A very basic question

"The Weiss Family" wrote in message ...
Thus, yaw results.
While it seems intuitive to me, I probably don't have the best explanation,
so can anyone else elaborate?


Tilting of the lift vector also results in a turn.

"Mike Rhodes" wrote in message
...
[...signed...]
(I think this is ~correct. Pretty sure.)


You ought to *know* before you post, I guess.

With respect to your specific comments:

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.

Wrong. In the theoretical case I describe (which isn't the reality case
anyway), banking would simply cause the airplane to sideslip sideways,
without any turn occurring.

The "1g of lift" stuff is irrelevant, except inasmuch as there IS lift (a
force) that is redirected sideways.

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.

Wrong, again. The center of lift is actually behind the center of gravity
(I screwed up in my original post). The horizontal stabilizer balances out
the difference in force to prevent the nose from dropping as a result of the
difference.

To revist my original post, the correct statement would have been "since the
'center of lift' is behind 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 *opposite to that intended*."

I apologize for resulting confusion, but the fact remains that your
statement is entirely incorrect.

[...]
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.

Heh...one of the few things you get right, and it's exactly what I wrote.

Adverse yaw is the ailerons acting in place of the rudder, and it
prevents the aircraft from lining perfectly into the wind.

"In place of"? Uh, okay...I guess you could say it that way.

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

No, it does not. Any turn as a result of bank is actually due to other
design features of the airplane, such as dihedral and a vertical stabilizer.

Pete

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?

The wings of an airplane produce lift. When the aircraft is in level flight, this
lift is pointed straight up and pulls up against gravity. When you bank the plane,
the lift now points partially in the direction of bank and pulls the plane in that
direction.

Someone mentioned the book "Stick and Rudder" some time back. That's one book you
could buy. There are many others that you could buy instead. I don't know of much on
the web for free.

George Patterson
If a man gets into a fight 3,000 miles away from home, he *had* to have
been looking for it.

Go to howstuffworks.com and search for airplane wing or airplane or
something like that and you will find a detailed description with pictures.
"Ramapriya" wrote in message
om...
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





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Dudely.. he said turning by banking only.. he said nothing of "inside
rudder"
at least not the way I read it

BT

"Dudley Henriques" wrote in message
news

"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

"BTIZ" wrote in message
news:Lphjd.90058$bk1.21776@fed1read05...
Dudely.. he said turning by banking only.. he said nothing of "inside
rudder"
at least not the way I read it

BT

I admit the question is a little vague to say the least. I think I might
have got caught up in that "turn"(yaw) thing and read it to mean
complimentary yaw producing turn as a secondary effect.
I read it as asking several things that were not exactly correct in
premise to begin with!

For example;
"Unlike the elevators and rudder that change an aircraft's pitch and
yaw with no other secondary effect,"

I have a bit of a problem with this premise before even getting into the
"question"
:-)
Then we have this;
"why does the banking of wings by
the use of ailerons not just roll an aircraft but also produces a turn
(yaw)? "

I read his context as aileron being used and producing turn which in the
turn (inside context) would be complimentary yaw.....which of course
wouldn't be the secondary effect of using aileron to begin
with.........are you following this........cause I'm getting lost!!!
:-)))
The parenthesis (yaw) opens up a whole deck of cards since banking the
airplane with just aileron would produce adverse yaw; not complimentary
yaw, and it will also as a secondary effect after adverse yaw had
stabilized, produce turn if not held back with anti turn controls. It's
puzzling the way he worded it really.
I'm not sure really what he was asking at this point!! :-)

Anyway, the answer for uncoordinated turn entry using various isolated
control inputs would be if aileron alone....adverse yaw followed by turn
after stabilization and vector split;
and inside rudder alone; turn as bank is introduced as the secondary and
the lift vector splits.
You are completely right of course about dihedral effect!
Anyway....I think I'll leave this for you guys to play with. I'm going
to bed!!
:-)
Have a good one,
Dudley

"Peter Duniho" wrote in message ...

There are many. The one already provided by Stan's reply is one of my
favorites. There are also several good books on the topic, including the
FAA's own flight training manuals (available for download from their web
site somewhere, but I don't have a link handy) and a book called
"Aerodynamics for Naval Aviators".

Pete

I love jsd's site too, and have condensed all those chapters into two
Word files (in case someone is interested!). But I wish Denker had
also written the stuff for a non-aviator like me in mind. For example,
he's written loads on trim but till this day, I don't know what
exactly trimming is and how it physically works

Ramapriya

"Ramapriya" wrote in message
om...
I love jsd's site too, and have condensed all those chapters into two
Word files (in case someone is interested!). But I wish Denker had
also written the stuff for a non-aviator like me in mind. For example,
he's written loads on trim but till this day, I don't know what
exactly trimming is and how it physically works

Well, trimming isn't complicated. But there are numerous methods for
actually *accomplishing* it, so perhaps that's why Denker sort of just
assumes you're familiar with the concept and doesn't get into how it
"physically works".

That is, the basic concept is simple: "trimming" simply means to set a
particular control (the "trim"...generally you may have elevator, rudder, or
aileron trim or any combination of the three, though I don't doubt there's
at least one unusual aircraft out there that has yet another possibility I'm
not aware of) so that instead of the pilot having to hold a particular
control input, the "trim" holds it for him.

So, for elevator trim (the most common type), once the pilot has selected a
pitch attitude for a climb (for example), along with the desired power
setting (often full power), he can then set the elevator trim to hold the
elevator control input at that particular pitch attitude.

It gets complicated when you start talking about each specific trim
mechanism, since they all have subtle differences in exactly how they
accomplish that "hold the control input" action, as well as effects of power
or airspeed changes on the effect of the trim.

As an example, look at elevator trim:

Generally speaking, elevator trim can be thought of as "setting" an
airspeed, since for a given power setting, airspeed varies precisely with
pitch attitude. A further generalization is that changes in power do NOT
actually change the "trimmed airspeed". That is, for a given trim setting,
increasing power will result in the nose pitching up and decreasing power
will result in the nose pitching down, with the airspeed remaining constant
in both cases.

For some aircraft, the airspeed literally remains constant. For others, you
will actually see slight variations in airspeed. But regardless, any
variations are almost always so small that you can still think of setting
airspeed rather than a specific trim setting. Since trim doesn't really set
a pitch attitude either (except for a given power setting), it's not like
there's really a more useful paradigm to use.

Just as an example of one elevator trim mechanism: in most of the
single-engine Cessnas (and maybe their piston twins, but I don't know those
airplanes well enough to say), elevator trim is accomplished through the use
of a moveable "trim tab" mounted on the trailing edge of the elevator.
There's a wheel in the cockpit that moves this trim tab up and down. When
the trim tab moves up, it exerts a downward force on the elevator and when
the trim tab moves down, it exerts an upward force on the elevator
(aerodynamically, in the exact same way that the elevator itself changes the
horizontal stabilizer's up or down force). The trim tab is relatively
small, so that by pushing down on the elevator, the net effect is to cause
the horizontal stabilizer to create an upward force (nose down pitch), just
as if the pilot had pushed forward on the yoke to deflect the elevator
downward.

Anyway, other aviation references will provide much more detailed
information on that sort of thing. "Stick and Rudder" will give you a good
pilot's view of things, while the "Aerodynamics for Naval Aviators" delves
more deeply into the actual mechanics of flight (naturally).

Pete

On 6 Nov 2004 07:37:15 -0800, (Ramapriya) wrote:

why does the banking of wings by
the use of ailerons not just roll an aircraft

Drag. The lower wing and its raised aileron produce more drag than the
upper with with its lowered aileron. There are little sketches in the
flying texts showing why this is the case. Would it be possible to
design ailerons that eliminated the difference? Maybe.

all the best -- Dan Ford
email: (put Cubdriver in subject line)

Warbird's Forum www.warbirdforum.com
Piper Cub Forum www.pipercubforum.com
the blog www.danford.net

On Sun, 07 Nov 2004 05:09:36 GMT, "Dudley Henriques"
wrote:

"why does the banking of wings by
the use of ailerons not just roll an aircraft but also produces a turn

He wants to know why his pilot can't simply do rolls around the
plane's longitudinal axis.

Perhaps it would help to know what inputs are necessary to make such a
roll? If you are rolling to your left, do you apply right rudder?

all the best -- Dan Ford
email: (put Cubdriver in subject line)

Warbird's Forum www.warbirdforum.com
Piper Cub Forum www.pipercubforum.com
the blog www.danford.net