Another stall spin

It's easy enough to practice low (within a few wing spans), slow, high bank angle turns in a power plane like a Super Cub or Husky. Not so many opportunities in a glider. To the uninitiated, there's a tendency to skid a turn when low, as some pilots try to minimize bank angle - too much bottom rudder, not enough aileron. Not a good situation to be.

On Sep 4, 10:34*am, bumper wrote:
It's easy enough to practice low (within a few wing spans), slow, high bank angle turns in a power plane like a Super Cub or Husky. Not so many opportunities in a glider. To the uninitiated, there's a tendency to skid a turn when low, as some pilots try to minimize bank angle - too much bottom rudder, not enough aileron. Not a good situation to be.

Yes, one thing to point out is that a lot of training spins emphasize
a lot of back-stick *plus* a punch on the rudder to initiate the
spin. But IMHO this isn't how spins develop in the real world. I
believe that many spins develop as the aircraft's situation degrades
over a couple of seconds (airspeed bleeds off, or back-stick/rudder is
slowly added in by the pilot without realizing they're "creeping" on
the controls).

Another item for thought: Using trim on an aircraft is great (I am
constantly re-trimming my aircraft). BUT if you trim the aircraft for
flight at a slow speed (say an approach-speed that's a little too
slow), the trim-spring is what is "pulling back" on the stick. YOU
will not feel yourself pulling on the stick. Yet the aircraft may be
dangerously close to a stall/spin. And once it starts to develop
you'll have to PUSH *against* the trim spring in order to un-stall the
wing! Simply "relaxing the back-pressure" will not break the stall or
stop the spin. This goes against a lot of the muscle-memory we learn
when we train in gliders and perform training stalls & spins, so
pilots are not likely (IMHO) to take the full corrective action.

Lastly, think about wind gradient and headwind/tailwind components...
Let's say we're making a landing pattern (and this could be
particularly bad in an off-field situation). There's a tailwind on
downwind so the ground rushes past and we try to slow down (perhaps
subconsciously). Then we turn base/final and while we get a bit of
the headwind, we also have to remember low level wind gradients mean
that as we descent down close to the ground that headwind goes away.
So we have pulled the stick back (from trying to "slow down" on
downwind) AND we lose lift as the headwind decreases. Stall, anyone?
And possibly a spin, if the wind gradient kicks in during the base-to-
final turn. Think about the typical base-to-final spin accident -
they tend to happen when people are low and not yet on final, right?
So isn't it possible that its not just them "skidding" the turn, but
also possibly aggravated by the wind gradient? How many instructors
discuss the wind gradient with their students? How many discuss it in
terms of a low base-to-final turn?

--Noel
(CFIG-in-training)

Good point on wind gradient. The aircraft here was an ASW19? That was my first ship.

My condolences to family,
Darren

On Tuesday, September 4, 2012 8:02:52 PM UTC-4, noel.wade wrote:
On Sep 4, 10:34*am, bumper wrote: It's easy enough to practice low (within a few wing spans), slow, high bank angle turns in a power plane like a Super Cub or Husky. Not so many opportunities in a glider. To the uninitiated, there's a tendency to skid a turn when low, as some pilots try to minimize bank angle - too much bottom rudder, not enough aileron. Not a good situation to be. Yes, one thing to point out is that a lot of training spins emphasize a lot of back-stick *plus* a punch on the rudder to initiate the spin. But IMHO this isn't how spins develop in the real world. I believe that many spins develop as the aircraft's situation degrades over a couple of seconds (airspeed bleeds off, or back-stick/rudder is slowly added in by the pilot without realizing they're "creeping" on the controls). Another item for thought: Using trim on an aircraft is great (I am constantly re-trimming my aircraft). BUT if you trim the aircraft for flight at a slow speed (say an approach-speed that's a little too slow), the trim-spring is what is "pulling back" on the stick. YOU will not feel yourself pulling on the stick. Yet the aircraft may be dangerously close to a stall/spin. And once it starts to develop you'll have to PUSH *against* the trim spring in order to un-stall the wing! Simply "relaxing the back-pressure" will not break the stall or stop the spin. This goes against a lot of the muscle-memory we learn when we train in gliders and perform training stalls & spins, so pilots are not likely (IMHO) to take the full corrective action. Lastly, think about wind gradient and headwind/tailwind components... Let's say we're making a landing pattern (and this could be particularly bad in an off-field situation). There's a tailwind on downwind so the ground rushes past and we try to slow down (perhaps subconsciously). Then we turn base/final and while we get a bit of the headwind, we also have to remember low level wind gradients mean that as we descent down close to the ground that headwind goes away. So we have pulled the stick back (from trying to "slow down" on downwind) AND we lose lift as the headwind decreases. Stall, anyone? And possibly a spin, if the wind gradient kicks in during the base-to- final turn. Think about the typical base-to-final spin accident - they tend to happen when people are low and not yet on final, right? So isn't it possible that its not just them "skidding" the turn, but also possibly aggravated by the wind gradient? How many instructors discuss the wind gradient with their students? How many discuss it in terms of a low base-to-final turn? --Noel (CFIG-in-training)

I teach the sneaky slow low banked turn with student looking into the turn(where are the "pilots" looking when they spin on base to final?) while I have them try to force "just a little more turn" while very subtly sneaking in some more inside rudder. When it goes, they are surprised. That is the point- it comes as a surprise, especially when the pilot isn't watching the attitude and yaw.
Add a bit of a gust or shear, and it is even more sudden.
Question- "how would you like to do that low?" gets the predictable answer.
UH

I prefer to move the trim full forward before entering the pattern. The
back pressure required has not been a problem with the various gliders I've
flown. If I get distracted for some reason I hopefully will be flying
faster than required, rather than slower. I too find it easier to control
air speed by varying the back pressure. If the glider is trimmed for
approach speed and there is a loss of headwind due to ground friction, the
forward pressure required to maintain airspeed feels unnatural to me.

At 00:02 05 September 2012, noel.wade wrote:
On Sep 4, 10:34=A0am, bumper wrote:
It's easy enough to practice low (within a few wing spans), slow, high
ba=
nk angle turns in a power plane like a Super Cub or Husky. Not so many
oppo=
rtunities in a glider. To the uninitiated, there's a tendency to skid a
tur=
n when low, as some pilots try to minimize bank angle - too much bottom
rud=
der, not enough aileron. Not a good situation to be.

Yes, one thing to point out is that a lot of training spins emphasize
a lot of back-stick *plus* a punch on the rudder to initiate the
spin. But IMHO this isn't how spins develop in the real world. I
believe that many spins develop as the aircraft's situation degrades
over a couple of seconds (airspeed bleeds off, or back-stick/rudder is
slowly added in by the pilot without realizing they're "creeping" on
the controls).

Another item for thought: Using trim on an aircraft is great (I am
constantly re-trimming my aircraft). BUT if you trim the aircraft for
flight at a slow speed (say an approach-speed that's a little too
slow), the trim-spring is what is "pulling back" on the stick. YOU
will not feel yourself pulling on the stick. Yet the aircraft may be
dangerously close to a stall/spin. And once it starts to develop
you'll have to PUSH *against* the trim spring in order to un-stall the
wing! Simply "relaxing the back-pressure" will not break the stall or
stop the spin. This goes against a lot of the muscle-memory we learn
when we train in gliders and perform training stalls & spins, so
pilots are not likely (IMHO) to take the full corrective action.

Lastly, think about wind gradient and headwind/tailwind components...
Let's say we're making a landing pattern (and this could be
particularly bad in an off-field situation). There's a tailwind on
downwind so the ground rushes past and we try to slow down (perhaps
subconsciously). Then we turn base/final and while we get a bit of
the headwind, we also have to remember low level wind gradients mean
that as we descent down close to the ground that headwind goes away.
So we have pulled the stick back (from trying to "slow down" on
downwind) AND we lose lift as the headwind decreases. Stall, anyone?
And possibly a spin, if the wind gradient kicks in during the base-to-
final turn. Think about the typical base-to-final spin accident -
they tend to happen when people are low and not yet on final, right?
So isn't it possible that its not just them "skidding" the turn, but
also possibly aggravated by the wind gradient? How many instructors
discuss the wind gradient with their students? How many discuss it in
terms of a low base-to-final turn?

--Noel
(CFIG-in-training)

I prefer to move the trim full forward before entering the pattern. The
back pressure required has not been a problem with the various gliders I've
flown. If I get distracted for some reason I hopefully will be flying
faster than required, rather than slower. I too find it easier to control
air speed by varying the back pressure. If the glider is trimmed for
approach speed and there is a loss of headwind due to ground friction, the
forward pressure required to maintain airspeed feels unnatural to me.

At 00:02 05 September 2012, noel.wade wrote:
On Sep 4, 10:34=A0am, bumper wrote:
It's easy enough to practice low (within a few wing spans), slow, high
ba=
nk angle turns in a power plane like a Super Cub or Husky. Not so many
oppo=
rtunities in a glider. To the uninitiated, there's a tendency to skid a
tur=
n when low, as some pilots try to minimize bank angle - too much bottom
rud=
der, not enough aileron. Not a good situation to be.

Yes, one thing to point out is that a lot of training spins emphasize
a lot of back-stick *plus* a punch on the rudder to initiate the
spin. But IMHO this isn't how spins develop in the real world. I
believe that many spins develop as the aircraft's situation degrades
over a couple of seconds (airspeed bleeds off, or back-stick/rudder is
slowly added in by the pilot without realizing they're "creeping" on
the controls).

Another item for thought: Using trim on an aircraft is great (I am
constantly re-trimming my aircraft). BUT if you trim the aircraft for
flight at a slow speed (say an approach-speed that's a little too
slow), the trim-spring is what is "pulling back" on the stick. YOU
will not feel yourself pulling on the stick. Yet the aircraft may be
dangerously close to a stall/spin. And once it starts to develop
you'll have to PUSH *against* the trim spring in order to un-stall the
wing! Simply "relaxing the back-pressure" will not break the stall or
stop the spin. This goes against a lot of the muscle-memory we learn
when we train in gliders and perform training stalls & spins, so
pilots are not likely (IMHO) to take the full corrective action.

Lastly, think about wind gradient and headwind/tailwind components...
Let's say we're making a landing pattern (and this could be
particularly bad in an off-field situation). There's a tailwind on
downwind so the ground rushes past and we try to slow down (perhaps
subconsciously). Then we turn base/final and while we get a bit of
the headwind, we also have to remember low level wind gradients mean
that as we descent down close to the ground that headwind goes away.
So we have pulled the stick back (from trying to "slow down" on
downwind) AND we lose lift as the headwind decreases. Stall, anyone?
And possibly a spin, if the wind gradient kicks in during the base-to-
final turn. Think about the typical base-to-final spin accident -
they tend to happen when people are low and not yet on final, right?
So isn't it possible that its not just them "skidding" the turn, but
also possibly aggravated by the wind gradient? How many instructors
discuss the wind gradient with their students? How many discuss it in
terms of a low base-to-final turn?

--Noel
(CFIG-in-training)

What is the lowest altitude at which you could recover from a spin, and still have enough safety margin to land? I would not thermal below this altitude, but that is just me.

I think we need to make a very clear distinction between incipient spin and developed spin. The SSA has a bronze badge study guide of which one of the questions is... "What corrective action should be taken if, while thermalling at minimum sink speed in turbulent air, the left wing drops while turning to the left" The answer to this question is NOT apply opposite rudder. The correct answer is "lower the nose before applying opposite rudder and aileron pressure"

I have never practiced spins in a glider. I'm wondering, for those who have done so. Is it common to become confused as to which direction you are spinning? I practice spins in Condor and this often happens. I'm curious if Condor spin characteristcs are very realistic. Based on recovery procedures, I'm guessing not. Incipient spins happen a lot in Condor, especially with full water working narrow thermals. Full water makes it much harder to recover.

.... Aaron

On 9/13/2012 9:39 PM, akiley wrote:
I think we need to make a very clear distinction between incipient spin and
developed spin. The SSA has a bronze badge study guide of which one of the
questions is... "What corrective action should be taken if, while
thermalling at minimum sink speed in turbulent air, the left wing drops
while turning to the left" The answer to this question is NOT apply
opposite rudder. The correct answer is "lower the nose before applying
opposite rudder and aileron pressure"

Whether we're talking "an uncommanded (by Joe Pilot) departure" or "a fully
developed spin", neither can happen unless one wing is sufficiently above its
critical angle of attack that lift-reduction/increased-drag leads to loss of
lateral stability (hence the uncommanded wing drop). Anything serving to
maintain the more-stalled wing in that condition will also serve to maintain
(in a fully developed spin) or worsen (in the case of an uncommanded
departure) the condition.

Presuming Joe Pilot doesn't want the condition to worsen or continue, a useful
way to think of "corrective action" is to prioritize the sequence of potential
actions by those most likely to reduce the critical AoA ASAP. Then the SSA's
answer makes perfect sense. Why?

Recovery can NOT occur until the wings are both again flying (i.e. below their
critical AoA). (Understanding - and *believing* the preceding claim is crucial
to burning the proper corrective actions into one's noodle.)

While "instant opposite rudder" *might* prove useful (by slewing the nose
around and thereby potentially reducing the lower wing's AoA due to the
hoped-for velocity increase), success along those lines presumes sufficient
rudder authority and aerodynamic energy/conditions to halt-then-overcome the
rotational inertia of the already-/increasingly-rotating glider.

OTOH, reducing AoA directly via the stick is almost *guaranteed* to have "an
instantaneous effect" because gravity never quits, and - in this situation -
is working *for* you. Once you're unstalled, the rudder has a better chance of
assisting with recovery...
- - - - - -


I have never practiced spins in a glider. I'm wondering, for those who
have done so. Is it common to become confused as to which direction you
are spinning?

Making no claims to be a spinning expert, and noting all my spins have been
upright (i.e. not inverted), I've never come close to being confused on spin
direction. Obviously (he sez! :-)) it IS possible to become confused, but I'd
guess most easily so in any simulator lacking "G-clues". Perhaps the real
world equivalent would be by entering a spin only after "sufficient preceding
aerobatics" to overwhelm Joe Pilot's experience base.

In "normal thermalling (and by extension, landing pattern) flight" when you
experience an uncommanded wing drop (meaning, possibly an uncommanded
departure/incipient spin), between a) the obvious "falling to one side"
sensation, and b) the rotation of the world beyond the canopy, direction has
always seemed to me immediately obvious...and of course, you probably had been
cheating toward the spin direction with rudder, too, right?!? (Meaning, a
halfway aware pilot should already know "without having to think about it"
when he's in a situation predisposing him to an uncommanded departure, and
WHY!!! What may happen next - and in what direction - "should be obvious...")

The above presumes we're NOT talking about the possibility of "over the top"
spin entries. While they're possible - and demonstrable in some gliders -
they're not the ones that commonly kill in the landing pattern, nor are they
commonly experienced while thermalling. Key word being "commonly"...

Stated another way, "in real life" you're "almost always" going to spin the
direction you're already turning. "No confusion necessary!"


I practice spins in Condor and this often happens. I'm
curious if Condor spin characteristcs are very realistic. Based on
recovery procedures, I'm guessing not. Incipient spins happen a lot in
Condor, especially with full water working narrow thermals. Full water
makes it much harder to recover.

... Aaron



HTH!
Bob W.