Leading Turns with Rudder - Revisited

Roy Clark, "B6" wrote:
So, I checked my home soaring library and found the following that
includes some ‘name brand’ opinions:

“For most beginners, making a turn is the most difficult step in
learning to fly. Two controls have to be operated together to perform
the evolution correctly. The rudder bar must be pushed back and the
stick tilted over. These movements must be made in coordination if the
glider is to be banked and turned at the same time.”
- Edwin Way Teale, The Book of Gliders, page 205, 1930

I agree with the statement above.

But the rudder can never produce a turn. It cannot “start” a turn or
even “help the turn get started.” It cannot “stop” a turn or even
“help the turn get stopped. The only effect the rudder can ever
produce is yaw.

some snipping.

- Wolfgang Langewiesche, Stick and Rudder: An Explanation of the Art
of
Flying, pages 192-3, 1944

I don't have the full context from the quote above, and while I am
normally loathe to contradict Langewiesche, I must report I have
successfully produced turns with just the rudder in gliders. Give it a
try, and you will find you can produce an adequate turn, because the
yawing causes the dihedral to bank the glider in the desired direction.
At thermalling speeds, the turn isn't entered as quickly or as neatly,
but it happens. The higher the speed, the better the rudder works to
turn the glider.

There is a situation where the rudder does a good job of turning the
glider, and that's when it's rolling fast on the ground. Doing a
"coordinated" turn, where you also use the ailerons, is going to get you
into trouble.

As an instructor, I discovered the emphasis on "coordinated turns" and
telling students "the rudder doesn't turn the glider" led to good
airwork but caused problems while rolling on the ground. I stopped
talking about WHAT turned the glider and started talking about each
controls primary function, and what you wanted to see through the canopy
when you did turns. I'd demonstrate the action of each control, and show
them what a good turn looked like, then let them try it themselves. I
emphasized using the controls to obtain/maintain the desired "picture"
(attitude) out of the canopy.

In the air, they very quickly learned to use the rudder to keep the nose
from yawing as they rolled into the turn. I didn't have to tell them
when to apply rudder or how much to use, as they could see for
themselves when the nose didn't move in the right direction, and correct
it. After some practice, it became automatic, and when they were too
early/late or too much/little with any control, they could recognize the
error and know which control was misapplied.

On the ground, they no longer had problems slavishly trying to
"coordinate", as they continued to use the ailerons to keep the wings in
the desired attitude and used the rudder to keep the nose pointed in the
desired direction.

So, I suggest we stop telling people "the rudder doesn't turn the
glider" because the statement is false, and tell them the truth: we use
the rudder to turn the glider on the ground, and in the air we use the
ailerons, rudder, and elevator to turn the glider.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

At 05:00 12 August 2008, Eric Greenwell wrote:
Roy Clark, "B6" wrote:
snipped

I don't have the full context from the quote above, and while I am
normally loathe to contradict Langewiesche, I must report I have
successfully produced turns with just the rudder in gliders. Give it a
try, and you will find you can produce an adequate turn, because the
yawing causes the dihedral to bank the glider in the desired direction.

I suggest you give it a try at or near the stall...

(Only in america would we come across such a technique even being
discussed!)

I don't have the full context from the quote above, and while I am
normally loathe to contradict Langewiesche, I must report I have
successfully produced turns with just the rudder in gliders. Give it a
try, and you will find you can produce an adequate turn, because the
yawing causes the dihedral to bank the glider in the desired direction.

I suggest you give it a try at or near the stall...

(Only in america would we come across such a technique even being
discussed!)

And only on the world wide web would an American assume they were the extent of the actual world.

Bagger
winter in Aus-bloody-stralia mate
:-)

On Aug 12, 6:33 am, bagmaker
wrote:
-
I don't have the full context from the quote above, and while I am
normally loathe to contradict Langewiesche, I must report I have
successfully produced turns with just the rudder in gliders. Give it a

try, and you will find you can produce an adequate turn, because the
yawing causes the dihedral to bank the glider in the desired direction.

I suggest you give it a try at or near the stall...

(Only in america would we come across such a technique even being
discussed!)-

And only on the world wide web would an American assume they were the
extent of the actual world.

Bagger
winter in Aus-bloody-stralia mate
:-)

--
bagmaker

Come now. The author of very silly comment you refer to has a .uk
address.

bagmaker wrote:
-
I don't have the full context from the quote above, and while I am
normally loathe to contradict Langewiesche, I must report I have
successfully produced turns with just the rudder in gliders. Give it a

try, and you will find you can produce an adequate turn, because the
yawing causes the dihedral to bank the glider in the desired direction.


I suggest you give it a try at or near the stall...

I've not done it myself, but I've read about how attempting a
coordinated turn at or near stall can cause an "over the top" spin entry
when the out-of-turn aileron is deflected downward and stalls the outer
wing tip. In any case, my experience (and the text books) indicates that
an attempt to turn at or near a stall risks entering into a spin, even
with "proper" use of the controls. The pilot should speed up before
attempting the turn, coordinated or not.

This reminds me of another frequently repeated statement: "you won't
spin if you keep the yaw string centered." Besides my amazing ability to
turn a glider with just the rudder, I also have the ability to enter a
spin from a coordinated turn! I've done it in our club's Blanik and my
current glider, and I think it works on most gliders. Here's my secret:

*enter a coordinated, shallow (say, about 10 degree bank) turn
*reduce the airspeed slowly while keeping the yaw string straight
*at some point, the inner wing will drop, and the spin begins (it might
be spiral dive with some gliders)
*recover in the usual fashion when desired (I prefer to do it sooner
than later)

Of course, the glider's attitude is nose high, along with other warning
signs that the pilot is not doing things right. Still, I wonder how many
pilots unintentionally flew too slowly, but thought they were safe
because the yaw string was centered.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

This is the situation in which having the yaw string slightly to the
outside is helpful; a slight amount of slip, which Dick Johnson
recommended for increasing climb.

At 20:09 12 August 2008, Eric Greenwell wrote:

This reminds me of another frequently repeated statement: "you won't
spin if you keep the yaw string centered." Besides my amazing ability to

turn a glider with just the rudder, I also have the ability to enter a
spin from a coordinated turn! I've done it in our club's Blanik and my

current glider, and I think it works on most gliders. Here's my secret:

*enter a coordinated, shallow (say, about 10 degree bank) turn
*reduce the airspeed slowly while keeping the yaw string straight
*at some point, the inner wing will drop, and the spin begins (it might
be spiral dive with some gliders)
*recover in the usual fashion when desired (I prefer to do it sooner
than later)

Of course, the glider's attitude is nose high, along with other warning

signs that the pilot is not doing things right. Still, I wonder how many

pilots unintentionally flew too slowly, but thought they were safe
because the yaw string was centered.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at
www.motorglider.org

On Tue, 12 Aug 2008 20:09:25 GMT, Eric Greenwell
wrote:

bagmaker wrote:
-
I don't have the full context from the quote above, and while I am
normally loathe to contradict Langewiesche, I must report I have
successfully produced turns with just the rudder in gliders. Give it a

try, and you will find you can produce an adequate turn, because the
yawing causes the dihedral to bank the glider in the desired direction.


I suggest you give it a try at or near the stall...

I've not done it myself, but I've read about how attempting a
coordinated turn at or near stall can cause an "over the top" spin entry
when the out-of-turn aileron is deflected downward and stalls the outer
wing tip. In any case, my experience (and the text books) indicates that
an attempt to turn at or near a stall risks entering into a spin, even
with "proper" use of the controls. The pilot should speed up before
attempting the turn, coordinated or not.

This reminds me of another frequently repeated statement: "you won't
spin if you keep the yaw string centered." Besides my amazing ability to
turn a glider with just the rudder, I also have the ability to enter a
spin from a coordinated turn! I've done it in our club's Blanik and my
current glider, and I think it works on most gliders. Here's my secret:

*enter a coordinated, shallow (say, about 10 degree bank) turn
*reduce the airspeed slowly while keeping the yaw string straight
*at some point, the inner wing will drop, and the spin begins (it might
be spiral dive with some gliders)
*recover in the usual fashion when desired (I prefer to do it sooner
than later)

Of course, the glider's attitude is nose high, along with other warning
signs that the pilot is not doing things right. Still, I wonder how many
pilots unintentionally flew too slowly, but thought they were safe
because the yaw string was centered.

The understanding of just what a centered yaw string indicates is
something I have always struggled with.

After some thought experiments, and some flying experiments too,
I have come to my own realization that I must never assume that
a centered yaw string indicates anything about the angle of attack
occuring on the left and right wings.

In a coordinated turn, that is, a turn during which the yaw string
is centered, the angle of attack of the inside and outside wings is
not the same. the AOA of the inside (on the turn side) wing is
greater than the AOA of the outside wing and will stall before the
outside wing, and if the pilot allows this process to further develop
the glider will enter a spin.. We all know this, but I have to keep
reminding myself. The centered yaw string is not an indication of
equal AOA of the two wings. It only indicates the direction of air
flow right where the yaw string is. I think I better write this
on a postit and stick it to my panel!

On Aug 12, 2:10*am, John Wright wrote:
At 05:00 12 August 2008, Eric Greenwell wrote:Roy Clark, "B6" wrote:

snipped

I don't have the full context from the quote above, and while I am
normally loathe to contradict Langewiesche, I must report I have
successfully produced turns with just the rudder in gliders. Give it a
try, and you will find you can produce an adequate turn, because the
yawing causes the dihedral to bank the glider in the desired direction.

I suggest you give it a try at or near the stall...

(Only in america would we come across such a technique even being
discussed!)

What it might stall/spin? Wow nobody would have known that. Thanks so
much for sharing.

Can we give this crap a rest? We all get the stall/spin issue. The
comment was if you stand on the rudder alone a glider will turn. Do
you really think that was being advocated as a method to use?

Darryl

On Tue, 12 Aug 2008 02:42:16 -0700, Darryl Ramm wrote:

The
comment was if you stand on the rudder alone a glider will turn. Do you
really think that was being advocated as a method to use?

No, but it is a useful reminder of the way some aircraft react.

I've always known that was possible to turn using just the rudder GIVEN
THE RIGHT AIRFRAME, because otherwise it would be impossible to fly an RC
model that lacks ailerons: I flew single channel rudder-only models when
I was a lad.

Eric specified it exactly right: to turn an aircraft using just the
rudder requires it to have fairly generous dihedral. The yaw induces a
turn as a secondary effect because dihedral increases the effective AOA
of the advancing wing while reducing it for the retreating one. If the
aircraft has little or no dihedral this secondary effect can be ignored.

All rudder only or rudder & elevator RC models have generous amounts of
dihedral.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

The further effect of rudder is ????????????

Of course that works but the original point of this whole thread was the
use of rudder slightly before airleron to overcome inertia (prevent the
adverse yaw) I think most agree it is a valid technique for experienced
pilots, who understand the problems, in some gliders.
It is NOT to be taught to ab initio students. They should be using less
aileron anyway so would not have to overcome the problem. It is only large
inputs of aileron in certain gliders where there is a problem.



At 10:58 12 August 2008, Martin Gregorie wrote:
On Tue, 12 Aug 2008 02:42:16 -0700, Darryl Ramm wrote:

The
comment was if you stand on the rudder alone a glider will turn. Do
you
really think that was being advocated as a method to use?

No, but it is a useful reminder of the way some aircraft react.

I've always known that was possible to turn using just the rudder GIVEN

THE RIGHT AIRFRAME, because otherwise it would be impossible to fly an RC

model that lacks ailerons: I flew single channel rudder-only models when

I was a lad.

Eric specified it exactly right: to turn an aircraft using just the
rudder requires it to have fairly generous dihedral. The yaw induces a
turn as a secondary effect because dihedral increases the effective AOA
of the advancing wing while reducing it for the retreating one. If the
aircraft has little or no dihedral this secondary effect can be ignored.

All rudder only or rudder & elevator RC models have generous amounts of
dihedral.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |