Slips and skids

Andrew Sarangan wrote in news:2a91a319-e4ad-48a0-
:

On Mar 16, 3:41 pm, wrote:
On Mar 15, 10:57 pm, wrote:

I think the more bottom rudder you give in a turn, the more the
nose
will appear to move lower against a given horizon. All the rudder
does
is pull the plane around an axis from ear-to-ear.

The rudder is intended to control adverse yaw, not to turn the
airplane. Banking the airplane turns it. Some airplanes, the "idiot-
proof" ones, sometimes need no rudder at all in a turn.

Dan

Actually, I beg to differ. Banking rotates the airplane about its
longitudinal axis. Yawing rotates about its vertical axis. Neither of
these causes the airplane to change heading. It is the aerodynamic
forces that streamlines the airplane with the relative wind is what
makes it turn (ie weather vaning).

For comparison, think of the space shuttle banking or yawing in orbit.
This does not change its heading because there is no streamlining
effect.





Also because there's no lift under the wings!

You can happily do a flat turn in a lot of airplanes. Wings level and
stomp on the rudder and around it will come. Some will even do it faster
with the outboard wing down a bit. I sued to do this in supercubs and
citabrias when towing so's i could enter the pattern at some insane
speed on base and then scrub it off base to final



Bertie

On Mar 16, 1:47 pm, Andrew Sarangan wrote:
On Mar 16, 3:41 pm, wrote:

On Mar 15, 10:57 pm, wrote:

I think the more bottom rudder you give in a turn, the more the nose
will appear to move lower against a given horizon. All the rudder does
is pull the plane around an axis from ear-to-ear.

The rudder is intended to control adverse yaw, not to turn the
airplane. Banking the airplane turns it. Some airplanes, the "idiot-
proof" ones, sometimes need no rudder at all in a turn.

Dan

Actually, I beg to differ. Banking rotates the airplane about its
longitudinal axis. Yawing rotates about its vertical axis. Neither of
these causes the airplane to change heading. It is the aerodynamic
forces that streamlines the airplane with the relative wind is what
makes it turn (ie weather vaning).

For comparison, think of the space shuttle banking or yawing in orbit.
This does not change its heading because there is no streamlining
effect.


http://www.av8n.com/how/htm/4forces.html#note64 Section 4.3

http://www.av8n.com/how/htm/yaw.html#sec-yaw-stability Section 8.2

The bank moves the airplane sideways. The fin, moved sideways,
points the airplane in the new direction. The rudder controls adverse
yaw, which tends to drag the nose away from the turn.

Dan

On Mar 16, 5:41*pm, wrote:

http://www.av8n.com/how/htm/4forces.html#note64* * *Section 4.3

http://www.av8n.com/how/htm/yaw.html#sec-yaw-stability* Section 8.2

* * *The bank moves the airplane sideways. The fin, moved sideways,
points the airplane in the new direction. The rudder controls adverse
yaw, which tends to drag the nose away from the turn.

Overcoming adverse yaw is only one of the reasons your reference gives
for using the rudder in a coordinated turn. The other is "You use the
rudder to change your heading (i.e. to overcome yaw-wise inertia, i.e.
to provide yaw-wise acceleration)" (section 8.8).

As the reference you cite explains, even apart from adverse yaw,
relying on weathervaning to realign the plane would not result in as
smooth a turn as properly coordinated use of the rudder.

On Mar 15, 4:38*pm, William Hung wrote:
I have heard definitions for both, but I'm still confused. *Anyone
care to elaborate?

Wil

A lot of good inputs, I'm going to need some time...

Thanks all,
Wil

On Mar 16, 2:42*pm, wrote:
On Mar 15, 9:23 pm, wrote:

Except when the control system is misrigged like a plane I flew
recently. In order to get a coordinated turn, I had to give "top"
rudder in a turn. That's wrong.

* * Is that the one in which I suggested a broken rudder bar spring?
Anything come of that?

* * * Dan

Yeah, I think so. Another person also emailed me private and said the
same.

The chief pilot and other instructors at the FBO got an email from me.
Never heard anything back. Maybe they checked it out and decided I was
wrong; or maybe I found a problem and they don't want to comment on it
in a traceable way. I think I'll switch to their 172, rather than fly
that 150.

On the other hand maybe they have fixed it and I just don't know about
it.

* * *The bank moves the airplane sideways. The fin, moved sideways,
points the airplane in the new direction. The rudder controls adverse
yaw, which tends to drag the nose away from the turn.

* * * Dan- Hide quoted text -

- Show quoted text -

I'd say that the rudder controls yaw, period.

You can change heading using the rudder. I've done it (hah, especially
a lot as a student trying to practice power on stalls), and it stands
to reason considering the force vectors acting on a fuselage that is
yawed into the relative wind. I've never tried to do what Bertie
describes though. But I will next time I'm up.

Nevertheless I follow the school that says the elevator is really the
main turn control (Langewiesche, Stowell, and many others).

Let's see what is it that you are experiencing. Before flight with the
plane sitting on level ground (at least as much as you can tell). Is the
ball centered? As you taxi and make small heading changes, does the ball
move freely in the raceway? In the practice area. Slow to 60 Kts, pitch
up and add full power, maintain 60 kts. You should immediately notice the
ball go right and you will need right rudder to center the ball. Keep the
plane from changing heading. Be sure to keep the wings level. Now notice
as you enter into a left turn, you DO NOT need to step on the left rudder
(you only maintain enough left rudder pressure to keep slack out of the
cable system) until you have released all the pressure from the right
rudder, then as you increase bank further you can add left rudder. In fact
you MIGHT not need left rudder at all. Keep the ball centered all the time.
Is that what you are seeing?

Now, In a glide situation, things should be more symmetrical. Lower the
nose, reduce power to say 1200 rpm, maintain 60 kts. As you bank right and
left the rudder pressures required to keep the ball centered each way should
be about the same. Do you see this effect? Please report if you know, or
try it the next time you go out.

--
Regards, BobF.
wrote in message
...
On Mar 16, 2:42 pm, wrote:
On Mar 15, 9:23 pm, wrote:

Except when the control system is misrigged like a plane I flew
recently. In order to get a coordinated turn, I had to give "top"
rudder in a turn. That's wrong.

Is that the one in which I suggested a broken rudder bar spring?
Anything come of that?

Dan

Yeah, I think so. Another person also emailed me private and said the
same.

The chief pilot and other instructors at the FBO got an email from me.
Never heard anything back. Maybe they checked it out and decided I was
wrong; or maybe I found a problem and they don't want to comment on it
in a traceable way. I think I'll switch to their 172, rather than fly
that 150.

On the other hand maybe they have fixed it and I just don't know about
it.

On Mar 16, 3:44 pm, wrote:

I'd say that the rudder controls yaw, period.

You can change heading using the rudder. I've done it (hah, especially
a lot as a student trying to practice power on stalls), and it stands
to reason considering the force vectors acting on a fuselage that is
yawed into the relative wind. I've never tried to do what Bertie
describes though. But I will next time I'm up.

Nevertheless I follow the school that says the elevator is really the
main turn control (Langewiesche, Stowell, and many others).


Which makes a lot of sense.
It's just that numerous authors hold the theory that if the left
vector is angled, the direction of flight is altered and the fin
points the nose in the new direction. And as I said, some airplanes
are so "well" designed (read: simple to fly) that no rudder input is
needed at all to keep the ball centered while going into the turn, or
keeping it there once established in the turn. Aileron geometry is
such that adverse yaw is completely eliminated. Elevator is still
necessary to counter the nose-drop as drag piles up, and there's no
argument from me that it contributes to the turn, especially a steep
turn.
I can just imagine that some clever engineer will soon design
an airplane that needs no elevator input in a turn. The R182
(colloquially known as the 182RG) is already a really tame airplane in
a steep turn; I don't know how they did it, but steep turns in it are
so easy, with an absolute minimum of back pressure. And that's with a
forward CG, too.

Dan

On Mar 16, 6:44 pm, wrote:


I'd say that the rudder controls yaw, period.

You can change heading using the rudder. I've done it (hah, especially
a lot as a student trying to practice power on stalls), and it stands
to reason considering the force vectors acting on a fuselage that is
yawed into the relative wind. I've never tried to do what Bertie
describes though. But I will next time I'm up.

Nevertheless I follow the school that says the elevator is really the
main turn control (Langewiesche, Stowell, and many others).

Yes, but (oh those exceptions)...

Rudder comes in handy for very small changes in course (such as
required on an ILS).

It's nearly impossible to bank 2 degrees, but very easy to correct 2
degrees with rudder.


Dan Mc

--
Regards, BobF.
"Dan" wrote in message
...
On Mar 16, 6:44 pm, wrote:


I'd say that the rudder controls yaw, period.

You can change heading using the rudder. I've done it (hah, especially
a lot as a student trying to practice power on stalls), and it stands
to reason considering the force vectors acting on a fuselage that is
yawed into the relative wind. I've never tried to do what Bertie
describes though. But I will next time I'm up.

Nevertheless I follow the school that says the elevator is really the
main turn control (Langewiesche, Stowell, and many others).

Yes, but (oh those exceptions)...

Rudder comes in handy for very small changes in course (such as
required on an ILS).

You know, yaw right! Seriously, I've used this technique a lot. Works
particularly well on large airplanes. I get mixed responses from DFE's
however and check with them before I turn a student loose on him. Some
don't mind it and another ripped one of students apart because of it.

It's nearly impossible to bank 2 degrees, but very easy to correct 2
degrees with rudder.


Dan Mc