How come the wings bank when I use the rudder

Isn't interesting that entry level RC Aircraft only have rudder and elevator
controls.. and then turn just fine.
Funny that a full sized airplane would react the same way.

Size does not matter here. It's the wing dihedral that does.

Bartek

I'm puzzled as to how you could be doing a solo X country and not know
this. Did you first lesson not include "effect of controls"? what
about your theory?

Cheers


On a 3 hour cross country today I was amusing myself by flying with
rudder pedals only (all right, OK, a little yoke usage to maintain
altitude). But then I got to wondering why applying rudder pressure
causes the plane to bank. All I could think of was that rudder usage
produces asymmetric lift because one wing is somewhat blanked by the
sideways motion induced by the rudder? Also, the rudder surface is
above the plane's center of lift but I don't know how much of a factor
that is.

Dudley Henriques wrote in
:

Paul kgyy wrote:
On a 3 hour cross country today I was amusing myself by flying with
rudder pedals only (all right, OK, a little yoke usage to maintain
altitude). But then I got to wondering why applying rudder pressure
causes the plane to bank. All I could think of was that rudder usage
produces asymmetric lift because one wing is somewhat blanked by the
sideways motion induced by the rudder? Also, the rudder surface is
above the plane's center of lift but I don't know how much of a
factor
that is.

It's called a yaw/roll couple. As you create yaw you acellerate the
outside wing which then has more lift. It raises coupling with roll
and
you have turn.


Gotta disagree there Dudley. While it is true, and that's what happening
to some degree initially, the majority of the yaw roll couple in
lightplanes comes from the dihedral. the wing opposite the direction of
yaw has a higher angle of attack and generates more lift then the
opposite, which now has a lower alpha. Airplanes with no dihedral will
still roll slightly in the direction of yaw but it's nearly zilch.
can prove the first statement for yourself by introducing the yaw so
slowly as to make the diffrence in speeds insignificant. The airplane
will still roll in the direction of the yaw.
The V1 cruise missile had no dihedral and no ailerons and was easily
upset for this reason. Once it was off a wings level flight path it's
gyros had no chance of getting it back into straight and level.
Swept wing airplanes can have a huge yaw roll couple because as you yaw,
the forward moving wing's aspect ratio becomes massive just as the aft
moving's wing shrinks.(transonic ones have a reverse effect couple at
altitude, but that's another story)


Bertie

"Montblack" wrote in
:

("Capt. Geoffrey Thorpe" wrote)
'cause if it didn't, your feet would have nothing to do ;-)


http://www.ercoupe.org/images/37.jpg
That would be awful...! :-)



It is. I flew one of the old pedal-less ones for a couple of days giving a
guy who had rebuilt one and hadn't flown for years a re-intro to flying.
God awful!
there is a brake pedal, though. A stalk type pedal I think it came out of a
'38 DeSoto.
The Pilot's handbook said that to deal with a too high situation on
approach you should pull th estickk full aft and let the rate of descent
increase that way until you were back in the slot..

Yech.

Always liked the look of them though. Could have been worse, it could have
been the Gwinn Air car hat filled that Niche!

Bertie

wrote in news:1192935582.999886.201640
@t8g2000prg.googlegroups.com:


In addition to what others have said, another interesting question to
ponder is why the airplane yaws when you bank.

The yaw is induced by the ailerons, so the only time you need to apply
rudder is when you are changing your bank angle with the ailerons. On
the side where the aileron is down, the wing has more lift, and more
drag. On the other side, the lift is spoiled and there is less drag.
The draggy wing yaws backwards, requiring opposite rudder.

that's adverse yaw. I beleive he meant why does the airplane yaw in the
same direction (eventually) as the direction of roll?


Bertie

Bob Clough wrote in news:nemoSat102007091418
@newsgroups.comcast.net:

What gives, guys? Good question followed by three answers that
actually agree? What's up with that? Where's the usenet controversy?


Hey, I gotta slep every now and again, ya know.


Bertie

Bertie the Bunyip wrote:
Dudley Henriques wrote in
:

Paul kgyy wrote:
On a 3 hour cross country today I was amusing myself by flying with
rudder pedals only (all right, OK, a little yoke usage to maintain
altitude). But then I got to wondering why applying rudder pressure
causes the plane to bank. All I could think of was that rudder usage
produces asymmetric lift because one wing is somewhat blanked by the
sideways motion induced by the rudder? Also, the rudder surface is
above the plane's center of lift but I don't know how much of a
factor
that is.

It's called a yaw/roll couple. As you create yaw you acellerate the
outside wing which then has more lift. It raises coupling with roll
and
you have turn.


Gotta disagree there Dudley. While it is true, and that's what happening
to some degree initially, the majority of the yaw roll couple in
lightplanes comes from the dihedral. the wing opposite the direction of
yaw has a higher angle of attack and generates more lift then the
opposite, which now has a lower alpha. Airplanes with no dihedral will
still roll slightly in the direction of yaw but it's nearly zilch.
can prove the first statement for yourself by introducing the yaw so
slowly as to make the diffrence in speeds insignificant. The airplane
will still roll in the direction of the yaw.
The V1 cruise missile had no dihedral and no ailerons and was easily
upset for this reason. Once it was off a wings level flight path it's
gyros had no chance of getting it back into straight and level.
Swept wing airplanes can have a huge yaw roll couple because as you yaw,
the forward moving wing's aspect ratio becomes massive just as the aft
moving's wing shrinks.(transonic ones have a reverse effect couple at
altitude, but that's another story)


Bertie

Not so much disagreement really. What you are saying is correct. All
these things happen. Technically however, the exact moment the yaw
induced higher angle of attack of the outside wing causes the excess
lift produced by the higher speed and alpha to introduce roll, a couple
has occurred and the aircraft is in an axis change from yaw only to
yaw/roll. It's a couple. Don't forget; there are complementary couplings
as well as adverse, and not all couplings result in divergence or departure.

It's really a matter of semantics and amplified explanation.
The dihedral actually stabilizes the airplane in roll and acts as you
have said.
A Cessna 195 would be one example of an airplane that will couple in yaw
without dihedral with no ill effect. A T38 however is an example of an
airplane that will couple in roll to departure if rolled at .9 mach with
a full lateral stick throw.

DH

--
Dudley Henriques

I'm puzzled as to how you could be doing a solo X country and not know
this. Did you first lesson not include "effect of controls"? what
about your theory?

Ah, that's better. I *knew* every thread had to devolve into
recriminations sooner or later...

;-)

In my case, my instructor NEVER discussed theories about flight. He
was a stick and rudder guy, could fly anything (and did), taught me
volumes, but rarely spoke about *why* certain things happened in
flight. I guess he just figured I would learn these things when
studying for the written.

I never did learn a lot of the subtle stuff (like why a rudder input
banks the wings) until much later. I suspect Paul is in the same boat.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck writes:

In my case, my instructor NEVER discussed theories about flight. He
was a stick and rudder guy, could fly anything (and did), taught me
volumes, but rarely spoke about *why* certain things happened in
flight. I guess he just figured I would learn these things when
studying for the written.

I never did learn a lot of the subtle stuff (like why a rudder input
banks the wings) until much later. I suspect Paul is in the same boat.

Most skills can be learned in a number of ways. Many skills are taught in
rote manner, i.e., "to accomplish x, do y," or "when the aircraft does x,
react with y." This is easy and fast to learn but makes exceptions harder to
handle. Skills can also be taught by teaching theory and then letting the
student apply the theory, but this is rather tedious and slow, and the student
must have good reasoning ability in order to succeed. To address the largest
possible audience, rote learning tends to be preferred, but that does
occasionally leave competent and curious students wondering about certain
things.

On Oct 21, 7:14 am, Mxsmanic wrote:
Jay Honeck writes:
In my case, my instructor NEVER discussed theories about flight. He
was a stick and rudder guy, could fly anything (and did), taught me
volumes, but rarely spoke about *why* certain things happened in
flight. I guess he just figured I would learn these things when
studying for the written.

I never did learn a lot of the subtle stuff (like why a rudder input
banks the wings) until much later. I suspect Paul is in the same boat.

Most skills can be learned in a number of ways. Many skills are taught in
rote manner, i.e., "to accomplish x, do y," or "when the aircraft does x,
react with y." This is easy and fast to learn but makes exceptions harder to
handle. Skills can also be taught by teaching theory and then letting the
student apply the theory, but this is rather tedious and slow, and the student
must have good reasoning ability in order to succeed. To address the largest
possible audience, rote learning tends to be preferred, but that does
occasionally leave competent and curious students wondering about certain
things.

I feel Bertie about to make an entrance,,,,, ;)