Engine out practice

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



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