A very basic question

(Ramapriya) wrote in news:30a8759c.0411060737.6b82f9c3
@posting.google.com:

Hi guys,

Unlike the elevators and rudder that change an aircraft's pitch and
yaw with no other secondary effect, why does the banking of wings by
the use of ailerons not just roll an aircraft but also produces a turn
(yaw)? Logically, one would expect an aircraft to keep going straight
ahead even if the pilot banked the aircraft left or right. Where does
the turning effect come from?

Is there a website you know of that can teach me such basics, without
having to bug you?

Cheers,

Ramapriya



When you bank, you create a horizontal component of lift. This will pull
the airplane to fly sideways. The natural weathervaning effect of the
airplane will steer the nose into the relative wind. You can help that
effect by adding rudder.

This is a good question. Even most instructors do not know the answer to
this questions.


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" jls" wrote in news:758jd.40492$T_.36816
@bignews4.bellsouth.net:


"James Robinson" wrote in message
...
Ramapriya wrote:

... why does the banking of wings by the use of ailerons not just
roll an aircraft but also produces a turn (yaw)?

Simply stated, when an aircraft is in level flight, the lift of the
wings works directly against gravity. When an aircraft rolls one
direction or the other, the lift of the wings rolls away from vertical,
remaining at 90 degrees to the wings. This means only part of the lift
works against gravity. The rest causes the aircraft to swing away from
straight flight. It is somewhat akin to the effect of banking on a race
track.

Fair enough. The turn is caused by the horizontal component of lift.




Sure, but that still does not explain why the airplane turns. A horizontal
component of lift will make the airplane side-slip, not turn. It is the
stability (weathervane effect) that makes the airplane turn.

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"BTIZ" wrote in message
news:K97jd.86842$bk1.136@fed1read05...
As to the aileron, think of the relative wind on the wings.
With an aileron dropped (looking like a flap), there will be
increased drag.
Of course the other one goes up, but I don't think the resultant
force is equal on both wings.
Thus, yaw results.

Brian, are you stating that this yaw causes the turn?, actually this
is adverse yaw and resists the turn.

Come, lets step into my flying laboratory, the Grob 103, and we'll
explore that interesting concept called adverse yaw.

BT
Inside rudder will most definitely produce bank which will produce turn
exactly as Brian said it would. There is a difference between adverse
and complimentary yaw. Actually, there will be no adverse yaw if inside
rudder alone is used to induce complimentary yaw. Only aileron
application into a bank with no inside rudder will produce adverse yaw.
If complimentary yaw (inside rudder) is used with no aileron, the speed
difference between the retreating inside wing and the forward moving
outside wing will cause bank, which will be a direct secondary result of
the complimentary yaw being produced.
In other words, insider rudder will most definitely produce bank as a
secondary effect and as such will produce turn...assuming no anti turn
control input is present.
Dudley Henriques
International Fighter Pilots Fellowship
for email; take out the trash

"Ramapriya" wrote in message
om...
Where does
the turning effect come from?

The most basic (maybe too basic) answer is generally this: When you bank,
the lift is at an angle, not straight vertical. That angle pushes it the
plane to the side as well as up.

On Sat, 6 Nov 2004 10:41:12 -0800, "Peter Duniho"
wrote:

"Ramapriya" wrote in message
. com...
Unlike the elevators and rudder that change an aircraft's pitch and
yaw with no other secondary effect, why does the banking of wings by
the use of ailerons not just roll an aircraft but also produces a turn
(yaw)?

The simple answer is that, theoretically, the ailerons act exactly as you
would think. That is, a turn is not caused by a change in bank.

In level flight, the wings are generating 1g of lift, equivalent to
the weight of the aircraft and all occupants inside. If this lift
vector is rotated by the ailerons then it will point in the direction
of the rotation, and therefore force the aircraft to change its
direction of flight, and therefore to turn.

And there will a corresponding loss of lift against gravity; all
simply calculated by geometric functions of sine and cosine. So the
aircraft will begin to descend, as it turns.


A more complicated answer is that since the "center of lift" is ahead of the
"center of gravity", having the lift vector tilted to one side or the other
by bank does pull the nose of the airplane around a bit, inducing a turn.

If the center of lift actually was ahead of the center of gravity then
the aircraft would loop nose-up, so it isn't. They are aligned. But
it is the acceleration in the direction of the rotated lift vector
which changes the direction of the airflow around the aircraft. So
the airfoils at the tail force the airplanes nose to point into the
direction of the changing wind.

This also changes the direction of the lift vector to the new
location, which is actually the same location, and it is known as the
center point of the circle the airplane is drawing out in 3-d space.
The circle is actually the bottom of a cone, with the cone drawn by
the lift vector of the aircraft. The tighter the turn then the
flatter the cone. If there is no turn then the cone is not a cone but
a flat plane instead.

In other words, the aircraft in a turn is flying in a circle, instead
of just accelerating sideways and retaining its former forward
velocity, which it does not do. The changing wind over the airfoils
rotate the aircraft into flying into a circle.


An even more complicated answer points out that the ailerons themselves
create increased drag on the raised wing and reduced drag on the lowered
wing, which creates a yaw opposite in direction to the intended turn.

More or less. A lowered aileron has the increased drag, while a
raised aileron has less drag. This will pull the nose around opposite
from the direction of expected bank.
Adverse yaw is the ailerons acting in place of the rudder, and it
prevents the aircraft from lining perfectly into the wind.

But once the aircraft is banked then the aircraft will turn. The
aircraft turns because it is banked.

A banked aircraft will not turn if, and only if, the wing is not
generating lift. A wing will not generate lift if its angle of attack
is so controlled by the horizontal stabilizer.

One other note, the aircraft will lose lift and so descend as it banks
into a turn. But as it descends, the wings will regain upward airflow
and restore the lift lossed. This stops the downward acceleration,
with the airplane having reached its terminal velocity. But the lift,
and the loads on the wing, have increased just from the aircraft going
into a bank; even if adjustments have not been made for level flight.

(I think this is ~correct. Pretty sure.)

--Mike

"The Weiss Family" wrote in message ...
Unlike the elevators and rudder that change an aircraft's pitch and
yaw with no other secondary effect, why does the banking of wings by
the use of ailerons not just roll an aircraft but also produces a turn
(yaw)? Logically, one would expect an aircraft to keep going straight
ahead even if the pilot banked the aircraft left or right. Where does
the turning effect come from?

Is there a website you know of that can teach me such basics, without
having to bug you?

Cheers,

Ramapriya


Rudder most definitely adds roll as a secondary effect.
In fact, I use rudder to momentarily keep the wings level when I'm changing
maps, etc.
At low speeds, when the ailerons are not that effective, rudder can be much
more effective.

As to the aileron, think of the relative wind on the wings.
With an aileron dropped (looking like a flap), there will be increased drag.
Of course the other one goes up, but I don't think the resultant force is
equal on both wings.
Thus, yaw results.
While it seems intuitive to me, I probably don't have the best explanation,
so can anyone else elaborate?

Adam
N7966L
Beech Super III

Because when the wing is level, the lift is up. When the wing is
banked to the right, the lift is also tilted to the right pulling the
plane in the direction. Same for the left.

Bryan

I was always under the impression that in most light a/c, the dominate
rolling effect from 'inside' rudder is the result of dihedral (or
alternatively, sweep back). RC modelers are pretty adept at setting up
aircraft for 'pure' yaw from rudder input - no dihedral, symmetrical layout,
etc. Or setting up aircraft to bank and turn without ailerons - lots of
didedral.

Though I'd agree that the "forward motion of the outside wing" explanation
accurately predicts the rolling effect from rudder input that occurs on most
a/c - which is ok for training purposes.

"Dudley Henriques"
snip
If complimentary yaw (inside rudder) is used with no aileron, the speed
difference between the retreating inside wing and the forward moving
outside wing will cause bank, which will be a direct secondary result of
the complimentary yaw being produced.
In other words, insider rudder will most definitely produce bank as a
secondary effect and as such will produce turn...assuming no anti turn
control input is present.
Dudley Henriques
International Fighter Pilots Fellowship
for email; take out the trash

"Maule Driver" wrote in message
om...
I was always under the impression that in most light a/c, the dominate
rolling effect from 'inside' rudder is the result of dihedral (or
alternatively, sweep back). RC modelers are pretty adept at setting
up
aircraft for 'pure' yaw from rudder input - no dihedral, symmetrical
layout,
etc. Or setting up aircraft to bank and turn without ailerons - lots
of
didedral.

Though I'd agree that the "forward motion of the outside wing"
explanation
accurately predicts the rolling effect from rudder input that occurs
on most
a/c - which is ok for training purposes.

I would agree with this completely. Dihedral contributes heavily to the
lateral stability of the aircraft if sideslip is present to be sure. The
prime contribution of dihedral is in the development of a stable rolling
moment with sideslip, which is consistent with what most of us are
saying.
The problem with answering many questions in aerodynamics is that there
isn't one single example or answer that will suffice.
(Lift is a PRIME example of this. ) Anyone trying to explain lift in a
simple sentence will find a slew of missing data soon to follow :-) The
problem in aerodynamics is that in much of what is happening, several
explanations are in force physically together at one instant in time.
The way we look at dihedral in the flight test community is primarily as
it's effect on the lateral stability scenario which relates with
sideslip present to relative wind, differential in angle of attack,
changes in lift raising a windward wing producing stability.
I think we're both on the same page, and dealing with the same effect
since all of what we're discussing is present in complimentary yaw IF
dihedral is present.
Now, if we inject an airplane into this equation like a Cessna 195 for
example.......... :-))))
Dudley Henriques
International Fighter Pilots Fellowship
for email; take out the trash

(Ramapriya) wrote in message . com...
Hi guys,

Unlike the elevators and rudder that change an aircraft's pitch and
yaw with no other secondary effect, why does the banking of wings by
the use of ailerons not just roll an aircraft but also produces a turn
(yaw)? Logically, one would expect an aircraft to keep going straight
ahead even if the pilot banked the aircraft left or right. Where does
the turning effect come from?

Is there a website you know of that can teach me such basics, without
having to bug you?

Cheers,

Ramapriya


Alas, Ramapriya, it is far more complex than that! First of all, the
rudder causes not only yaw, but by virtue of the yaw accelerating the
outside wing and effectively increasing lift, causes bank toward the
inside of the turn.

The ailerons cause both roll AND yaw...but counterintuitively, the yaw
is to the outside of the turn. That is because the creation of lift
also creates drag. And when you use the ailerons to bank, you are
increasing the lift on the outside wing...and therefore yawing toward
the "outside" of the turn. The rudder largely is used to counter that
force.

And none of that is why an airplane turns. The true cause of the turn
is...well, we need to look at an airplane in our mind's eye...picture
it in level flight. The force of gravity is offset by the force of
lift...generated by the wings. We can say that there is a downward
vector...gravity...and an upward vector...lift, which is perpendicular
to the airplane's wing. Now, let us bank the airplane. The lift vector
is still perpendicular to the airplane's wing, but now it is directed
somewhat toward the inside of the bank. And the airplane therefore
turns that way...is pulled that way, if you will. Oh, and yes, since
the lift vector is directed toward the inside of the turn, the amount
of lift to counteract gravity is decreased...and the airplane will
descend unless something is done...usually the addition of power or an
increase in the angle of attack...increases the antigravity portion of
the lift vector.

That will either help or totally confuse you. Feel free to email me
for a dialog.

Jim

I strongly suggest that you visit

www.whittsflying.com

It will answer pretty much any flying question that you have.

I also suggest that you go for a discovery flight - sounds like you are
moree than ready

Of course, you are also still welcome to ask here.

Tony

--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE





In article ,
(Ramapriya) wrote:

Hi guys,

Unlike the elevators and rudder that change an aircraft's pitch and
yaw with no other secondary effect, why does the banking of wings by
the use of ailerons not just roll an aircraft but also produces a turn
(yaw)? Logically, one would expect an aircraft to keep going straight
ahead even if the pilot banked the aircraft left or right. Where does
the turning effect come from?

Is there a website you know of that can teach me such basics, without
having to bug you?

Cheers,

Ramapriya