Coordinated turns without rudder, and autopilots

On May 29, 2:43 pm, Mxsmanic wrote:

I have an aversion to stalls and I usually stay well away from them.

Why don't you like flying real aeroplanes?
Solution
you are afraid of stalling so you'd never be able to land

"Mxsmanic" wrote ...

What errors are there in the simulated model? Be specific.


MSFS has for a long time been known to have a rather inaccurate flight
model. MS tends to focus on the eye candy aspects of simulation.

In my own experience, the stall/spin entry behavior is an easily explored
area which quite clearly reveals the inadequacies of MSFS' flight modeling
as compared to the real world. And it reflects of course as well in other
areas of the flight envelope.

Years ago I flew extensively with a popular WWII networked combat airplane
simulator (Warbirds). One of its claims to fame was that its flight dynamics
model was based on actual real-time calculation of the motional differential
equations that govern the flight dynamics of an aircraft. This in contrast
to the "simplistic table-driven flight dynamics model of the mainstream PC
simulators" probably referring to MSFS.
Marketing talk aside, I found that simulator MUCH more realistic in the
flight dynamics modeling than MSFS. Especially at the edges of the flight
envelope, where the differences between different airplanes were very
significant. Different airplanes bite you in different ways ;-)

Mxsmanic wrote:
John Theune writes:

Or D: Nobody wants to answer your question.

Rest assured, if some of the most vocal posters here actually knew the correct
answer, their egos would compel them to immediately provide it for all to see.
It's much more satisfying to such people to post a correct answer than it is
for them to pretend they have the answer and just don't want to reveal it.

Or most posters have decided that you are such an arrogant, self-righteous,
nit-picking, trolling, whinny, thick-headed, obnoxious snot you can
go **** up a rope.

--
Jim Pennino

Remove .spam.sux to reply.

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

...
Do you know how it's done, or don't you?

Yes I do. And I will repeat the answer one last time.

Your simulated autopilot in your simulated Baron appears to make
"coordinated turns" without using the simulated rudder because that's how
Microsoft wrote the software. (I had considered the posibility that you were
having problems flying, but based on other comments it now appears to me
that the problem really is with the autopilot code in your simulator).

Flesh and blood Barons do _not_, however, make coordinated turns without
using the rudder when flown by _either_ the human or auto pilots. (Confirmed
by Mr. Viperodoc who happens to actually own one - as you know). However, in
this case, the turns are close enough for government work.
Other aircraft are different. Some use things like Friese ailerons or
aileron/rudder interconnects to make it easy for the pilot and will make
coordinated turns across a limited speed range without the use of the
rudder. Some aircraft don't even have rudder pedals for the pilot to use.

Many very efficient aircraft (e.g. Nimbus III, ASH-25) typically require
LOTS of rudder to keep turns coordinated because they are designed to be
efficient, not to make it easy for lazy pilots. Adding an autopilot will not
change this. However, a simulated Nimbus could be made to do whatever the
programmer wants.

In summary - the answer to your original question is: "Your simulated
autopilot does not reflect actual aircraft capability and/or behavior."

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

jesus...this is a bizarre thread.
I have never seen a troller so well fed.

wrote:
Or D: Nobody wants to answer your question.

Rest assured, if some of the most vocal posters here actually knew the correct
answer, their egos would compel them to immediately provide it for all to see.
It's much more satisfying to such people to post a correct answer than it is
for them to pretend they have the answer and just don't want to reveal it.

Or most posters have decided that you are such an arrogant, self-righteous,
nit-picking, trolling, whinny, thick-headed, obnoxious snot you can
go **** up a rope.


--
Message posted via AviationKB.com
http://www.aviationkb.com/Uwe/Forums...ation/200705/1

OK- one more time: I fly a real Baron with an autopilot, and I can
categorically tell you that the autopilot does not command a coordinated
turn. However, the plane itself does not have a lot of adverse yaw, and even
at a standard rate turn it only goes around half a ball into the turn on the
TC. It is not noticeable by any seat of the pants criteria.

This is the way a real Baron flies, and I have been in more than a few.

If you believe that your game is more accurate than a real plane with a real
pilot, you are more delusional than you appear. Your game lacks an accurate
representation of the actual behavior of a real plane, as it also does for
the Extra, where it is especially weak.

Unless you've flown a real Baron (or Extra) as well as played MSFS, you have
no basis of comparison.

"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote in
news:nPSdnV8rxqg8aMDbnZ2dnUVZ_qiqnZ2d@wideopenwest .com:

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

...
Do you know how it's done, or don't you?

Yes I do. And I will repeat the answer one last time.

Your simulated autopilot in your simulated Baron appears to make
"coordinated turns" without using the simulated rudder because that's
how Microsoft wrote the software. (I had considered the posibility
that you were having problems flying, but based on other comments it
now appears to me that the problem really is with the autopilot code
in your simulator).

Flesh and blood Barons do _not_, however, make coordinated turns
without using the rudder when flown by _either_ the human or auto
pilots. (Confirmed by Mr. Viperodoc who happens to actually own one -
as you know). However, in this case, the turns are close enough for
government work. Other aircraft are different. Some use things like
Friese ailerons or aileron/rudder interconnects to make it easy for
the pilot and will make coordinated turns across a limited speed range
without the use of the rudder. Some aircraft don't even have rudder
pedals for the pilot to use.

Many very efficient aircraft (e.g. Nimbus III, ASH-25) typically
require LOTS of rudder to keep turns coordinated because they are
designed to be efficient, not to make it easy for lazy pilots. Adding
an autopilot will not change this. However, a simulated Nimbus could
be made to do whatever the programmer wants.

In summary - the answer to your original question is: "Your simulated
autopilot does not reflect actual aircraft capability and/or
behavior."


wow, talk about wasting band width, d00d.

?want to try and explain it to my pet stoat next?

He'd have a better chance of understanding it.

Bertie

"Mxsmanic" wrote in message
...
...
What errors are there in the simulated model? Be specific.

The autopilot makes coordinated turns even though it is not supposed to be
connected to the rudder.

Specific enough?

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

On May 30, 5:57 am, Matt Whiting wrote:
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

Matt.

Consistently excellent explanations. It is amazing to me how people
tend to view (in its simplist form) that a fixed torque can overcome
consistently a variable one under "all" circumstances.

Nice job.

Robert

Mxsmanic opined

Ash Wyllie writes:

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

But the AP aileron deflections do not appear to be small, as it rolls the
aircraft rapidly and smoothly into a coordinated turn. And this is on an
aircraft designed sixty years ago.

force variess with the velocity squared. Think about it.


-ash
Cthulhu in 2007!
Why wait for nature?