Coordinated turns without rudder, and autopilots

"Mxsmanic" wrote in message
...
Ash Wyllie writes:

Looks like you found a simulator error.

Load a 172, and try very slow flight without using the rudder. Use power,
hold
altitude and keep slowing until you stall.

You should emd up in a spin.

Why would I do that? It has nothing to do with my question: How can
autopilots make coordinated turns without control of the rudder?

They don't moron, and you have been told. It's just not necessary. Sorry
your sim can't duplicate it.

"Mxsmanic" wrote in message
...
Paul kgyy writes:

They also start the turn rather gradually, which minimizes the adverse
yaw.

They turn quickly considering that they are not touching the rudder. I
want
to know how they do it.

They don't and you know it. You're just trolling.

"Mxsmanic" wrote in message
...
Maxwell writes:

Nothing, the turns are not perfectly coordinated, they don't have to be.

The ball hardly moves. It moves a lot more if I attempt to roll into a
turn
myself without using the rudder. Why?

HELLO!!! YOU'RE FLYING A DESK YOU MORON!!!!

Andrew Sarangan wrote:


Your analogy with driving tells me a little about your line of
thinking. In that case, why does the car to slow down when it hits a
steep hill? It is due to the inability of the engine to respond fast
enough for the sudden demand in power.

No, it is because there is always a lag in a real world feedback control
system or it goes into oscillation.

The lag is due to what is called the margin of stability.

It is possible to design a control system that is virtually instantaneous.

This is called a critically damped system.

The problem with that is that if anything changes, like linkages wear,
the system can easily go underdamped and it goes into oscillation.

You don't want to be in a vehicle at 65 MPH with the cruise control
going into oscillation.

So for safety, cruise control systems are over damped, i.e. have a
large margin of stability.

For a fair explanation of control systems and stability, see
http://en.wikipedia.org/wiki/Control_theory

snip rest

--
Jim Pennino

Remove .spam.sux to reply.

"Mxsmanic" wrote in message
...

Then my attempts to keep it centered with the rudder are not necessary,
either.

That's correct, and if you sim doesn't work that way, it's wrong.


Also, a standard rate turn is not
necessarily a coordinated turn, although some of your statements
suggested
that you do not know the difference.

I know the difference.

Apparently not.


As good as you might think it is, do not mistake the flying model of a
$50
computer game with real flying. Your presumed knowledge and the basis of
your questions are obviously limited by the shortcomings of MSFS.

Do not assume that every anomaly is a simulator defect. The simulator is
a
lot better than you think. Indeed, it predicts the behavior of an
aircraft a
lot better than anyone here does.

Only in your mind, moron, only in you mind.

Mxsmanic wrote:
"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com writes:

What in the world makes you think that an autopilot can make a "coordinated"
turn without using the rudder if a pilot can't?

Presumably a pilot can; I want to know how. And nobody has been able to tell
me thus far.

If you have "observed" this then, either A) Your simulation falls a bit
short in terms of simulating how the simulated autopilot works - I assume
it's easier to program a simulated autopilot without adding the "make it
appear un-coordinated" feature. Or, B) You only think that the autopilot
does a much better job than a pilot does - perhaps you are a bit ham-fisted
with your simulation - without ever being in in airplane, it would be easy
to not realize what you are doing given the lack of feedback and the fact
that no one has ever "flown" with you - I find that I "overcontrol" when
flying a sim...

Or (C) nobody here has a clue and nobody wants to admit it, even though their
argument among themselves makes it obvious.

Do you know how it's done, or don't you?
Or D: Nobody wants to answer your question.

Andrew Sarangan wrote:

Your analogy with driving tells me a little about your line of
thinking. In that case, why does the car to slow down when it hits a
steep hill? It is due to the inability of the engine to respond fast
enough for the sudden demand in power. Obviously, the cruise control
does a pretty good job over small hills otherwise we would not be
using them at all. If the engine were powerful enough and had a quick
response, it should be able to maintain a constant speed over a steep
hill. When you manually apply some extra throttle in anticipation of
the approaching the hill, you are in fact 'helping' the cruise control
do its job better. You are not doing something the cruise control is
inherently incapable of doing. You are simply reducing the transient
period. If left to its own device, the cruise control should
eventually reach the set cruise speed over the hill, unless the engine
is too small for the hill.

No, it still isn't the same. No matter how large the engine, or how
fast it responds, the end result is that a control system takes no
action until an error is present. So at least SOME loss or gain in
speed is required for the cruise to work, that is inherent in any
feedback control system. Sure, if you can measure the error with
greater resolution, and have a very large actuator with very fast
response, you can make the amount of divergence from set point ever
smaller, but you can't take it to zero.


Consider an imaginary airplane with an infinitely large vertical fin.
Would it need rudder to fly co-ordinated? I hope you would agree that
the answer is no. The infinitely sized fin will generate an infinite
restoring force, which really means the airplane will never deviate
from co-ordinated flight. Now reduce the fin size to something smaller
and practical. The restoring force will also scale down. In this case,
the force may not be large enough to restore co-ordinated flight in
all possible scenarios, such as slow flight and steep turns. In some
cases it may experience a longer transient, and in some cases it may
not reach co-ordinated flight at all. It all depends on how large the
fin is, and how much air is flowing around it. In such cases where the
fin can't do its job satisfactorily, the rudder is used to help it
along.

Same here. An infinitely large fin has infinite drag and thus the
airplane would not fly so stability would not be an issue. :-)
However, for any practical airplane with any adverse yaw forces during a
turn, a fin alone will not maintain coordinated flight. A larger fin on
a longer tail will get closer to be sure, but at least SOME yaw
divergence is required for the fin to work. It is inherent in the way
it works. There simply is not way to eliminate that fact. A rudder
works differently since it gets its ability to act from other than
aerodynamic forces (the pilot pushing on the rudder provides the
actuation force). The rudder than thus provide yaw forces independent
of any yaw displacement. The fin simply can't do this.


So I still do not see your line of thinking.

Well, I've given it my best shot, so I'll sign off now. I can't think
of any other way to explain it.


Matt

Mxsmanic opined

Ash Wyllie writes:

Looks like you found a simulator error.

Load a 172, and try very slow flight without using the rudder. Use power,
hold altitude and keep slowing until you stall.

You should emd up in a spin.

Why would I do that? It has nothing to do with my question: How can
autopilots make coordinated turns without control of the rudder?

1) To test the simulator.

2) Newer light aircraft are designed so that at cruise speed and small aileron
deflections rudder input is not needed.


-ash
Cthulhu in 2007!
Why wait for nature?

Mxsmanic wrote in
:

Viperdoc writes:

Hey Anthony you butthead- your basic premise is incorrect: the
autopilot in small planes (like the Baron I've flown for around 500
hours) does not do coordinated turns. Just because there might be
some anomalous behavior in your game does not make is so in real
life.

There is no anomaly in the game. The only anomaly I see is that
nobody here knows the answer.

Yeah, right, fjukktyard


Berti e

Just to reiterate- the autopilot does not do a coordinated turn. It may do
so in your game. It may be different when hand flying versus while on
autopilot, but this is in your game.

I have many hours in a real Baron and this is how it works. Some real
planes require more or less rudder, as others have pointed out. My Extra
takes a little rudder pressure for a coordinated turn, while even with my
limited time in F-16's, it's pretty much feet on the floor.

You try to look for answers based upon some premise that your game is a real
representation of an actual flying experience. Yet, MSFS is notably week in
some areas, like the Extra, where the roll rate and flying model are nowhere
close to reality. The Baron model is far from accurate, and even the
multimillion dollar one I rode in at Simcomm wasn't that close.

Why can't you accept this and stop trolling? As good as it might be, it is
still just a game you're playing.
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