Forward CG Experience

With no control inputs after the forward c.g. shift, you will
experience a lower pitch attitude and a subsequent sink rate at
constant airspeed.

Moving the CG forward, with no control inputs, will change the
equilibrium lift coefficient for the aircraft, making it smaller. The
aircraft's velocity will increase, using gravity for thrust.

You can see this in a 152. Both pilots lean forward, and the aircraft
descends and speeds up. Both pilots lean back, and the aircraft
climbs and slows down.

If you move the CG forward, and want to keep the same airspeed, you
will have to increase the tail down force, i.e., nose up trim. In
this scenario, you will have the same airspeed, but slightly higher
drag and will incur a slight descent.

With no control inputs after the forward c.g. shift, you will
experience a lower pitch attitude and a subsequent sink rate at
constant airspeed.

Moving the CG forward, with no control inputs, will change the
equilibrium lift coefficient for the aircraft, making it smaller. The
aircraft's velocity will increase, using gravity for thrust.


The increased thrust component from gravity will offset the increase
in drag due to forward c.g. The trimmed speed should not change.


You can see this in a 152. Both pilots lean forward, and the aircraft
descends and speeds up. Both pilots lean back, and the aircraft
climbs and slows down.


I've never noticed that leaning forward and back changed attitude or
airspeed.


If you move the CG forward, and want to keep the same airspeed, you
will have to increase the tail down force, i.e., nose up trim. In
this scenario, you will have the same airspeed, but slightly higher
drag and will incur a slight descent.

*****I've never noticed that leaning forward and back changed attitude or
airspeed****

That just shows a low level of knowledge and awareness. I was going to say
"perception" but I didn't want to use any advanced vocabulary on you.


Karl

My "perception" is that you feel better now, pointing out the
shortcomings in others. Glad I could make your day.


*****I've never noticed that leaning forward and back changed attitude or
airspeed****

That just shows a low level of knowledge and awareness. I was going to say
"perception" but I didn't want to use any advanced vocabulary on you.


Karl

My "perception" is that you feel better now, pointing out the
shortcomings in others. Glad I could make your day.

Koopas, Koopas, Koopas. This is not a place for the thin-skinned. Both
Karl and Pete appear to be having a bad week (month? millennium?), and can't
seem to keep their tone and conversation civil.

Just presume they were abused children, make plans to pee in their gas tanks
at OSH 2004, and cheerily move on to the next thread...
;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Koopas, Koopas, Koopas. This is not a place for the thin-skinned.

Indeed, it is not How do you do it?

Both Karl and Pete appear to be having a bad week (month? millennium?), and can't seem to keep their tone and conversation civil.

Just presume they were abused children,

Wait...isn't that a line from Top Gun?


make plans to pee in their gas tanks
at OSH 2004, and cheerily move on to the next thread...
;-)

Thanks for the support. :-

Koopas, Koopas, Koopas. This is not a place for the thin-skinned.

Indeed, it is not How do you do it?

I've always liked verbal repartee, and I'm not easily intimidated. I like
to think that I know what I don't know, and that I'm here to learn.

As I'm fond of saying, I have learned more about flying here (and on the
..owning group) than I have in all my years of hanging out at airports. We
just have to separate the wheat from the chaff once in a while.

Just presume they were abused children,

Wait...isn't that a line from Top Gun?

It appears that they've lost that "Lovin' Feelin'", too... ;-)

Thanks for the support. :-

From what I've read, you've got much to contribute here. Please don't let a
few barbs chase you away!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

The increased thrust component from gravity will offset the increase
in drag due to forward c.g. The trimmed speed should not change.

I'm not talking about drag.

This is a stability/control issue. By moving the CG, you are changing
the speed for which the aircraft is trimmed.

My understanding is that hang gliders use this technique by shifting
their bodies forward and aft. I've never flown one, so I can't say
from personal experience.

I've never noticed that leaning forward and back changed attitude or
airspeed.

Well, either go try it, or trust me. g Probably takes a small
plane before the effect is noticable. I've only done it in a 152. I
will occasionally demonstrate to a student how they can climb,
descend, and turn using only body shifts and opening and closing the
doors.

On Mon, 17 Nov 2003 01:38:16 GMT, Greg Esres
wrote:

I've never noticed that leaning forward and back changed attitude or
airspeed.

Well, either go try it, or trust me. g Probably takes a small
plane before the effect is noticable. I've only done it in a 152.

I've done it in a 172, and demonstrated it to interested pax. The
pitch changes, 'cause the CG changes.

I noticed it for the first time on my long cross country, while
stretching.

Rob

--
[You] don't make your kids P.C.-proof by keeping them
ignorant, you do it by helping them learn how to
educate themselves.

-- Orson Scott Card

Greg,

Please see comments below:

The increased thrust component from gravity will offset the increase
in drag due to forward c.g. The trimmed speed should not change.

I'm not talking about drag.

This is a stability/control issue. By moving the CG, you are changing
the speed for which the aircraft is trimmed.

Alright, so to sum up the situation (please correct me if I am wrong)

1. If you have a forward shift in c.g. without touching the controls,
you'll have an imbalance in pitching moment that translates into a
pitch-down attitude. Your angle of attack is reduced, and the
airplane will speed up. If you're in the front of the power curve,
your drag will also increase with the higher airspeed. The angle of
descent will be such that the thrust provided by gravity will offset
the drag increase.

2. In a previous post, you wrote "If you move the CG forward, and want
to keep the same airspeed, you will have to increase the tail down
force, i.e., nose up trim. In this scenario, you will have the same
airspeed, but slightly higher drag and will incur a slight descent.".

My question is this: When you increase the downforce, lift must also
be increased for the balance of forces in the "vertical direction".
Since neither your angle of attack nor airspeed are changing, how do
you maintain Lift = Weight in this case? Unless your nose-up trim
change upped the angle of attack...


My understanding is that hang gliders use this technique by shifting
their bodies forward and aft. I've never flown one, so I can't say
from personal experience.

I've never noticed that leaning forward and back changed attitude or
airspeed.

Well, either go try it, or trust me. g Probably takes a small
plane before the effect is noticable. I've only done it in a 152. I
will occasionally demonstrate to a student how they can climb,
descend, and turn using only body shifts and opening and closing the
doors.

Thanks for pointing that out. I definitely will try it next time. Do
you use the door trick to induce more drag and increase your descent
path as if you're you're adding more flaps?

Alex