When do controls return to neutral?

In a typical small GA aircraft, do the controls have a natural
tendency to return exactly to their neutral positions when you aren't
holding them and when you are on the ground? Do they have a tendency
to return to exactly neutral in flight if you release them in level
flight?

The reason I ask is that sometimes the controls I use in simulation
don't snap back to exactly neutral when I release them, and I'm trying
to determine whether this is more realistic or less realistic with
respect to a real aircaft.

I suppose it depends on the aircraft, but what is the usual case? And
if you happen to know how it behaves specifically on a Baron or an
A36, I'd be particularly interested to know that.

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Usually, in a non-aerobatic plane, ailerons and rudder will return
close to neutral. Elevator will go to its trim position. Several of the
classic planes I've flow do not have this tendency, so it really can go
either way, but most planes today are designed to be easy to fly.

-Robert, CFII

Mxsmanic wrote:
In a typical small GA aircraft, do the controls have a natural
tendency to return exactly to their neutral positions when you aren't
holding them and when you are on the ground? Do they have a tendency
to return to exactly neutral in flight if you release them in level
flight?

The reason I ask is that sometimes the controls I use in simulation
don't snap back to exactly neutral when I release them, and I'm trying
to determine whether this is more realistic or less realistic with
respect to a real aircaft.

I suppose it depends on the aircraft, but what is the usual case? And
if you happen to know how it behaves specifically on a Baron or an
A36, I'd be particularly interested to know that.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Robert M. Gary writes:

Usually, in a non-aerobatic plane, ailerons and rudder will return
close to neutral. Elevator will go to its trim position. Several of the
classic planes I've flow do not have this tendency, so it really can go
either way, but most planes today are designed to be easy to fly.

Is there any tendency for the control surfaces to set in positions
slightly off neutral? For example, if you have to use rudder a lot to
counter torque on every flight, is there any tendency of the rudder
over time to stay a little bit on that side?

My joystick seems to do this, very slightly, and since it is
mechanical like control surfaces, I wonder if things like a rudder
might do the same. Not a very big deflection, of course, but enough
that you might notice it in otherwise perfect level flight (although
with the engine running, I suppose there would always be torque acting
more strongly in the opposite direction, so how would you know?).

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Mxsmanic wrote:
Robert M. Gary writes:
Is there any tendency for the control surfaces to set in positions
slightly off neutral? For example, if you have to use rudder a lot to
counter torque on every flight, is there any tendency of the rudder
over time to stay a little bit on that side?

Usage doesn't cause this. However with age sometimes a plane doesn't
fly as straight as it used to. If the plane isn't flying straight (i.e.
the ball isn't in the middle when you take your feet off the rudders)
you can adjust it. On my plane there is a bolt that adjust the throw
but a lot of planes just have metal trim tabs.
What you are asking about is referred to as "rigging" and is one of the
great dark arts in aviation. The manual will tell you how to do it but
only a few really good A&P's can really get your bird (especially a
more complex one like mine) to fly straight. Right now my plane slips
to the right about 1/2 ball when I put the gear out. Not sure why, it
didn't used to. With rigging you usually want to seek out an A&P
familiar with your plane (especially if you have rigging wires, don't
ever let a generic A&P touch rigging wires if you fly a classic).
-Robert

In article . com,
"Robert M. Gary" wrote:

Mxsmanic wrote:
Robert M. Gary writes:
Is there any tendency for the control surfaces to set in positions
slightly off neutral? For example, if you have to use rudder a lot to
counter torque on every flight, is there any tendency of the rudder
over time to stay a little bit on that side?

Usage doesn't cause this. However with age sometimes a plane doesn't
fly as straight as it used to. If the plane isn't flying straight (i.e.
the ball isn't in the middle when you take your feet off the rudders)
you can adjust it. On my plane there is a bolt that adjust the throw
but a lot of planes just have metal trim tabs.
What you are asking about is referred to as "rigging" and is one of the
great dark arts in aviation. The manual will tell you how to do it but
only a few really good A&P's can really get your bird (especially a
more complex one like mine) to fly straight. Right now my plane slips
to the right about 1/2 ball when I put the gear out. Not sure why, it
didn't used to. With rigging you usually want to seek out an A&P
familiar with your plane (especially if you have rigging wires, don't
ever let a generic A&P touch rigging wires if you fly a classic).

Aircraft without adjustable rudder trim have a ground adjustable piece
of metal (a "tab") attached to the trailing edge of the rudder. This tab
is bent at an angle to the plane of the rudder so that the aircraft will
fly with no yaw (theoretically) at "cruise" speed. Change the airspeed
and the aircraft will yaw right or left.

Yeah - essentially what you're talking about is the fundamental point
of trim devices on modern aircraft.

Neutral position is a bit of a 'bad' term here, because unlike a
simulator's joystick, there is no defined "Central" location for a
yoke. Yes, of course wing's level is fairly 'central', but for rudder
and elevator, there is quite a bit of play as to where 'neutral' is
(where neutral is fundamentally defined as the point at which the
controls naturally go when you apply no force to them).

The "neutral point" described above is is set by your trimming
mechanisms. In my PA-28-140, I have 3 mechanisms to trim the plane - I
have the pitch trim handle, I have a rudder trim mechanism (which
actually just manipulates the pedals) and I have the ability to control
my fuel burn on one side or the other to trim for roll.

This is one of the areas where flying a real plane is fundamentally
different than flying with a computer joystick. with a computer
joystick, there is always a "center point", and trim is simulated by
having the aircraft turn to one side or the other while the joystick is
in the center point. In a real aircraft, the physical point where the
control's center themselves varies based on trim, but AOA effect of
having the controls at any given point is usually the same. (I.E,
having the yoke 3" out from the panel will try to move the aircraft
towards the same AOA, regardless if this is 'trimmed as neutral' and I
can take my hand off, or the aircraft is trimmed for another speed and
the yoke is pushing against my hand).

Also note that this is all very delibrate- The anti-servo tab on a
PA-28's tail is explicitly designed to provide this very type of
tactile feedback - that's its whole point.


On Nov 7, 3:18 pm, Mxsmanic wrote:
In a typical small GA aircraft, do the controls have a natural
tendency to return exactly to their neutral positions when you aren't
holding them and when you are on the ground? Do they have a tendency
to return to exactly neutral in flight if you release them in level
flight?

The reason I ask is that sometimes the controls I use in simulation
don't snap back to exactly neutral when I release them, and I'm trying
to determine whether this is more realistic or less realistic with
respect to a real aircaft.

I suppose it depends on the aircraft, but what is the usual case? And
if you happen to know how it behaves specifically on a Baron or an
A36, I'd be particularly interested to know that.

--
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On Wed, 08 Nov 2006 00:18:15 +0100, Mxsmanic wrote:

In a typical small GA aircraft, do the controls have a natural
tendency to return exactly to their neutral positions when you aren't
holding them and when you are on the ground?

Generally, no. The weight of the elevators usually put them in the full-down
position. Ailerons may be one way or the other, depending upon the wind, as
will the rudder. Rudders often have springs associated with them (via the
nosewheel or tailwheel controls) and have a better tendency to go back to
near-zero.

Do they have a tendency to return to exactly neutral in flight if you
release them in level flight?

Depends on how you define "neutral." If you define "neutral" as "faired with
the airfoil they're part of" the answer depends on the loading and trim
condition of the aircraft. If you define "neutral" as "in position for straight
and level flight," the answer is, "generally no," depending, again, on the
loading and trim condition. If you define "neutral" as "least pressure on the
controls," the answer is, "always."

Keep in mind that most airplanes do not have cockpit indication of control
position. We can look towards the wing and make a pretty good estimate of the
aileron position, but the elevators and rudders aren't easily visible from the
cockpit of many airplanes. Even those planes where they are visible, you're
looking at them from such an angle where the precise position (e.g, zero degrees
vs. 5 degrees) is difficult to determine.

My airplane has differential gearing on the ailerons (downgoing aileron doesn't
move as far as the upgoing one) so despite having a good view, it makes it a bit
more complicated.


Ron Wanttaja

Mxsmanic wrote:
In a typical small GA aircraft, do the controls have a natural
tendency to return exactly to their neutral positions when you aren't
holding them and when you are on the ground? Do they have a tendency
to return to exactly neutral in flight if you release them in level
flight?

The reason I ask is that sometimes the controls I use in simulation
don't snap back to exactly neutral when I release them, and I'm trying
to determine whether this is more realistic or less realistic with
respect to a real aircaft.

I suppose it depends on the aircraft, but what is the usual case? And
if you happen to know how it behaves specifically on a Baron or an
A36, I'd be particularly interested to know that.

--
Transpose mxsmanic and gmail to reach me by e-mail.



Its different for every aircraft. Generally cessnas mooneys and pipers
will return to neutral on the rudder and elevators but the aleirons
will go to trim setting. Some other aircraft will stay at last input
position, or "positive"

If it slips with gear extended, probably a door is not
aligned and is acting as a rudder.



"Robert M. Gary" wrote in message
ups.com...
|
| Mxsmanic wrote:
| Robert M. Gary writes:
| Is there any tendency for the control surfaces to set in
positions
| slightly off neutral? For example, if you have to use
rudder a lot to
| counter torque on every flight, is there any tendency of
the rudder
| over time to stay a little bit on that side?
|
| Usage doesn't cause this. However with age sometimes a
plane doesn't
| fly as straight as it used to. If the plane isn't flying
straight (i.e.
| the ball isn't in the middle when you take your feet off
the rudders)
| you can adjust it. On my plane there is a bolt that adjust
the throw
| but a lot of planes just have metal trim tabs.
| What you are asking about is referred to as "rigging" and
is one of the
| great dark arts in aviation. The manual will tell you how
to do it but
| only a few really good A&P's can really get your bird
(especially a
| more complex one like mine) to fly straight. Right now my
plane slips
| to the right about 1/2 ball when I put the gear out. Not
sure why, it
| didn't used to. With rigging you usually want to seek out
an A&P
| familiar with your plane (especially if you have rigging
wires, don't
| ever let a generic A&P touch rigging wires if you fly a
classic).
| -Robert
|

EridanMan writes:

Neutral position is a bit of a 'bad' term here, because unlike a
simulator's joystick, there is no defined "Central" location for a
yoke. Yes, of course wing's level is fairly 'central', but for rudder
and elevator, there is quite a bit of play as to where 'neutral' is
(where neutral is fundamentally defined as the point at which the
controls naturally go when you apply no force to them).

I was kind of thinking along those lines. So I presume that I need
not fret about not necessarily having an obvious neutral position in
the sim. If I understand correctly, in a real aircraft, it all just
depends on circumstances, and you don't have to know or care about any
"exact" neutral (?).

The "neutral point" described above is is set by your trimming
mechanisms. In my PA-28-140, I have 3 mechanisms to trim the plane - I
have the pitch trim handle, I have a rudder trim mechanism (which
actually just manipulates the pedals) and I have the ability to control
my fuel burn on one side or the other to trim for roll.

Do you have a marked "zero point" for the trim, or do you just trim
until it feels right for the circumstances, and then trim again the
next time as required, without worrying about whether the trim is
truly "zero" or not?

This is one of the areas where flying a real plane is fundamentally
different than flying with a computer joystick. with a computer
joystick, there is always a "center point", and trim is simulated by
having the aircraft turn to one side or the other while the joystick is
in the center point. In a real aircraft, the physical point where the
control's center themselves varies based on trim, but AOA effect of
having the controls at any given point is usually the same. (I.E,
having the yoke 3" out from the panel will try to move the aircraft
towards the same AOA, regardless if this is 'trimmed as neutral' and I
can take my hand off, or the aircraft is trimmed for another speed and
the yoke is pushing against my hand).

So in a real aircraft, a different trim position also represents a
different yoke position? That seems logical.

I wonder how fly-by-wire aircraft handle this.

Also note that this is all very delibrate- The anti-servo tab on a
PA-28's tail is explicitly designed to provide this very type of
tactile feedback - that's its whole point.

I read that a drawback to Cirrus aircraft is that they use springs for
feedback, so it's hard to tell where the control surfaces actually
are.

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