preparing for commercial oral and practical

Additionally, your CG probably changes when you retract your gear. That's one of my commercial DE's pet points.

Do you mean the actual CG (from the repositioning of the gear further
back, such as in a C172RG) or the change in flight behavior due to the
change in CP from removing the gear from the slipstream (such as in an
Arrow, where the gear retracts straight up)?

Jose
--
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except there's no God, and there's no dice. And maybe there's no universe.
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Jose wrote:
Additionally, your CG probably changes when you retract your gear.
That's one of my commercial DE's pet points.

Do you mean the actual CG (from the repositioning of the gear further
back, such as in a C172RG)

The actual CG. I would think that most retracts would change CG since
at least the nose gear is in a different position relative to the datum,
but I can only speak for the Arrow that I flew for my checkride.


or the change in flight behavior due to the
change in CP from removing the gear from the slipstream (such as in an
Arrow, where the gear retracts straight up)?

Only the mains. The nose gear moves back.


-m
--
## Mark T. Dame
## CP-ASEL, AGI
## insert tail number here
## KHAO, KISZ
"Every time you lose you die a little bit. You die inside, a portion of
you. Not all of your organs, maybe just your liver."
-- George Allen

The actual CG. I would think that most retracts would change CG since at least the nose gear is in a different position relative to the datum, but I can only speak for the Arrow that I flew for my checkride.

Interesting - never thought much about it. Looking at the Arrow manual,
I see "moment due to retraction of landing gear" 819 in-lbs". Dividing
by 2000 lbs gives a CG change of about a half an inch.

Thanks.

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.

Mark T. Dame wrote:
The intricacy's of weight and balance similar to the knowledge test
questions. Load, fly, unload, fly, refuel, load, fly unload, refuel....
what's your weight, where's your CG, what about if you have to hold, when
will you reach bingo fuel and where will your CG be then? Talk to a Bonanza
owner about CG changes with fuel burn.

Additionally, your CG probably changes when you retract your gear.
That's one of my commercial DE's pet points.


While being technically correct (if he says so), what difference does it make?
Are you going to fly with the gear down to keep the CG in the same place that
you used to figure your W&B?

Cocktail party facts....



--
Mortimer Schnerd, RN
mschnerdatcarolina.rr.com

While being technically correct (if he says so), what difference does it make?

Half an inch in an Arrow.

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.

On 05/14/07 14:03, Mortimer Schnerd, RN wrote:
Mark T. Dame wrote:
The intricacy's of weight and balance similar to the knowledge test
questions. Load, fly, unload, fly, refuel, load, fly unload, refuel....
what's your weight, where's your CG, what about if you have to hold, when
will you reach bingo fuel and where will your CG be then? Talk to a Bonanza
owner about CG changes with fuel burn.

Additionally, your CG probably changes when you retract your gear.
That's one of my commercial DE's pet points.


While being technically correct (if he says so), what difference does it make?
Are you going to fly with the gear down to keep the CG in the same place that
you used to figure your W&B?

Cocktail party facts....




I'm sure it was more a matter of making sure the pilot understood how the
gear affected the CG - and not that it would change the flight characteristics
all that much.


--
Mark Hansen, PP-ASEL, Instrument Airplane, USUA Ultralight Pilot
Cal Aggie Flying Farmers
Sacramento, CA

Mortimer Schnerd, RN wrote:
Mark T. Dame wrote:
The intricacy's of weight and balance similar to the knowledge test
questions. Load, fly, unload, fly, refuel, load, fly unload, refuel....
what's your weight, where's your CG, what about if you have to hold, when
will you reach bingo fuel and where will your CG be then? Talk to a Bonanza
owner about CG changes with fuel burn.
Additionally, your CG probably changes when you retract your gear.
That's one of my commercial DE's pet points.


While being technically correct (if he says so), what difference does it make?
Are you going to fly with the gear down to keep the CG in the same place that
you used to figure your W&B?

You calculate balance for both gear down and gear up for both takeoff
and landing loading. All four must be within the envelope or you don't go.

Matt

Matt Whiting wrote:
While being technically correct (if he says so), what difference does it
make? Are you going to fly with the gear down to keep the CG in the same
place that you used to figure your W&B?

You calculate balance for both gear down and gear up for both takeoff
and landing loading. All four must be within the envelope or you don't go.



Really? In the C-210 if I couldn't get the doors closed we wouldn't go, but I
don't recall any other occasions. G

Seriously, I've never been required to do more than one W&B for any flight I've
ever made, and I don't recall that the gear position was ever even considered.
I've never failed a written test or check ride either, including regular part
135 rides.



--
Mortimer Schnerd, RN
mschnerdatcarolina.rr.com

Mortimer Schnerd, RN wrote:
Mark T. Dame wrote:
The intricacy's of weight and balance similar to the knowledge test
questions. Load, fly, unload, fly, refuel, load, fly unload, refuel....
what's your weight, where's your CG, what about if you have to hold, when
will you reach bingo fuel and where will your CG be then? Talk to a Bonanza
owner about CG changes with fuel burn.
Additionally, your CG probably changes when you retract your gear.
That's one of my commercial DE's pet points.


While being technically correct (if he says so), what difference does it make?
Are you going to fly with the gear down to keep the CG in the same place that
you used to figure your W&B?

Cocktail party facts....

Not at all. We're talking about a commercial pilot checkride. As such,
you need to know more than for a private certificate. The point of the
exercise is to show the examiner that you understand these concepts and
actually do it.

Additionally, you do have the gear in both positions in flight. You
have it down at take off. You need to make sure that putting it up
isn't going to put your CG outside of the envelope right after take off
when you are still low, slow, and nose high. This could lead to a
departure stall. When you are landing, you put your gear down well
before you touch down, and you will be low and slow on final. The
difference between gear up and down may be a factor.

Now, as Jose pointed out, on the Arrow it's not very significant, but
that doesn't mean that it's that way for all planes.

Finally, as I said, we're talking about a checkride. Checkrides often
have you do things that you may not do in your day to day flying, but
you need to know and understand in case you need it. In any case, I'm
just giving advice on what to expect on the checkride.


-m
--
## Mark T. Dame
## CP-ASEL, AGI
## insert tail number here
## KHAO, KISZ
"Love is a snowmobile racing across the tundra and then
suddenly it flips over, pinning you underneath. At night,
the ice weasels come."
-- Matt Groening

Now, as Jose pointed out, on the Arrow it's not very significant

Actually I wasn't implying (half an inch) that it wasn't very
significant - when the CG range is only a handful of inches, it's
significant. And certainly when you're near the edge it bears watching.

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.