Leading Turns with Rudder - Revisited

At 20:40 07 August 2008, Jim White wrote:
At 17:36 07 August 2008, Shawn wrote:
Jim White wrote:
At 16:16 07 August 2008, J a c k wrote:
Jim White wrote:


...what's the lowest height one should start an
aerobatic manoeuvre?


How low do you want to recover?



Jack



Above ground
Jim

How low do you want to recover if a Fed is watching. :-)



Shawn

Behind a hill or a hedge

Jim

I would give up if I were you chaps, his replies are about as accurate and
truthful as a 9 bob watch (that's Brit speak for very cheap) :-)

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
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* "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!)

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

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 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 |

At 09:10 12 August 2008, John Wright 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!)

So what would you do if your aileron's became disconnected
from the control stick in flight? Interesting problem, right?

It happened to a partner of mine several years ago, in
his 1-26. Exactly how is a bit of a mystery, but using one
safety pin for both control pins was certainly a contributing
factor, and he doesn't do that anymore.

Anyway, what would you have done? He proceeded just as
outlined in the double-indented comment above, flew a wide
pattern and landed successfully back at home base. Of
course, the fact that he was dealing with a 1-26 made the
task somewhat easier than it might have been.

Jim Beckman

“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...

I agree with the statement above.

I don't, because it is twofold wrong.

First, not two controls must be operated together, but all three.

Second, it is not the most difficult step in learning to fly. It is only
difficult if the instructor tells the student that it is difficult makes
a big fuss about it. If however you show he student with some kind of
aircraft model (your hands may be adequate) that the aircraft must turn
around all three axes, then this will be the most natural thing for the
student. Just be sure that you mention adverse yaw and such esotheric
things only after the student has mastered to make perfect turns.

Jim Beckman wrote:
It happened to a partner of mine several years ago, in
his 1-26. Exactly how is a bit of a mystery, but using one
safety pin for both control pins was certainly a contributing
factor, and he doesn't do that anymore.

Could you elaborate on why that was a contributing factor? Is it just the
fact that if you forget a single safety pin, you lose both ailerons?

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon