Prop to High RPM on downwind

On 21 Nov 2004 20:04:44 -0600, Andrew Sarangan
wrote:

Do you do a final gear check on final?
Yes
If so, then how much extra work
is it to push the prop to forward on final?
For my philosophy the final check, should be just that - only a check,
no work unless an error has occurred. Subtle I'm sure, but the less
"work" on short final the better IMO.

This will only become an
issue if you are performing a go-around *and* you forget to push the
prop forward. Even if you forget the prop on final, I don't see how you
can forget it again on a go-around. The go-around procedure calls for
everything forward, and you will catch it if the prop is out.
If in your mind you think you pushed it forward you'll probably
realize it isn't only after the throttle has been pushed full forward.
(I know not an absolute, but more likely than not for an average
person). If it does happen you'll be way "over square" and
potentially do alot of engine damage. Not withstanding the damage
potential, you could get alarmed by the condition, fixate on
rectifying it, and relax the pitch control. In heavier airplanes you
could get enough of a pitch up that it's hard for a person to recover.
I'm not being sexist, but I had this happen to a woman I was flying
with, lets just say it was a good learning experience for her. g
This was in a 172RG so heavy is a relative term.


Going prop forward after the governor has hit the limit is a good
practice. It makes less noise, and it demonstrates that you are smooth
at the controls.
Now i"m confused. It seems like we agree. I may not have been clear,
or may have missed something, but this is what I meant when I said to
go full forward after throttle reduction.

z

zatatime wrote in message . ..
On 21 Nov 2004 20:04:44 -0600, Andrew Sarangan
wrote:


Going prop forward after the governor has hit the limit is a good
practice. It makes less noise, and it demonstrates that you are smooth
at the controls.
Now i"m confused. It seems like we agree. I may not have been clear,
or may have missed something, but this is what I meant when I said to
go full forward after throttle reduction.



I was not specifically responding to your comment. It was in response
to the original poster who wanted to bring the prop forward on
downwind prior to power reduction. Whether the prop is brought forward
at downwind, base or final is not important as long as it is done
after power reduction. Earlier the better I suppose. On a VFR traffic
pattern, I bring the prop forward after power reduction just as I am
turning base. On an instrument approach, I would do that after the
power reduction at the final approach fix.

"zatatime" wrote in message
...
On 21 Nov 2004 20:04:44 -0600, Andrew Sarangan
wrote:

Do you do a final gear check on final?
Yes
If so, then how much extra work
is it to push the prop to forward on final?
For my philosophy the final check, should be just that - only a check,
no work unless an error has occurred. Subtle I'm sure, but the less
"work" on short final the better IMO.

This will only become an
issue if you are performing a go-around *and* you forget to push the
prop forward. Even if you forget the prop on final, I don't see how you
can forget it again on a go-around. The go-around procedure calls for
everything forward, and you will catch it if the prop is out.
If in your mind you think you pushed it forward you'll probably
realize it isn't only after the throttle has been pushed full forward.
(I know not an absolute, but more likely than not for an average
person). If it does happen you'll be way "over square" and
potentially do alot of engine damage. Not withstanding the damage
potential, you could get alarmed by the condition, fixate on
rectifying it, and relax the pitch control. In heavier airplanes you
could get enough of a pitch up that it's hard for a person to recover.
I'm not being sexist, but I had this happen to a woman I was flying
with, lets just say it was a good learning experience for her. g
This was in a 172RG so heavy is a relative term.


Almost every turbocharged airplane engine ever built operates "over square"
on every takeoff and many operate "way over square". "Square" and
"oversquare" are myths that need to be buried alongside "the step". The
whole notion of "square" is simply an artifact of the units we choose for
MP. If we used inches of water or psi or anything besides the height of a
colum of a particular metal which conviently happens to be a liquid are room
temperature, the whole notion of "square" would never have come about. I'll
step down from my soapbox now.

Mike
MU-2
Helio Courier.

On Tue, 23 Nov 2004 21:08:45 GMT, "Mike Rapoport"
wrote:

Almost every turbocharged airplane engine ever built operates "over square"


We're not talking turbocharges airplanes for this one, however I do
understand the over square concept in takeoff, and other operations.
Aside from that, its a relationship that has been established. When
flying at 2200 RPM or so and going full power you run a greater risk
of breaking something than at full pitch (high RPM). This is all I
was trying to say.

z

Zatatime,

When
flying at 2200 RPM or so and going full power you run a greater risk
of breaking something than at full pitch (high RPM).


How?

--
Thomas Borchert (EDDH)

Thomas Borchert writes:

When flying at 2200 RPM or so and going full power you run a
greater risk of breaking something than at full pitch (high RPM).

How?

Some airplanes have limitations on the space of usable RPM-vs-MP
settings. For example, on the pair of IO-540s in mine, prohibit
operation at MP25 with RPM2300, or MP20 with RPM2000. (I believe
the reason relates to resonance.) That is I push the blue levers
forward from 2200RPM (cruise) to do approaches at 2400RPM: this allow
harsher throttle swings if needed.

- FChE

Frank,

very interesting, thanks. Of course, as the first set of limitations
show, this has nothing to do with "oversquare", since the limit starts
at a "serious oversquare" condition.

--
Thomas Borchert (EDDH)

On Fri, 26 Nov 2004 18:23:13 +0100, Thomas Borchert
wrote:

Frank,

very interesting, thanks. Of course, as the first set of limitations
show, this has nothing to do with "oversquare", since the limit starts
at a "serious oversquare" condition.


Does this mean yo now understand my "way over square" comment, and why
I put over square in quotes?

z

Zatatime,

If it does happen you'll be way "over square" and
potentially do alot of engine damage.


Proof? Numbers? At least a working theory? "Oversquare" is a myth.
Operating out of allowed limits isn't, but "oversquare" is irrelevant.

--
Thomas Borchert (EDDH)