How Low to Spin??

Don't get me wrong: I am very cautious close to the ground, even though I
did extensive spin testing with my ship. I actually very often do not come
to the conclusion that this or that low level IS safe, and then I don't do
it.
It's just statements like "never thermal below 400ft" which I don't like,
although I agree that in many (maybe most) cases it would be unsafe. "Never"
and "always" don't help people to practise actively thinking about every
single situation they're in, and I think that it this lack of active
situational awareness which is a main cause of fatal accidents.
If you keep telling that "never below x feet", some will think "well my
alti reads x+100ft, so I can safely thermal" - and that might be totally
wrong for a special situation.

--
Bert Willing

ASW20 "TW"


"Bruce Greeff" a écrit dans le message de
...
Bert Willing wrote:
Putting spin behaviour of a modern glass ship in this general way is
pure
nonsense. Spin behaviour is different for every model, and even a model
with
and without winglets enters differently. I wouldn't think about 300ft
revoveries with a Ventus b, but on my 20 w/ winglets I would at least
think
about it.
But as a general rule, I avoid flying ships in the mountains which
depart
violently and use 500ft to recover.

Sorry all - I was generalising, but even the ASW20 spins interestingly,
and will
sometimes reverse it's spin direction instead of recovering if the pilot's
technique is poor. Under the right (wrong) conditions even a K13 will
depart
violently.

My point is that you should have a very good idea of exactly how much
height
your aircraft uses in a spin, including the half second or more it takes
you to
realise you have lost it, for you to recover in. Not the absolute minimum,
in a
factory perfect example in still conditions with a test pilot at the
controls.
Winglets, repairs, control wear and slop and build variations all change
the
behaviour.

I think if you set up a logger and tested you might be a little more
conservative close to the ground.

Bert Willing wrote:
Don't get me wrong: I am very cautious close to the ground, even though I
did extensive spin testing with my ship. I actually very often do not come
to the conclusion that this or that low level IS safe, and then I don't do
it.
It's just statements like "never thermal below 400ft" which I don't like,
although I agree that in many (maybe most) cases it would be unsafe. "Never"
and "always" don't help people to practise actively thinking about every
single situation they're in, and I think that it this lack of active
situational awareness which is a main cause of fatal accidents.
If you keep telling that "never below x feet", some will think "well my
alti reads x+100ft, so I can safely thermal" - and that might be totally
wrong for a special situation.

Hi Bert

In this case I am entirely in agreement - situational awareness and evaluation
of the possible outcomes is fundamental. The "I will never spin THIS plane
unintentionally so it is always safe" is equally dangerous to the "never thermal
below x feet rule"

Know your aircraft, evaluate the situation and the weather and make a reasoned
decision as to how much risk to take. This is OK, and some people will accept
different risk levels, and what is dangerous for a low timer may be safer for an
experienced pilot. Note I did not say safe - just safer. Flying gliders is
dangerous - accepting that and managing the risk is the key step to being safer.

There has to be some motivation to take risk though, and hubris is a poor
reason. The complications arise with objectivity - most people are less
objective about their own capabilities than they think (me included)

If you are low and in the circuit I still believe you should land unless there
is some hazard on the runway that increases the risk of landing above the risk
involved in thermalling low down, possibly below spin recovery height, where
there is the probability of conflicting traffic. Under pressure objectivity
tends to decrease - rather err on the side of caution, as you said.

To paraphrase a bumper sticker - A bad day retrieving beats a good day in hospital.

Bruce

(Mark James Boyd) wrote in message news:412b9c97

Not always true. An aircraft that has done a complete 180 during the
spin still has momentum, and is now to some degree flying backwards.
The excess forward momentum translates into excess reduction of airspeed.

Think about it for a minute. If you're going 50 knots in one direction,
and then one-half second later the nose of the glider is 180 degrees
pointed the other way, does this mean you are doing 50 knots in the other
direction? That's some G's, and I don't feel them in a spin.

Oh cmon, that's about the oddest explanation of what happens during a
spin entry I can imagine! Try this: a spin happens when both wings
are stalled, with one stalled more than the other. Stalled means a
lot less lift, so the flight path curves down (gravity is a wonderful
thing). If you do a snap roll, which is a spin in the horizontal
plane, you initially go pretty much level until speed is lost then
your flight path curves down. And what do you mean by doing "a
complete 180 during the spin ...and is now to some degree flying
backwards." That isn't a spin, it's a frisbee! As far as G's, if you
enter a spin at low speed (not accelerated), you can't pull any G's -
as the plane unloads and goes down there is actually a decrease in
G's!

This is why aircraft oscillate pitch up and down for a few turns before
stabilizing in a spin. For the first few turns, the aircraft momentum
is still slogging through the air.

I don't have a spin text handy, but I would think the oscillation is
more due to angular momentum and changing AOA as the glider rotates
around it's pitch and roll axes than from "flying backwards".

But some of what you point out is true. Aircraft without enough
elevator authority to stall, and with forward CG, won't have the
ability to stall in a steep bank. But if the CG is back a bit, the
elevator has a lot of authority because the glider is designed for a
wide range of speeds, and the pilot has in aileron to resist overbanking,
then whoa nellie!

Even with an aft CG, any glider is fully controllable up to the spin -
it's recovering that would be interesting. It's not going to make you
spin more. And I feel the whole aft CG is a bit of a bogyman to scare
people - It's pretty hard to get the CG that far aft (it can be done,
especially if you are light, but any sort of preflight should find it)
and if discovered the plane is still fully controllable - unlike a too
far forward CG that can lead to a heavy landing. Just my opinion, but
I bet there have been very few spin accidents caused by aft CGs (CG
out of the aft limit, not just at the aft limit). As far as
overbanking - It's not going to roll you over in a turn! You need to
hold off some aileron to compensate, but it's never so strong as to
cause control problems. It's a secondary result of use of the flight
controls (actually of the glider's attitude), like adverse yaw.
Coarse use of controls at or near stall speed IS a problem, that
reflects serious lack of knowledge by the pilot of how a plane works!

If we are not teaching pilots to do steep (60 degree) windup turns
until they recognize the approach of a stall/spin, then immediately
recover by releasing backpressure and continuing the turn, then we are
setting then up to be a statistic. Oh, BTW, try that in a 2-33!

A properly flown steep turn at higher speed isn't what I'm talking about.
I'm considering a 30-45 degree bank turn at low speed.

This thermal was very smooth and regular and wide. I was feeling it
out on the first turn, and was not eager to make any coarse inputs or
lose sight of my landing site or get vertigo during the circle.

Sounds like trying to turn via ground references down low - a big
no-no and probably the real reason for low altitude "stall-spin"
accidents. Airspeed, yaw string, bank angle, vario, altimeter, clear
the airspace - then check where you are. The ground isn't going
anywhere fast, so don't stare at it!!

The classic spin entry from a shallow bank is uninteresting.
I won't be jamming in the rudder for a skid at some obviously
low speed close to the ground. I think the focus on the classic case
is niave and dangerous. Yes, it's easy to teach and demonstrate,
but it ignores too much. The more complex, less discussed
spin entry is the one in the accident reports: tight pattern,
higher speed, steep bank, lots of inside rudder, pilot focussed on
keeping the yaw string straight, quite a bit of opposite aileron
in the steep bank, in vertigo, pulling stick back to tighten up the
turn, and then wham! I'll look back through the accident reports, but
the ones I recall, and the B-52 and the DG spin I saw on video, involved
stabilized, 30-45 deg bank turns before each of the spins. In each,
it looked like the craft was overbanking, and the pilot put in more
opposite aileron and more elevator and WHAM! Instant spin...

Again, you are describing a pilot who has no clue how to fly his
glider. A stabilized steep turn doesn't call for a lot of inside
rudder. When rolling the glider, you use as much as you need to
coordinate. An you ALWAYS make sure you have enough airspeed
(actually AOA, which is why I would love to have an audio AOA
intrument, set to replace the vario when the gear is down, that would
always indicate the optimum AOA regardless of bankangle and gross
weight - like a lot of military jets have). The solution is not to
take away a tool (steep turns) but to teach the proper use of all a
pilots tools. And I am a bit confused by your reference to vertigo -
again, this is avoidable (don't stare at the ground, no rapid head
movements, etc) and should be taught. If a pilot continually gets
vertigo in steep turns (and I have some really good friends who do,
unfortunately) they need to seriously consider the ramifications of it
and fly accordingly!

Too much rudder, maybe, but it wasn't because he moved it. It was
because the pilot put in more dragging aileron without RELEASING
inside rudder.

Practice, practice, practice...

This is usually the case for me on cloudless days (like that one).
High over the terrain, I usually just bump into a thermal. Of course,
at altitude, while thermalling, slow is good, and trim is your friend...

So true out here in AZ, too...

Shallow turns in power? Why? Just jam the throttle all the way in,
full flaps, and yo-yo base to final at 60 degrees. Gas is a good
substitute for brains ;PPPP

And burning JP-4 was so much more satisfying than AVGAS - especially
at the taxpayers expense! Noisier, too.

Power planes (except maybe the DA-20) often have lower
aspect ratios. Some even have frieze ailerons. And if the left turns
are flown with power off, there's even a little slip provided by the
P-factor of the prop. There's enough differences between the two
that the USA CFI practical tests require training and evaluation in each
category seperately (CFI transition from one to the other requires
spin training in the new class, except for Sport Pilots, but that's
another thread).

And some power planes are rolled primarily with rudder at low speeds,
including in the pattern! (F-4 comes to mind) In fact, the rudder is
also used to adjust pattern altitude during steep turns, such as the
90 degree break turn to downwind. It sure looks better and was easier
than trying to adjust altitude by changing bank angle.


Power flying can be boring. If an autopilot can do it, why do they
need me?

To feed the dog. His job is to keep you from touching the autopilot
controls.

Anyway Kirk, I welcome some more discussion. As you can see, there
are quite a few points where we agree, and a few nuanced ones where
we don't. I hope you have time to continue another response...

Fun discussion. Back to work, the dog looks hungry...

Kirk

Barb ,

Perhaps "routine" isn't the right word, as like you, it's not something I
see our fellow (local) pilots doing. I have however heard several of them
talk about contests where the only way to a particular turnpoint was to fly
a stretch with no known landing options from the top of the lift, and I
*have* heard at least a couple of them talk about "no option" situations
they knowingly entered. (There are parts of GW's flight from Turf to
Moriarty in April where I have no idea where he could have landed without
another thermal, and I recall him mentioning something to that effect in his
discussion of that remarkable flight.)

Of course, I've participated in only one sanctioned contest, so the
frequency that competitive pilots (not to be confused with me!) actually do
this, and how they handle it, is something I have to accept at face value
from other competitors.

-ted


"BMacLean" wrote in message
news:zJMWc.60231$wo.50491@okepread06...
I fly with the same group as you Ted and I wonder where you get the idea
that it is "routine" to fly with no landing options, even in hardcore
competition. I don't believe this to be the case and I agree with Eric.
I
have found that when a pilot is relating a story of some scary situation
they got themselves into and I ask them where they would have landed, 99%
of
the time they have an answer.

Barb

Kirk Stant wrote:
(Mark James Boyd) wrote in message news:412b9c97

Think about it for a minute. If you're going 50 knots in one direction,
and then one-half second later the nose of the glider is 180 degrees
pointed the other way, does this mean you are doing 50 knots in the other
direction? That's some G's, and I don't feel them in a spin.

And what do you mean by doing "a
complete 180 during the spin ...and is now to some degree flying
backwards." That isn't a spin, it's a frisbee! As far as G's, if you
enter a spin at low speed (not accelerated), you can't pull any G's -
as the plane unloads and goes down there is actually a decrease in
G's!

Some aircraft have a very nose low spin (Blanik), others have a much
flatter spin (Katana). The Katana, which spins very flat on the horizon,
is going North at 30 knots. I stall it and spin. Over the course of
a second, the nose is now pointed South. Is the Katana moving
South with an airspeed of 30 knots? No, it is not. This is
part of the reason why, during the first turn or two, the
pitch oscillates more violently than in a fully developed spin.

Because of momentum, the airspeed from front to back of the
wings is less during the South pointed nose part of the spin than
during the entry of North.

And yes, this is a frisbee. At least for the first 180 anyway...

This is why aircraft oscillate pitch up and down for a few turns before
stabilizing in a spin. For the first few turns, the aircraft momentum
is still slogging through the air.

I don't have a spin text handy, but I would think the oscillation is
more due to angular momentum and changing AOA as the glider rotates
around it's pitch and roll axes than from "flying backwards".

Yes, and part of this changing AOA is due to momentum in the
Northerly direction.

Even with an aft CG, any glider is fully controllable up to the spin -
it's recovering that would be interesting.

True, true. The more aft the CG, the more controllability.

It's pretty hard to get the CG that far aft (it can be done,
especially if you are light, but any sort of preflight should find it)

Ms. Campbell is the Hawaii state altitude record holder. She
worked at Dillingham as a CFI. She told me during a ground session
she was in an uncontrolled spin for more than 5,000 feet at one point,
with a passenger, before recovering.
She said after landing, she weighed the glider and the CG
was well aft of what was on the 10+ year old "official" form.
And her new calculated CG for that flight was well aft of limits.

In my experience, the older the calculation, the further back
the actual CG is from it. Dirt and crap on the long lever arm
of the tail do a lot more than crap in the short nose.

and if discovered the plane is still fully controllable - unlike a too
far forward CG that can lead to a heavy landing. Just my opinion, but
I bet there have been very few spin accidents caused by aft CGs (CG
out of the aft limit, not just at the aft limit).

Except for that 1 in 10 case, I'd guess aft CG is just a contributing
factor, not a cause. But I'd like to see data. When I hear of
a winch launch by an experienced pilot during the first
flight of the season, ending in a fatality, I have to wonder if
he took something out of the nose, or put something in the
tail, and so his stick pressure feel and initial trim setting
were off... Of the stall spin fatalities on record, I'd
bet most, if not all, had CG further back than the 60-70%
forward that Eric described...

Sounds like trying to turn via ground references down low - a big
no-no

This is required to fly a rectangular pattern with wind correction,
and still part of the PTS...

and probably the real reason for low altitude "stall-spin"
accidents.

Clearly true. If one weren't trying to land on a particular
bit of ground, and the world was just one big flat runway,
I'm certain landing accidents would be more rare.

The classic spin entry from a shallow bank is uninteresting.
I won't be jamming in the rudder for a skid at some obviously
low speed close to the ground. I think the focus on the classic case
is niave and dangerous. Yes, it's easy to teach and demonstrate,
but it ignores too much. The more complex, less discussed
spin entry is the one in the accident reports: tight pattern,
higher speed, steep bank, lots of inside rudder, pilot focussed on
keeping the yaw string straight, quite a bit of opposite aileron
in the steep bank, in vertigo, pulling stick back to tighten up the
turn, and then wham! I'll look back through the accident reports, but
the ones I recall, and the B-52 and the DG spin I saw on video, involved
stabilized, 30-45 deg bank turns before each of the spins. In each,
it looked like the craft was overbanking, and the pilot put in more
opposite aileron and more elevator and WHAM! Instant spin...

Again, you are describing a pilot who has no clue how to fly his
glider.

Hard to quiz them, the dead are VERY quiet...

A stabilized steep turn doesn't call for a lot of inside
rudder.

Many of the 10 reports seem to indicate the spirals/spins happened
during the roll, not the turn. High roll rates require a lot of
rudder (and then rudder release), used quite precisely.

And I am a bit confused by your reference to vertigo -
again, this is avoidable (don't stare at the ground, no rapid head
movements, etc) and should be taught.

I commonly induce vertigo in students to demonstrate unusual attitude
recovery. Although easiest to induce by rapid head movements,
I can also induce it with nothing more than a rapid, perfectly
coordinated roll into a steep bank, and then a rapid coordinated
roll to level flight. I've done this with pilots from 10-30,000 hours.
In all of them, if I cover all the instruments on a nice dark night
with foggles on, they get vertigo. Not staring at the ground and
avoiding rapid head movements is a start, but is an incomplete
solution...rapid roll rates and dramatic G changes are another
factor.

When I fly gliders, I have to remind myself to fly at least a 1/4 mile
out pattern. I normally fly a power plane (day VFR only) with a 5:1
glide ratio, and a tight pattern, with steeper banks and
faster roll rates at higher airspeed. I don't do this when
in a glider approaching an unmarked landout field with mountains and
no horizon around.

If a pilot continually gets
vertigo in steep turns (and I have some really good friends who do,
unfortunately) they need to seriously consider the ramifications of it
and fly accordingly!

I see we are agreeing again
--

------------+
Mark Boyd
Avenal, California, USA

In article ,
Marc Ramsey wrote:
Mark James Boyd wrote:
One flat skidding turn, the others were in a bank. At least one
looks like an aileron spin (this can be done with feet off the rudders
completely, but is very hard to time correctly). Several don't
look like spins at all, but overbanking that led to a steep spiral
close to the ground. In others, it seems possible the steep bank was
after the spin entry, perhaps not before it.

I've witnessed three stall/spin accidents over the years, two gliders
turning base to final, and one power plane during departure. At the
end, all of them looked like a steeply banked turn into the ground.
Most eyewitnesses, particularly non-pilots, aren't going to notice
anything is wrong until after the spin has started, at which point it
will look very much like an abnormally steep turn.

I've also been in a G103 that was about to depart into a spin from a low
shallow left turn after a botched low finish at a contest. I was PIC,
but a CFIG (!) in back was flying. I noticed things were getting a bit
quiet, the left wing was starting to drop, and the stick was moving
toward the right. I reflexively slammed the stick forward, which was
probably what prevented us from making like a cartwheel.

In most gliders (and there are exceptions), when you stall in a turn the
inner wing is going to start dropping. If you release back pressure at
this point, you'll be fine. But, the natural reaction of too many
pilots is to try to pick up the low wing with aileron, which increases
the angle of attack on the already stalled wing, increasing drag and
decreasing lift, resulting in more bank, until the nose drops and you're
spinning for real.

Marc

It's too bad we can't tell the "well-trained" from the "poorly-trained"
pilots until after they've done something wrong, don't you
think?

;P
--

------------+
Mark Boyd
Avenal, California, USA

Mark James Boyd wrote:

Some aircraft have a very nose low spin (Blanik), others have a much
flatter spin (Katana). The Katana, which spins very flat on the horizon,
is going North at 30 knots. I stall it and spin. Over the course of
a second, the nose is now pointed South.

Why do you think it takes only one second? Even a aerobatic glider can't
reverse direction that quickly - that would be such a violent manuever.
Think about it: a 60 knot change in one second takes over 3 gs, and a
spin entry produces nothing like that.

Try timing a spin entry sometime with stopwatch or a recorder on board.

Is the Katana moving
South with an airspeed of 30 knots? No, it is not.

It's probably still got about 30 knots airspeed (do they really stall at
such a low speed?), but because it is pointed down, the southerly
component is less than 30 knots.

snip

Except for that 1 in 10 case, I'd guess aft CG is just a contributing
factor, not a cause. But I'd like to see data. When I hear of
a winch launch by an experienced pilot during the first
flight of the season, ending in a fatality, I have to wonder if
he took something out of the nose, or put something in the
tail, and so his stick pressure feel and initial trim setting
were off... Of the stall spin fatalities on record, I'd
bet most, if not all, had CG further back than the 60-70%
forward that Eric described...

Just to be clear here, the convention is: 0% is at the front of the
range; 100% is at the aft end of the range. It sounds like you have it
backwards.

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

Eric Greenwell
Washington State
USA

Eric Greenwell wrote:

Just to be clear here, the convention is: 0% is at the front of the
range; 100% is at the aft end of the range. It sounds like you have it
backwards.

My mistake. I wasn't expecting you to have flown
aircraft in such an aft CG range, and inverted it in my mind.

Really. So the aircraft were in the aft 1/3 of the range?
And still wouldn't stall at 45 deg bank? Interesting...

I believe you, I'd just like to see this myself as well.

As far as stalls in a steep bank, without uncoordinated
inputs, I've noticed many aircraft roll wings level,
just like the GFH and AFH (and Marc, it seems) say...

One thing I haven't tried that I recall is banking into
a turn and then just failing to take rudder out
while rolling level at a high rate (all while at low
airspeed). This should get a nice spin entry too...

Maybe there are spin fatalities in this category too...steep
bank close to the ground, more elevator to tighten the
turn to final, then an attempt at a quick roll to level wings...
--

------------+
Mark Boyd
Avenal, California, USA

Mark James Boyd wrote:

Eric Greenwell wrote:

Just to be clear here, the convention is: 0% is at the front of the
range; 100% is at the aft end of the range. It sounds like you have it
backwards.


My mistake. I wasn't expecting you to have flown
aircraft in such an aft CG range, and inverted it in my mind.

Really. So the aircraft were in the aft 1/3 of the range?
And still wouldn't stall at 45 deg bank? Interesting...

70% is a common CG location, because (for many/most gliders, especially
the newer they are) the glider handles pleasantly, recovers easily from
spins, and is close to the optimum CG for cross-country performance.


I believe you, I'd just like to see this myself as well.

The limit on elevator "authority" isn't so much the force it can
generate (except at the most forward positions) but more the angle of
attack reduction on the elevator that occurs in steep turns. I'm sure
the bank angle you can stall at is higher with a more aft CG, but in the
commonly used 60-80% range, you do run out of elevator in the steeper turns.

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

Eric Greenwell
Washington State
USA

(Mark James Boyd) wrote in message news:412ce2c4$1@darkstar...

Some aircraft have a very nose low spin (Blanik), others have a much
flatter spin (Katana). The Katana, which spins very flat on the horizon,
is going North at 30 knots. I stall it and spin. Over the course of
a second, the nose is now pointed South. Is the Katana moving
South with an airspeed of 30 knots? No, it is not. This is
part of the reason why, during the first turn or two, the
pitch oscillates more violently than in a fully developed spin.

I still don't buy your explanation. A spin is a combination of roll,
pitch, and yaw, all happening at the same time. As a result, the
actual flight path (motion of the CG through space) is hard to see,
especially from inside the cockpit, but conservation of momentum
cannot be violated. From 30 knots, the first half turn/half roll
(which probably takes a bit more than one second, I would think) will
corkscrew the nose down and around, but you are not flying backward!
And until you are established is a steady spin, you will get pitch
motion due to the inclination of the spin axis to the horizon. Once
you are established in the spin, with your CG motion basically
straight down, the spin is usually pretty stabilized (with the usual
exceptions, including Maverick's F-14 spinning out to sea after
departing over the desert - I would have loved to have seen that for
real!)

It's normal for a power plane to spin flatter than a glider - more
weight in the nose (and probably tail) makes for more inertial weight
tending to level the fuselage.

Because of momentum, the airspeed from front to back of the
wings is less during the South pointed nose part of the spin than
during the entry of North.

Still a bad analogy, in my opinion. Think of the snap roll example -
at what point do you stop "rolling" and start "frisbeeing"? You
don't, your flightpath just curves more downward as you initiate the
spin slower.

It sure would be fun to take up a nice spinning glider (a 2-32 for
example), instument it, then take turns trying to make each other
sick!

And yes, this is a frisbee. At least for the first 180 anyway...

Nope. Although, look up Zurakowski Cartwheel - some testpilot used to
do 540 degree rotation hammerheads in a Gloster Meteor, long before
the current airshow acts started doing it in monster Pitts (which I
think are about as interesting to watch as a radio controlled model).
Not a stalled maneuver, though.

Ms. Campbell is the Hawaii state altitude record holder. She
worked at Dillingham as a CFI. She told me during a ground session
she was in an uncontrolled spin for more than 5,000 feet at one point,
with a passenger, before recovering.
She said after landing, she weighed the glider and the CG
was well aft of what was on the 10+ year old "official" form.
And her new calculated CG for that flight was well aft of limits.

Must have been in a 2-32. G

In my experience, the older the calculation, the further back
the actual CG is from it. Dirt and crap on the long lever arm
of the tail do a lot more than crap in the short nose.

Broken glass ships have the same problem with weight in the tail...
G-103s are notorious for it. Othewise, instruments, batteries,
cheeseburgers, and beer tend to move the CG forward.

Except for that 1 in 10 case, I'd guess aft CG is just a contributing
factor, not a cause. But I'd like to see data. When I hear of
a winch launch by an experienced pilot during the first
flight of the season, ending in a fatality, I have to wonder if
he took something out of the nose, or put something in the
tail, and so his stick pressure feel and initial trim setting
were off... Of the stall spin fatalities on record, I'd
bet most, if not all, had CG further back than the 60-70%
forward that Eric described...

Again, the aft CG doesn't cause the spin, it just make it easier to
initiate, and maybe harder to recover. You still have to exceed the
stalling AOA, regardless of CG location. Winch launching is probably
a lot safer overall than aerotowing (from my limited experience in
Germany), with fewer potential gotcha's - plus it's really hard to
kill the winch operator (unless you crash on the winch, of course).

Sounds like trying to turn via ground references down low - a big
no-no

This is required to fly a rectangular pattern with wind correction,
and still part of the PTS...

Not the same as max performance low altitude turning (thermalling),
which are definitely NOT ground reference maneuvers. Pattern turns,
on the otherhand, should always have enough airspeed to be safe - so
are not really "max performance" turns, and are usually no more than
90 - 100 degrees (unless you prefer the 180 degree one turn to final
approach, which I do).

Clearly true. If one weren't trying to land on a particular
bit of ground, and the world was just one big flat runway,
I'm certain landing accidents would be more rare.
Hard to quiz them, the dead are VERY quiet...

Well, most glider landing accidents only break the glider, or maybe a
bush or two - and the reasons are usually pretty consistent. The main
thread seems to be a certain rigidity in the pattern, reliance on
ground references and the altimeter for turns, and failure to engage
brain and remember to fly the plane.

Many of the 10 reports seem to indicate the spirals/spins happened
during the roll, not the turn. High roll rates require a lot of
rudder (and then rudder release), used quite precisely.

Again, AOA is the key. By itself, high roll rates shouldn't lead to a
spin. There is a situation where it can: Initiate a rapid roll after
a push-over from a steep climb to below stall speed. More of a winch
launch cable break scenario, and hard to duplicate while just flying
around, as it requires a transient airspeed below 1-G stall speed
(but at less than 1-G, so not stalled) then increasing the angle of
attack coupled with a lot of aileron. I've tried to get there in my
glider but haven't been sucessful yet.

I commonly induce vertigo in students to demonstrate unusual attitude
recovery. Although easiest to induce by rapid head movements,
I can also induce it with nothing more than a rapid, perfectly
coordinated roll into a steep bank, and then a rapid coordinated
roll to level flight. I've done this with pilots from 10-30,000 hours.
In all of them, if I cover all the instruments on a nice dark night
with foggles on, they get vertigo. Not staring at the ground and
avoiding rapid head movements is a start, but is an incomplete
solution...rapid roll rates and dramatic G changes are another
factor.

Not necessarily - the key is the lack of outside references, coupled
with moving the head too much so as to confuse the inner ear. Then
again, it is also person dependent - some people are very susceptible
to vertigo (and get sick during acro, or just thermalling), I think of
them as inner-ear dependent. Their bodies believe their inner ears,
not their eyes - not good in a plane. Other people are eye-dependent,
and could care less what their inner ear is saying, as long as they
have a good visual reference. I'm in the latter group, I can thermal
all day long and do acro and feel fine, but I have had the leans in
formation in cloud - interesting when you pop out and your internal
gyros cage up!

When I fly gliders, I have to remind myself to fly at least a 1/4 mile
out pattern. I normally fly a power plane (day VFR only) with a 5:1
glide ratio, and a tight pattern, with steeper banks and
faster roll rates at higher airspeed. I don't do this when
in a glider approaching an unmarked landout field with mountains and
no horizon around.

I fly my pattern based on where I want to touch down, and adjust the
pattern accoding to my altitude and the wind. I prefer low, tight,
fast patterns, so I can see what I'm getting into during a landout!
It helps that my glider can get rid of a lot of energy fast when I
need to.

I see we are agreeing again

On the whole, just a different interpretation of the same facts.

Kirk