the airflow enough to keep the elevator flying?

Dan

Souns about right. The Bird dog's reaction was anything but mild, but with
60 degrees of flap it's not surprising really. Teh 172 this DE claims to
have had problems with was a relatively late one, but I could have been
anything that caused it. Some turbulence or maybe his mimagination coupled
with the horrow stories about it.

Seems if one must use full flaps AND slip in landing, I would say the
approach was an abortion that lived. I prefer slips to flaps as you can
instantly remove a slip but the same can't be said for flaps...

Just MY personal opinion...not trying to slam anybody.

Scott


Bob Moore wrote:
Bertie the Bunyip wrote

This examiner had had a fright in a 172 and
did not alow anyone to slip with flaps out.
While I am firmly in the camp that says some
cessnas can get a litle fuzzy in pitch with
full flaps, this is just stupidity incarnate.


About once-a-year I post the following excerpt from "Cessna, Wings for
the World", a book by William D. Thompson.

Bill Thompson is an Aeronautical engineer from Purdue University and
worked for Cessna Aircraft Company for 28 years as an engineering test
pilot and later as the Manager of Flight Test & Aerodynamics.

-------------------------------------------------------------------
"With the advent of the large slotted flaps in the C-170, C-180, and C-
172 we encountered a nose down pitch in forward slips with the wing
flaps deflected. In some cases it was severe enough to lift the pilot
against his seat belt if he was slow in checking the motion. For this
reason a caution note was placed in most of the owner's manuals under
"Landings" reading "Slips should be avoided with flap settings greater
than 30° due to a downward pitch encountered under certain combinations
of airspeed, side-slip angle, and center of gravity loadings". Since
wing-low drift correction in cross-wind landings is normally performed
with a minimum flap setting (for better rudder control) this limitation
did not apply to that maneuver. The cause of the pitching motion is the
transition of a strong wing downwash over the tail in straight flight to
a lessened downwash angle over part of the horizontal tail caused by the
influence of a relative "upwash increment" from the upturned aileron in
slipping flight. Although not stated in the owner's manuals, we
privately encouraged flight instructors to explore these effects at high
altitude, and to pass on the information to their students. This
phenomenon was elusive and sometimes hard to duplicate, but it was
thought that a pilot should be aware of its existence and know how to
counter-act it if it occurs close to the ground.
When the larger dorsal fin was adopted in the 1972 C-172L, this side-
slip pitch phenomenon was eliminated, but the cautionary placard was
retained. In the higher-powered C-172P and C-R172 the placard was
applicable to a mild pitch "pumping" motion resulting from flap
outboard-end vortex impingement on the horizontal tail at some
combinations of side-slip angle, power, and airspeed."
--------------------------------------------------------------------
1959 C-172
Notice that this prohibition appears in Section III, Operating Details
of the C-172Owner's Manual and NOT in Section IV, Operating Limitations.
It is NOT an FAA limitation. Sounds more like "Lawyer" talk to me.

"LANDING
Normal landings are made power off with any flap setting. Slips are
prohibited in full flap approaches because of a downward pitch
encountered under certain combinations of airspeed and sideslip angle."
---------------------------------------------------------------------

I wear my "Slips with Flaps" T-Shirt proudly!

Bob Moore
12 years instructing in Skyhawks

--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

On Oct 16, 7:52 am, wrote:
On Oct 16, 12:43 am, Bertie the Bunyip wrote:



wrote in news:1192492570.300275.289550
@i38g2000prf.googlegroups.com:

On Oct 15, 8:49 am, Bertie the Bunyip wrote:

The examiner wouldn't allow him to slip because he reckons they are
dangerous with the flaps out and that he should wiggle the ailerons back
and forth to lose height. He didn't even want him to slip clean.

Jesus wept.

This examiner had had a fright in a 172 (this was an archer anyway) and
did not alow anyone to slip with flaps out.
While I am firmly in the camp that says some cessnas can get a litle
fuzzy in pitch with full flaps, this is just stupidity incarnate.

Shoot. We do slips with full flaps all the time in 172s, have
done so for years, and never had a scare. I wonder if that "Avoid
Slips With Flaps Extended" applied to some earlier models? I'll have
to check the TCDS sometime.

Dan

Dunno. the manual in a 172 makes reference to a possibility of degraded
elevator control, but I think it's only a bit of a nod, really.
The Bird dog suffers from this ailment big time, though. it has,
essentially, the 172's wing, but the flaps go to 60 degrees. I can tell you
first hand that blanking of both the rudder and elevator are a very real
characteristic of that airplane if you slip it ith full flaps. I did it
once close to the ground and never even thought about it again..

Here's what the Type Certificate Data Sheet says:
.................................................. ..................................

D. On flap handle, Models 172 through 172E

(1) "Flaps - Pull to extend
Takeoff Retract 0°
1st notch 10°
Landing 0° - 40°

(2) "Avoid slips with flaps down."

E. Near flap indicator Models 172F (electric flaps) through 17271034,
excluding 17270050)

"Avoid slips with flaps extended."
.................................................. ........................................

The applicable models, 172 through 172F, were built between
1956 and 1964 ('65 model?). There's no mention of the slip with flaps
thing for later models. I wonder if the addition of the back window
changed the airflow enough to keep the elevator flying?

Dan

Wait a minute. I just noticed something, and it's not clear
from the way Cessna put it on the TCDS. It says under "E" that the
avoid slips thing applies to the 172F through 17271034. That serial
number is the end of the 1978 172 N production, so the warning applies
to a lot more that I though it did. I hope nobody's gone out and hurt
themselves, now.
But we still slip with full flaps.

Dan