Leading Turns With Rudder

I suspect it's a Nimbus 1 specific quote (Open Cirrus fuselage with huge
wings) - see Moffat's Winning on the Wind 1st ed for a description of
the fun he had flying this beast.

I'm told the Nimbus 2 is *way* better handling (even though almost all
opinions I've heard on the 2 - as opposed to the 2c - are not
complimentary).

phil collin wrote:
Tony Verhulst wrote:
Chris Reed wrote:
I'd say this post provides an excellent summary.

There are gliders where, to obtain improved performance, it is
sometimes helpful to fly uncoordinated. For example, to persuade my
Open Cirrus (1967 design, 17.7m span) to turn into a strong thermal,
it's sometimes most effective to yaw it towards the thermal enough to
induce the beginning of a wing drop - then catch it and continue into
the turn.

In the (most excellent) video "A Fine Week of Soaring", George Moffat
says that the handling of some first generation glass ships was so
poor that you could initiate a turn substantially faster by first
moving the stick in the opposite direction. Once the adverse yaw (in
the desired direction)had kicked in, THEN you'd move the ailerons into
the turn.

Tony V
Sounds like a Nimbus 2 specific quote....

Let me suggest that what cuts across all types of glider, angles of
attack and back, phases of flight, is the goal of the maneuver. Both
the CFI-G referred to in the OP, Paul, and most others agree that they
wish to perform a coordinated turn entry (setting aside circumstances
where slipping is advisable or fruitful). So, in teaching, why not
stress monitoring methods first -- primarily visual (yaw string staring
in the face for just that purpose), and then also aural (screaming
vent), kinesthetic ("falling" to the inside is a classic sign of
slipping to avoid initial discomfort at leaning from the vertical,
"cracking the whip" a danger sign), control positions. So, "leading
with the rudder" could be appropriate IF IT WORKS, but how about making
it an incidental discovery, a consequence, as opposed to a primary cause
or goal. In introducing maneuvers, I favor discussion and demonstration
(student following through) of "it should look like this" before
admonitions of "move this to there to achieve that goal". Also, even
following RUAC, I favor avoiding "always" and "never".

--JHC

John H. Campbell wrote:
..... So, in teaching, why not
stress monitoring methods first -- primarily visual (yaw string staring
in the face for just that purpose)


Mostly because if you do that from the start, the student will focus on
the yaw string and drop everything else (an exaggeration, but you get
the point). I think that Piggott may have it right when he says that the
yaw string is most useful for long straight glides - to ensure that you
have no inadvertent slip. I tell students about the yaw string, of
course, but I also say that I can tell if their turns are coordinated
with my eyes closed because my shoulders won't move.

Tony V.

On Jul 31, 6:59 am, "user" wrote:

sniped alot
Slewing the nose before banking... every time you turn?

"Leading with the rudder" does NOT equal "Slewing the nose before
banking" !

You can lead with the rudder and still get a coordinated turn entry.
You might only lead by a fraction of a second, but you can push on the
rudder before the stick. If that is what works best in the glider
that you are flying.

Todd Smith
3S

Then you're talking about a mental game, which is fine. Focus on the rudder
since it requires a larger movement at low speed.

Nontheless, the rudder balances aileron drag. Coordination is simply defined
as balancing the yaw moment from the ailerons with a SIMULTANEOUS and
opposing yaw moment from the rudder. The amount of rudder needed to
compensate for aileron drag is inversely proportional to speed. The question
in my mind is, does the original post's premise of a regimen of

"...the FIRST thing you do is feed in rudder. On his 1-5 list of making a
turn in a glider, #1 is rudder (as its own separate input)."

produce a good pilot? At anything more than a few knots above MCA, this
formula will lead to a slewing nose, in equal proportion as I would expect
to see in an underruddered turn entry near MCA.

But maybe I'm just over sensitive to yaw motion... or maybe I'm just being
too dogmatic about sloppy flying (or thinking).


"toad" wrote in message
...
On Jul 31, 6:59 am, "user" wrote:

sniped alot
Slewing the nose before banking... every time you turn?

"Leading with the rudder" does NOT equal "Slewing the nose before
banking" !

You can lead with the rudder and still get a coordinated turn entry.
You might only lead by a fraction of a second, but you can push on the
rudder before the stick. If that is what works best in the glider
that you are flying.

Todd Smith
3S

Except in the case of very long span gliders, I wonder if the "lead with
rudder" pilots are actually flying very differently from the "both
together" pilots? I think that they may simply be describing what it
feels like to initiate a turn. Here's a hypothesis based on four
knowns:

The primary effect of the aileron is as a *rate* of roll control - keep
the deflection applied and the glider keeps rolling.

The primary effect of the rudder is *degree* of yaw control - keep the
deflection applied and the yaw stays steady.

For a given airspeed and a given aileron deflection at 1g there is an
appropriate amount of rudder deflection.

The forces required to apply rudder are generally higher than to apply
aileron.

Therefore, when we begin a coordinated turn and apply the appropriately
coordinated rudder and aileron deflections at the same rates - say over
one second (and let's say that the glider takes 2-4 seconds to roll into
the full turn) then the pilot will be aware that all of application of the
rudder deflection will all have taken place in the first half to quarter of
the of the roll into the turn and will also sense that more force was
required to apply the rudder than the aileron i.e. what feels like leading
with the rudder may a lot closer to coordinated flying than is apparent
from the words used to describe it.

John Galloway




At 11:35 02 August 2008, user wrote:
Then you're talking about a mental game, which is fine. Focus on the
rudder

since it requires a larger movement at low speed.

Nontheless, the rudder balances aileron drag. Coordination is simply
defined
as balancing the yaw moment from the ailerons with a SIMULTANEOUS and
opposing yaw moment from the rudder. The amount of rudder needed to
compensate for aileron drag is inversely proportional to speed. The
question
in my mind is, does the original post's premise of a regimen of

"...the FIRST thing you do is feed in rudder. On his 1-5 list of making
a
turn in a glider, #1 is rudder (as its own separate input)."

produce a good pilot? At anything more than a few knots above MCA, this
formula will lead to a slewing nose, in equal proportion as I would
expect

to see in an underruddered turn entry near MCA.

But maybe I'm just over sensitive to yaw motion... or maybe I'm just
being

too dogmatic about sloppy flying (or thinking).


"toad" wrote in message
...
On Jul 31, 6:59 am, "user" wrote:


Slewing the nose before banking... every time you turn?

"Leading with the rudder" does NOT equal "Slewing the nose before
banking" !

You can lead with the rudder and still get a coordinated turn entry.
You might only lead by a fraction of a second, but you can push on the
rudder before the stick. If that is what works best in the glider
that you are flying.

Todd Smith
3S

On Aug 2, 7:35*am, "user" wrote:
Then you're talking about a mental game, which is fine. Focus on the rudder
since it requires a larger movement at low speed.

... snip ...

The question
in my mind is, does the original post's premise of a regimen of

"...the FIRST thing you do is feed in rudder. On his 1-5 list of making a
turn in a glider, #1 is rudder (as its own separate input)."

produce a good pilot? At anything more than a few knots above MCA, this
formula will lead to a slewing nose, in equal proportion as I would expect
to see in an underruddered turn entry near MCA.


Yes, it is a mental game. The instructor's job is to train the
student to fly correctly. The talking is just a means to the end. I
don't care if the instructor tells the student to first yell "olly
olly oxen free" before he turns. If the student performs a good
coordinated turn entry, then the instructor has done their job.

Todd
3S

"toad" wrote in message
...
On Aug 2, 7:35 am, "user" wrote:
Then you're talking about a mental game, which is fine. Focus on the
rudder
since it requires a larger movement at low speed.

.... snip ...

The question
in my mind is, does the original post's premise of a regimen of

"...the FIRST thing you do is feed in rudder. On his 1-5 list of making a
turn in a glider, #1 is rudder (as its own separate input)."

produce a good pilot? At anything more than a few knots above MCA, this
formula will lead to a slewing nose, in equal proportion as I would expect
to see in an underruddered turn entry near MCA.


Yes, it is a mental game. The instructor's job is to train the
student to fly correctly. The talking is just a means to the end. I
don't care if the instructor tells the student to first yell "olly
olly oxen free" before he turns. If the student performs a good
coordinated turn entry, then the instructor has done their job.

Todd
3S

Well, yes, but...

The goal should be to train pilots for a lifetime of safe, high performance
flying. Merely training them to the standards needed for solo or the
practical test is shortchanging them. Beware the knock on ramifications of
"primacy".

If taught to "lead with the rudder" when in fact the goal is simultaneous
application of rudder and aileron, that will come back to bite the trainee
when feet reaction times improve with increasing experience. "Lead with
rudder" is, in fact, only a shortcut that helps the instructor move the
student along faster. In the long run, it puts the student at risk for
skidding turns and stall/spin accidents.

The fact that certain big wing gliders and antiques actually benefit from
this technique doesn't excuse teaching it to primary students. The student
should first learn to do it 'right' and then learn the exceptions.

Teach them correct theory and help them use their feet in coordination with
their hands. It will be hard for them to use their feet in coordination
with their hands at first, but they will learn to do it eventually.

If you want your student to improve coordination of turn entries, try "use
less aileron" rather than "lead with rudder". Or: "Dont use more aileron
than the rudder can cope with".

Bill Daniels

In article , "user" writes:

Nontheless, the rudder balances aileron drag.

To be more precise, the rudder primarily balances the fore/aft
tilting of the lift vectors on the left and right wings,
which is a result of _roll rate_. The aileron drag difference
has a much smaller contribution.
The PDF diagram in this link illustrates the effect:
http://www.rcgroups.com/forums/showp...0&postcount=31


Coordination is simply defined
as balancing the yaw moment from the ailerons with a SIMULTANEOUS and
opposing yaw moment from the rudder. The amount of rudder needed to
compensate for aileron drag is inversely proportional to speed.

Correct.
But the required rudder deflection is actually inversely proportional
to CL, and hence to the _square_ of the speed.

At 23:44 07 August 2008, Mark Drela wrote:
In article , "user" writes:

Nontheless, the rudder balances aileron drag.

To be more precise, the rudder primarily balances the fore/aft
tilting of the lift vectors on the left and right wings,
which is a result of _roll rate_. The aileron drag difference
has a much smaller contribution.
The PDF diagram in this link illustrates the effect:
http://www.rcgroups.com/forums/showp...0&postcount=31


No sure that the above is the complete answer as it covers profile drag
but completely ignores induced (lift dependent) drag.

Consider a glider wing in level flight and assume we have a drag factor of
2 (Newtons, foot pounds,bananas, doesn't matter)
The airlerons to roll and the lift on the down going aileron wing is
doubled over the area influenced by the aileron, the induced drag
increases by 4. If the ailerons are non differential the lift over the
same area on the opposite wing is reduced by half to 1 giving a total
force of 5 trying to induce yaw. On a glider with long wings the leverage
of these forces will produce a significant adverse yaw while the aileron
is applied. I would agree that when the glider starts to roll the upgoing
wing suffers a reduced angle of attack, over it's whole area, reducing
the lift and vice versa for the other wing, these forces tending to
mitigate the adverse yaw caused by lift inbalance between the two wings.