A new direction for an old thread: Crosswind landings

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

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

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

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

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?

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----------

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'

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'

By all means.

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'