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

On Sat, 20 Oct 2007 22:13:36 -0700, "BT" wrote:

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.

Yes, but you're not sitting *in* the R/C model, so you don't realize
that it's slipping and skidding all over the sky. Wouldn't be so
comfortable in a real airplane... though many of the older low end
ultralights had only rudder, no ailerons, either.

A high wing plane gets some dihedral effect from the wing position,
even if the actual geometric dihedral is zero. Sweep also acts as
dihedral, too.

OTOH, my Kolb has zero dihedral... and the rudder has just about nil
roll effect.

-Dana
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On Oct 21, 7:13 am, "BT" wrote:
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.

In a stall, you pick up the low wing with rudder, not aileron, that only
adds adverse yaw, more drag on the low wing, and fights the rudder.
BT

Using aileron to try to raise a dropping wing in a stall
increases the AOA on that wing and can aggravate the drop, causing a
spin. That's the real reason for using rudder.
The roll couple when we add rudder has a lot to do with
wingtip vortices. The vortex costs some lift as the air flows off the
bottom of the wing and over the tip. Sticking a wing ahead interferes
with that and can improve the lift on that side.

Dan (currently in Africa, where I find the Internet alive and
well)

BT wrote:
Isn't interesting that entry level RC Aircraft only have rudder and elevator
controls.. and then turn just fine.

When the rudder is applied, a skid and a turn follow. The skid is of no
consequence, but any turn rate at all is of great consequence, since tht
makes the outside wing fly faster, creating more lift, and a bank is the
result; a two-stage event where succession is important.

Sort of like turning a bicycle, where a small jink to the outside of
the intended turn is required to establish the bank needed for the turn.

In a stall, you pick up the low wing with rudder, not aileron, that only
adds adverse yaw, more drag on the low wing, and fights the rudder.

Aileron action, following the wright Brothers wing warping, was
intentionally symmetrical (same magnitude both sides) and all pilot
training through and after WWII were taught "Coordination"; one applied
rudder and aileron simultaneously. After WWII, civil airplane designers
acted to make life simpler for the pilot by tweaking aileron action.

The adverse yaw is caused by the extra induced* drag of a wing that is
obliged to lift more ends up also dragging more, The inbord wing is
casued to drop by an up-aileron, and any increase in parasite (non-lift)
drag is exceeded by the lack of induced drag. One day the light came on
and it was deduced that if only the inbirad aileron deflected up, the
adverse yaw would ve greately reduced if not eliminated. Sa ther wwas
born "differential movement" and belcrakx and levers were rigged such
that the inbord aileron deflected up a lot, while the outboard aileron
deflected very little.

[*"Induced" means that it is not real friction or turbulence drag, but
a new rearward force that results from a wing or aileron that is
creating extra lift.]

So today, most civit aircraft can be put into and out of gentle turns
with aileron alone, and that's what makes single-axis autopilots
(aileron only) so successful.

Angelo Campanella

Angelo Campanella wrote in
:

BT wrote:
Isn't interesting that entry level RC Aircraft only have rudder and
elevator controls.. and then turn just fine.

When the rudder is applied, a skid and a turn follow. The skid is
of no
consequence, but any turn rate at all is of great consequence, since
tht makes the outside wing fly faster, creating more lift, and a bank
is the result; a two-stage event where succession is important.




Not true.

All the evidence you need to the contrary can be supplied by simply yawing
the airplane while holding opposite aileron, thus inducing a skid, and then
neutralising the ailerons.

the airplane will roll left and nothing to do with the differntial speed of
the wing, because there won;t be any!


Bertie

....but if the wing has any significant dihedral, the 'upwind' wing will be
flying at a higher angle of attack than the 'downwind' wing, causing a roll
towards the downwind wing. The 'downwind' wing inboard section will also be
partially blanked by the fuselage which will also produce asymmetrical lift
on the wing.

--
Best Regards,
Mike

http://photoshow.comcast.net/mikenoel

"Bertie the Bunyip" wrote in message
.. .
Angelo Campanella wrote in
:

BT wrote:
Isn't interesting that entry level RC Aircraft only have rudder and
elevator controls.. and then turn just fine.

When the rudder is applied, a skid and a turn follow. The skid is
of no
consequence, but any turn rate at all is of great consequence, since
tht makes the outside wing fly faster, creating more lift, and a bank
is the result; a two-stage event where succession is important.




Not true.

All the evidence you need to the contrary can be supplied by simply yawing
the airplane while holding opposite aileron, thus inducing a skid, and
then
neutralising the ailerons.

the airplane will roll left and nothing to do with the differntial speed
of
the wing, because there won;t be any!


Bertie

"Mike Noel" wrote in
:

...but if the wing has any significant dihedral, the 'upwind' wing
will be flying at a higher angle of attack than the 'downwind' wing,
causing a roll towards the downwind wing. The 'downwind' wing inboard
section will also be partially blanked by the fuselage which will also
produce asymmetrical lift on the wing.


Xactly.


Bertie

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.

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.