Matt Whiting > wrote in
:

> 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.
>

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.

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

Matt Whiting > wrote in
:

> 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 think that has more to do with the gradient along the cylinder as the
combustion chamber expands and the gasses cool. There's a lot more heat
produced up top, thus the intricate finning all over the head. In fact,
in the early days , it was improved casting techniques that alowed this
finning which in turn gave large horsepower boosts to the engines back
then. This was particulalry true in the 20s and thirties, but it still a
widely putsued goal today. the better the cooling, the more fire you can
make and the more fire..
I'll still hold to my original thoughts on it, though. I think the
difficulty in getting heat away from some parts as opposed to others
makes the temp gradient across the cylinder walls uneven in spots and
since I consider I've seen the proof of the pudding I can't shake the
habits of a lifetime as easily as al that!

>
> 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.

I'm not paranoid about it, I just don;t think it;s a myth.
>
> 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.
>


I agree and I don't subscribe to that stance in any way shape or form. I
was only picking a nit about shick cooling being a myth.
You have to do what you have to do in an airplane. You have to have some
respect for the engine, but you don;t have to go nuts!
UI mentioned earlier a place I worked did ab initio training in a J-3
(BTW, with no radios, starter or intercom) and, as you might imagine the
engine was up and down a lot.
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!


Oh, and the J-3? Last time I saw it it had over 4,000 hours on the
engine and hadn;t even had a top.
I think it;s stil flying, though hopefuly it's had a bit of work since
then. Poor old thing!


Bertie

> Oh, and the J-3? Last time I saw it it had over 4,000 hours on the
> engine and hadn;t even had a top.

Those things run forever. Of course, they've got no compression or
power to begin with, so you won't notice any further loss...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck > wrote in news:1192454721.367225.108920
@i13g2000prf.googlegroups.com:

>> Oh, and the J-3? Last time I saw it it had over 4,000 hours on the
>> engine and hadn;t even had a top.
>
> Those things run forever. Of course, they've got no compression or
> power to begin with, so you won't notice any further loss...
>
> ;-)

There wasn't any further loss. I did the compression checks on it myself
sometimes, and they were still in the 70s then. We rented it out and we
couldn;t have done that if it wasn't sound.
the rest of the airplane, however, was a bit of a mess!
Still it held together the whole time I flew it. Mostly.

Bertie

Bertie the Bunyip > wrote:
>You have to do what you have to do in an airplane. You have to
>have some respect for the engine, but you don;t have to go nuts!
>UI mentioned earlier a place I worked did ab initio training in a J-3
>(BTW, with no radios, starter or intercom) and, as you might
>imagine the engine was up and down a lot. 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.

That's the method my CFI used.

>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!

I'll bite (re the new thread)...

In an accident here last year, two pilots (CFI and a student) flying an
A-36 from a local airline-pilot factory came over the fence at around
120 and bounced after their initial touchdown. The CFI finally attempted
to take control (too late) without announcing the exchange of controls
while the student applied power (presumably for a go-round). The plane
veered off the runway at high speed, across the ramp, miraculously
missed tied-down planes in the first couple of rows and then slammed
into a V-tail Bo tied-down on the ramp, completely cutting it up w/the
prop, ripping the chains out of the ground, pushing it into the middle
of the rows, and destroying it. The two pilots were shaken but fine, and
the A-36 had substantial damage but nothing like the V-tail.

After the accident, their excessive over-the-fence speed was discussed,
and it was said that the school does not teach airspeeds during
approaches -- since the students are largely airline-bound individuals,
they teach "descent-rate". Much discussion ensued in the following weeks
about teaching the proper approach *for the airplane you're in at the
time* vs teaching airliner approaches in small, single-engine aircraft.

Your comment caused me to do some Googling. This had some in interesting
stats for a limited accident database.

archive.aya.org/safety/levyhibbler200207.pdf

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.

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.

Dan

Bertie:
> >> Oh, and the J-3? Last time I saw it it had over 4,000 hours on the
> >> engine and hadn;t even had a top.

Jay:
> > Those things run forever. Of course, they've got no compression or
> > power to begin with, so you won't notice any further loss...
> >
> > ;-)

Bertie:
> There wasn't any further loss. I did the compression checks on it myself
> sometimes, and they were still in the 70s then. We rented it out and we
> couldn;t have done that if it wasn't sound.
> the rest of the airplane, however, was a bit of a mess!
> Still it held together the whole time I flew it. Mostly.

How does that work with regard to the 100-hr and annual inspections for
a rental aircraft? When I worked at the flight school, our mechanics
said you can run an engine past TBO, but they won't sign off an annual
or 100-hr beyond the manufacturer's published TBO. Is signing it off
after TBO not a direct violation of mechanic regs but just a matter of
finding a mechanic willing to take the risk (ours wouldn't do it)?

Shirl > wrote in news:Xmnushal8y-
:

>
> I'll bite (re the new thread)...
>
> In an accident here last year, two pilots (CFI and a student) flying
an
> A-36 from a local airline-pilot factory came over the fence at around
> 120 and bounced after their initial touchdown. The CFI finally
attempted
> to take control (too late) without announcing the exchange of controls
> while the student applied power (presumably for a go-round). The plane
> veered off the runway at high speed, across the ramp, miraculously
> missed tied-down planes in the first couple of rows and then slammed
> into a V-tail Bo tied-down on the ramp, completely cutting it up w/the
> prop, ripping the chains out of the ground, pushing it into the middle
> of the rows, and destroying it. The two pilots were shaken but fine,
and
> the A-36 had substantial damage but nothing like the V-tail.
>
> After the accident, their excessive over-the-fence speed was
discussed,
> and it was said that the school does not teach airspeeds during
> approaches -- since the students are largely airline-bound
individuals,
> they teach "descent-rate". Much discussion ensued in the following
weeks
> about teaching the proper approach *for the airplane you're in at the
> time* vs teaching airliner approaches in small, single-engine
aircraft.
>
> Your comment caused me to do some Googling. This had some in
interesting
> stats for a limited accident database.
>
> archive.aya.org/safety/levyhibbler200207.pdf


Thank you!
And kudos to your instructor.

This is exactly the sort of crap I'm talking about. I fly lightplanes
and I also fly jets. I've flown five of your more poplualr sorts of jets
weighing anything up to 350,000 lbs.
they fly just like airplanes. The only tow things that are even half
true are the neccesisty for stabilised approaches, and even then you can
fudge it a bit, and the "kck it straight n a crosswind " thing. Which is
only the case for some airplanes and even then is widely misunderstood.
In the former instance, the main reason we get stabilised is because in
big swept wing airplanes, it can be hard to control the speed and rate
of descent fo ra couple of reasons. One, the swept wing has a very flat
drag curve, and two, the engines are sometimes slow to spool up (not so
much wiht newer engines) however, you can still do practice deadstick
landings all day in them if you want. They will do them, no problem. We
don't, though. however, n a light single, I think it's a very good idea
to at least keep it on the high side if nothing else and even better,
leave the final a deadstick every time. And yes, I've fown Bonanzas,
Commanches, all sorts. They are all better off doing approaches like
this, at least once you pass below the altitude where all other options
are closed off to you.
Even in light twins, guys tend to drag them in over the fence if the
field is anyways short. Completely unneccesary and very poor technique..

The "they don't put a wing down in a crosswind" thing is complete crap.
There are several jets you have to land wings level (and th ercoupe, of
course, shudder! ) and they are most of th efour engine thingies, the
727 and DC-9/MD80s
( very low wing and outboard flaps) and a couple of other for various
ground contact reasons.
However, corrct technique for this entails crossing the controls as you
would as if you had just done a slip to touchdown and maintaining it
though the landing roll. It feels awful when you do it first, but you
get the hang of it. If you land some of the long ones, like the 727 in a
max crosswind and the runway is narrow, you are acually out over the
edge of the runway as you touch down! You have to squeeze the nose
straight while it is still in the air whilst adding oppistie aileron.
Feels funny but works.
Everything else I've flown lands much better with a wing down and the
fuselage tracking straight down the runway. No question about it. In
fact the autoplit will cross the controls from about 300 feet down when
you're autolanding in most of them nowadays.


End rant.

Shirl > wrote in
:

> Bertie:
>> >> Oh, and the J-3? Last time I saw it it had over 4,000 hours on the
>> >> engine and hadn;t even had a top.
>
> Jay:
>> > Those things run forever. Of course, they've got no compression or
>> > power to begin with, so you won't notice any further loss...
>> >
>> > ;-)
>
> Bertie:
>> There wasn't any further loss. I did the compression checks on it
>> myself sometimes, and they were still in the 70s then. We rented it
>> out and we couldn;t have done that if it wasn't sound.
>> the rest of the airplane, however, was a bit of a mess!
>> Still it held together the whole time I flew it. Mostly.
>
> How does that work with regard to the 100-hr and annual inspections
> for a rental aircraft? When I worked at the flight school, our
> mechanics said you can run an engine past TBO, but they won't sign off
> an annual or 100-hr beyond the manufacturer's published TBO. Is
> signing it off after TBO not a direct violation of mechanic regs but
> just a matter of finding a mechanic willing to take the risk (ours
> wouldn't do it)?
>


Dunno nowadays. but then it was legal. I think it probably still is.
Our operation, though commercial, was part 91 and I'm not aware of any
changes in that rule.
Nowadays I'm only ever involved with club activity and that strictly on
condition. I'd tear down an antique engine every now and again myself,
though.They're too valuable to put a leg out of bed on.

Someone here will know for sure, though.

Interestingly, if you wanted to goto the boundaries of what's legal
commercailly, and someone will certainly correct me if I'm wrong, but
you could still buy an old OX-5, get a set of drawings and a dataplate
for something like a Waco9 or Alexander Eaglerock, build it, certify it
and then operate it out of a cow pasture with your commercial licence,
all legally. #

Oh yeah, no radio.

And why not?
If the operator knew what he was doing why not indeed?

Mind you , I'd get the OX-5 millerised first.


Bertie

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

On Oct 16, 11:25 am, Scott > wrote:
> 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.

Need to know how to do it for forced approaches. The stress
of an actual failure (I've had two) will make things difficult enough,
and slipping with flap might be the only way to get down soon enough
in the only field available.
I miss manual flaps. They were handy. You could dump them
right at touchdown and get weight on the mains for braking. Electric
flaps are so slow that they are passing through 20°, the max-lift/min
drag position, just when you want to brake, so it's better to leave
them alone. My old Auster had huge Zap flaps that lowered the stall by
a wide margin, and dumping them right at a minimum-speed touchdown
allowed full braking and stopping in unbelievably short spaces.

Dan

> wrote

I miss manual flaps. They were handy. You could dump them
right at touchdown and get weight on the mains for braking. Electric
flaps are so slow that they are passing through 20°, the max-lift/min
drag position, just when you want to brake, so it's better to leave
them alone. My old Auster had huge Zap flaps that lowered the stall by
a wide margin, and dumping them right at a minimum-speed touchdown
allowed full braking and stopping in unbelievably short spaces.

It would be nice if there was a manual release, something like the manual
release on an automatic garage door, then a spring and aerodynamic forces
could pull them back to "dumped."

Hey, something new to add to your design! <g>
--
Jim in NC

I think I would still use an agressive slip and then dump the full
flaps as close to touchdown as possible to be SURE you have the field
made. Of course, there will be a fly in the oitment if the forced
landing is due to smoke in the cockpit and you have those electric flaps...

$0.02 worth of free advice ;)

Scott

wrote:
> On Oct 16, 11:25 am, Scott > wrote:
>
>>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.
>
>
> Need to know how to do it for forced approaches. The stress
> of an actual failure (I've had two) will make things difficult enough,
> and slipping with flap might be the only way to get down soon enough
> in the only field available.
> I miss manual flaps. They were handy. You could dump them
> right at touchdown and get weight on the mains for braking. Electric
> flaps are so slow that they are passing through 20°, the max-lift/min
> drag position, just when you want to brake, so it's better to leave
> them alone. My old Auster had huge Zap flaps that lowered the stall by
> a wide margin, and dumping them right at a minimum-speed touchdown
> allowed full braking and stopping in unbelievably short spaces.
>
> Dan
>

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

Of course, that system would lead to dumps on short final at about 50
feet up on a nice day under other than emergency conditions (except for
the one just created)...

Scott


Morgans wrote:

> > wrote
>
> I miss manual flaps. They were handy. You could dump them
> right at touchdown and get weight on the mains for braking. Electric
> flaps are so slow that they are passing through 20°, the max-lift/min
> drag position, just when you want to brake, so it's better to leave
> them alone. My old Auster had huge Zap flaps that lowered the stall by
> a wide margin, and dumping them right at a minimum-speed touchdown
> allowed full braking and stopping in unbelievably short spaces.
>
> It would be nice if there was a manual release, something like the manual
> release on an automatic garage door, then a spring and aerodynamic forces
> could pull them back to "dumped."
>
> Hey, something new to add to your design! <g>

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

Ernest Christley wrote:
> 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.

The heat doesn't come from the air, but from the fuel.

Matt

Bertie the Bunyip wrote:
> 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, he thinks the heat comes from the air so trying to explain an
acetylene torch will be a real challenge! :-)

Matt

Steve Hix wrote:

> 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.

Got to love those urban legends!

Matt

"Bob Moore" > wrote in message
46.128...
> 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

great stuff snipped...


>
> I wear my "Slips with Flaps" T-Shirt proudly!
>
> Bob Moore
> 12 years instructing in Skyhawks



Thanks Bob.

Al G, 30 years instructing in Skyhawks

Matt Whiting > wrote in
:

> Bertie the Bunyip wrote:
>> 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, he thinks the heat comes from the air so trying to explain an
> acetylene torch will be a real challenge! :-)
>

Mm, possibly..

but to be fair it is partly the air !

Bertie

"Bertie the Bunyip" > wrote

> but to be fair it is partly the air !

Only if you consider the oxy in the tank, as air.
--
Jim in NC

Ernest Christley > wrote in
:

> Matt Whiting wrote:
>> Ernest Christley wrote:
>>> 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.
>>
>> The heat doesn't come from the air, but from the fuel.
>>
>> Matt
>
> - Heat comes from the reaction of the fuel vapors with the oxygen in
> the air.
> - Once the fuel is vaporized, isn't it also part of the air.
>
> Semantics aside, the point is, you have a limited amount of BTU
> available from the fuel-air mixture. Since some of those BTU's are
> carried away even as the engine is warming up, the heating will be
> gradual. It will heat until a dynamic equilibrium is reached between
> the heat from combustion and the cooling from air flow. Hopefully at
> 350 degrees F or less.
>
> Pull the heating part of the equation out, and all you have is
> cooling.
> All the air around you is a really large heat sink to dump into.
> Push
> that engine through the air at 100mph, and the heat will come out
> FAST!!
>
> When you cut the power, you cut the heat, but the pistons are still
> moving. The cylinders cool quickly. They're exposed to the air, and
> have lots of vanes designed to give up that heat. The piston is
> insulated...by the cylinder, coatings of oil, etc. The cylinder
> shrinks, clamps the moving piston, and parts give up shortly
> thereafter.
> I'm not brave/fool (you pick) enough to test this, but the engine
> might never crack if you stopped the windmilling when you chop the
> power.
>
> Your welding torch example is not germane.


You have to pump pure
> oxygen into an acetylene flame to get welding temps. Acetylene gives
> up more BTUs that gasoline, and it won't work with normal atmosphere
> which is mostly nitrogen. You won't ever be able to reach the 6000
> degree max temp of a welding flame inside a normal combustion engine.
> Even then, try to weld a dirty piece of metal sometime. Even the
> thinnest coat of crud is enough to insulate the metal enough to make
> welding a frustrating experience.




That's beside the point.


Bertie
>

"Bob Moore" wrote in message...
> I wear my "Slips with Flaps" T-Shirt proudly!
>

Mine's totally worn out, even though I only wore it to fly-in events. I
wonder if Tina will ever resurface and run another batch???

In article >,
Matt Whiting > wrote:

> Steve Hix wrote:
>
> > 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.
>
> Got to love those urban legends!

I was sitting at the FBO front desk when Lynn and Fred went out to see
what would happen, and was there when they returned about a half hour
later.

They told me then what had happened, and agreed that they weren't
inclined to try it again with our 172. They weren't sufficiently
interested to see if it was affected one way or another by changing
payload, CG location, etc.

Not an urban legend, sorry if that disappoints you.

Matt Whiting wrote:
> 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

Shock cooling damage is merely the effect of different rates of thermal
dimensional change between the aluminum cylinder head and the steel
valve seats and possibly between the head and the barrel where its
threaded on. When contracting, the head shrinks faster than the valve
seats and barrel and huge tension stresses are built up in the area of
the head between the valve and the nearest hole, which is usually the
spark plug. Most shock cooling damage is a crack between the exhaust
valve and the nearest plug hole.

It's not a problem when heating because the head expands faster than the
steel parts so the stress effects are reversed. This is why the
manufacturers have no problem with going from idle to full power as soon
as the engine will take it without stumbling. There is no such thing as
shock heating...

Shock cooling is generally a problem when at the extremes, going from
full power to idle. You won't get enough stress to cause damage going
from cruise power to idle, so for airplanes not used for towing, or
aerobatics or some flight training scenarios, it's not a problem.

John

"J.Kahn" > wrote in
:

> Matt Whiting wrote:
>> 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
>
> Shock cooling damage is merely the effect of different rates of
> thermal dimensional change between the aluminum cylinder head and the
> steel valve seats and possibly between the head and the barrel where
> its threaded on. When contracting, the head shrinks faster than the
> valve seats and barrel and huge tension stresses are built up in the
> area of the head between the valve and the nearest hole, which is
> usually the spark plug. Most shock cooling damage is a crack between
> the exhaust valve and the nearest plug hole.
>
> It's not a problem when heating because the head expands faster than
> the steel parts so the stress effects are reversed. This is why the
> manufacturers have no problem with going from idle to full power as
> soon as the engine will take it without stumbling. There is no such
> thing as shock heating...
>
> Shock cooling is generally a problem when at the extremes, going from
> full power to idle. You won't get enough stress to cause damage
> going from cruise power to idle, so for airplanes not used for towing,
> or aerobatics or some flight training scenarios, it's not a problem.
>


I can buy that..

Bertie
>

"J.Kahn" > wrote

> Shock cooling damage is merely the effect of different rates of thermal
> dimensional change between the aluminum cylinder head and the steel valve
> seats and possibly between the head and the barrel where its threaded on.
> When contracting, the head shrinks faster than the valve seats and barrel
> and huge tension stresses are built up in the area of the head between the
> valve and the nearest hole, which is usually the spark plug. Most shock
> cooling damage is a crack between the exhaust valve and the nearest plug
> hole.
>
> It's not a problem when heating because the head expands faster than the
> steel parts so the stress effects are reversed. This is why the
> manufacturers have no problem with going from idle to full power as soon
> as the engine will take it without stumbling. There is no such thing as
> shock heating...
>
> Shock cooling is generally a problem when at the extremes, going from full
> power to idle. You won't get enough stress to cause damage going from
> cruise power to idle, so for airplanes not used for towing, or aerobatics
> or some flight training scenarios, it's not a problem.

Yours is the first explanation that I can believe. Thanks.

I can also believe that cruise power to idle is not a huge problem, and that
perhaps it is even more true if the airspeed is kept down a bit, while the
power comes off.
--
Jim in NC

Steve Hix wrote:
> In article >,
> Matt Whiting > wrote:
>
>> Steve Hix wrote:
>>
>>> 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.
>> Got to love those urban legends!
>
> I was sitting at the FBO front desk when Lynn and Fred went out to see
> what would happen, and was there when they returned about a half hour
> later.
>
> They told me then what had happened, and agreed that they weren't
> inclined to try it again with our 172. They weren't sufficiently
> interested to see if it was affected one way or another by changing
> payload, CG location, etc.
>
> Not an urban legend, sorry if that disappoints you.

I don't for a second believe that a slip with flaps turned them over. I
suspect they STALLED it and went inverted, but that wasn't due to a slip
with flaps.

Matt

J.Kahn wrote:

> It's not a problem when heating because the head expands faster than the
> steel parts so the stress effects are reversed. This is why the
> manufacturers have no problem with going from idle to full power as soon
> as the engine will take it without stumbling. There is no such thing as
> shock heating...

What about the aluminum piston in the steel cylinder?

Matt

In article >,
Matt Whiting > wrote:

> Steve Hix wrote:
> > In article >,
> > Matt Whiting > wrote:
> >
> >> Steve Hix wrote:
> >>
> >>> 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.
> >> Got to love those urban legends!
> >
> > I was sitting at the FBO front desk when Lynn and Fred went out to see
> > what would happen, and was there when they returned about a half hour
> > later.
> >
> > They told me then what had happened, and agreed that they weren't
> > inclined to try it again with our 172. They weren't sufficiently
> > interested to see if it was affected one way or another by changing
> > payload, CG location, etc.
> >
> > Not an urban legend, sorry if that disappoints you.
>
> I don't for a second believe that a slip with flaps turned them over. I
> suspect they STALLED it and went inverted, but that wasn't due to a slip
> with flaps.

Kewl. Believe whatever floats your boat.

They were both experienced CFIs, one with a good deal of A-26 and T-28
time. If they'd stalled it, I would think they'd said so.

Steve Hix wrote:
> In article >,
> Matt Whiting > wrote:
>
>
>>Steve Hix wrote:
>>
>>>In article >,
>>> Matt Whiting > wrote:
>>>
>>>
>>>>Steve Hix wrote:
>>>>
>>>>
>>>>>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.
>>>>
>>>>Got to love those urban legends!
>>>
>>>I was sitting at the FBO front desk when Lynn and Fred went out to see
>>>what would happen, and was there when they returned about a half hour
>>>later.
>>>
>>>They told me then what had happened, and agreed that they weren't
>>>inclined to try it again with our 172. They weren't sufficiently
>>>interested to see if it was affected one way or another by changing
>>>payload, CG location, etc.
>>>
>>>Not an urban legend, sorry if that disappoints you.
>>
>>I don't for a second believe that a slip with flaps turned them over. I
>>suspect they STALLED it and went inverted, but that wasn't due to a slip
>>with flaps.
>
>
> Kewl. Believe whatever floats your boat.
>
> They were both experienced CFIs, one with a good deal of A-26 and T-28
> time. If they'd stalled it, I would think they'd said so.

It did not go inverted from slipping with flaps.

Matt Whiting > wrote in
:

> J.Kahn wrote:
>
>> It's not a problem when heating because the head expands faster than
>> the steel parts so the stress effects are reversed. This is why the
>> manufacturers have no problem with going from idle to full power as
>> soon as the engine will take it without stumbling. There is no such
>> thing as shock heating...
>
> What about the aluminum piston in the steel cylinder?
>

That can happen too! But the clearances are cgrater ther than it would be
in a valve stem or head to cylinder seat.

Bertie

Steve Hix wrote:
> In article >,
> Matt Whiting > wrote:
>
>> Steve Hix wrote:
>>> In article >,
>>> Matt Whiting > wrote:
>>>
>>>> Steve Hix wrote:
>>>>
>>>>> 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.
>>>> Got to love those urban legends!
>>> I was sitting at the FBO front desk when Lynn and Fred went out to see
>>> what would happen, and was there when they returned about a half hour
>>> later.
>>>
>>> They told me then what had happened, and agreed that they weren't
>>> inclined to try it again with our 172. They weren't sufficiently
>>> interested to see if it was affected one way or another by changing
>>> payload, CG location, etc.
>>>
>>> Not an urban legend, sorry if that disappoints you.
>> I don't for a second believe that a slip with flaps turned them over. I
>> suspect they STALLED it and went inverted, but that wasn't due to a slip
>> with flaps.
>
> Kewl. Believe whatever floats your boat.
>
> They were both experienced CFIs, one with a good deal of A-26 and T-28
> time. If they'd stalled it, I would think they'd said so.

Likewise, believe all of the urban legends you want.

Matt

On Fri, 19 Oct 2007 11:05:32 +0000 (UTC), Bertie the Bunyip >
wrote:

>Matt Whiting > wrote in
:
>
>> J.Kahn wrote:
>>
>>> It's not a problem when heating because the head expands faster than
>>> the steel parts so the stress effects are reversed. This is why the
>>> manufacturers have no problem with going from idle to full power as
>>> soon as the engine will take it without stumbling. There is no such
>>> thing as shock heating...
>>
>> What about the aluminum piston in the steel cylinder?
>>
>
>That can happen too! But the clearances are cgrater ther than it would be
>in a valve stem or head to cylinder seat.

If we had that kind of piston to cylinder clearance in an automotive
engine we'd think it was worn out. <:-)) At least in the "old days".

Roger (K8RI)

>
>Bertie

"Roger (K8RI)" > wrote in
:

> On Fri, 19 Oct 2007 11:05:32 +0000 (UTC), Bertie the Bunyip >
> wrote:
>
>>Matt Whiting > wrote in
:
>>
>>> J.Kahn wrote:
>>>
>>>> It's not a problem when heating because the head expands faster
>>>> than the steel parts so the stress effects are reversed. This is
>>>> why the manufacturers have no problem with going from idle to full
>>>> power as soon as the engine will take it without stumbling. There
>>>> is no such thing as shock heating...
>>>
>>> What about the aluminum piston in the steel cylinder?
>>>
>>
>>That can happen too! But the clearances are cgrater ther than it would
>>be in a valve stem or head to cylinder seat.
>
> If we had that kind of piston to cylinder clearance in an automotive
> engine we'd think it was worn out. <:-)) At least in the "old days".
>


Yes, some air cooled engines have tapered bores (when cold) to allow for
different rates of expansion in cylinder base-to-head so that it's
perfectly cylindrical when up to temp, but i don't know of any aircraft
engines that have that feature.



Bertie

Steve Hix wrote:
>
> Kewl. Believe whatever floats your boat.
>
> They were both experienced CFIs, one with a good deal of A-26 and T-28
> time. If they'd stalled it, I would think they'd said so.


Why belabor the painfully obvious?

In article >,
Matt Whiting > wrote:

> Steve Hix wrote:
> > In article >,
> > Matt Whiting > wrote:
> >
> >> Steve Hix wrote:
> >>> In article >,
> >>> Matt Whiting > wrote:
> >>>
> >>>> Steve Hix wrote:
> >>>>
> >>>>> 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.
> >>>> Got to love those urban legends!
> >>> I was sitting at the FBO front desk when Lynn and Fred went out to see
> >>> what would happen, and was there when they returned about a half hour
> >>> later.
> >>>
> >>> They told me then what had happened, and agreed that they weren't
> >>> inclined to try it again with our 172. They weren't sufficiently
> >>> interested to see if it was affected one way or another by changing
> >>> payload, CG location, etc.
> >>>
> >>> Not an urban legend, sorry if that disappoints you.
> >> I don't for a second believe that a slip with flaps turned them over.

On second take, agreed.

> >> I suspect they STALLED it and went inverted, but that wasn't due to a slip
> >> with flaps.

Or a stall, alone.

On first pass, I read it as either/or, rather than combination.

> > Kewl. Believe whatever floats your boat.
> >
> > They were both experienced CFIs, one with a good deal of A-26 and T-28
> > time. If they'd stalled it, I would think they'd said so.
>
> Likewise, believe all of the urban legends you want.

Look, it was 30+ years ago. I was barely paying attention at the time,
and not knowing where either are today, I can't very well ask them for
more information.

Did whatever happen result solely from slipping with full flaps? I
really doubt it, unless they were at some extreme weight/CG limit (both
of them being average size, probably not).

So yeah, they likely did something else at the time that carried things
further. Stall alone? Doubt it. Slip with full flaps alone. Doubt it.

I still wouldn't want to play with something against which the aircraft
is placarded, not without a lot of cushion.

As for urban legend, you looking at the wrong guy. Spent too much time
studying physics/chemistry, and working in systems engineering for that.
(And doubly skeptical of conspiracy nonsense.)

And I apologize for blowing you off earlier; it's been a series of bad
months at work (I avoided the layoff, not everyone else in the group
did), and working 6 1/2 day weeks for 10 to 14 hrs/day for the last
month hasn't helped. Mea culpa.

Meanwhile, in Dec. I take off for what's going to turn out to be the
better part of four weeks vacation (else I start losing what's
accumulated), and after 31 years, get back into flying.

I may end up being civil by then.

"Bertie the Bunyip" > wrote

> Yes, some air cooled engines have tapered bores (when cold) to allow for
> different rates of expansion in cylinder base-to-head so that it's
> perfectly cylindrical when up to temp, but i don't know of any aircraft
> engines that have that feature.

Really? I thought that they did have a tighter bore at the top. I guess I
read wrong, or remember wrong.
--
Jim in NC

"Morgans" > wrote in
:

>
> "Bertie the Bunyip" > wrote
>
>> Yes, some air cooled engines have tapered bores (when cold) to allow
>> for different rates of expansion in cylinder base-to-head so that
>> it's perfectly cylindrical when up to temp, but i don't know of any
>> aircraft engines that have that feature.
>
> Really? I thought that they did have a tighter bore at the top. I
> guess I read wrong, or remember wrong.

Maybe. I didn't know that they did. It would make sense if they did, all
right. I don't do machining. I just run my fingers over the pretty parts
when they come out of the machine shop!

Bertie

Steve Hix wrote:

> And I apologize for blowing you off earlier; it's been a series of bad
> months at work (I avoided the layoff, not everyone else in the group
> did), and working 6 1/2 day weeks for 10 to 14 hrs/day for the last
> month hasn't helped. Mea culpa.
>
> Meanwhile, in Dec. I take off for what's going to turn out to be the
> better part of four weeks vacation (else I start losing what's
> accumulated), and after 31 years, get back into flying.
>
> I may end up being civil by then.

Steve, don't sweat it. I enjoy a good debate and rarely take offense at
anything and certainly took no offense at your comments as they were
quite civil.

Cheers,
Matt

>>> Yes, some air cooled engines have tapered bores (when cold) to allow
>>> for different rates of expansion in cylinder base-to-head so that
>>> it's perfectly cylindrical when up to temp, but i don't know of any
>>> aircraft engines that have that feature.
>>
>> Really? I thought that they did have a tighter bore at the top. I
>> guess I read wrong, or remember wrong.
>
> Maybe. I didn't know that they did. It would make sense if they did, all
> right. I don't do machining. I just run my fingers over the pretty parts
> when they come out of the machine shop!

This ought to be an easy question for someone in the group. Surely, there
is someone that does do machining on engines that hangs out here, that would
know for sure.

Anyone?
--
Jim in NC

On Oct 20, 4:41 am, "Morgans" > wrote:
> >>> Yes, some air cooled engines have tapered bores (when cold) to allow
> >>> for different rates of expansion in cylinder base-to-head so that
> >>> it's perfectly cylindrical when up to temp, but i don't know of any
> >>> aircraft engines that have that feature.
>
> >> Really? I thought that they did have a tighter bore at the top. I
> >> guess I read wrong, or remember wrong.
>
> > Maybe. I didn't know that they did. It would make sense if they did, all
> > right. I don't do machining. I just run my fingers over the pretty parts
> > when they come out of the machine shop!
>
> This ought to be an easy question for someone in the group. Surely, there
> is someone that does do machining on engines that hangs out here, that would
> know for sure.
>
> Anyone?
> --
> Jim in NC

Ok, First off don't call me Surely. <GGGG>.
The concept is question is called "choke bore" and the idea is the
bottom of the cylinder that's close to the case runs at a much lower
temp since combustion happens at the other end. The top end grows at a
greater rate because of this. In theory when the engine is up to temp
the cylinder ends up being pretty straight. I have the specs around
here somewhere but if I remember correctly the bore when cold is in
the .006-.008 smaller at the top. Boring one is usually done by using
a tool post grinder and performing the taper feature is a calculated
process. Honing one with a flex hone is straight forward and easy,
using a Sunnen CK-10 or a CV-616 takes ALOT more practice...

Ben
www.haaspowerair.com

" > wrote in
ups.com:

> On Oct 20, 4:41 am, "Morgans" > wrote:
>> >>> Yes, some air cooled engines have tapered bores (when cold) to
>> >>> allow for different rates of expansion in cylinder base-to-head
>> >>> so that it's perfectly cylindrical when up to temp, but i don't
>> >>> know of any aircraft engines that have that feature.
>>
>> >> Really? I thought that they did have a tighter bore at the top.
>> >> I guess I read wrong, or remember wrong.
>>
>> > Maybe. I didn't know that they did. It would make sense if they
>> > did, all right. I don't do machining. I just run my fingers over
>> > the pretty parts when they come out of the machine shop!
>>
>> This ought to be an easy question for someone in the group. Surely,
>> there is someone that does do machining on engines that hangs out
>> here, that would know for sure.
>>
>> Anyone?
>> --
>> Jim in NC
>
> Ok, First off don't call me Surely. <GGGG>.
> The concept is question is called "choke bore" and the idea is the
> bottom of the cylinder that's close to the case runs at a much lower
> temp since combustion happens at the other end. The top end grows at a
> greater rate because of this. In theory when the engine is up to temp
> the cylinder ends up being pretty straight. I have the specs around
> here somewhere but if I remember correctly the bore when cold is in
> the .006-.008 smaller at the top. Boring one is usually done by using
> a tool post grinder and performing the taper feature is a calculated
> process. Honing one with a flex hone is straight forward and easy,
> using a Sunnen CK-10 or a CV-616 takes ALOT more practice...

And I thought it was just my old model airplane engines and bikes that
had that feature. Who would have guessed a Lycoming could clamber to the
height of sophistication reached by Ohlsson and Rice?

Bertie
>

On Sat, 20 Oct 2007 12:31:57 +0000 (UTC), Bertie the Bunyip >
wrote:

snip

>And I thought it was just my old model airplane engines and bikes that
>had that feature. Who would have guessed a Lycoming could clamber to the
>height of sophistication reached by Ohlsson and Rice?
>
>Bertie

Been awhile since Continental spec'ed a choke bore, unsure if Lycoming
ever did (I've never come across one-does not mean it does not exist).

What is curious is that on the Conti's you could "straighten out" the
choke and be within service limits in most cases.

Factory new Lycoming cylinders can tend to be a little smaller at the
upper 1/4 of the bore, but that's because the head gets shrunk onto
the cylinder after it is initially machined & nitrided. Sorta
important to check min. ring gap up there when working with a new jug.

Again, it can be a straight bore and be within new & service limits.

TC

wrote in news:ec1lh3tqmfri1006j5c5nqsbho0g0mnidi@
4ax.com:

> On Sat, 20 Oct 2007 12:31:57 +0000 (UTC), Bertie the Bunyip >
> wrote:
>
> snip
>
>>And I thought it was just my old model airplane engines and bikes that
>>had that feature. Who would have guessed a Lycoming could clamber to the
>>height of sophistication reached by Ohlsson and Rice?
>>
>>Bertie
>
> Been awhile since Continental spec'ed a choke bore, unsure if Lycoming
> ever did (I've never come across one-does not mean it does not exist).
>
> What is curious is that on the Conti's you could "straighten out" the
> choke and be within service limits in most cases.
>
> Factory new Lycoming cylinders can tend to be a little smaller at the
> upper 1/4 of the bore, but that's because the head gets shrunk onto
> the cylinder after it is initially machined & nitrided. Sorta
> important to check min. ring gap up there when working with a new jug.
>
> Again, it can be a straight bore and be within new & service limits
>


Learn sumpin new every day!

Bertie
>

> wrote in message
ups.com...
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

I believe that the advice against slips with (full) flaps ended when the
maximum flap extension changed from 40 to 30 degrees.

On the very early swept tail 172 (1959 model, IIRC) that I had some time in,
a slip with full flaps resulted in a buffet--but I don't recall that being
done with aft CG at any time that I was aboard.

Peter

"Scott" > wrote in message
.. .
> Of course, that system would lead to dumps on short final at about 50 feet
> up on a nice day under other than emergency conditions (except for the one
> just created)...
>
> Scott
>
There really is a big difference between dumping the flaps, and bringing
them quickly back to the point of greatest lift relative to added
drag--usually around 20 degrees. I've had instructors who insisted on
milking the flaps off, despite the contrary advice in the POH.

Peter

"Peter Dohm" > wrote in
:

>
> "Scott" > wrote in message
> .. .
>> Of course, that system would lead to dumps on short final at about 50
>> feet up on a nice day under other than emergency conditions (except
>> for the one just created)...
>>
>> Scott
>>
> There really is a big difference between dumping the flaps, and
> bringing them quickly back to the point of greatest lift relative to
> added drag--usually around 20 degrees. I've had instructors who
> insisted on milking the flaps off, despite the contrary advice in the
> POH.
>


Well, ultimately you will get the best rate of climb clean after you have
reached best limb speed, of course, but it's not al that significant at the
begining unless you have a big obstacle problem off in the distance, so
you're right, best flap position is usually around 20 or 15 or whatever is
handy!


Bertie

Ï "Bertie the Bunyip" > Ýãñáøå óôï ìÞíõìá
...
>
> Well, ultimately you will get the best rate of climb clean after you have
> reached best limb speed, of course, but it's not al that significant at
> the
> begining unless you have a big obstacle problem off in the distance, so
> you're right, best flap position is usually around 20 or 15 or whatever is
> handy! >
>
> Bertie


An old rule-of-thumb I remember has it that aligning the flap with a down
aileron gives you the best (most lift) flap position (assuming, i presume,
that the ailerons deflect to maximum effectiveness=lift).
FWIW, G.

"gpaleo" > wrote in
news:1192979491.466999@athprx03:

> Ï "Bertie the Bunyip" > Ýãñáøå óôï ìÞíõìá
> ...
>>
>> Well, ultimately you will get the best rate of climb clean after you
>> have reached best limb speed, of course, but it's not al that
>> significant at the
>> begining unless you have a big obstacle problem off in the distance,
>> so you're right, best flap position is usually around 20 or 15 or
>> whatever is handy! >
>>
>> Bertie
>
>
> An old rule-of-thumb I remember has it that aligning the flap with a
> down aileron gives you the best (most lift) flap position (assuming, i
> presume, that the ailerons deflect to maximum effectiveness=lift)

Never heard it but it sounds like a good bush piloty sort of thing to do.




Bertie
>
>

On Oct 21, 7:56 pm, Bertie the Bunyip > wrote:
> "gpaleo" > wrote innews:1192979491.466999@athprx03:
>
>
>
>
>
> > Ï "Bertie the Bunyip" > Ýãñáøå óôï ìÞíõìá
> ...
>
> >> Well, ultimately you will get the best rate of climb clean after you
> >> have reached best limb speed, of course, but it's not al that
> >> significant at the
> >> begining unless you have a big obstacle problem off in the distance,
> >> so you're right, best flap position is usually around 20 or 15 or
> >> whatever is handy! >
>
> >> Bertie
>
> > An old rule-of-thumb I remember has it that aligning the flap with a
> > down aileron gives you the best (most lift) flap position (assuming, i
> > presume, that the ailerons deflect to maximum effectiveness=lift)
>
> Never heard it but it sounds like a good bush piloty sort of thing to do.
>
> Bertie
>
>
>
> - Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -

Hence the reason why some of us fly planes that have flaperons instead
of flaps/ailerons..

" > wrote in
oups.com:

> On Oct 21, 7:56 pm, Bertie the Bunyip > wrote:
>> "gpaleo" > wrote
>> innews:1192979491.466999@athprx03:
>>
>>
>>
>>
>>
>> > Ï "Bertie the Bunyip" > Ýãñáøå óôï ìÞ
> íõìá
>> ...
>>
>> >> Well, ultimately you will get the best rate of climb clean after
>> >> you have reached best limb speed, of course, but it's not al that
>> >> significant at the
>> >> begining unless you have a big obstacle problem off in the
>> >> distance, so you're right, best flap position is usually around 20
>> >> or 15 or whatever is handy! >
>>
>> >> Bertie
>>
>> > An old rule-of-thumb I remember has it that aligning the flap with
>> > a down aileron gives you the best (most lift) flap position
>> > (assuming, i presume, that the ailerons deflect to maximum
>> > effectiveness=lift)
>>
>> Never heard it but it sounds like a good bush piloty sort of thing to
>> do.
>>
>> Bertie
>>
>>
>>
>> - Hide quoted text -
>>
>> - Show quoted text -- Hide quoted text -
>>
>> - Show quoted text -
>
> Hence the reason why some of us fly planes that have flaperons instead
> of flaps/ailerons..
>
>


Eh,OK.

Bertie

Bertie

Did you read "Nobody believed that we walked away" that I posted about
Bud Warrens crash near here in Houston?

I probably should have used a different title but that is how the
newspaper article in paper was headed.

Good Pilot and very lucky.

Big John

In article >,
Bertie the Bunyip > wrote:

> > An old rule-of-thumb I remember has it that aligning the flap with a
> > down aileron gives you the best (most lift) flap position (assuming, i
> > presume, that the ailerons deflect to maximum effectiveness=lift)
>
> Never heard it but it sounds like a good bush piloty sort of thing to do.

My flight instructor, a former drug-smuggler, taught me that very
technique.

Dan Nafe wrote:

> In article >,
> Bertie the Bunyip > wrote:
>
>
>>>An old rule-of-thumb I remember has it that aligning the flap with a
>>>down aileron gives you the best (most lift) flap position (assuming, i
>>>presume, that the ailerons deflect to maximum effectiveness=lift)
>>
>>Never heard it but it sounds like a good bush piloty sort of thing to do.
>
>
> My flight instructor, a former drug-smuggler, taught me that very
> technique.


The most lift is always gained with the most flaps.

"Newps" > wrote in message
. ..
>
>
> Dan Nafe wrote:
>
>> In article >,
>> Bertie the Bunyip > wrote:
>>
>>
>>>>An old rule-of-thumb I remember has it that aligning the flap with a
>>>>down aileron gives you the best (most lift) flap position (assuming, i
>>>>presume, that the ailerons deflect to maximum effectiveness=lift)
>>>
>>>Never heard it but it sounds like a good bush piloty sort of thing to do.
>>
>>
>> My flight instructor, a former drug-smuggler, taught me that very
>> technique.
>
>
> The most lift is always gained with the most flaps.

I try to shy away from the use of the word "always". There are some
aircraft that use flaps for their induced drag. An example is a glider with
large span 90 degree flaps. As an owner of such a craft I can testify that
increased lift is not associated with flap setting greater then 40 degrees.
Setting beyond 45 definitely exist only for the drag they create.
(http://tinyurl.com/2w6fuk)

Wayne
HP-14 "6F"
http://www.soaridaho.com/Schreder

In article >,
Newps > wrote:

> Dan Nafe wrote:
>
> > In article >,
> > Bertie the Bunyip > wrote:
> >
> >
> >>>An old rule-of-thumb I remember has it that aligning the flap with a
> >>>down aileron gives you the best (most lift) flap position (assuming, i
> >>>presume, that the ailerons deflect to maximum effectiveness=lift)
> >>
> >>Never heard it but it sounds like a good bush piloty sort of thing to do.
> >
> >
> > My flight instructor, a former drug-smuggler, taught me that very
> > technique.
>
>
> The most lift is always gained with the most flaps.

Really?

Even if true, you sometimes end up picking up drag faster than increased
lift at extreme flap settings, depending on the aircraft.

Steve Hix wrote:


>>The most lift is always gained with the most flaps.
>
>
> Really?
>
> Even if true, you sometimes end up picking up drag faster than increased
> lift at extreme flap settings, depending on the aircraft.


On your typical Cessna 152, 172, 182 206, etc the most lift for the
least drag is approx 20 degrees. Flaps at 40 degrees gives you the most
lift but also more drag than at 20 degrees. Just depends on what you're
trying to accomplish. The first 20 years of Bonanza production there
wasn't a flap indicator in the aircraft, don't have one in mine. The
factory put a stripe that you could line up with the trailing edge of
the wing to get 20 degrees. Those disappear with the first paint job.

On Mon, 05 Nov 2007 16:53:42 -0700, Newps > wrote:

>
>
>Steve Hix wrote:
>
>
>>>The most lift is always gained with the most flaps.
>>
>>
>> Really?
>>
>> Even if true, you sometimes end up picking up drag faster than increased
>> lift at extreme flap settings, depending on the aircraft.
>
>
>On your typical Cessna 152, 172, 182 206, etc the most lift for the
>least drag is approx 20 degrees. Flaps at 40 degrees gives you the most
>lift but also more drag than at 20 degrees. Just depends on what you're
>trying to accomplish. The first 20 years of Bonanza production there
>wasn't a flap indicator in the aircraft, don't have one in mine. The


One thousand one...Onethousand two...onethousand threee...
Who needs marks or indicators?

Roger (K8RI)

>factory put a stripe that you could line up with the trailing edge of
>the wing to get 20 degrees. Those disappear with the first paint job.

> factory put a stripe that you could line up with the trailing edge of
> the wing to get 20 degrees. Those disappear with the first paint job.

I'll bet there's a Gummint regulation that sez you can't hide that stripe.
:)

Rich S.

In article >,
"Rich S." > wrote:

> > factory put a stripe that you could line up with the trailing edge of
> > the wing to get 20 degrees. Those disappear with the first paint job.
>
> I'll bet there's a Gummint regulation that sez you can't hide that stripe.
> :)
>
> Rich S.
>
>

I re-marked mine with a Sharpie.