A new direction for an old thread: Crosswind landings

[[email protected]]

The last few threads I initiated were preambles to a discussion I don't
think we've sufficiently explored. Those of you who keep track will
recall that I've asked first, whether we are sufficiently well-trained
(Dear Burt), and second, if some of the models we use to understand
flight couldn't stand improvement.

Let me preface this thread with an analogy. I think we can agree the
that the majority of drivers have little understanding of how their
vehicles work. They have learned that certain control movements result
in changes of direction and speed, but if asked to work their way
intellectually though the process, most would fall short of the level
of knowledge demanded of a pilot about his/her aircraft. And yet, the
vast majority of drivers manage to operate their vehicles successfully
(and safely).

My point is, just because we ask pilots to acquire more knowledge than
drivers, it isn't necessarily required to effectively pilot an
aircraft. And by extension, just because the pilot can control the
aircraft, doesn't necessarily mean that the intellectual models he uses
are accurate.

My object was to get us on a path where we could look more closely at
these models to discern where they might stand improvement.

Obviously, I have a very high opinion of the RAS!

That said, let's talk crosswind landings again. And to start the
discussion, one area of false intuition may result from the differing
nature of wind for an aircraft on the ground and one in the air. While
on the ground, the wind exerts a force on the aircraft. In the air, it
does not. This dichotomy becomes very important during a crosswind
landing, when we transition from being a part of the airmass to
becoming an object on the ground.

I've found that pilots can speak very clearly about the role of wind on
navigation when they are in cruising flight. But the closer they get to
the ground, I start to see control usage more appropriate for taxiing
than flying. Has our understanding of the effect of wind as viewed from
the ground infected our understanding of its effect on flight? And do
these become more obvious as we get approach the transition from flight
to taxiing? And perhaps, thus, much of the confusion pilots suffer over
side slips?

Asking pilots to describe the crosswind approach leads to a variety of
inaccurate language. Digging deeper will lead, almost inevitably, to
the conclusion that the wind is exerting a force on the glider, and
that the wing must be tilted in order to counteract that force (and the
rudder applied against the bank to keep the glider from turning). This
works, and even makes some sense. But the notion that the tilted lift
vector is compensating for wind drift is flawed. Useful, but flawed.

The Soaring Flight Manual (1999) says the following on the subject of
Crosswind Landings (page 14-15):

"The traffic pattern for crosswind landings is the same up to the final
approach using crab to maintain pattern alignment. In light to moderate
crosswinds, a wing-low sideslip or crab may be used on final to
maintain runway alignment. A strong crosswind usually REQUIRES a
COMBINATION of the two."
[the emphasis is mine]

This is an interesting mix of useful yet incorrect information. What
concerns me most is the implication that crabbig and side slipping are
additive. They are not. But if you deconstruct the implicit logic, you
are led to the conclusion that side slips counteract the force of the
wind. Otherwise, how can the effects be additive?

I suspect there is a visual/pschological effect that has crept its way
into the way we rationalize control use during the crosswind approach.
Consider it from another point of view. You adjust your path across the
ground by changing your direction. The most efficient way to do this is
by executing a coordinated turn. Once on the appropriate heading to
achieve a desired ground track, you fly wings level. If there is a
crosswind and your heading differs from your ground track, you are
crabbing. Just that simple. Whether you are 10 feet, 100 feet, or 1,000
feet above the ground.

The role of the side slip, then, since it is aerodynamically the same
as a forward slip, is solely to change the heading (but not the
direction) of the aircraft. The effect on flight path is exactly the
same as applying some spoiler. The advantage gained is that it brings
the landing gear more closely aligned to the aircraft's direction over
the ground, and thus reduces any sideloadings at touchdown. This is one
of two reasons to perform a slip during a crosswind landing: aligning
the gear with the direction of travel. The other, to steepen the glide.

So why might a pilot think that the side slip adds "additional force"
against the crosswind? Perhaps we are put ill at ease by a large crab
angle. Pointing the fuselage more directly down the runway makes the
approach look better (closer to "normal") and perhaps gives the
impression of additional control. But it doesn't add any force, and, in
fact, reduces the freedom of control.

I know one direction this thread will follow... a perfectly reasonable
one, but let me color it a little: is it appropriate that we should ask
fledgling pilots to handle the controls differently in the riskiest
flight environments? We are taught, rehearsed, and tested on our
abilities to maintain coordinated flight. Then, under the most trying
conditions, we are asked to apply counter intuitive control movements
at low altitudes, many of them based on a false impression of the
forces acting on the aircraft and the effects control usage has on
balancing those "external" forces. It should be mantra with us all,
that when things are going bad, the first thing we should do is return
to and/or maintain coordinated flight. Understanding the foundations of
crosswind navigation are critical to helping all pilots fly more
safely. If you are confused about what keeps the aircraft tracking down
the runway, you may find yourself making control inputs against upsets
that increase your risk of loss of control.

Shouldn't every pilot know that when things are going bad on final, you
should return to a wings level, coordinated crab, where your ASI is
accurate, you have full control available, and you are exercising those
skills which your training has made most instinctive. Once you've
sorted out the upset, then you can return to your "runway alignment"
slip.

Lately I've been testing an exercise, one I tried years ago with
several students (with good results) but never formalized: I would have
pilots establish their final leg with a crab. Then I would have them
enter and recover from a slip, descibing is utility in aligning the
gear with the runway, noting its increased drag. This reinforced the
role of the slip, the role of the crab angle, and the necessity to exit
the slip if you needed to extend your glide. Two distinctly different
maneuvers meant to achieve different ends, applied together to ease the
tranistion from flight to taxi.

You might want to run through the Building Models thread where I've
tried to address the false dichotomy of side and foward slips. Viewing
a side slip as two distinct maneuvers... a turn and a slip, migh help
to put my last paragraph in context.

I'm hoping you'll poke holes, and not take too much offense when I
return your efforts in kind. That's the point of this thread.

[Stewart Kissel]

I don't necesarily disagree with your analysis...if
I understand it. But the idea of waiting to kick out
of a full crab to a full slip(or however you want to
word this), does not seem to me any improvement of
using a combination of both...particularly in strong
crosswind conditions.

Personally I think one should fly whatever he/she is
most comfortable with...because rarely are short final
approaches the same in extreme crosswind conditions.
And I think for the most part...these strong crosswinds
are not seen much during training...rather we self-teach
ourselves the technique that works best for us. Personally
my preference is to not practice new techniques when
I have something that seems to keep me on the runway
when the crosswind is 20+.

On the flip side...I see some instructrion manuals
that recomend no crabbing whatsoever.

[Stefan]

Stewart Kissel wrote:

> On the flip side...I see some instructrion manuals
> that recomend no crabbing whatsoever.

Makes crosswind landings interesting in a 20+ meter ship.

Stefan

[HL Falbaum]

OK I'll take the bait.
Just how does one deal with a crosswind in a 25m ship? I have some guesses
but no experience. 15m does not seem to be much of a problem--lots of
experience there.

--
Hartley Falbaum
"Stefan" > wrote in message
...
> Stewart Kissel wrote:
>
>> On the flip side...I see some instructrion manuals
>> that recomend no crabbing whatsoever.
>
> Makes crosswind landings interesting in a 20+ meter ship.
>
> Stefan

[Stefan]

HL Falbaum wrote:

> OK I'll take the bait.
> Just how does one deal with a crosswind in a 25m ship?

I can't tell you what "one" does. But I know what I do: I simply crab
into the roundout and then use the rudder to align, carefully keeping
the wings level with the ailerons. Inertia combined with the slippery
fuselage is plenty enough to hold the glider on track during the short
flare. In fact, I never even thought of not keeping the wings level near
the ground, even in a 15 meter glider.

Stefan

[bumper]

"HL Falbaum" > wrote in message
...
> OK I'll take the bait.
> Just how does one deal with a crosswind in a 25m ship? I have some guesses
> but no experience. 15m does not seem to be much of a problem--lots of
> experience there.
>
> --
> Hartley Falbaum


No experience with a 25 meter ship, but in a 23 meter Stemme S10-VT,
crosswinds aren't a problem. Ground handling and taxiing is possible in 35
knots, as evidenced by the four Stemmes that had to make multiple taxi turns
to launch out of Cedar City, Utah while on a safari 4 years ago. Though I've
not done so, I'm told the factory has taken off and landed in up to 25 knots
crosswind.

The Stemme's relatively low dihedral (.75 degrees), high conventional gear,
and shoulder mounted wing, make for good wing-tip ground clearance. Plus,
most all glass gliders have a slippery side profile compared to power
aircraft, so it doesn't take a lot of a slip bank angle to get a fair amount
of sideways movement to counter crosswind drift.

On the other hand, my ham-fisted handling and poor decision making (I
shouldn't have even tried it) attempt at launching an 18 meter ASH26E in 15
knots of crosswind at Minden, resulted only in a cloud of dust and a ground
loop. I'll add that Schleicher's main gear is hell for stout!

all the best,

bumper

[Don Johnstone]

Can't speak for 25 metres but I can for 20 metres and
it's crabbing. I fly an ASW 17 and the tips are not
that far from the ground, even when the wings are level,
and sideslipping (using bank) near the ground has never
appealed to me. My aim is to keep the wings level near
the ground and kick off the drift at the point of flare
but I have often wondered if it is a really good idea
to apply yaw at the same time as increasing the angle
of attack of the wing. Of course to conteract the further
effect of rudder opposite aileron may have to be applied
to keep the wings level but can be avoided by not being
too heavy footed with the rudder. The upside is I am
in ground effect when I do that.
Thi biggest problem with a large span (any) glider
is keeping it straight as the speed decreases and with
a really stong crosswind there comes a point where
overcoming the tendency to 'weathercock' into wind
is impossible. Perhaps that emphasises the importance
of staying within the published crosswind limits and
another good reason for stopping as soon after touchdown
as is safely possible.



At 15:00 20 February 2005, Hl Falbaum wrote:
>OK I'll take the bait.
>Just how does one deal with a crosswind in a 25m ship?
>I have some guesses
>but no experience. 15m does not seem to be much of
>a problem--lots of
>experience there.
>
>--
>Hartley Falbaum
>'Stefan' wrote in message
...
>> Stewart Kissel wrote:
>>
>>> On the flip side...I see some instructrion manuals
>>> that recomend no crabbing whatsoever.
>>
>> Makes crosswind landings interesting in a 20+ meter
>>ship.
>>
>> Stefan
>
>
>

[[email protected]]

I would counter that the only way to maintain a track is by crabbing. I
think we confuse the role of the slip. In order to track straight down
the runway in a crosswind, we must adjust the direction of the glider
so the sin of the angle equals the crosswind component. This is
accomplished by turning, our yaw string ultimatley revealing our path
through the air. If you recover from your side slip, you will point at
that angle while continuing to track down the runway. Side slip,
recover, side slip, recover. The side slip has nothing to do with your
direction... it simply changes your heading so you can land with the
wheels straight.

And thus my quibble with calling crabs and side slips additive.

The advantage of using a side slip for alignment is that it reduces
variables: once the slip is established, the pilot uses the controls as
normal (or very nearly so).

My intent here is not to discern which approach is better... to me they
are pretty much the same... with preference for when the alignment
correction is made... early on final or just before touchdown. Instead,
I want to point out that there are some published, formal notions that
appear at least to cause confusion and at worst are simply WRONG.

Someone come to the defense of the sages of sport, the authors of the
Soaring Flight Manual!! How are a crab and side slip additive?

[Bruce Hoult]

In article >,
Don Johnstone > wrote:

> Can't speak for 25 metres but I can for 20 metres and
> it's crabbing. I fly an ASW 17 and the tips are not
> that far from the ground, even when the wings are level,
> and sideslipping (using bank) near the ground has never
> appealed to me. My aim is to keep the wings level near
> the ground and kick off the drift at the point of flare
> but I have often wondered if it is a really good idea
> to apply yaw at the same time as increasing the angle
> of attack of the wing. Of course to conteract the further
> effect of rudder opposite aileron may have to be applied
> to keep the wings level but can be avoided by not being
> too heavy footed with the rudder.

If you want, you can side slip and when close to the ground use the
ailerons to level the wings. You are then in precisely the same
situation as if you crabbed and then kicked in rudder, except that
levelling the wings is probably easier and less critical than precisely
timing and judging a bootfull of rudder.

--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------

[Graeme Cant]

Bruce Hoult wrote:

> If you want, you can side slip and when close to the ground use the
> ailerons to level the wings. You are then in precisely the same
> situation as if you crabbed and then kicked in rudder, except that
> levelling the wings is probably easier and less critical than precisely
> timing and judging a bootfull of rudder.

I think both are equally hard/easy in timing. Levelling the wings and
yawing straight both start the aircraft moving sideways across the
runway/strip and require the same accuracy of timing.

Judging the required control input is different. You used the phrase
"use the ailerons to level the wings". Why didn't you say "use rudder
to yaw the glider straight"?

The colourful phrase you actually used - "a bootfull of rudder" - from
an instructor has probably caused more students to find crosswind
landings difficult than any other aspect of the manoeuvre. Do you teach
the final part of a slipped landing as "shove the stick over"?

In my experience, old multiengine pilots like to crab and use rudder.
Old single engine pilots like to slip and use aileron. Which technique
is used just reflects the tribe you give your allegiance to. Both of
them work well if taught properly.

GC

[Stefan]

Graeme Cant wrote:

> Judging the required control input is different. You used the phrase
> "use the ailerons to level the wings". Why didn't you say "use rudder
> to yaw the glider straight"?
>
> The colourful phrase you actually used - "a bootfull of rudder" - from
> an instructor has probably caused more students to find crosswind
> landings difficult than any other aspect of the manoeuvre.

My opinion exactly. How many pilots use slipping to correct for wind
while flying cross country? My wild guess is: none. We all crab without
even talking about it. So what is the reason they don't do so during the
landing?

I can think of only two reasons: They've never learnt to master the
rudder or they've never learnt to recognize and hold the runway axis
unless it's right ahead of their nose. Both reasons claim for more
training, not a change of method.

Stefan

[Bert Willing]

Additionally, if you don't crab to stay centered during final, you stalling
speed will be higher. I never saw anybody slipping for wind correction in a
glider in Europe...

--
Bert Willing

ASW20 "TW"


"Stefan" > a écrit dans le message de news:
...
> Graeme Cant wrote:
>
>> Judging the required control input is different. You used the phrase
>> "use the ailerons to level the wings". Why didn't you say "use rudder to
>> yaw the glider straight"?
>>
>> The colourful phrase you actually used - "a bootfull of rudder" - from an
>> instructor has probably caused more students to find crosswind landings
>> difficult than any other aspect of the manoeuvre.
>
> My opinion exactly. How many pilots use slipping to correct for wind while
> flying cross country? My wild guess is: none. We all crab without even
> talking about it. So what is the reason they don't do so during the
> landing?
>
> I can think of only two reasons: They've never learnt to master the rudder
> or they've never learnt to recognize and hold the runway axis unless it's
> right ahead of their nose. Both reasons claim for more training, not a
> change of method.
>
> Stefan

[Nyal Williams]

One advantage for the slip is that it has the upwind
wing low at touchdown. I prefer to have that wing
just a bit down so that the wind is less likely to
get under it on rollout. (Same reason I want that
wing just a bit down for a crosswind launch.


At 12:30 21 February 2005, Bert Willing wrote:
>Additionally, if you don't crab to stay centered during
>final, you stalling
>speed will be higher. I never saw anybody slipping
>for wind correction in a
>glider in Europe...
>
>--
>Bert Willing
>
>ASW20 'TW'
>
>
>'Stefan' a écrit dans le message de news:
...
>> Graeme Cant wrote:
>>
>>> Judging the required control input is different.
>>>You used the phrase
>>> 'use the ailerons to level the wings'. Why didn't
>>>you say 'use rudder to
>>> yaw the glider straight'?
>>>
>>> The colourful phrase you actually used - 'a bootfull
>>>of rudder' - from an
>>> instructor has probably caused more students to find
>>>crosswind landings
>>> difficult than any other aspect of the manoeuvre.
>>
>> My opinion exactly. How many pilots use slipping to
>>correct for wind while
>> flying cross country? My wild guess is: none. We all
>>crab without even
>> talking about it. So what is the reason they don't
>>do so during the
>> landing?
>>
>> I can think of only two reasons: They've never learnt
>>to master the rudder
>> or they've never learnt to recognize and hold the
>>runway axis unless it's
>> right ahead of their nose. Both reasons claim for
>>more training, not a
>> change of method.
>>
>> Stefan
>
>
>

[Stefan]

Nyal Williams wrote:

> One advantage for the slip is that it has the upwind
> wing low at touchdown. I prefer to have that wing
> just a bit down so that the wind is less likely to
> get under it on rollout. (Same reason I want that
> wing just a bit down for a crosswind launch.

One advantage for the crab is that it has the wings level. I prefer to
have the wings level so that the grass is less likely to catch the wing
and cause a ground loop. Especially important when grass and wings are
both somewhat longer. (Same reason I carefully hold the wings level
during the launch.)

Stefan

[Don Johnstone]

At 16:00 21 February 2005, Stefan wrote:
>Nyal Williams wrote:
>
>> One advantage for the slip is that it has the upwind
>> wing low at touchdown. I prefer to have that wing
>> just a bit down so that the wind is less likely to
>> get under it on rollout. (Same reason I want that
>> wing just a bit down for a crosswind launch.
>
>One advantage for the crab is that it has the wings
>level. I prefer to
>have the wings level so that the grass is less likely
>to catch the wing
>and cause a ground loop. Especially important when
>grass and wings are
>both somewhat longer. (Same reason I carefully hold
>the wings level
>during the launch.)
>
>Stefan

Amen to that. Long wings tend to be on the floppy side
as well. Do we want to expand this thread to include
launching?

[[email protected]]

Bruce,

An even better way to think of this is simply to let the dihedral
effect roll the wings level. An intent to "roll" the glider level will
produce aileron drag with a yaw in the wrong direction. Since we're
holding stick into the slip, the process only requires a relaxation of
this force. And not even to neutral.

That said, the majority of competent crosswind landings I've seen in
open class ships usually involve flying the glider (wing low) onto the
runway. The big gliders clearly require greater competence and a more
flexible, not necessarily ideal approach to dealing with such problems.

Also, I note that Don used the words "Kick off the drift." This is
inaccurate. Since the crab is used to track down the runway, there is
no longer a "drift." He is, in fact, kicking to align the gear with the
runway. I point this out because sloppiness with terminology percolates
up to our understanding of the model. And then back down to the control
inputs we make.

As for concerns of yawing while increasing angle of attack, remember
you are near the ground. The real disadvantage of the wings level skid
to align the gear is that you are introducing an unbalanced force. If
your touch down is delayed, or you bounce, you will begin to turn
downwind. It is an interesting dilemma. On the one hand, the alignment
slip requires greater skill and understanding. On the other, the
alignment skid requires a "touch" on both the rudder and the stick. I
suspect the wings level approach is safer of low time pilots since they
have greater controlability in the event of turbulence. But the wing
low landing is easier since control movements are intuitive.

There is a great big HOWEVER. A wing low landing into crops is
completely unacceptable (as is flying the glider on). Each method has
its role. We should be competent at both. But to be competent we need
to clearly understand not just the obvious differences, but the
similarities as well.


Those of you who would prefer not to make the "additive" argument in
public, please back channel. I am genuinely interested in understanding
why this concept works... or perhaps, doesn't.

OC


Bruce Hoult wrote:
> In article >,
> Don Johnstone > wrote:
>
> > Can't speak for 25 metres but I can for 20 metres and
> > it's crabbing. I fly an ASW 17 and the tips are not
> > that far from the ground, even when the wings are level,
> > and sideslipping (using bank) near the ground has never
> > appealed to me. My aim is to keep the wings level near
> > the ground and kick off the drift at the point of flare
> > but I have often wondered if it is a really good idea
> > to apply yaw at the same time as increasing the angle
> > of attack of the wing. Of course to conteract the further
> > effect of rudder opposite aileron may have to be applied
> > to keep the wings level but can be avoided by not being
> > too heavy footed with the rudder.
>
> If you want, you can side slip and when close to the ground use the
> ailerons to level the wings. You are then in precisely the same
> situation as if you crabbed and then kicked in rudder, except that
> levelling the wings is probably easier and less critical than
precisely
> timing and judging a bootfull of rudder.
>
> --
> Bruce | 41.1670S | \ spoken | -+-
> Hoult | 174.8263E | /\ here. | ----------O----------

[J.A.M.]

Excuse me... I slip for crosswind correction on final, rather than crab
(wich I assume is to correct the wind with heading; sorry, english is not my
native language).
I find it more effective as the fuselage is already aligned with the runway,
and a more elegant manouevre as well.
I live in Spain. Does it count as Europe?
A lot of people does it here. I teach both methods, being crab easier to
grasp at the beggining, slipping more effective and elegant when the student
becomes proficient, IMHO.

Jose M. Alvarez.
ASW-24 'BR'

> At 12:30 21 February 2005, Bert Willing wrote:
>Additionally, if you don't crab to stay centered during
>final, you stalling
>speed will be higher. I never saw anybody slipping
>for wind correction in a
>glider in Europe...
>
>--
>Bert Willing
>
>ASW20 'TW'
>

[Bert Willing]

Appearently, it doesn't count for Europe :-))

--
Bert Willing

ASW20 "TW"


"J.A.M." > a écrit dans le message de news:
...
> Excuse me... I slip for crosswind correction on final, rather than crab
> (wich I assume is to correct the wind with heading; sorry, english is not
> my
> native language).
> I find it more effective as the fuselage is already aligned with the
> runway,
> and a more elegant manouevre as well.
> I live in Spain. Does it count as Europe?
> A lot of people does it here. I teach both methods, being crab easier to
> grasp at the beggining, slipping more effective and elegant when the
> student
> becomes proficient, IMHO.
>
> Jose M. Alvarez.
> ASW-24 'BR'
>
>> At 12:30 21 February 2005, Bert Willing wrote:
>>Additionally, if you don't crab to stay centered during
>>final, you stalling
> >speed will be higher. I never saw anybody slipping
> >for wind correction in a
> >glider in Europe...
> >
> >--
> >Bert Willing
> >
> >ASW20 'TW'
> >
>
>

[[email protected]]

By all means.

[Don Johnstone]

First , sorry for the kick off the drift, you are absolutely
right.
I have used both methods and in a high wing glider
with the tips well clear of the ground wings level
I would agree the wing down (slipping) method is OK.
Even in a 15 metre glass glider I would accept that
it is a matter of choice. Big wings, especially where
the wing is already low is a different matter. I would
rather make an untidy arrival than catch a wingtip.
The lesser of two evils and I KNOW which is lesser
in that case. Remember the force required at the wingtip
to induce a ground loop reduces in proportion to the
increase in span. With full flap deployed the roll
rate is not exactly sparkling either.

Both should be taught, it then becomes a matter of
choice for the pilot, what he is most comfortable with.
I am not saying my way is better but it works for me.


At 17:30 21 February 2005, J.A.M. wrote:
>Excuse me... I slip for crosswind correction on final,
>rather than crab
>(wich I assume is to correct the wind with heading;
>sorry, english is not my
>native language).
>I find it more effective as the fuselage is already
>aligned with the runway,
>and a more elegant manouevre as well.
>I live in Spain. Does it count as Europe?
>A lot of people does it here. I teach both methods,
>being crab easier to
>grasp at the beggining, slipping more effective and
>elegant when the student
>becomes proficient, IMHO.
>
>Jose M. Alvarez.
>ASW-24 'BR'
>
>> At 12:30 21 February 2005, Bert Willing wrote:
>>Additionally, if you don't crab to stay centered during
>>final, you stalling
> >speed will be higher. I never saw anybody slipping
> >for wind correction in a
> >glider in Europe...
> >
> >--
> >Bert Willing
> >
> >ASW20 'TW'
> >
>
>
>

[Stewart Kissel]

>My opinion exactly. How many pilots use slipping to
>correct for wind
>while flying cross country?

Landing and flying cross country are comparing apples
and orange...at altitude you don't have to worry about
damaging gear from landing in a crab, so don't consider
your analogy accurate.



My wild guess is: none. We all crab without
>even talking about it. So what is the reason they don't
>do so during the
>landing?

Uhh...here in the colonies, we don't have a lot of
grass to land on...and grass is much more forgiving
for a crabbed touchdown. Try landing less then straight
on asphalt a few times. Likewise asphalt does not
grab wingtips like grass.
>
>I can think of only two reasons: They've never learnt
>to master the
>rudder or they've never learnt to recognize and hold
>the runway axis
>unless it's right ahead of their nose.

Hmmm....no comment. You seem to be assuming a lot
though :)
Both reasons claim for more
>training, not a change of method.

Seems like we do what works best for us....suggest
the same for you :)
>
>Stefan
>

[[email protected]]

Agreed. A pilot should be the master of both. And I believe the first
step in that direction is to divorce these two maneuvers, slips and
skids, from any discussion of "compensating" for a crosswind. These are
alignment maneuvers only, each having its relative merits.
Don Johnstone wrote:
> First , sorry for the kick off the drift, you are absolutely
> right.
> I have used both methods and in a high wing glider
> with the tips well clear of the ground wings level
> I would agree the wing down (slipping) method is OK.
> Even in a 15 metre glass glider I would accept that
> it is a matter of choice. Big wings, especially where
> the wing is already low is a different matter. I would
> rather make an untidy arrival than catch a wingtip.
> The lesser of two evils and I KNOW which is lesser
> in that case. Remember the force required at the wingtip
> to induce a ground loop reduces in proportion to the
> increase in span. With full flap deployed the roll
> rate is not exactly sparkling either.
>
> Both should be taught, it then becomes a matter of
> choice for the pilot, what he is most comfortable with.
> I am not saying my way is better but it works for me.
>
>
> At 17:30 21 February 2005, J.A.M. wrote:
> >Excuse me... I slip for crosswind correction on final,
> >rather than crab
> >(wich I assume is to correct the wind with heading;
> >sorry, english is not my
> >native language).
> >I find it more effective as the fuselage is already
> >aligned with the runway,
> >and a more elegant manouevre as well.
> >I live in Spain. Does it count as Europe?
> >A lot of people does it here. I teach both methods,
> >being crab easier to
> >grasp at the beggining, slipping more effective and
> >elegant when the student
> >becomes proficient, IMHO.
> >
> >Jose M. Alvarez.
> >ASW-24 'BR'
> >
> >> At 12:30 21 February 2005, Bert Willing wrote:
> >>Additionally, if you don't crab to stay centered during
> >>final, you stalling
> > >speed will be higher. I never saw anybody slipping
> > >for wind correction in a
> > >glider in Europe...
> > >
> > >--
> > >Bert Willing
> > >
> > >ASW20 'TW'
> > >
> >
> >
> >

[Bob Korves]

I fly a lot at a mountain site where the winds can be strong, gusty and
turbulent; 20 to 60 degrees (or more) off the runway heading, and constantly
changing. The pattern there can be wicked at times. I am flying 18 and 20
meter gliders off a runway that is 75 feet (22.9 meters) wide with lights,
sagebrush, and rocks past the edges.

On days like that and at places like that there is no time for asking myself
whether I should slip or crab. I just want to get the damn sailplane down
in one piece. For flying like this you need to have your spurs on (be
proactive and decisive). The only rules are: Don't ground loop. Don't
cartwheel. Don't hurt the pilot or glider.

I would bet that if you debriefed me just after I stopped and got out of the
glider, I would not be able to tell you very well what I had just done. One
just does what is necessary to get down safely. When you get it slowed down
somewhere near the ground in the middle of the runway and pointed pretty
much down the runway, you had better plant it right then. Better safe than
pretty.

I do know that I have used a combination slip and crab many times, just so I
don't run out of control travel before I get the desired response. Is that
additive? You just lift the upwind wing before it hits the runway and use
rudder as needed to establish/maintain heading. The upwind wing stays
slightly down throughout the flare and rollout.

At a sea level site with a steady wind and no upwind obstructions one can
(yawn) take the time to worry about style points for slipping or crabbing
approaches. :-)

Teaching pilots to fly is, of course, a very different proposition.
-Bob Korves

> wrote in message
oups.com...
> Bruce,
>
> An even better way to think of this is simply to let the dihedral
> effect roll the wings level. An intent to "roll" the glider level will
> produce aileron drag with a yaw in the wrong direction. Since we're
> holding stick into the slip, the process only requires a relaxation of
> this force. And not even to neutral.
>
> That said, the majority of competent crosswind landings I've seen in
> open class ships usually involve flying the glider (wing low) onto the
> runway. The big gliders clearly require greater competence and a more
> flexible, not necessarily ideal approach to dealing with such problems.
>
> Also, I note that Don used the words "Kick off the drift." This is
> inaccurate. Since the crab is used to track down the runway, there is
> no longer a "drift." He is, in fact, kicking to align the gear with the
> runway. I point this out because sloppiness with terminology percolates
> up to our understanding of the model. And then back down to the control
> inputs we make.
>
> As for concerns of yawing while increasing angle of attack, remember
> you are near the ground. The real disadvantage of the wings level skid
> to align the gear is that you are introducing an unbalanced force. If
> your touch down is delayed, or you bounce, you will begin to turn
> downwind. It is an interesting dilemma. On the one hand, the alignment
> slip requires greater skill and understanding. On the other, the
> alignment skid requires a "touch" on both the rudder and the stick. I
> suspect the wings level approach is safer of low time pilots since they
> have greater controlability in the event of turbulence. But the wing
> low landing is easier since control movements are intuitive.
>
> There is a great big HOWEVER. A wing low landing into crops is
> completely unacceptable (as is flying the glider on). Each method has
> its role. We should be competent at both. But to be competent we need
> to clearly understand not just the obvious differences, but the
> similarities as well.
>
>
> Those of you who would prefer not to make the "additive" argument in
> public, please back channel. I am genuinely interested in understanding
> why this concept works... or perhaps, doesn't.
>
> OC
>
>
> Bruce Hoult wrote:
> > In article >,
> > Don Johnstone > wrote:
> >
> > > Can't speak for 25 metres but I can for 20 metres and
> > > it's crabbing. I fly an ASW 17 and the tips are not
> > > that far from the ground, even when the wings are level,
> > > and sideslipping (using bank) near the ground has never
> > > appealed to me. My aim is to keep the wings level near
> > > the ground and kick off the drift at the point of flare
> > > but I have often wondered if it is a really good idea
> > > to apply yaw at the same time as increasing the angle
> > > of attack of the wing. Of course to conteract the further
> > > effect of rudder opposite aileron may have to be applied
> > > to keep the wings level but can be avoided by not being
> > > too heavy footed with the rudder.
> >
> > If you want, you can side slip and when close to the ground use the
> > ailerons to level the wings. You are then in precisely the same
> > situation as if you crabbed and then kicked in rudder, except that
> > levelling the wings is probably easier and less critical than
> precisely
> > timing and judging a bootfull of rudder.
> >
> > --
> > Bruce | 41.1670S | \ spoken | -+-
> > Hoult | 174.8263E | /\ here. | ----------O----------
>

[[email protected]]

I don't agree that they aren't additive.

Say you are side slipping, but are still drifting off centerline. So
you turn into the wind (crab) and hold the same amount of slip. It
seems to me that you are combining, i.e. "adding", the crab component
to the slip component. Works with vector arithmetic, should work in the
air, too.

Tom

[[email protected]]

As often happens, the discussion is digressing into the particulars of
landing in a crosswind, and I couldn't be happier. Watching pilots
wrangle through the explanation of why they do what they do is
fascinating, especially since the inference chain gets all kinds of
twisted as they work their way back up to the model.

The trick, I'm convinced, is to completely divorce the slip/skid
alignment maneuvers from the maneuver required to establish a track
down the runway. Once we've determined that there is a crosswind, the
only way to establish a proper track is to change our direction through
the airmass. The problem arises when pilots confuse the alignment
maneuver with the turn. We've discovered this slick maneuver where we
can turn base to final and initiate the slip all in one motion. Which
leads to a false perception that we only turned 90 degrees, then used
the wing to compensate for crosswind. But we have in fact changed our
direction by more than 90 degrees and inserted our alignment slip early
on final. But whether your turn is coordinated throughout, or slipped,
the means by which we change direction is exactly the same. Remove the
slip, and you'll point upwind, put the slip back in and you'll point
down the runway. The forces produced by the glider remain balanced
throughout.

Maybe it is easier to conceptualize this if you simply ignore the
direction the nose is pointing and think of it in terms of the glider's
path through the air. Because in a side slip the nose is pointing down
the runway, there is an illusion that the lowered wing is dragging the
glider sideways, compensating for the "force" of the wind. But in a
side slip (as in a foward slip), the horizontal component of lift is
exactly balanced by the force created by sideways motion of the
fuselage. There is no extra force to compensate for an external force.
Which is a good thing since there is no external force from the wind.

That said, an unbalanced force is required to establish a new direction
through the air that will produce a desired ground track. And this is
only accomplished by turning. Whether the turn is slipped or skidded or
coordinated is a matter of pilot choice. It is nonetheless a turn since
the direction of the glider changes. When the new direction is
achieved, the turn ceases. Whether this is accomplished by rolling the
wings level or increasing beta to balance the wing turning force is a
matter of pilot choice.

[Andreas Maurer]

On 22 Feb 2005 05:51:33 -0800, wrote:


>Maybe it is easier to conceptualize this if you simply ignore the
>direction the nose is pointing and think of it in terms of the glider's
>path through the air.

Why not simply fly according to the feeling in your pants?
I've seen a lot of bad landings - but I never saw a landing where the
pilot had difficulties with crosswind. Therefore I think the whole
discusion is not really ... necessary.

Why make things more difficult than they are in real life?





Bye
Andreas

[Don Johnstone]

I am getting a little lost here. If you are trying
to say that an aircraft when flying moves relative
to the airmass it happens to be in you are right. The
direction in which the airmass is moving is unimportant
as far as the aircraft is concerned, as long as it
remains flyng. The concept of what happens when a pilot
has to change the movement of his glider from relative
to the air to releative to the ground because it is
about to become a wheeled vehicle with wings is not
that important. What is vital is that pilots are trained
how to change from being a vehicle moving relative
to the airmass to one moving relative to the ground.
As pilots, unlike the aircraft, we are more concerned
with our movement relative to the ground.
Do we really seek to change our direction through the
airmass? What we seek to achieve is changing our direction
relative to the ground, to align track and heading,
we don't really care a jot that our movement relative
to the airmass has changed (or not) until we try to
operate outside the limits of the aircraft, then we
care a lot. I suppose what I am trying to say is that
the procedure is a very human thing, a skill that requires
teaching, and not one which deep scientific analysis
will help as there are so many variables.

At 14:00 22 February 2005,
wrote:
>As often happens, the discussion is digressing into
>the particulars of
>landing in a crosswind, and I couldn't be happier.
>Watching pilots
>wrangle through the explanation of why they do what
>they do is
>fascinating, especially since the inference chain gets
>all kinds of
>twisted as they work their way back up to the model.
>
>The trick, I'm convinced, is to completely divorce
>the slip/skid
>alignment maneuvers from the maneuver required to establish
>a track
>down the runway. Once we've determined that there is
>a crosswind, the
>only way to establish a proper track is to change our
>direction through
>the airmass. The problem arises when pilots confuse
>the alignment
>maneuver with the turn. We've discovered this slick
>maneuver where we
>can turn base to final and initiate the slip all in
>one motion. Which
>leads to a false perception that we only turned 90
>degrees, then used
>the wing to compensate for crosswind. But we have in
>fact changed our
>direction by more than 90 degrees and inserted our
>alignment slip early
>on final. But whether your turn is coordinated throughout,
>or slipped,
>the means by which we change direction is exactly the
>same. Remove the
>slip, and you'll point upwind, put the slip back in
>and you'll point
>down the runway. The forces produced by the glider
>remain balanced
>throughout.
>
>Maybe it is easier to conceptualize this if you simply
>ignore the
>direction the nose is pointing and think of it in terms
>of the glider's
>path through the air. Because in a side slip the nose
>is pointing down
>the runway, there is an illusion that the lowered wing
>is dragging the
>glider sideways, compensating for the 'force' of the
>wind. But in a
>side slip (as in a foward slip), the horizontal component
>of lift is
>exactly balanced by the force created by sideways motion
>of the
>fuselage. There is no extra force to compensate for
>an external force.
>Which is a good thing since there is no external force
>from the wind.
>
>That said, an unbalanced force is required to establish
>a new direction
>through the air that will produce a desired ground
>track. And this is
>only accomplished by turning. Whether the turn is slipped
>or skidded or
>coordinated is a matter of pilot choice. It is nonetheless
>a turn since
>the direction of the glider changes. When the new direction
>is
>achieved, the turn ceases. Whether this is accomplished
>by rolling the
>wings level or increasing beta to balance the wing
>turning force is a
>matter of pilot choice.
>
>

[Martin Eiler]

While I agree with the majority of Todd's post, it
would be beneficial to have some clarification on point
5.

T O D D P A T T I S T wrote:
>5) If you slip while flying straight for very long,
>you need
>to lower the opposite wing or you will begin a skidding
>turn. Modern gliders have a low fuselage side area
>and take
>a while to begin this type of skidding turn.

I know this may sound petty but considering how
this thread has evolved, it's appropriate.
Exactly what is your definition of 'flying straight'
and 'turn'? Remember what Clinton taught us about
something we thought was as simple as the word 'is'.


Apparently the consensus seems to be that there are
three types of crosswind landing techniqes used. Crab
or side slip or some combination of both. Would it
be commonly accepted to say that while using the same
spoiler setting for both a crab and a side slip crosswind
landing, that the glider side slipping will have a
higher rate of descent?

M Eiler

[Bruce]

A fun intellectual exercise, but you have to fly the airplane. You also have to
make the transition to ground transport in such a way as to avoid unpleasant
noises and disorienting motion...

Most pilots I have observed use a combination of slip and crab depending on a
number of factors. Not always voluntary.

My experience is that you have to be very careful in a vintage wood and fabric
job. When the crab angle is extreme, and you have all the penetration of a well
thrown wet tissue, and there is a strong wind gradient it is doubtful whether
you would want to use a slip to increase your drag.

Lower drag means more options, so a 'higher performance' airplane can do both,
and may need to do both if you have carried extra height for whatever reason.

Not a bad idea to think it through on the ground - at least you can change your
mind without damage, in the circuit might not be a good place to be
philosophizing about it all.

Don Johnstone wrote:
> I am getting a little lost here. If you are trying
> to say that an aircraft when flying moves relative
> to the airmass it happens to be in you are right. The
> direction in which the airmass is moving is unimportant
> as far as the aircraft is concerned, as long as it
> remains flyng. The concept of what happens when a pilot
> has to change the movement of his glider from relative
> to the air to releative to the ground because it is
> about to become a wheeled vehicle with wings is not
> that important. What is vital is that pilots are trained
> how to change from being a vehicle moving relative
> to the airmass to one moving relative to the ground.
> As pilots, unlike the aircraft, we are more concerned
> with our movement relative to the ground.
> Do we really seek to change our direction through the
> airmass? What we seek to achieve is changing our direction
> relative to the ground, to align track and heading,
> we don't really care a jot that our movement relative
> to the airmass has changed (or not) until we try to
> operate outside the limits of the aircraft, then we
> care a lot. I suppose what I am trying to say is that
> the procedure is a very human thing, a skill that requires
> teaching, and not one which deep scientific analysis
> will help as there are so many variables.
>
> At 14:00 22 February 2005,
> wrote:
>
>>As often happens, the discussion is digressing into
>>the particulars of
>>landing in a crosswind, and I couldn't be happier.
>>Watching pilots
>>wrangle through the explanation of why they do what
>>they do is
>>fascinating, especially since the inference chain gets
>>all kinds of
>>twisted as they work their way back up to the model.
>>
>>The trick, I'm convinced, is to completely divorce
>>the slip/skid
>>alignment maneuvers from the maneuver required to establish
>>a track
>>down the runway. Once we've determined that there is
>>a crosswind, the
>>only way to establish a proper track is to change our
>>direction through
>>the airmass. The problem arises when pilots confuse
>>the alignment
>>maneuver with the turn. We've discovered this slick
>>maneuver where we
>>can turn base to final and initiate the slip all in
>>one motion. Which
>>leads to a false perception that we only turned 90
>>degrees, then used
>>the wing to compensate for crosswind. But we have in
>>fact changed our
>>direction by more than 90 degrees and inserted our
>>alignment slip early
>>on final. But whether your turn is coordinated throughout,
>>or slipped,
>>the means by which we change direction is exactly the
>>same. Remove the
>>slip, and you'll point upwind, put the slip back in
>>and you'll point
>>down the runway. The forces produced by the glider
>>remain balanced
>>throughout.
>>
>>Maybe it is easier to conceptualize this if you simply
>>ignore the
>>direction the nose is pointing and think of it in terms
>>of the glider's
>>path through the air. Because in a side slip the nose
>>is pointing down
>>the runway, there is an illusion that the lowered wing
>>is dragging the
>>glider sideways, compensating for the 'force' of the
>>wind. But in a
>>side slip (as in a foward slip), the horizontal component
>>of lift is
>>exactly balanced by the force created by sideways motion
>>of the
>>fuselage. There is no extra force to compensate for
>>an external force.
>>Which is a good thing since there is no external force
>
>>from the wind.
>
>>That said, an unbalanced force is required to establish
>>a new direction
>>through the air that will produce a desired ground
>>track. And this is
>>only accomplished by turning. Whether the turn is slipped
>>or skidded or
>>coordinated is a matter of pilot choice. It is nonetheless
>>a turn since
>>the direction of the glider changes. When the new direction
>>is
>>achieved, the turn ceases. Whether this is accomplished
>>by rolling the
>>wings level or increasing beta to balance the wing
>>turning force is a
>>matter of pilot choice.
>>
>>
>
>
>
>

[Martin Eiler]

While I agree with the majority of Todd's post, it
would be beneficial to have some clarification on point
5.

T O D D P A T T I S T wrote:
>5) If you slip while flying straight for very long,
>you need
>to lower the opposite wing or you will begin a skidding
>turn. Modern gliders have a low fuselage side area
>and take
>a while to begin this type of skidding turn.

I know this may sound petty but considering how
this thread has evolved, it's appropriate.
Exactly what is your definition of 'flying straight'
and 'turn'? Remember what Clinton taught us about
something we thought was as simple as the word 'is'.


Apparently the consensus seems to be that there are
three types of crosswind landing techniqes used. Crab
or side slip or some combination of both. Would it
be commonly accepted to say that while using the same
spoiler setting for both a crab and a side slip crosswind
landing, that the glider side slipping will have a
higher rate of descent?

M Eiler

[5Z]

It's interesting that everyone is talking about aligning with the
centerline of the runway.

Why not set up a diagonal landing and thus reduce the crosswind
component at touchdown. Even on a narrow runway, one can line up on
the downwind side and touch down maybe 20 degrees or more into the
wind.

With practice, one can land even more into the wind, then while the
rudder is still effective, make a gentle downwind turn so the nose is
again away from the crosswind and as speed drops, the glider will
finally weathervane into the wind. The ground track is a kind of S
turn.

-Tom

[Stefan]

5Z wrote:

> Even on a narrow runway, one can line up on
> the downwind side and touch down maybe 20 degrees or more into the
> wind.

A recipe for disaster. Obviously you've never seen a narrow runway.

Reminds me of that old joke where a navy pilot talks about a somewhat
short, but very large runway.

Stefan

[Stefan]

Martin Eiler wrote:

....
> Exactly what is your definition of 'flying straight'
> and 'turn'?
....

I'm always amused to see to which degree a very simple action can be
artificially complicated. Just land that plane.

When I talked about crabbing as the natural, most comfortable, most
flexible and simply best method for crosswind correction, I thought of a
stedy crosswind, of course. When it's gusty and turbulent, as a former
poster mentioned, then me too, I just do what has to be done to keep the
ship and me in one piece, and think about it later, if at all. Heck,
I've even flown regular *turns* (yuck!) in the final, when conditions
asked for them! But I wouldn't teach that to a student.

Stefan

[5Z]

Stefan wrote:
> A recipe for disaster. Obviously you've never seen a narrow runway.

With that tone, I assume you've never seen a wide runway! :)

I think it's obvious that each landing requires a unique set of tools
to be applied.

Where I fly, the runway is about 14M wide with grass on either side and
no lights. Easy to apply some of my techniques. At another airport
the runway is maybe 25M wide with lights and a bit of a dropoff from
pavenent to rough dirt on the sides. Still easy to land diagonally.

I have also landed on areas that are just a few meters wide (of smooth
ground) with rough terrain on either side. In this case I would indeed
line up on the centerline and stay there.

I have also landed in the "paddock" in the middle of the airport, and
flown the approach at 90 degrees to the paved runway when the wind was
40-50 knots.

A recipe for disaster is to not make the best approach for the
conditions.

-Tom

[Stefan]

5Z wrote:

> With that tone, I assume you've never seen a wide runway! :)

You're partly correct. I still remember my first landing on a paved
runway with actual, painted numbers and a real center line. Just like
the big guys! Now *that* was an adventure!

> Where I fly, the runway is about 14M wide with grass on either side and
> no lights. Easy to apply some of my techniques. At another airport
> the runway is maybe 25M wide with lights and a bit of a dropoff from
> pavenent to rough dirt on the sides. Still easy to land diagonally.

At my home base, the runway (sort of, difficult to tell on grass) is
about 20 meters wide. On One side, there are often some gliders parked
along the runway, on the other side are 30 cm high markers. I don't like
the idea of landing diagonally.

> A recipe for disaster is to not make the best approach for the
> conditions.

I fully agree.

Stefan

[Shawn]

Stefan wrote:
> 5Z wrote:
>
>> Even on a narrow runway, one can line up on
>> the downwind side and touch down maybe 20 degrees or more into the
>> wind.
>
>
> A recipe for disaster. Obviously you've never seen a narrow runway.

I saw Tom at Boulder once, before the runway was widened to 16 feet or
so. :-)

> Reminds me of that old joke where a navy pilot talks about a somewhat
> short, but very large runway.
>
> Stefan

[[email protected]]

Ok here is a little video gem for you all....in the middle of this
video

http://www.silentflight.com/movies/silentflight.wmv

there is a crosswind landing (30 degree + in 20+ knots of wind) in my
ASW22.

Big Plane, Big wind, Big crosswind angle.

Note the yaw string in the incockpit footage.

enjoy...

Al

[[email protected]]

I've seen quite a few. And the reason to have the discussion is because
competent pilots continue to break themselves and their gliders as a
result of pilot error. Why? Well, we're exploring one avenue. You are
welcome to help us or not.

Cheers

[[email protected]]

"My god," the pilot exclaimed as the plane screeched to a halt. "That
has to be the shortest runway I've ever had to land on."

"Yeah," replied the copilot, "But look how wide it is!"

[[email protected]]

Todd,

You have the advantage of a pretty clear understanding of what's going
on in the air. In yearspast (yes, years... arrrgh!), the "difference"
between crabbing and slipping has been a bone of contention. As I noted
earlier in the thread, the Soaring Flight Manual presents crabbing and
side slipping as additive. The new direction is to divorce this notion
from discussion of crosswind landings.

[[email protected]]

Ah, but the side slip confuses this. In order to change your ground
track by 20 degrees, you need to change your direction through the
airmass by 20 degerees. No argument there I'll guess. But your question
is, why do we care? Because a turn to final that includes a side slip
at the end gives a false impression of which way the aircraft is really
going. In fact, there's no reason to align track and heading until
touchdown. We've already discussed why you might choose not to.

Clearly many pilots get this. But many more do not. Though I suspect
they are becoming less certain about their own notions of how this
stuff works.

If the deconstructions are too simplistic (or obvious), I'd argue that
it's needed. I quoted the Soaring Flight Manual earlier to demonstrate
that even our textbooks promote some questionable notions of flight.
(I'll offer some more examples later this week.) Remember my question:
are crabs and side slips additive? Why would you NEED both in a strong
crosswind? If you think they ARE additive, I'd like to understand how
and why.

As for the art of flight (your last few sentences), I'd counter that
any maneuver that we cannot adequately (and simply) deconstruct,
shouldn't be in our repertoire. Why? Because when things go wrong, as
they sometimes do, you may not have the "rote" skills to quickly and
effectively correct them. Remember, we're doing these maneuvers
infrequently, near the ground, in turbulence. Not a forgiving
environment.

If I'm digging deep, it's so I can backfill with a better grade of
soil. I'd like to condense this down to several paragraphs, but getting
it short takes time and effort and a lot of words. If, on the other
hand, you have a concise, accurate description, please share it.

[[email protected]]

Interesting. But I think what you're saying is that many pilots feel
uncomfortable lowering the wing enough to fully align the gear with
their ground track, so when they land, they still need to skid the
fuselage around. I suppose this makes the flare a little less dramatic,
and therefore less error prone. And keeps the lowered wing a
comfortable distance above the ground. My quibble then is only with how
you describe. I don't think you combine a side slip with a crab: this
gets back to that implication that they are somehow additive. Instead,
you are combining a side slip with a pretouchdown skid. The primary
advantage is that you get a more wholesom view of the runway on final.
The disadvantage is that you have less yaw authority to swing the
glider during the flair. (Remember the ailerons have some effect as
well. You can increase the rate of yaw significantly with crossed
controls: kicking down wind while lowering the upwind wing as you
flare.)

[Stewart Kissel]

Or for that matter landing on the lee side of the runway...knowing
that the crosswind weather vaning is going to be steering
you back to centerline and over to the windward side.


fiveniner-Although I sorta understand your analysis,
I gotta say at some point this is going to be like
writing down on paper every variable in thermalling.
:)

Stefan-My hope is that you are not an English as first
language guy...because your tone is not helping your
cause.



At 18:30 22 February 2005, 5z wrote:
>It's interesting that everyone is talking about aligning
>with the
>centerline of the runway.
>
>Why not set up a diagonal landing and thus reduce the
>crosswind
>component at touchdown.

[[email protected]]

Bill Clinton, like him or not, is a shrewd fellow. When asked a
question that put his political life at risk, he made damn sure just
what the questioner meant. And the crux rested on "is." Now the more
astute of you will realize that "to be" is a tautology: state of being.
While some would think this a foundational word, a skilled speaker can
imbue it with all sorts of meaning, including confusing its tense.

If you understanding of flight depends on words (think back to your
time as a student), then should we be any less certain of the meaning
of those words since our lives may depend on them? Think of how many
times loose language in the cockpit led to accidents (take off power,
for example)... Why shouldn't equally loose language in textbooks be
just as hazardous?

Remember, it's winter. We can afford to look behind the words while we
wait for the weather to improve. (a norther point of view)

[Andreas Maurer]

On 22 Feb 2005 16:22:06 -0800, wrote:

>I've seen quite a few. And the reason to have the discussion is because
>competent pilots continue to break themselves and their gliders as a
>result of pilot error. Why? Well, we're exploring one avenue. You are
>welcome to help us or not.

I'm afraid that I can't be any help here.
The only thing I know about crosswind landings is to crab and (during
the flare) to align with the runway with the rudder, wings level.

To me this is such a natural maneuvre that I happen to be unable to
see why there is a need to discuss this matter - but obviously others
see things in a different way. :)




Bye
Andreas

[Bryan]

Pretty cool.

Bryan

> wrote in message
oups.com...
> Ok here is a little video gem for you all....in the middle of this
> video
>
> http://www.silentflight.com/movies/silentflight.wmv
>
> there is a crosswind landing (30 degree + in 20+ knots of wind) in my
> ASW22.
>
> Big Plane, Big wind, Big crosswind angle.
>
> Note the yaw string in the incockpit footage.
>
> enjoy...
>
> Al
>

[[email protected]]

Pilot's discussing engineering allways scare the be-jesus out of me.

The good thing is that the pilot does not need to understand physics
to fly, since 95% of the talk is complete BS, and the pilot's
still seem to manage the actual flying.

Toad

[Eric Greenwell]

Could you quote the poster you are replying too? At least the portion
you are replying to? The length of the
thread is making it very difficult to know what you are replying to.

wrote:
> Interesting. But I think what you're saying is that many pilots feel
> uncomfortable lowering the wing enough to fully align the gear with
> their ground track, so when they land, they still need to skid the
> fuselage around. I suppose this makes the flare a little less
> dramatic, and therefore less error prone. And keeps the lowered wing
> a comfortable distance above the ground. My quibble then is only with
> how you describe. I don't think you combine a side slip with a crab:
> this gets back to that implication that they are somehow additive.
> Instead, you are combining a side slip with a pretouchdown skid. The
> primary advantage is that you get a more wholesom view of the runway
> on final. The disadvantage is that you have less yaw authority to
> swing the glider during the flair. (Remember the ailerons have some
> effect as well. You can increase the rate of yaw significantly with
> crossed controls: kicking down wind while lowering the upwind wing as
> you flare.)
>


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Mark James Boyd]

Why would anyone use a sideslip instead of a crab during
landing? I've always thought it was to avoid sideloading the
tire (or tires) and thereby causing them to
go flat.

This is also why I like grass or dirt runways for students.
If they mess up the sideslip, then the side load is still
"detectable" but doesn't damage anything. I could see how
pilots of long-winged low-wing gliders might like grass or
dirt too, so they can land wings level in a crab. The guy who posted
that he does this on a narrow runway with obstructions
sounds like he's cuttin' it pretty close. :O

I prefer to teach the side slip technique, because it seems
less dynamic to me. It seems like a more stabilized approach,
since the sight picture doesn't dramatically change right at
touchdown. The guys who say crab and then straighten it right at
touchdown are doing something quite dynamic at the last second,
which isn't my preference. Also, at that last second on touchdown,
if it's a cement runway, they are putting at least some side load on the
tire, whether it is going sideways during touchdown or whether
they touch down and then are turning during rollout. If the wings
are really that long you have to do this, then I guess you
gotta do what you gotta do.

If the wind is really that strong, the ground roll will be shorter
too, so that helps the crabbing guys a bit. Even a direct crosswind
gets some headwind component in a 20 degree crab, right?

I also fly stuff that has SOME dihedral, and haven't flown anything over
20 meters, and I haven't flown a Pegasus (which some of you say
has flexing wings) so I haven't even ever seen a windward wing need to
be dropped below the gear in a full forward slip with the fuselage
straight down the runway. I have run out of rudder, and run out of
aileron before, in both power and gliders, and have landed with
both crab and sideslip due to this. Then I've benignly run off the
side of the runways/strips. In each of these cases there was
extra "room" to breathe, with no runway lights or signs, etc, just dirt.

Is a sideslip the only way to do it? No. If I feared catching a wingtip
would I land in a crab? Yes. I'd rather shear off the tire than
groundloop. If I could find grass or dirt, though, I think
I'd prefer that.

I've found that sideslips are also really challenging for new students.
They have a little trouble conceiving crossed-controls until they've
practiced it quite a bit. I found that I too wasn't able to
do a crosswind landing to the full crosswind component until
I had several hundreds of hours. Partly because I just wasn't
exposed to that heavy of crosswinds until then.

I try to set up a stabilized final approach at 400ft or so.
If it looks like I'm gonna run out of rudder or aileron in that
stabilized descent with a ground track straight down the runway
in a sideslip, then I make other plans. If the runway is wide, then
land diagonally. If there is a spot that allows me to go off the
runway weathervaning, then land at that spot (if the wind is that
strong I'm not gonna roll very far anyway).

My main concern is that if I barely have enough control authority
at approach speed, then the controls won't be able to hold that
slip when my airspeed decreases on rollout. To some degree
the wind gets a little lighter as I descend, however, so
if I can see the sock isn't as fierce as what I see at
400 ft, the lesser control authority on rollout may be enough
with the lighter wind.

Lots of stuff going on! And yes, practice makes perfect.
In conclusion, this is maybe a little more related to
"expense" and not "safety" as a botched crosswind landing on the
runway can certainly cost some serious $$$$s, but I'm not aware
of glider fatalities from botched runway crosswind landings.
Off field landings are perhaps another story...and of course
there could be crosswind there too...but somebody else will
need to talk about those intelligently...

In article . com>,
> wrote:
>Ah, but the side slip confuses this. In order to change your ground
>track by 20 degrees, you need to change your direction through the
>airmass by 20 degerees. No argument there I'll guess. But your question
>is, why do we care? Because a turn to final that includes a side slip
>at the end gives a false impression of which way the aircraft is really
>going. In fact, there's no reason to align track and heading until
>touchdown. We've already discussed why you might choose not to.
>
>Clearly many pilots get this. But many more do not. Though I suspect
>they are becoming less certain about their own notions of how this
>stuff works.
>
>If the deconstructions are too simplistic (or obvious), I'd argue that
>it's needed. I quoted the Soaring Flight Manual earlier to demonstrate
>that even our textbooks promote some questionable notions of flight.
>(I'll offer some more examples later this week.) Remember my question:
>are crabs and side slips additive? Why would you NEED both in a strong
>crosswind? If you think they ARE additive, I'd like to understand how
>and why.
>
>As for the art of flight (your last few sentences), I'd counter that
>any maneuver that we cannot adequately (and simply) deconstruct,
>shouldn't be in our repertoire. Why? Because when things go wrong, as
>they sometimes do, you may not have the "rote" skills to quickly and
>effectively correct them. Remember, we're doing these maneuvers
>infrequently, near the ground, in turbulence. Not a forgiving
>environment.
>
>If I'm digging deep, it's so I can backfill with a better grade of
>soil. I'd like to condense this down to several paragraphs, but getting
>it short takes time and effort and a lot of words. If, on the other
>hand, you have a concise, accurate description, please share it.
>


--

------------+
Mark J. Boyd

[Mark James Boyd]

Quite recently a commercial glider applicant was asked to
demonstrate a slipping turn downwind to final, and do everything
including landing with no spoilers.

He did so, with the wing into the wind, but once he found himself
180 deg in the other direction, he forgot to "switch" the
slip to have the lowered wing into the wind. So it was a "bumpy"
landing with a crab.

So what is a slip? Well, a forward slip or side slip to
me is an uncordinated manuever where both wingtips
are at the same airspeed. A turning slip is when the
wingtips are at different airspeeds, and the uncoordinated
part means the low wing and the rudder are opposite (outside rudder).
If the rudder and low wing are the same, then it may be a skid.

If the ball and the low wing are the same, it's a slip, if the
ball and low wing are opposite, it's a skid.

Is that about right? Or have I missed something obvious?

In article >,
Martin Eiler > wrote:
>While I agree with the majority of Todd's post, it
>would be beneficial to have some clarification on point
>5.
>
>T O D D P A T T I S T wrote:
>>5) If you slip while flying straight for very long,
>>you need
>>to lower the opposite wing or you will begin a skidding
>>turn. Modern gliders have a low fuselage side area
>>and take
>>a while to begin this type of skidding turn.
>
>I know this may sound petty but considering how
>this thread has evolved, it's appropriate.
>Exactly what is your definition of 'flying straight'
>and 'turn'? Remember what Clinton taught us about
>something we thought was as simple as the word 'is'.
>
>
>Apparently the consensus seems to be that there are
>three types of crosswind landing techniqes used. Crab
>or side slip or some combination of both. Would it
>be commonly accepted to say that while using the same
>spoiler setting for both a crab and a side slip crosswind
>landing, that the glider side slipping will have a
> higher rate of descent?
>
>M Eiler
>
>
>


--

------------+
Mark J. Boyd

[Graeme Cant]

Andreas Maurer wrote:
>
> I'm afraid that I can't be any help here.
> The only thing I know about crosswind landings is to crab and (during
> the flare) to align with the runway with the rudder, wings level.

I think you fly at a winch site but there's another way some tug pilots
use. On final the aircraft maintains alignment with a sideslip - so it
approaches wing-down. High wing, single-engine aeroplanes find this a
good technique because they land without levelling the wings (on one
wheel) and this makes landing simpler.

It appears from the discussion to have been carried over to gliders in
the US but since it's generally a bad idea to land a glider with a wing
down, the major benefit of the technique is lost and it's probably
inappropriate.

The explanation may lie in the widespread use of Schweizer 2-33s in the
US whose high wing allows wing-down landings - and it works even better
than a Cezzna because it only has one main wheel and it slows down
quickly. Since the technique is a bit doubtful with the more common
mid-wing, high aspect ratio gliders that many pilots will move to, it
seems silly to teach it in the first place but that's their business and
it seems to work for them. Like you, I was only ever taught crabbed
landings.

As far as I can make out, that's what this discussion is all about and
it's really not for us aliens.

> To me this is such a natural maneuvre that I happen to be unable to
> see why there is a need to discuss this matter - but obviously others
> see things in a different way. :)

I see it your way. Too many words to no useful purpose. But it's
actually a private conversation, I guess.

I've yet to see a broken glider just from a crosswind landing.
Shattered egos? Yes. Broken gliders? No.

GC

>
>
>
>
> Bye
> Andreas

[[email protected]]

If an approach is completed successfully to touchdown, the likely
damage is minimal, save poor airmanship aims the glider as something
substantial. The discussion was not intended to focus on the safety of
the touchdown, but the thought process of the pilot while on final.
(BTW, I've seen a glider wind up on its back after a botched crosswind
landing. The only solution, however, would have been to land on another
runway!)

Why, in god's name, do otherwise competent pilots abuse the controls
while turning from base to final? The classic situation is the low
turn, the pilot trying to hurry its completion with rudder, and then an
inopportune gust inviting him to snatch up an inside dropping wing with
aileron. In fact, altitude doesn't appear to be a key issue. My own
suspicion is that visual effects play a key role (with lack of altitude
emphasizing the effects). If a pilot doesn't understand the component
elements of that turn from base to final, isn't he more likely to abuse
the controls, especially if the motion he observes doesn't match up
with his expectations? And on what does a pilot base his expectations?
Experience and a conceptual model of flight. If slipping on final,
isn't he more likely to misuse the controls as he responds to
turbulence? A slip can turn quickly to a skid as a pilot reacts to wind
shear or other turbulence. (A question to US instructors: Isn't counter
productive to teach a pilot to ignore the yaw string in the pattern?
And having taught him to ignore the yaw string, to not thoroughly
assess the ways he might wind up getting himself in trouble while
reacting to low level turbulence? When was the last time you spent
several minutes explaining how to maintain a track while slipping, and
at the same time addressing the fact that this requires occasional use
of a skid? And can you think of any good reason a pilot should skid an
aircraft in that critical altitude band below 500 feet and above 3
feet?

I agree, the problem is solved completely if you simply drop the side
slip from your vocabulary and keep the yaw string straight right to the
point of touchdown. But in the US, you will immediately shut down all
discussion if you say that a side slip has no useful purpose, and, in
fact, that a side slip may be counter productive.

One way to say just that is to get people understanding what a side
slip is and what it is for. There is no reason not to use this
technique on a wide, smooth, flat runway. However, there is absolutely
no good reason to enter the sideslip until after you've cleared the
last obtacle and you are over the selfsame wide, smooth runway. But
kudos to those who know and have stated that it is the lesser of the
two alignment options: slipping versus skidding.




Graeme Cant wrote:
> Andreas Maurer wrote:
> >
> > I'm afraid that I can't be any help here.
> > The only thing I know about crosswind landings is to crab and
(during
> > the flare) to align with the runway with the rudder, wings level.
>
> I think you fly at a winch site but there's another way some tug
pilots
> use. On final the aircraft maintains alignment with a sideslip - so
it
> approaches wing-down. High wing, single-engine aeroplanes find this
a
> good technique because they land without levelling the wings (on one
> wheel) and this makes landing simpler.
>
> It appears from the discussion to have been carried over to gliders
in
> the US but since it's generally a bad idea to land a glider with a
wing
> down, the major benefit of the technique is lost and it's probably
> inappropriate.
>
> The explanation may lie in the widespread use of Schweizer 2-33s in
the
> US whose high wing allows wing-down landings - and it works even
better
> than a Cezzna because it only has one main wheel and it slows down
> quickly. Since the technique is a bit doubtful with the more common
> mid-wing, high aspect ratio gliders that many pilots will move to, it

> seems silly to teach it in the first place but that's their business
and
> it seems to work for them. Like you, I was only ever taught crabbed
> landings.
>
> As far as I can make out, that's what this discussion is all about
and
> it's really not for us aliens.
>
> > To me this is such a natural maneuvre that I happen to be unable to
> > see why there is a need to discuss this matter - but obviously
others
> > see things in a different way. :)
>
> I see it your way. Too many words to no useful purpose. But it's
> actually a private conversation, I guess.
>
> I've yet to see a broken glider just from a crosswind landing.
> Shattered egos? Yes. Broken gliders? No.
>
> GC
>
> >
> >
> >
> >
> > Bye
> > Andreas

[Bert Willing]

So, what do you want to say?

--
Bert Willing

ASW20 "TW"


> a écrit dans le message de news:
om...
> If an approach is completed successfully to touchdown, the likely
> damage is minimal, save poor airmanship aims the glider as something
> substantial. The discussion was not intended to focus on the safety of
> the touchdown, but the thought process of the pilot while on final.
> (BTW, I've seen a glider wind up on its back after a botched crosswind
> landing. The only solution, however, would have been to land on another
> runway!)
>
> Why, in god's name, do otherwise competent pilots abuse the controls
> while turning from base to final? The classic situation is the low
> turn, the pilot trying to hurry its completion with rudder, and then an
> inopportune gust inviting him to snatch up an inside dropping wing with
> aileron. In fact, altitude doesn't appear to be a key issue. My own
> suspicion is that visual effects play a key role (with lack of altitude
> emphasizing the effects). If a pilot doesn't understand the component
> elements of that turn from base to final, isn't he more likely to abuse
> the controls, especially if the motion he observes doesn't match up
> with his expectations? And on what does a pilot base his expectations?
> Experience and a conceptual model of flight. If slipping on final,
> isn't he more likely to misuse the controls as he responds to
> turbulence? A slip can turn quickly to a skid as a pilot reacts to wind
> shear or other turbulence. (A question to US instructors: Isn't counter
> productive to teach a pilot to ignore the yaw string in the pattern?
> And having taught him to ignore the yaw string, to not thoroughly
> assess the ways he might wind up getting himself in trouble while
> reacting to low level turbulence? When was the last time you spent
> several minutes explaining how to maintain a track while slipping, and
> at the same time addressing the fact that this requires occasional use
> of a skid? And can you think of any good reason a pilot should skid an
> aircraft in that critical altitude band below 500 feet and above 3
> feet?
>
> I agree, the problem is solved completely if you simply drop the side
> slip from your vocabulary and keep the yaw string straight right to the
> point of touchdown. But in the US, you will immediately shut down all
> discussion if you say that a side slip has no useful purpose, and, in
> fact, that a side slip may be counter productive.
>
> One way to say just that is to get people understanding what a side
> slip is and what it is for. There is no reason not to use this
> technique on a wide, smooth, flat runway. However, there is absolutely
> no good reason to enter the sideslip until after you've cleared the
> last obtacle and you are over the selfsame wide, smooth runway. But
> kudos to those who know and have stated that it is the lesser of the
> two alignment options: slipping versus skidding.
>
>
>
>
> Graeme Cant wrote:
>> Andreas Maurer wrote:
>> >
>> > I'm afraid that I can't be any help here.
>> > The only thing I know about crosswind landings is to crab and
> (during
>> > the flare) to align with the runway with the rudder, wings level.
>>
>> I think you fly at a winch site but there's another way some tug
> pilots
>> use. On final the aircraft maintains alignment with a sideslip - so
> it
>> approaches wing-down. High wing, single-engine aeroplanes find this
> a
>> good technique because they land without levelling the wings (on one
>> wheel) and this makes landing simpler.
>>
>> It appears from the discussion to have been carried over to gliders
> in
>> the US but since it's generally a bad idea to land a glider with a
> wing
>> down, the major benefit of the technique is lost and it's probably
>> inappropriate.
>>
>> The explanation may lie in the widespread use of Schweizer 2-33s in
> the
>> US whose high wing allows wing-down landings - and it works even
> better
>> than a Cezzna because it only has one main wheel and it slows down
>> quickly. Since the technique is a bit doubtful with the more common
>> mid-wing, high aspect ratio gliders that many pilots will move to, it
>
>> seems silly to teach it in the first place but that's their business
> and
>> it seems to work for them. Like you, I was only ever taught crabbed
>> landings.
>>
>> As far as I can make out, that's what this discussion is all about
> and
>> it's really not for us aliens.
>>
>> > To me this is such a natural maneuvre that I happen to be unable to
>> > see why there is a need to discuss this matter - but obviously
> others
>> > see things in a different way. :)
>>
>> I see it your way. Too many words to no useful purpose. But it's
>> actually a private conversation, I guess.
>>
>> I've yet to see a broken glider just from a crosswind landing.
>> Shattered egos? Yes. Broken gliders? No.
>>
>> GC
>>
>> >
>> >
>> >
>> >
>> > Bye
>> > Andreas
>

[Bert Willing]

Of course teaching "crabbed landing" means teaching a crab during final into
the flare, and then a last second slip. Litteral crabbed landing would be
way too expensive.

--
Bert Willing

ASW20 "TW"


"T o d d P a t t i s t" > a écrit dans le
message de news: ...
> Graeme Cant > wrote:
>
>>I think you fly at a winch site but there's another way some tug pilots
>>use. On final the aircraft maintains alignment with a sideslip - so it
>>approaches wing-down. High wing, single-engine aeroplanes find this a
>>good technique because they land without levelling the wings (on one
>>wheel) and this makes landing simpler.
>
> Touching down in a slip has nothing to do with making
> landings "simpler." If you don't understand why a slip is
> needed in a crosswind, then you don't understand the
> aerodynamics involved.
>
>>The explanation may lie in the widespread use of Schweizer 2-33s in the
>>US whose high wing allows wing-down landings - and it works even better
>>than a Cezzna because it only has one main wheel and it slows down
>>quickly. Since the technique is a bit doubtful with the more common
>>mid-wing, high aspect ratio gliders that many pilots will move to, it
>>seems silly to teach it in the first place but that's their business and
>>it seems to work for them. Like you, I was only ever taught crabbed
>>landings.
>
> If you only know crabbed landings, then you will land
> sideways every time. That's just the reality of the
> physics. In a high crosswind on a hard surface, landing
> crabbed is very bad.
>
> I seriously doubt that you were taught to land crabbed.
> Most likely you were taught to use a combination of last
> minute rudder to align with the runway (that ,maneuver puts
> you in a slip just before touchdown) and to carefully keep
> the upwind wing no higher than the downwind wing.

[Andreas Maurer]

On Thu, 24 Feb 2005 22:51:39 +1100, Graeme Cant >
wrote:

>I think you fly at a winch site but there's another way some tug pilots
>use.

Plenty of aerotows here, too... :)

>On final the aircraft maintains alignment with a sideslip - so it
>approaches wing-down. High wing, single-engine aeroplanes find this a
>good technique because they land without levelling the wings (on one
>wheel) and this makes landing simpler.

I know... :)
I'm using this technique in our Dimona motorglider, too.


>The explanation may lie in the widespread use of Schweizer 2-33s in the
>US whose high wing allows wing-down landings

Good point - I guess you are correct here.


>As far as I can make out, that's what this discussion is all about and
>it's really not for us aliens.

LMAO. Yup.

>I've yet to see a broken glider just from a crosswind landing.
>Shattered egos? Yes. Broken gliders? No.

Not even a shattered ego yet... :)



Bye
Andreas

[J.A.M.]

And landing gears are way too expensive...
Here's the method I like and use most:
Slip to control crosswind, and about 6 feet high, wings level, start the
flare. No time for the glider to accumulate enough lateral speed (refering
to the centerline) to be a problem.
If a student (or any pilot) is not comfortable with the techniques needed to
make a safe landing in crosswinds... don't fly that day!

Jose M. Alvarez.
ASW-24 'BR'

"Bert Willing" > escribió en
el mensaje ...
> Of course teaching "crabbed landing" means teaching a crab during final
into
> the flare, and then a last second slip. Litteral crabbed landing would be
> way too expensive.
>
> --
> Bert Willing
>
> ASW20 "TW"
>
>

[[email protected]]

Bert Willing wrote:
> So, what do you want to say?

There's something amiss with the way we teach people to fly. Not in all
aspects, but certainly in some critical ones. And while we are largely
successful, I could make an argument that our failures outnumber our
successes. A widespread misunderstanding of slips is one indication.

I was an enthusiastic student, well trained, well read. I've averaged
more than 200 hours PIC per year in gliders for the past 27 years. As a
commercial ride pilot and instructor (summers in college) I would make
as many as 10 take offs and landings per day and/or watch as many
again. Over those years I noticed conflicts, in how we teach on the
ground, the materials we assign for reading, and the control use we
demonstrate and drill in the air. What we do is 99% effective. But it
can be better. And since we all subscribe to the notion that aviation
is an unforgiving business, why not make a constant effort to improve?

The most succinct advice I've seen in this thread is "Geez, just do
it!" My sentiments exactly. But not very helpful for a confused pilot.
Wouldn't we prefer that new pilots apply knowledge rather than muscle
memory?

I pointed out at the top of this thread that it is confusing to tell a
pilot that he can either "crab" or "side slip" on crosswind final. It
gives the impression that these are two separate maneuvers that produce
similar effects. And that used together, their effects are somehow
additive. They are neither similar nor additive. We should find a way
to clear this up and make it part of our methodolgy for introducing and
practicing crosswind landings.

[[email protected]]

"Slip to CONTROL crosswind."

This is confusing. How does the slip control crosswind?

Next, "wings level..." Does that mean the rudder is brought to neutral?
If so, you have introduced a crab angle. If not, then you have
inititiated a skid. Do you see why? If you disagree, please take a few
lines to explain it so I'll understand.

[J.A.M.]

Ok... When the sailplane is under crosswind, it's velocity vector is altered
and it's not folowing a straight course over ground. To compensate for this
you change the direction of the lift vector sideways (rolling the wings with
ailerons) while keeping the nose pointed where you want (opposite rudder, a
slip).
This changes the velocity vector of the glider, making it follow a straight
course over ground, but a somewhat uncoordinated flight in the airmass (in a
slip, the velocity vector is not aligned with the fuselage; the glider does
not flies straight).
Wings level means... wings level... angle of bank zero, level with the
horizon, horizontal. I'm sorry I'm unable to explain better. The rudder goes
where it needs to go to keep the string centered (coordinated)
The glider is not skidding, it's just between a skid and a crab. I think
that it's flying coordinated (centered ball, centered string). You are
drifting with the wind, but only a little. The glider is close enough to the
contact point as to not be very affected by the wind in the, say, two
seconds of flight time remaining.

It would only take me a flight to explain it (to show, really) but I'm
afraid that I can't be more clear writing!
If I'm still unclear I'll try to elaborate more.


> escribió en el mensaje
ups.com...
> "Slip to CONTROL crosswind."
>
> This is confusing. How does the slip control crosswind?
>
> Next, "wings level..." Does that mean the rudder is brought to neutral?
> If so, you have introduced a crab angle. If not, then you have
> inititiated a skid. Do you see why? If you disagree, please take a few
> lines to explain it so I'll understand.
>

[Stefan]

T o d d P a t t i s t wrote:

> Are you saying you land wings level in a crosswind, your
> wheel is aligned with the runway AND your yaw string is
> straight (coordinated flight)? It just isn't possible.

Inertia makes it possible.

Stefan

[Andreas Maurer]

On 24 Feb 2005 09:33:40 -0800, wrote:


>The most succinct advice I've seen in this thread is "Geez, just do
>it!" My sentiments exactly. But not very helpful for a confused pilot.
>Wouldn't we prefer that new pilots apply knowledge rather than muscle
>memory?

Well... I've got a couple to thousands flights, most of them as
instructor. But I have to admit that I'm being very confused over this
discussion. I gave up trying to follow the more technical aspects
(like these forward slips and sideslips.. lol. How glad I am that this
difference doesn't exists in the German language.).

Why make things more difficult than they are? In my opinion this
thread is beating a dead horse.

Of course it's essential for a student pilot to know his basics - but
why tell them about all aspects of a topic if they only need to know
some "how-to" 's?
For most things there's more than one way to accomplish them, but it's
not required to know all of them, don't you agree?



>I pointed out at the top of this thread that it is confusing to tell a
>pilot that he can either "crab" or "side slip" on crosswind final. It
>gives the impression that these are two separate maneuvers that produce
>similar effects. And that used together, their effects are somehow
>additive. They are neither similar nor additive. We should find a way
>to clear this up and make it part of our methodolgy for introducing and
>practicing crosswind landings.

Simple. Teach the guys to grab and use their rudder during the flare.
Period.
Seems to work like a charm for *any* glider on my side of the pond
which is by far the majority of the gliders in the world.
<very big grin>.



Bye
Andreas

[Robert Ehrlich]

wrote:
> ...
> Why would you NEED both in a strong
> crosswind? If you think they ARE additive, I'd like to understand how
> and why.

You don't NEED both. You can achieve the needed angle between ground track
and direction of airspeed just by using crabbing, since there is no limit
to the angle you can obtain by crabbing. However if your mind is to use
slipping there is a limit to the angle that can be achieved by slipping,
if you think the thing to its extreme, when slipping with a 90 degrees
bank the useful angle is reverted to zero, so there is a maximum somewhere.
So if the crosswind is so strong that the needed angle exceeds this maximum,
even if you want to use slipping, you have to add some crabbing, in this
sense slipping and crabbing are additive, i.e. the resulting angle may be
due partly to slip and partly to crab if both are used.

[Graeme Cant]

T o d d P a t t i s t wrote:
> Touching down in a slip has nothing to do with making
> landings "simpler."

No. But approaching in a slip does.

>...If you don't understand why a slip is
> needed in a crosswind, then you don't understand the
> aerodynamics involved.

Probably true but I was actually discussing the approach technique, not
the landing. I assumed we all understood that the variations being
discussed were in the approach, not in the touchdown - especially since
the turn from base to final (a fair way before touchdown) has figured
prominently in your and 59yahoo's discussion. Sorry if I confused you
but I must say the aim of 59yahoo's rambling essays has confused me.

>>...
>>it seems to work for them. Like you, I was only ever taught crabbed
>>landings.

> If you only know crabbed landings, then you will land
> sideways every time. That's just the reality of the
> physics. In a high crosswind on a hard surface, landing
> crabbed is very bad.

Sorry. "crabbed landings" was intended as shorthand for "crabbed
approach to landing in a crosswind". I hope you were the only one
confused but I'm glad to sort it out.

> I seriously doubt that you were taught to land crabbed.
> Most likely you were taught to use a combination of last
> minute rudder to align with the runway (that ,maneuver puts
> you in a slip just before touchdown) and to carefully keep
> the upwind wing no higher than the downwind wing.

Interestingly, the most common accident or incident "during the rollout
following a crosswind landing" (so I don't confuse anyone) is ground
contact by the UPWIND wing or pod.

GC

[Graeme Cant]

J.A.M. wrote:

> It would only take me a flight to explain it (to show, really) but I'm
> afraid that I can't be more clear writing!
> If I'm still unclear I'll try to elaborate more.

Don't waste your life, Jose. He understands you perfectly well.
They're playing language games. It's got nothing to do with actually
flying gliders.

> > escribió en el mensaje

>>"Slip to CONTROL crosswind."
>>This is confusing. How does the slip control crosswind?
>>Next, "wings level..." Does that mean the rudder is brought to neutral?

He's just a pedantic ****ant. :)

He probably understands "semiotics". Language games can take several forms!

GC

[Eric Greenwell]

Graeme Cant wrote:
> The explanation may lie in the widespread use of Schweizer 2-33s in the
> US whose high wing allows wing-down landings - and it works even better
> than a Cezzna because it only has one main wheel and it slows down
> quickly. Since the technique is a bit doubtful with the more common
> mid-wing, high aspect ratio gliders that many pilots will move to, it
> seems silly to teach it in the first place but that's their business and
> it seems to work for them. Like you, I was only ever taught crabbed
> landings.

Perhaps that is why the a side-slipped landing seems "doubtful" to you?
If you had training and experience in the technique, it might seem as
sensible and as easy as it does to me. I was trained in an ASK 13, I've
flown the usual fiberglass ships for 1000's of hours, and I've used both
techniques. After a while, found I preferred a side-slip to a crab; even
so, I still use some crab in a strong crosswind.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Albert Gold]

If the cross wind is straight across the runway and strong enough you
can crab 90 degrees and land vertically, like a helicopter. Though I've
never actually done this I have "parked" a 1-26 above the middle of the
field at 1,500 feet and descended vertically to pattern altitude before
putting the nose down and proceeding. Of course, folks "park" in wave
all of the time.

Al


Robert Ehrlich wrote:
> wrote:
>
>>...
>>Why would you NEED both in a strong
>>crosswind? If you think they ARE additive, I'd like to understand how
>>and why.
>
>
> You don't NEED both. You can achieve the needed angle between ground track
> and direction of airspeed just by using crabbing, since there is no limit
> to the angle you can obtain by crabbing. However if your mind is to use
> slipping there is a limit to the angle that can be achieved by slipping,
> if you think the thing to its extreme, when slipping with a 90 degrees
> bank the useful angle is reverted to zero, so there is a maximum somewhere.
> So if the crosswind is so strong that the needed angle exceeds this maximum,
> even if you want to use slipping, you have to add some crabbing, in this
> sense slipping and crabbing are additive, i.e. the resulting angle may be
> due partly to slip and partly to crab if both are used.

[Martin Eiler]

The following is a snip from one of Fiveniner’s
early posts regarding the use of side slips for
dealing with wind drift while on final.

At 00:00 20 February 2005,
wrote:
>But the notion that the tilted lift vector is compensating
>for
>wind drift is flawed. Useful, but flawed.

Having read all of his posts in this thread, it is
apparent that he has supplied no real data
capable of substantiating his position that side
slips cannot compensate for wind drift. Yes,
there is a portion of the soaring community
that are die-hard crab pilots. That does not
mean that their choice automatically validates
his opinion that side slips can’t compensate for
cross wind. Those pilots who are experienced
with side slips seem to agree with the SSA’s
Soaring Manual, in that a side slip does have
some limitations, and consequently at some point,
some amount of crab may be needed to be added
to the side slip to achieve the desired result.

Interestingly, after rereading his other posts, it
becomes quite obvious that he is obsessed with
the opinion that pilots should only be allowed to
fly coordinated while at or below pattern altitude.
Although he is entitled to his opinion, few other
pilots would support the concept that a pilot who
intentionally flies uncoordinated on final is operating
dangerously.

Generally speaking having lofty ideals is admirable,
however it is more warmly accepted when an
individual signs his post with his real name.

M Eiler

[J.A.M.]

When I said straight I meant aligned with the runway axis, and with the
fuselage as well (in a slip).

"T o d d P a t t i s t" > escribió en el
mensaje ...
> "J.A.M." > wrote:
>
> >Ok... When the sailplane is under crosswind, it's velocity vector is
altered
> >and it's not folowing a straight course over ground.
>
> If the crosswind is constant and the sailplane is flying
> constant speed and heading, the ground track is straight.
> The problem is that the straight ground track may not be
> aligned with the runway. If it's not, you must turn to a
> new heading.
>
> >To compensate for this
> >you change the direction of the lift vector sideways (rolling the wings
with
> >ailerons) while keeping the nose pointed where you want (opposite rudder,
a
> >slip).
>
> Banking the wings and changing the lift vector produces a
> side force in the direction you are banked. Pointing the
> nose opposite the banked wings produces an opposing force
> due to the angle of attack of the fuselage. These two
> effect balance out and the track remains straight.
>
> >This changes the velocity vector of the glider,
>
> The velocity vector changes only if the pilot delays the
> opposite rudder enough to allow the uncompensated bank to
> turn the glider, change the track and compensate for the
> wind. If the pilot was initially crabbing sufficiently,
> then he would not delay the opposite rudder and the glider
> would not turn, the track would remain unchanged, and the
> only difference would be the increased descent rate and the
> fuselage would now be aligned with the runway.
>
> >making it follow a straight course over ground,
>
> It's always straight, during crab and slip.
>
> >but a somewhat uncoordinated flight in the airmass (in a
> >slip, the velocity vector is not aligned with the fuselage; the glider
does
> >not flies straight).
>
> Correct.
>
> >Wings level means... wings level... angle of bank zero, level with the
> >horizon, horizontal. I'm sorry I'm unable to explain better. The rudder
goes
> >where it needs to go to keep the string centered (coordinated)
>
> Are you saying you land wings level in a crosswind, your
> wheel is aligned with the runway AND your yaw string is
> straight (coordinated flight)? It just isn't possible.
>
> >The glider is not skidding, it's just between a skid and a crab.
>
> I have no idea what this is supposed to mean. If your yaw
> string is straight, you are crabbed. If it's off to the
> side, you are either slipping or skidding.
>
> You seem to be confused about the exact issue that drives
> this discussion.
>
>

[Bert Willing]

I thought that with a 1-26, that's actually how they operate even at 0 wind
:-))))

--
Bert Willing

ASW20 "TW"


"Albert Gold" > a écrit dans le message de news:
...
> If the cross wind is straight across the runway and strong enough you can
> crab 90 degrees and land vertically, like a helicopter. Though I've never
> actually done this I have "parked" a 1-26 above the middle of the field at
> 1,500 feet and descended vertically to pattern altitude before putting the
> nose down and proceeding. Of course, folks "park" in wave all of the time.
>
> Al
>
>
> Robert Ehrlich wrote:
>> wrote:
>>
>>>...
>>>Why would you NEED both in a strong
>>>crosswind? If you think they ARE additive, I'd like to understand how
>>>and why.
>>
>>
>> You don't NEED both. You can achieve the needed angle between ground
>> track
>> and direction of airspeed just by using crabbing, since there is no limit
>> to the angle you can obtain by crabbing. However if your mind is to use
>> slipping there is a limit to the angle that can be achieved by slipping,
>> if you think the thing to its extreme, when slipping with a 90 degrees
>> bank the useful angle is reverted to zero, so there is a maximum
>> somewhere.
>> So if the crosswind is so strong that the needed angle exceeds this
>> maximum,
>> even if you want to use slipping, you have to add some crabbing, in this
>> sense slipping and crabbing are additive, i.e. the resulting angle may be
>> due partly to slip and partly to crab if both are used.
>

[Graeme Cant]

Eric Greenwell wrote:
snip...
> After a while, found I preferred a side-slip to a crab;

So do I. Much more fun. but I do it in Cezznas, not my ASW20.

> even so, I still use some crab in a strong crosswind.

I think that makes my point. Very sensible with 18 metres of floppy
Schleicher wing to keep dust-free. :)

GC

[[email protected]]

Martin, you are entirely wrong. I'm not obsessed. Really. No, I mean
it. ;-)

I use slips as a matter of course because I understand their USE and
RISKS and I am competent. What I am obsessed with is finding the
language that will let me explain clearly, succinctly, that crabbing
and slipping are not means to the same end. Perhaps I should refocus
attention on the word crabbing... which give the impression that it is
a maneuver as opposed to being normal wings level flight. Maybe the
better way to discuss this is to talk about approaches being
coordinated or uncoordinated.

We all agree that in order to transition to the ground in a crosswind
situation, we must move from coordinated to uncoordinated flight. You
have a choice when to apply controls to establish uncoordinated flight.
You can do it just before touch down (in which case the turn that
accompanies a skid is manageable), or you may do it earlier on final.
What I want to knock down is this notion of either a crab or a slip as
it infects our understanding of the purpose of the slip.

In order to establish a new ground track, you must turn. A side slip is
not a turn. All forces are balanced. As I've already described, many
pilots are confused about this difference. They explain that the side
slip works because the tilted left vector points into the crosswind,
dragging the glider sideways and compensating for wind drift. This
works in practice, but is wrong in fact because the tilted lift vector
is exactly matched by fuselage drag. If there were an unbalance force,
the glider's direction would continue to change... that is, circle. The
point is to find a better way of saying this. The place I'm trying to
get to is that when we compensate for crosswind on final, what we are
really doing when we initiate the side slip is a turn... what is in the
first instant a coordinated turn (remember which way the nose goes if
we don't use coordinating rudder while we roll into the bank), which
becomes a slipped turn as we reverse the progressively rudder against
the turn to keep heading aligned with runway, until we reach a beta
where the wing turning force is exactly compensated by the fuselage
force.

A better way to teach this and practice it is to keep the turn
coordinated until the desired ground track is achieved. This
demonstrates clearly the only way to establish a new ground track... by
turning to what we typcially call a crabbed approach. Then, at the
pilot's option, he may enter a slip, which will align the gliders
heading with its ground track. This crearly demonstrates that the
slip's only purpuse is alignment, just as the only purpose for the
rudder kick before touchdown is alignment (the only purpose of which is
to reduce side loading on the gear). The advantage of the slip is that,
unlike the rudder kick, all foreces are balanced. If the touch down is
delayed, you are much less likely to have to make large corrections in
direction.

In your experience, how many pilots stick with this sport. I've heard
commercial operators say it's about 1 in 5. Twenty percent get it.
Eighty percent don't. And of the 20% that get, how many really get it?

I already know how to do it. Now I'm trying to "get it" in a way that I
can easily explain, and maybe help that other 80% figure things out.

Martin Eiler wrote:
> The following is a snip from one of Fiveniner's
> early posts regarding the use of side slips for
> dealing with wind drift while on final.
>
> At 00:00 20 February 2005,
> wrote:
> >But the notion that the tilted lift vector is compensating
> >for
> >wind drift is flawed. Useful, but flawed.
>
> Having read all of his posts in this thread, it is
> apparent that he has supplied no real data
> capable of substantiating his position that side
> slips cannot compensate for wind drift. Yes,
> there is a portion of the soaring community
> that are die-hard crab pilots. That does not
> mean that their choice automatically validates
> his opinion that side slips can't compensate for
> cross wind. Those pilots who are experienced
> with side slips seem to agree with the SSA's
> Soaring Manual, in that a side slip does have
> some limitations, and consequently at some point,
> some amount of crab may be needed to be added
> to the side slip to achieve the desired result.
>
> Interestingly, after rereading his other posts, it
> becomes quite obvious that he is obsessed with
> the opinion that pilots should only be allowed to
> fly coordinated while at or below pattern altitude.
> Although he is entitled to his opinion, few other
> pilots would support the concept that a pilot who
> intentionally flies uncoordinated on final is operating
> dangerously.
>
> Generally speaking having lofty ideals is admirable,
> however it is more warmly accepted when an
> individual signs his post with his real name.
>
> M Eiler

[[email protected]]

Sorry Marty. I type at warp speed and don't always leave a name at the
end. For 17 years my contest ID was 59, thus the yahoo address. And
perhaps as a frequent contributor to the group, I've let my ego swell
to the point that I figure others will recognize me by content or
style.

Chris O'Callaghan
Ventus 2bx -- Oscar Charlie
Frederick, Maryland
Member of the Mid-Atlantic Soaring Association

[[email protected]]

OK. I think this thread has served its purpose, at least for me. It
looks like the key may be centered on "coordination."

Might I suggest to active instructors that you try my exercise and
report back: coordinated turn to a heading that establishes ground
track as you would at altitude, the entry and recovery from a slip to
demonstrate gear alignment and return to wings level coordinated
flight. You might preface this with a forward slip demonstration in
light winds and comment on the misalignment of the gear with the runway
and the need to align before touch down. When might this misalignment
be useful? Let the student mull that over... then start talking about
crosswind navigation and see if he makes the connection.

I'm checking out for the next week. If someone has an epiphany, please
copy me back channel.

Cheers,

Chris O'Callaghan

[Bert Willing]

Still, Martin's point stands - you don't sign with your name.

And the whole thing somehow looks pretty much like intellectual
masturbation. Getting a ship onto a runway in a crosswind isn't the most
diffult thing in flying glider, and if a student doesn' get it, he wouldn't
get a number of things anyway.

--
Bert Willing

ASW20 "TW"


> a écrit dans le message de news:
. com...
> Martin, you are entirely wrong. I'm not obsessed. Really. No, I mean
> it. ;-)
>
> I use slips as a matter of course because I understand their USE and
> RISKS and I am competent. What I am obsessed with is finding the
> language that will let me explain clearly, succinctly, that crabbing
> and slipping are not means to the same end. Perhaps I should refocus
> attention on the word crabbing... which give the impression that it is
> a maneuver as opposed to being normal wings level flight. Maybe the
> better way to discuss this is to talk about approaches being
> coordinated or uncoordinated.
>
> We all agree that in order to transition to the ground in a crosswind
> situation, we must move from coordinated to uncoordinated flight. You
> have a choice when to apply controls to establish uncoordinated flight.
> You can do it just before touch down (in which case the turn that
> accompanies a skid is manageable), or you may do it earlier on final.
> What I want to knock down is this notion of either a crab or a slip as
> it infects our understanding of the purpose of the slip.
>
> In order to establish a new ground track, you must turn. A side slip is
> not a turn. All forces are balanced. As I've already described, many
> pilots are confused about this difference. They explain that the side
> slip works because the tilted left vector points into the crosswind,
> dragging the glider sideways and compensating for wind drift. This
> works in practice, but is wrong in fact because the tilted lift vector
> is exactly matched by fuselage drag. If there were an unbalance force,
> the glider's direction would continue to change... that is, circle. The
> point is to find a better way of saying this. The place I'm trying to
> get to is that when we compensate for crosswind on final, what we are
> really doing when we initiate the side slip is a turn... what is in the
> first instant a coordinated turn (remember which way the nose goes if
> we don't use coordinating rudder while we roll into the bank), which
> becomes a slipped turn as we reverse the progressively rudder against
> the turn to keep heading aligned with runway, until we reach a beta
> where the wing turning force is exactly compensated by the fuselage
> force.
>
> A better way to teach this and practice it is to keep the turn
> coordinated until the desired ground track is achieved. This
> demonstrates clearly the only way to establish a new ground track... by
> turning to what we typcially call a crabbed approach. Then, at the
> pilot's option, he may enter a slip, which will align the gliders
> heading with its ground track. This crearly demonstrates that the
> slip's only purpuse is alignment, just as the only purpose for the
> rudder kick before touchdown is alignment (the only purpose of which is
> to reduce side loading on the gear). The advantage of the slip is that,
> unlike the rudder kick, all foreces are balanced. If the touch down is
> delayed, you are much less likely to have to make large corrections in
> direction.
>
> In your experience, how many pilots stick with this sport. I've heard
> commercial operators say it's about 1 in 5. Twenty percent get it.
> Eighty percent don't. And of the 20% that get, how many really get it?
>
> I already know how to do it. Now I'm trying to "get it" in a way that I
> can easily explain, and maybe help that other 80% figure things out.
>
> Martin Eiler wrote:
>> The following is a snip from one of Fiveniner's
>> early posts regarding the use of side slips for
>> dealing with wind drift while on final.
>>
>> At 00:00 20 February 2005,
>> wrote:
>> >But the notion that the tilted lift vector is compensating
>> >for
>> >wind drift is flawed. Useful, but flawed.
>>
>> Having read all of his posts in this thread, it is
>> apparent that he has supplied no real data
>> capable of substantiating his position that side
>> slips cannot compensate for wind drift. Yes,
>> there is a portion of the soaring community
>> that are die-hard crab pilots. That does not
>> mean that their choice automatically validates
>> his opinion that side slips can't compensate for
>> cross wind. Those pilots who are experienced
>> with side slips seem to agree with the SSA's
>> Soaring Manual, in that a side slip does have
>> some limitations, and consequently at some point,
>> some amount of crab may be needed to be added
>> to the side slip to achieve the desired result.
>>
>> Interestingly, after rereading his other posts, it
>> becomes quite obvious that he is obsessed with
>> the opinion that pilots should only be allowed to
>> fly coordinated while at or below pattern altitude.
>> Although he is entitled to his opinion, few other
>> pilots would support the concept that a pilot who
>> intentionally flies uncoordinated on final is operating
>> dangerously.
>>
>> Generally speaking having lofty ideals is admirable,
>> however it is more warmly accepted when an
>> individual signs his post with his real name.
>>
>> M Eiler
>

[Bert Willing]

Oups - I take back my first remark.

--
Bert Willing

ASW20 "TW"


> a écrit dans le message de news:
om...
> Sorry Marty. I type at warp speed and don't always leave a name at the
> end. For 17 years my contest ID was 59, thus the yahoo address. And
> perhaps as a frequent contributor to the group, I've let my ego swell
> to the point that I figure others will recognize me by content or
> style.
>
> Chris O'Callaghan
> Ventus 2bx -- Oscar Charlie
> Frederick, Maryland
> Member of the Mid-Atlantic Soaring Association
>

[[email protected]]

Yes, well said. But still wrong, in this sense:

Side slipping does not change your direction. What you have done is to
define the limits of side slipping as an alignment maneuver. This
doesn't make side slipping and crabbing additive. It simply says that
you've been taught or you prefer to uncoordinate the aircraft early on
final to align the gear with the runway. However, the rudder will only
allow a finite maximum angle of yaw, which limits the amount of bank
you can use before the wing turning force exceeds the fuselage force
and you start turning. So put another way, a side slip is only useful
for gear alignment up to some fixed crosswind component speed. Above
that speed, you will need to add a skid before touch down... but
wait... your rudder is already full over. How will you align the gear?
Well, if you had both the full authority of the rudder and the adverse
yaw or you ailerons, you might be able to manage it. But that would
require a crabbed (coordinated) approach. Which just happens to be the
same path you were moving through the air while side slipping "plus"
crabbing. Do you see why I just can't stomach the notion of side slips
and crabs being additive? There is a reverse logic at work here which
gives the side slip a false role in crosswind management.

Put another way, a side slip is only appropriate for light to moderate
crosswind components and flat landing surfaces. The stronger the
crosswind, the rougher the runway, the more critical it is to have
maximum yaw performance at touch down. Side slips and skids are
additive, but only to the degree that you have any rudder left to yaw
the glider. Since everyone seems to have a preference, I would guess
this is the worst of both worlds.

Think of it another way... if I slow down on final, I'll need to change
my direction to maintain a constant ground track. (This is simple trig
that I'll leave to you.) I cannot accomplish this by adding side slip.
A side slip changes heading only, not track. I must turn in order to
maintain track. This isn't even apples and oranges. This trying to add
fruits and vegetables.

So here I am on final in calm conditions... I slip to the right. I
recover. I slip to the left. I recover. Net force always equals zero.
My flight path remains the same. Track, the same. Heading swings 20
degrees either side of the runway center line. Same thing in a cross
wind. I establish a ground track. I point down the runway. I recover
form the side slip. For amusement I slip in the other direction - with
the downwind wing low (is this a side slip or a forward slip???!!!). I
recover. Net force always equals zero. My track remains exactly the
same while my heading swings through 40 total degrees, centered on my
path through the air.

I'll see if I can't find a new direction to come at this. Redefining
the approach in terms of coordination may be the way. But I really do
need to check out. Be back in a week or two.

OC aka 59 aka Chris O'Callaghan

[Greg Arnold]

It obviously has been a long winter in your part of the country. You
badly need to go flying!


wrote:
> Yes, well said. But still wrong, in this sense:
>
> Side slipping does not change your direction. What you have done is to
> define the limits of side slipping as an alignment maneuver. This
> doesn't make side slipping and crabbing additive. It simply says that
> you've been taught or you prefer to uncoordinate the aircraft early on
> final to align the gear with the runway. However, the rudder will only
> allow a finite maximum angle of yaw, which limits the amount of bank
> you can use before the wing turning force exceeds the fuselage force
> and you start turning. So put another way, a side slip is only useful
> for gear alignment up to some fixed crosswind component speed. Above
> that speed, you will need to add a skid before touch down... but
> wait... your rudder is already full over. How will you align the gear?
> Well, if you had both the full authority of the rudder and the adverse
> yaw or you ailerons, you might be able to manage it. But that would
> require a crabbed (coordinated) approach. Which just happens to be the
> same path you were moving through the air while side slipping "plus"
> crabbing. Do you see why I just can't stomach the notion of side slips
> and crabs being additive? There is a reverse logic at work here which
> gives the side slip a false role in crosswind management.
>
> Put another way, a side slip is only appropriate for light to moderate
> crosswind components and flat landing surfaces. The stronger the
> crosswind, the rougher the runway, the more critical it is to have
> maximum yaw performance at touch down. Side slips and skids are
> additive, but only to the degree that you have any rudder left to yaw
> the glider. Since everyone seems to have a preference, I would guess
> this is the worst of both worlds.
>
> Think of it another way... if I slow down on final, I'll need to change
> my direction to maintain a constant ground track. (This is simple trig
> that I'll leave to you.) I cannot accomplish this by adding side slip.
> A side slip changes heading only, not track. I must turn in order to
> maintain track. This isn't even apples and oranges. This trying to add
> fruits and vegetables.
>
> So here I am on final in calm conditions... I slip to the right. I
> recover. I slip to the left. I recover. Net force always equals zero.
> My flight path remains the same. Track, the same. Heading swings 20
> degrees either side of the runway center line. Same thing in a cross
> wind. I establish a ground track. I point down the runway. I recover
> form the side slip. For amusement I slip in the other direction - with
> the downwind wing low (is this a side slip or a forward slip???!!!). I
> recover. Net force always equals zero. My track remains exactly the
> same while my heading swings through 40 total degrees, centered on my
> path through the air.
>
> I'll see if I can't find a new direction to come at this. Redefining
> the approach in terms of coordination may be the way. But I really do
> need to check out. Be back in a week or two.
>
> OC aka 59 aka Chris O'Callaghan
>

[Kilo Whiskey]

wrote:
> As often happens, the discussion is digressing into the particulars
of
> landing in a crosswind, and I couldn't be happier. Watching pilots
> wrangle through the explanation of why they do what they do is
> fascinating, especially since the inference chain gets all kinds of
> twisted as they work their way back up to the model.
>
> The trick, I'm convinced, is to completely divorce the slip/skid
> alignment maneuvers from the maneuver required to establish a track
> down the runway. Once we've determined that there is a crosswind, the
> only way to establish a proper track is to change our direction
through
> the airmass. The problem arises when pilots confuse the alignment
> maneuver with the turn. We've discovered this slick maneuver where we
> can turn base to final and initiate the slip all in one motion. Which
> leads to a false perception that we only turned 90 degrees, then used
> the wing to compensate for crosswind. But we have in fact changed our
> direction by more than 90 degrees and inserted our alignment slip
early
> on final. But whether your turn is coordinated throughout, or
slipped,
> the means by which we change direction is exactly the same. Remove
the
> slip, and you'll point upwind, put the slip back in and you'll point
> down the runway. The forces produced by the glider remain balanced
> throughout.
>
> Maybe it is easier to conceptualize this if you simply ignore the
> direction the nose is pointing and think of it in terms of the
glider's
> path through the air. Because in a side slip the nose is pointing
down
> the runway, there is an illusion that the lowered wing is dragging
the
> glider sideways, compensating for the "force" of the wind. But in a
> side slip (as in a foward slip), the horizontal component of lift is
> exactly balanced by the force created by sideways motion of the
> fuselage. There is no extra force to compensate for an external
force.
> Which is a good thing since there is no external force from the wind.
>
> That said, an unbalanced force is required to establish a new
direction
> through the air that will produce a desired ground track. And this is
> only accomplished by turning. Whether the turn is slipped or skidded
or
> coordinated is a matter of pilot choice. It is nonetheless a turn
since
> the direction of the glider changes. When the new direction is
> achieved, the turn ceases. Whether this is accomplished by rolling
the
> wings level or increasing beta to balance the wing turning force is a
> matter of pilot choice.

[Z Goudie]

At 18:30 25 February 2005,
wrote:
>Yes, well said. But still wrong, in this sense:

Most of us mere mortals are very broad minded about
this; why don't you just fly the bleedin' picture as
it changes!

[Stefan]

T o d d P a t t i s t wrote:

> However, your yaw string will NOT be straight when you apply
> rudder to line up and you will NOT be in coordinated
> flight.

Got me. But then, who looks at the yaw string during the flare anyway?

BTW: I know that in the US, you make a difference about "forward" and
"side" slip. How would this one be called? Maybe a "wing level straight
forward slip"? :-)

> I'd like to emphasize that I usually land in a crosswind
> pretty much as you are describing, I fly coordinated until

Thank you, Todd. Makes me sleep better. :-)

Stefan

[Stefan]

T o d d P a t t i s t wrote:

> However, your yaw string will NOT be straight when you apply
> rudder to line up and you will NOT be in coordinated
> flight.


Got me. But then, who looks at the yaw string during the flare anyway?

BTW: I know that in the US, you make a difference about "forward" and
"side" slip. How would this one be called? Maybe an "inertia induced
wing level straight forward slip"? :-)

> I'd like to emphasize that I usually land in a crosswind
> pretty much as you are describing, I fly coordinated until


Thank you, Todd. Makes me sleep better. :-)

Stefan

[Kilo Whiskey]

Hello everyone!

I have been following ras for a few years now and have finally felt
compelled to add my voice. Other than the threads on V-tails& flaps of
death, this has been the most interesting discussion although for an
entirely differing reason. Usually there is no need for comment as most
important bases on topics generally get equal time. Aside from wading
or suffering through some personal opinions I have enjoyed the comments
and insights.

The opinions that I have been hearing in this thread have all sounded
as if they have come from mostly instructors and or folks who fly
primarily slippery glass.One day I will be there as well, but for the
past 6 years I have been flying an SGS 1-35c model on the East coast w/
a commercial ticket. If any of you do not know them, they have only
flaps or slips for vertical glidepath control. My introduction to
soaring instruction began in 1998 and still is as fresh today as it was
then. On more than one occasion my instructor's voice has come back
when things were not very plesant in the air. And having said that, I
believe how information is passed along to be very important. I
consider all landings as practice for off field landings of which I
have my share, some of which have been done in rotor in and near
Petersburg W.Va. W-99.I am chiming into this thread because I still
have pretty vivid recollection of my training.

As I recall, slips were taught to me after stalls but before spin
entry and exits.At our club, I observe both slipping and crabbing style
allignments. Our strip is wide grass adjacent a hardpaved runway. It is
my opinion that the more experienced pilots choose the slip method and
the less experienced generally opt for the crab. I believe the reason
goes back to their training. With the less experienced being closer to
theirs. When learning the stall warning signs in most any older early
training ship ie; 2-33, Ka-13, Ka7 the pre-stall buffeting is quite
pronounced and makes quite an impression on the student. Therefore I
believe that early pilots transfer the pre-stall noises to a ship
slipping and are therefore uncomfortable doing so, esp closing in on
the grounds proximity! As for myself I agree that I use both and
sometimes together although generally I prefer the slip. I only tend to
use the crab as a combination during high x-wind.

Last fall one of our glass pilots had his canopy come loose on base.
Concentrating on the canopy, he failed to control his decent and
eventually his directional control. Extensive damage to the ship but
no more than an ego bruise to the pilot. During the ensuing discussions
slipping to keep the canopy closed was pretty generally the method we
all agreed we would have chosen. Of those in the discussion I might
have been the only one to have had practice at this during my late
stage training.That due to my instructor's foresight.

After all was said and done, one of my instructors challenged me
again. He asked me what I would do if one day while checking my flaps
upon entering the pattern the lever arm came off in my hands
essentially eliminating their use? Obviously slipping is the answer, so
I began to try this method.To this day I have only witnessed one other
club member attempt it.

Which brings me to my point. I believe having an effective slip in
every pilot's pocket is an essential thing. That pre-solo students
should be able to land their ship without the use of additional
mechanical devices.Taught late in the program to the point of
proficiency. If slips were used more, possibly even the deadly canopy
open on tow might loose some of it's near certainty! I do not see this
@ our club but wish I did.If slipping had been regularly practiced by
the accident pilot,he might have used it rather than his hand to keep
the canopy closed freeing up one for the divebreaks.

I have had the opportunity to to add a full slip to 75 deg. flaps @
90 mph. to extricate myself from a fast closing wave system. You need
to do it once to appreciate the view!

Paul Rehm KW

[Eric Greenwell]

Graeme Cant wrote:
> Eric Greenwell wrote:
> snip...
> > After a while, found I preferred a side-slip to a crab;
>
> So do I. Much more fun. but I do it in Cezznas, not my ASW20.
>
>> even so, I still use some crab in a strong crosswind.
>
>
> I think that makes my point. Very sensible with 18 metres of floppy
> Schleicher wing to keep dust-free. :)

My 18 meter Schleicher (ASH 26 E) doesn't have a floppy wing like my ASW
20 C did. I start using crab when I"m close to full rudder in the
side-slip, which can happen in strong cross winds. The low wing still
seems sufficiently high at that point, but I don't have a measurement
for the angle it makes with the ground.

Regardless, it's very rare that I've had to land where the height of the
grass or bushes was a concern. If I routinely landed where the wing tips
were over 20"-30" high grass, perhaps I'd be using a crab instead.
--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Martin Eiler]

At 06:00 26 February 2005, Eric Greenwell wrote:
>I start using crab when I'm close to full rudder in
>the
>side-slip, which can happen in strong cross winds.
>The low wing still seems sufficiently high at that
>point,
>but I don't have a measurement for the angle it makes
>with the ground.
>
>Regardless, it's very rare that I've had to land where
> the height of the grass or bushes was a concern.
>If I routinely landed where the wing tips were over
>20'-30' high grass, perhaps I'd be using a crab instead.

Here's some interesting data. ASK-21's have quite
a bit of dihedral and relatively stiff wings as
compared to most fiberglass single place gliders.
A K-21 pilot landing with the upwind wing leading
edge parallel to the ground has a 3.5 degree bank.
If he was foolhardy enough to touch down with the
main wheel and upwind wing at the same time,
he would be in a 6.5 degree bank. So it might
seem reasonable to expect that a pilot proficient
in side slips would therefore maybe be willing to
touch down with a 5 degree bank.
M Eiler

[Mark James Boyd]

I was doing side slips and forward slips a few weeks ago with
a well respected SSA Master X-C instructor. He pointed out that
to lose altitude, slipping with the down wing AWAY from the airport
during the base leg makes the glider go further from the
airport and this helps by allowing a longer final.
I taught this technique this weekend in an, ahem, towplane
to lose altitude, and it worked great! Funny I hadn't read
this anywhere...

I prefer to avoid forward slips or crabs on short final
because I like to see a stabilized approach, instead of
a dramatic yaw right at the very end. Forward slips right
down to the last part of final also means not good ASI indications.
I wish I had a braunschweig tube on these gliders! ;)

But a forward slip on base seems to work very, very well.
Although I teach turning slips also, I've found that
maintaining a rectangular pattern is easier to describe, teach,
and judge. You can still do a turning slip base to final, for example,
but I don't generally teach a 180 degree turning slip from downwind
to final.

In article >,
T o d d P a t t i s t > wrote:
wrote:
>
>>Yes, well said. But still wrong, in this sense:
>
>I'll take this as directed to me, since it seems to be under
>my post, but it would have helped to quote some of the
>original post, for context. :-)
>
>>Side slipping does not change your direction.
>
>Agreed. In a stable side slip you are flying straight.
>Entering the side slip can be done to maintain the original
>heading or to turn during the entry. I think we agree on
>this.
>
>>What you have done is to
>>define the limits of side slipping as an alignment maneuver.
>
>Agreed.
>
>>This doesn't make side slipping and crabbing additive.
>
>Depends on what you mean by "additive." The track over the
>ground and through the air mass are not additive. The angle
>between the nose and the runway are - although in a negative
>sense. You have to deal with both during a landing.
>
>>It simply says that
>>you've been taught or you prefer to uncoordinate the aircraft early on
>>final to align the gear with the runway. However, the rudder will only
>>allow a finite maximum angle of yaw, which limits the amount of bank
>>you can use before the wing turning force exceeds the fuselage force
>>and you start turning. So put another way, a side slip is only useful
>>for gear alignment up to some fixed crosswind component speed. Above
>>that speed, you will need to add a skid before touch down... but
>>wait... your rudder is already full over. How will you align the gear?
>>Well, if you had both the full authority of the rudder and the adverse
>>yaw or you ailerons, you might be able to manage it. But that would
>>require a crabbed (coordinated) approach.
>
>This point has theoretical merit, but in practice, a glider
>will fly at an amazing angle with only a small amount of
>wing down. We have a rudder large enough to counter
>significant adverse yaw and a small fuselage cross section,
>so if you truly need more than full rudder as you reach the
>lower speed crosswind at touchdown, you are probably in a
>world of hurt crabbing or slipping. Conversely, I add
>slipping into my approach in a strong crosswind. I want to
>minimize the large yaw change required at touchdown, I can
>see the runway better, and it seems to be more in control
>for me in gusts.
>
>>Which just happens to be the
>>same path you were moving through the air while side slipping "plus"
>>crabbing. Do you see why I just can't stomach the notion of side slips
>>and crabs being additive?
>
>I think you are emphasizing the fact that both approaches
>must follow the same path over ground and through moving
>airmass. That leads you to believe that both are a crabbed
>approach, while slipping is just an optional alignment
>issue. That's fair, but alignment is important too and your
>position ignores the fact that historically we differentiate
>the two approaches based on the fuselage alignment.
>
>>There is a reverse logic at work here which
>>gives the side slip a false role in crosswind management.
>
>The pilot has to manage both the approach and the touchdown.
>Slip plays an essential part mostly in the latter, but
>putting some in the former may help manage the latter.
>
>>Put another way, a side slip is only appropriate for light to moderate
>>crosswind components and flat landing surfaces.
>
>I disagree. In a strong crosswind, I'm more likely to add
>slip to my approach.
>
>>The stronger the
>>crosswind, the rougher the runway, the more critical it is to have
>>maximum yaw performance at touch down.
>
>I find I use full rudder many times during a typical
>thermalling flight, but I can't recall ever needing it as I
>touched down.
>
>>Side slips and skids are additive,
>
>Huh? They are opposites.
>
>>but only to the degree that you have any rudder left to yaw
>>the glider. Since everyone seems to have a preference, I would guess
>>this is the worst of both worlds.
>
>What is the worst of both worlds? I missed something here/
>
>>Think of it another way... if I slow down on final, I'll need to change
>>my direction to maintain a constant ground track.
>
>Agreed. It also changes as wind speed and direction change
>with altitude, a common occurrence.
>
>>(This is simple trig
>>that I'll leave to you.) I cannot accomplish this by adding side slip.
>
>Depends on how you use side slip. A slight differential in
>the timing of the balanced rudder produces a slipping turn
>and the desired new heading.
>
>>A side slip changes heading only, not track. I must turn in order to
>>maintain track. This isn't even apples and oranges. This trying to add
>>fruits and vegetables.
>
>See above.
>
>>So here I am on final in calm conditions... I slip to the right. I
>>recover. I slip to the left. I recover. Net force always equals zero.
>
>As long as you enter it in a balanced way, but the pilot is
>not required to do that, and often does not want to.
>
>>My flight path remains the same. Track, the same. Heading swings 20
>>degrees either side of the runway center line. Same thing in a cross
>>wind. I establish a ground track. I point down the runway. I recover
>>form the side slip. For amusement I slip in the other direction - with
>>the downwind wing low (is this a side slip or a forward slip???!!!). I
>>recover. Net force always equals zero. My track remains exactly the
>>same while my heading swings through 40 total degrees, centered on my
>>path through the air.
>>
>>I'll see if I can't find a new direction to come at this. Redefining
>>the approach in terms of coordination may be the way. But I really do
>>need to check out. Be back in a week or two.
>>
>>OC aka 59 aka Chris O'Callaghan
>
>Have a good trip, wherever you're going.
>


--

------------+
Mark J. Boyd

[J.A.M.]

"T o d d P a t t i s t" > escribió en el
mensaje ...
> wrote:
>
> >What I am obsessed with is finding the
> >language that will let me explain clearly, succinctly, that crabbing
> >and slipping are not means to the same end.
>
> Why not just say that in a crosswind landing, on final, you
> always have to fly an upwind course through the air to
> achieve a ground track aligned with the runway. Always.
>

Because it is not true...

[jonnyboy]

.... that the slip's only purpuse is alignment, just as the only purpose
for the
rudder kick before touchdown is alignment (the only purpose of which is

to reduce side loading on the gear). The advantage of the slip is that,

unlike the rudder kick, all foreces are balanced.

... etcetera
... etcetera

it is not that complex.
or that subtle
approaching it with the "it is hard to understand" attitude maybe one
reason why
the pilots at your club go all "eyes glaze over" when you offer to run
through the 'subtleties of the slip/crab interaction at point of
flight/landing interface' with them 'just one more time'.

p.s. why not discuss ground erffect again - I *love* that one.

- what I know about ground effect from things pilots have told me:
* the vortex at the tips gets cut in half so the drag is reduced
* list improved relative to the 'thicker' air squashed under the wings

hello & love to all who rig and then de-rig without flying

jonny.

Jonny.

Jonny ;-)

[jonnyboy]

is that Zeb?
jon gogan

[J.A.M.]

"T o d d P a t t i s t" > escribió en el
mensaje ...
> "J.A.M." > wrote:
>
> >> Why not just say that in a crosswind landing, on final, you
> >> always have to fly an upwind course through the air to
> >> achieve a ground track aligned with the runway. Always.
> >>
> >
> >Because it is not true...
>
> More?

No thank you!!!
Obviously I lack the ability to explain myself well enough to be understood.
You see, english is not my craddle language, and I am having some trouble
with it...
And from other posts, as the one you don't see how a slip on base will get
you a longer final, I'm afraid that we have some confusion going here about
the manouever discussed. Maybe we are talking about different manouevers.
I'll try to make a diagram (one image is worth a thousand words...) and post
it somewhere.

Just for this one, I'll fall, though...
Imagine a runway, a left crosswind, for example, and you trying to land. If
your fuselage is aligned with the runway the wind will blow you to the right
of the centerline. You can turn left, into the wind, and then compensate as
you say. Your nose will point left of the runway, and your ground track
(velocity vector) will be aligned with the runway.
Or you can put the left wing down. The glider will try to turn to the left
(uncoordinated), but then you, as a savvy pilot, push the right rudder to
mantain the fuselage aligned with the runway. Ah and pull the nose slightly
up to compensate for the lift loss resulting from moving the lift vector
from the vertical when you banked. Maybe if you are already on the desired
glide slope, you will hide some airbrake to compensate for that lift loss
and not become one with the earth prematurely.
Well, now we are aligned with the runway, wind wing (left) down, right
rudder to mantain alignment... the wind drift now is compensated with the
lateral force produced by the banked wings. So you are not turning upwind as
you suggest, and your ground track is aligned with the runway. Voila!!!
When you are closer to the ground as to concern you, reduce the bank and the
rudder as fit. It'll be for a few seconds anyway.
I've used this technique many times. I have also induced severe slips to
augment my descent rate and make for steeper approaches into short fields
(outlandings) and with obstacles.

Anyway it's sunny outside, I'll be flying again soon! Suggest you to do the
same.
And sorry for the large post!

Jose M. Alvarez.
ASW-24 'BR'

[Don Johnstone]

It would appear that there has been confusion over
track and heading, I know you have susssed it Todd
but others may not.

If we consider the relative airflow in the horizontal,
Ignoring the vertical, it is simple. With the wings
level the relative airflow is straight down the fuselage,
the string is in the middle. With a slipping approach
the relative airflow is at an angle from the side of
the lowered wing, the string will be blowing away from
the lowered wing. The aircraft is balanced as you say.

In both cases the track over the ground will, if we
have got it right be lined up with the runway centreline/direction
What puzzles me is that we fly around all day using
the first method to achieve our required track, why
complicate things near the ground.


At 19:30 28 February 2005, T O D D P A T T I S T wrote:
>>> >> Why not just say that in a crosswind landing, on
>>>>>final, you
>>> >> always have to fly an upwind course through the air
>>>>>to
>>> >> achieve a ground track aligned with the runway.
>>>>>Always.
>
>'J.A.M.' wrote:
>>> >Because it is not true...
>
>>Obviously I lack the ability to explain myself well
>>enough to be understood.
>
>You are doing fine - better than my Spanish, which
>is the
>closest I can come to a second language :-)
>
>>You see, english is not my craddle language, and I
>>am having some trouble
>>with it...
>>And from other posts, as the one you don't see how
>>a slip on base will get
>>you a longer final, I'm afraid that we have some confusion
>>going here about
>>the manouever discussed. Maybe we are talking about
>>different manouevers.
>
>Perhaps
>
>>I'll try to make a diagram (one image is worth a thousand
>>words...) and post
>>it somewhere.
>>
>>Just for this one, I'll fall, though...
>>Imagine a runway, a left crosswind, for example, and
>>you trying to land. If
>>your fuselage is aligned with the runway the wind will
>>blow you to the right
>>of the centerline.
>
>That's clear.
>
>>You can turn left, into the wind, and then compensate
>>as
>>you say. Your nose will point left of the runway, and
>>your ground track
>>(velocity vector) will be aligned with the runway.
>
>Correct - we agree. At this point, your flight through
>the
>air is angled to the left of the runway to achieve
>the
>ground track carrying you straight to the runway, or
>as I
>originally wrote, you are flying 'an upwind course
>through
>the air to achieve a ground track aligned with the
>runway.'
>
>>Or you can put the left wing down. The glider will
>>try to turn to the left
>>(uncoordinated), but then you, as a savvy pilot, push
>>the right rudder to
>>mantain the fuselage aligned with the runway.
>
>Correct. This is the upwind wing down slipping approach.
>The first was the level wings, nose pointed upwind,
>crabbing
>approach.
>
>>Well, now we are aligned with the runway, wind wing
>>(left) down, right
>>rudder to mantain alignment...
>
>We are in agreement to here.
>
>>the wind drift now is compensated with the
>>lateral force produced by the banked wings.
>
>But here we disagree. The drift is not stopped by
>'lateral
>force produced by the banked wings.' It is stopped
>because
>you are flying a course upwind. You are confused with
>exactly the confusion that the original poster felt
>was a
>problem. Lowering the upwind wing does not oppose
>the wind
>with a force. The force produced by the wing is countered
>by an opposite force produced by the fuselage that
>is flying
>at an angle to the direction of motion. The direction
>of
>motion is upwind relative to the air to achieve motion
>over
>the ground straight towards the runway.
>
>>So you are not turning upwind as
>>you suggest,
>
>Yes, you are. You suffer from the same misunderstanding
>that started this thread - a belief that the lowered
>upwind
>wing produces an unbalanced force. It does not..
>You can
>see that by considering that you can fly straight towards
>the runway in a slip when there is no crosswind, only
>by
>pointing the fuselage to the side. When slipping the
>direction you are going through the air is never aligned
>with the fuselage.
>
>>and your ground track is aligned with the runway. Voila!!!
>
>Think carefully again.
>
>>When you are closer to the ground as to concern you,
>>reduce the bank and the
>>rudder as fit. It'll be for a few seconds anyway.
>>I've used this technique many times.
>
>So have I. It is not the technique that is wrong,
>just your
>understanding of the aerodynamics.
>
>>I have also induced severe slips to
>>augment my descent rate and make for steeper approaches
>>into short fields
>>(outlandings) and with obstacles.
>
>And when you did that, you should have noticed that
>your
>nose was pointed to the side of the direction you were
>actually traveling.
>
>>Anyway it's sunny outside, I'll be flying again soon!
>>Suggest you to do the
>>same.
>
>It's getting closer to that time - can't wait.
>
>

[Mark James Boyd]

I meant to clarify in one of my
original posts that I meant that doing a base leg
using a sideslip, with the wing away from the airport
down, gets the glider further from the runway then
doing it with inner wing down instead.

Oh, and I just realized that if I use a sideslip
instead of a crab on final because I want
"to keep a stabilized final approach" I might
end up undershooting if it was a close call.
An example of "negative transfer." This is a great "correlation"
question for a student pilot!


In article >,
T o d d P a t t i s t > wrote:
>Don Johnstone >
>wrote:
>
>> What puzzles me is that we fly around all day using
>>the first method [wings level] to achieve our required track, why
>>complicate things near the ground.
>
>The most common answer is that it's a tricky timing issue to
>swing the nose at just the right time for touchdown. No
>matter what you do, things at the ground are more
>complicated than in the air. You have to meet conflicting
>requirements imposed by the ground and the crosswind.
>
>Slipping is a bit more stabilized between approach and
>touchdown and is preferred by some.
>


--

------------+
Mark J. Boyd

[Stefan]

T o d d P a t t i s t wrote:

> I still don't understand this comment. Your base leg (and
> distance from the airport) is exactly what it is. You can
> fly that base leg coordinated, or slipping to either side.

The difference is that slipping with the wing away from the airport
down, you can't see the runway anymore, which is a bad thing. On the
other hand, slipping to the other side, you won't see the approach,
which is also a bad thing. You can avoid this dilemma by not slipping on
base at all, so you can see both, and spare the slip for the final. If
you misjudged your height so badly that you need a slip at all, that is.

Stefan

[Stefan]

T o d d P a t t i s t wrote:

> You've pointed to differences in visibility, and I certainly
> agree there are such differences, but the original post says
> slipping one way or the other changes your distance from the
> airport.

I've understood the original post, but gave it that different twist to
express my opinion that slipping on base is a bad idea in my opinion.
The fact that a proper slip doesn't change the track is so trivial that
I hope we won't have to discuss it.

Stefan

[Eric Greenwell]

T o d d P a t t i s t wrote:
> Stefan > wrote:
>
>
>>The difference is that slipping with the wing away from the airport
>>down, you can't see the runway anymore, which is a bad thing. On the
>>other hand, slipping to the other side, you won't see the approach,
>>which is also a bad thing. You can avoid this dilemma by not slipping on
>>base at all, so you can see both, and spare the slip for the final. If
>>you misjudged your height so badly that you need a slip at all, that is.
>
>
> You've pointed to differences in visibility, and I certainly
> agree there are such differences, but the original post says
> slipping one way or the other changes your distance from the
> airport.

I'm guessing he means it changes the distance compared to flying the
same heading, but wings level and coordinated.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Bob Korves]

A pattern slip with inside rudder and the outside wing further down than
usual sounds a lot like a skid to me. I don't want any part of it.
-Bob Korves

"T o d d P a t t i s t" > wrote in message
...
> (Mark James Boyd) wrote:
>
> >I meant to clarify in one of my
> >original posts that I meant that doing a base leg
> >using a sideslip, with the wing away from the airport
> >down, gets the glider further from the runway then
> >doing it with inner wing down instead.
>
> I still don't understand this comment. Your base leg (and
> distance from the airport) is exactly what it is. You can
> fly that base leg coordinated, or slipping to either side.
> Flying in a slip will cause you to lose altitude faster, but
> won't change your distance from the airport.
>
> I agree that with the wing down away from the airport, it's
> easier to make a turn away from the airport than if you slip
> wing down towards the airport. Is that what you're saying?

[Steve Hill]

Todd P. Wrote: "Forward slips to either side are not skids. In a typical
left pattern, this would be left rudder and right
aileron/wing down on base. "

Just checking...but do you mean that in a left pattern, you reccomend
turning to the left, then rolling the aircraft into a slip the opposite
direction?? If you do, I think that is wrong. I fly most of my patterns with
a more rounded base and final and if I were in a left pattern, slipping in
a turn to final to the left, the rudder would be nearly neutral or slightly
biased to the right, and the left wing would be down...Opposite of what you
wrote...

Am I confused here..??


Steve.

[Bob Korves]

"T o d d P a t t i s t" > wrote in message
...
> "Bob Korves" <bkorves@winfirstDECIMALcom> wrote:
>
> >A pattern slip with inside rudder and the outside wing further down than
> >usual sounds a lot like a skid to me. I don't want any part of it.
>
> Forward slips to either side are not skids. In a typical
> left pattern, this would be left rudder and right
> aileron/wing down on base.
>
> However there are some good reasons not to slip outside wing
> down that have nothing to do with whether it's a skid. The
> main one is that, even if there's no wind, you would have to
> reverse the bank to turn the corner onto final. Slipping
> inside wing down makes that turn easier, and if you are
> slipping to kill altitude, you can do that throughout the
> turn.
>

I agree that a slip is not a skid (though really they are the same except
for your frame of reference) and that straight slips with either wing down
will work. It's the transition from an "outside wing down" base leg slip
with extra inside rudder to a turn to final that is developing too slowly
because of the outside wing being too low... well, it just seems to me that
the slip could very easily change into a skid to final. If the slip was
correctly ended and followed by a coordinated turn to final, then no
problem, but if one tried to do it all at once then the temptation would be
to increase rudder into the turn even more than the slip required, and now
we have a potential problem. Am I missing something?
-Bob