How Low to Spin??

Lower, but not low. You can carry the same total energy
throughout the pattern.

9B

At 05:06 30 August 2004, Eric Greenwell wrote:

I can see how the 'fast' part can help, but not the
'low' part. Being low doesn't seem like an asset if
you are worried about stalls and spins.

With the big spoilers on modern gliders, there's not much risk in
adding 10 extra knots, and while your argument that it adds an
increased cushion before stall is unarguable, I guess the measure of
value comes in whether that reduced risk is a justified departure from
the "correct" pattern airspeed. I'm with Mark... it deserves some more
discussion.

BTW, as I noted in another thread, spins are not caused by lack of
airspeed, but uncoordinated use of the controls -- at least in modern
sailplanes. Two things must happen to enter a spin: 1) you must
stall, and 2) you must fail to apply sufficient rudder during your
attempt to pick up the low wing with aileron. That is, the sailplane
is designed with enough rudder to stop autorotation, even with full
deflection of the aileron throughout the stall break.

As demonstrated by my thread last fall, a Ventus 2 won't spin if the
controls remain coordinated (half stick/half rudder... full
stick/rudder). It enters a controlable spiral, instead. However, half
rudder and full stick (or half stick and no rudder) would induce a
spin if the stick is held full back throughout the stall break.

Avoiding the stall is the first most important step, but thorough
training of the appropriate response during an inadvertent stall is a
close, close second. And I could even argue that it's more important,
since once you've stalled by accident, the outcome is determined by
how well you've been trained to recover (that is, it becomes the
failsafe for your stall avoidance error).

Though I'm not a fan of axiomatic training, there's some value in
remembering that you can stall at any attitude and any speed. If you
wear that axiom on your sleeve, then you'd be best served by
understanding and practicing superlative stall recovery technique in
addition to practicing stall avoidance.

That so many capable pilots have stall/spun in relatively docile
aircraft indicates to me that there is a training gap. We are clearly
handling the controls diffently at low altitudes. Why? If we can agree
that this is the case, then adding speed is good insurance. But it
doesn't address the cause.

Andy, apologies for being the pedant. I'm spitting this stuff out at
60 words per minute, so I'm not giving much thought to "balance."

"Ian Johnston" wrote in message news:cCUlhtvFIYkV-pn2-BdEMqrRprN20@localhost...
On Fri, 27 Aug 2004 18:02:44 UTC, (Kirk Stant)
wrote:

: But you
: shouldn't be jerking your head around while flying!

Except to scan for other aircraft.

Ian

It's tough to see other aircraft by rapidly moving your head - you
need to stop and methodically scan areas of the sky.

No disagreement about the need to keep looking around at all times.
But scanning, like just about everything else in flying, is a skill
that needs to be taught, learned, and practiced to be effective.

Kirk

On Mon, 30 Aug 2004 15:55:11 UTC, (Kirk Stant)
wrote:

: "Ian Johnston" wrote in message news:cCUlhtvFIYkV-pn2-BdEMqrRprN20@localhost...
: On Fri, 27 Aug 2004 18:02:44 UTC, (Kirk Stant)
: wrote:
:
: : But you
: : shouldn't be jerking your head around while flying!
:
: Except to scan for other aircraft.

: It's tough to see other aircraft by rapidly moving your head - you
: need to stop and methodically scan areas of the sky.

Exactly. It's done with rapid movements and pauses rather than a
smooth motion. Which for many of us is the best way of inducing
nausea. I suspect that this is why so many people thermal with their
heads rigidly held in position. I find that rotating my head around a
true vertical axis, rather than the local one, works to reduce this -
ie scan across the hosiron, not across the wings.

Ian

(Mark James Boyd) wrote in message news:412fa9ba$1@darkstar...
Kirk Stant wrote:

1) If they ain't locked for takeoff, a gnarly pio

1. Use a checklist. Oh, and why is the tow pilot fanning his rudder
at me?

LOL! "use a checklist."
Kind of covers everything, huh?

"Oh yeah? He had an accident? I bet he
didn't use the checklist!"

So Mark, you don't use any checklist before taking off? Yeah right,
bull****. What is it, not macho enough for you?

I use CBSIFTCBE (instead of the useless SSA ABCCCDDEEEEFGHHHwhatever)
RELIGIOUSLY before every takeoff. It's as sacred as the old GUMP
checklist. No paper required, only need one brain cell awake to run
it. And even with that, I've managed to get airborne twice with my
spoilers unlocked - in an LS4 and my current LS6. Both due to
interrupted/rushed launches. No big deal, the tow didn't even notice
(because LS brakes don't suck open, they just stay cracked) the
decreased climb rate. I caught them both below 100', closed the
boards, swore a bunch, then went on to convincingly blow the task of
the day.

Seriously, if your students aren't going through a "last chance" check
before commiting to takeoff, they have really bad instructors, to say
the least. And that is "using a checklist". And it will usually
prevent brainfade idiotic accidents from happening. Usually.

Kirk

Bruce Hoult wrote:

In article ,
Robert Ehrlich wrote:

Well, I disagree, and I strongly believe that a well-trained glider
pilot, in any glider, low or high, should be every bit as comfortable
and safe (if not more so) in a 50 degree bank as in a 20 degree bank.

Marc

Agreed for feeling safe, but when comfortable is the question, I think
most pilots would find 1.02g is much more comfortable than 1.75g.

That's 1.06 vs 1.56, actually.


I agree, some mistyping probably in my previous calculation.

Chris OCallaghan wrote:

BTW, as I noted in another thread, spins are not caused by lack of
airspeed, but uncoordinated use of the controls -- at least in modern
sailplanes. Two things must happen to enter a spin: 1) you must
stall, and 2) you must fail to apply sufficient rudder during your
attempt to pick up the low wing with aileron. That is, the sailplane
is designed with enough rudder to stop autorotation, even with full
deflection of the aileron throughout the stall break.


Well, you have to precise what you are calling "uncoordinated use". I
remember an incipient spin in an ASH25 (can be considered as a modern
sailplane, although it existed well before I started gliding 9 years ago).
My mistake was only a to high nose up attitude while circling, which was
not obvious to me as it was my first flight in the aircraft (with an
instructor of course). Due to its high inertia, the sailplane was slowing
down very slowly to the speed corresponding to its attitude, and needed
while slowing down more and more action on controls to counter induced
roll and induced bank up to the point where I had almost full out stick
and a lot of inner rudder when the inner wing dropped. Of course the controls
were badly crossed, but some amount of cross control is normal in order
to counter induced roll and induced yaw, this is not an uncoordinated
flight, the yaw string is is the middle. The excess in cross control
was due to the fact that both induced effects increase when speed decrease,
not to a lack of coordination.

Another experience I had, which is also in contradiction with this opinion
(i.e. spin can only occur by lack of coordination) was when I was
preparing my instructor rating. As there was no other spinable glider
available, we had to demonstrate spin entry and recovery in a Fox, an
aerobatic glider. My instructor was Katona, a well known aerobatic
pilot, and he explained that in order to spin this glider I should
slow it down just very close to the stall and then have stick and rudder
to the same side. I objected that I had always be taught to push the
rudder to the side I want to spin ans the stick to the opposite side.
He said that in this case the Fox would do a flat spin, which is difficult
to exit and was not the objective of the present exercise.

"Ian Johnston" wrote in message news:cCUlhtvFIYkV-pn2-8OXf57VN35wC@localhost...
On Fri, 27 Aug 2004 21:38:02 UTC, (Mark James
Boyd) wrote:

: "Oh yeah? He had an accident? I bet he
: didn't use the checklist!"

I once had someone try to persuade me to use a checklist for a winch
cable break. Yes, great, run through a list of actions which have to
be started within a second and completed within a few ... the idiot's
an instructor now, and feedback tells me that he's no less of an
idiot...

I recently read the accident report of the ASW20 crash (fatal) at
Williams, CA. Per the check list, they did a positive control check of
the elevator by having the assistant (co-owner) hold the elevator
while the pilot applied force on the stick. Resistance was felt, check
list passed. Only problem was the elevator was not hooked up and what
the pilot felt was the push rod hitting the bottom of the elevator.
Now, if the guy just LOOKED at the connection it would have been
obvious that it was not hooked up (it is in plain site).

Still, he had a second chance to save himself. When the glider decided
to launch itself he could have immediately released and delt with the
situation at a more survivable attitude (the tow pilot released him
instead).

Check lists are not substitutes for plain common sense. If you use
them, do another walk around the glider without the list, looking for
things you might have missed. Following a list may give you tunnel
vision. A DC-9 was landed gear up by two experienced pilots following
a check list (they missed one step). They were so certain that they
had done everything right that they ignored the lack of the sound and
thump of the gear lowering (common sense, again).

Tom

Chris - always thoughtful and articulate - even when
pedantic. ;-)

Seriously, I agree with your point about avoidance
AND early, reflexive recovery to avoid a full-on spin.
I used to work on wing-drop recovery in an early S/N
Ventus A/16.6 - which had the most pronounced stall
break of any glider I can recall. The control input
was stick forward and into the turn plus top rudder.
It takes some practice to make it reflexive.

I recall the main reasons for teaching stabilized approach
are to provide a consistent visual reference for the
pilot and to keep from changing too many flight variables
at the same time. Honestly, I don't know how they
come up with recommended 'correct' pattern speeds -
nor how scientific or precise the algorithm. My assumption
is that the speed is picked as a tradeoff between stall
margin and approach energy - but that there is an acceptable
range. We regularly add 1/2 the wind speed - how exact
is that?

My personal experience is that it's quite easy to bleed
off 5-10 knots by accident in a moment of distraction,
but 15-20 knots takes longer and is more apparent.


9B


At 15:36 30 August 2004, Chris Ocallaghan wrote:
With the big spoilers on modern gliders, there's not
much risk in
adding 10 extra knots, and while your argument that
it adds an
increased cushion before stall is unarguable, I guess
the measure of
value comes in whether that reduced risk is a justified
departure from
the 'correct' pattern airspeed. I'm with Mark... it
deserves some more
discussion.

BTW, as I noted in another thread, spins are not caused
by lack of
airspeed, but uncoordinated use of the controls --
at least in modern
sailplanes. Two things must happen to enter a spin:
1) you must
stall, and 2) you must fail to apply sufficient rudder
during your
attempt to pick up the low wing with aileron. That
is, the sailplane
is designed with enough rudder to stop autorotation,
even with full
deflection of the aileron throughout the stall break.

As demonstrated by my thread last fall, a Ventus 2
won't spin if the
controls remain coordinated (half stick/half rudder...
full
stick/rudder). It enters a controlable spiral, instead.
However, half
rudder and full stick (or half stick and no rudder)
would induce a
spin if the stick is held full back throughout the
stall break.

Avoiding the stall is the first most important step,
but thorough
training of the appropriate response during an inadvertent
stall is a
close, close second. And I could even argue that it's
more important,
since once you've stalled by accident, the outcome
is determined by
how well you've been trained to recover (that is, it
becomes the
failsafe for your stall avoidance error).

Though I'm not a fan of axiomatic training, there's
some value in
remembering that you can stall at any attitude and
any speed. If you
wear that axiom on your sleeve, then you'd be best
served by
understanding and practicing superlative stall recovery
technique in
addition to practicing stall avoidance.

That so many capable pilots have stall/spun in relatively
docile
aircraft indicates to me that there is a training gap.
We are clearly
handling the controls diffently at low altitudes. Why?
If we can agree
that this is the case, then adding speed is good insurance.
But it
doesn't address the cause.

Andy, apologies for being the pedant. I'm spitting
this stuff out at
60 words per minute, so I'm not giving much thought
to 'balance.'

Knowing your glider is the key. Open class ships are built to the
limits of acceptable flying characteristics, as is the case with
aerobatic aircraft (one reason they are typically certified
"experimental"). You must read and understand the flight manual,
noting the divergence from the norm, which is what I cited in this and
previous threads.

I suspect that many pilots are simply not used to the difference in
force required to displace the rudder equally with the aileron. A
tendency to underrudder at flying speed is common. Applying the same
"balance" near the stall would produce much less rudder force, which
means that the greatly increased and unbalanced aileron drag will
produce a skid, and the angular momentum required to start
autorotation.

Flying your glider at MCA and experimenting with various displacements
of the controls is a good exercise. Gentle turning stalls while using
coordinated aileron and rudder (not solely determined by the yaw
string but also by percentage of travel applied) to pick up the lower
wing will help you understand what your glider can and cannot do in
the stall.

In previous threads, we discussed intentionally spinning at pattern
altitudes to acclimate pilots to this "view." Such practices are
patently absurd. However, regular practice flying on the edge of the
stall while applying coordinated aileron and rudder should have real
(and much more valuable) benefits. Does your yaw string act differntly
at low speed? Are you able to accurately judge onset of the stall?
During a stall, are you applying sufficient rudder? We all make
assumptions that we will react correctly, but I'd guess that without
regular practice of the type I descibed above, we're probably not
flying as efficiently near the stall as we think. So if we get there
by accident, is it possible that we might not be aggrevating the
situation through improper control inputs?

BTW, recall that during my test flights, I was able to avoid a spin
while holding full back stick throughout the stall and ensuing spiral.
Simultaneous release of back pressure and coordinated use of aileron
and rudder is the key. Flying MCA and reacting this way to any sign of
an impending stall is the best training you can give yourself. Then
add 15 knots in the pattern to be sure you won't have to exercise
those skills.

Honestly, how many of you really practice stall recognition and
recovery as a regular flight proficiency routine? I typically only fly
on the cusp of a stall for several seconds each flight: as I take off
(I get impatient) and just before I touch down. That's not a whole lot
of opportunity to experience a critically important flight regime.

Over my quota for the week. I'll check in next week.

OC



Robert Ehrlich wrote in message ...
Chris OCallaghan wrote:

BTW, as I noted in another thread, spins are not caused by lack of
airspeed, but uncoordinated use of the controls -- at least in modern
sailplanes. Two things must happen to enter a spin: 1) you must
stall, and 2) you must fail to apply sufficient rudder during your
attempt to pick up the low wing with aileron. That is, the sailplane
is designed with enough rudder to stop autorotation, even with full
deflection of the aileron throughout the stall break.


Well, you have to precise what you are calling "uncoordinated use". I
remember an incipient spin in an ASH25 (can be considered as a modern
sailplane, although it existed well before I started gliding 9 years ago).
My mistake was only a to high nose up attitude while circling, which was
not obvious to me as it was my first flight in the aircraft (with an
instructor of course). Due to its high inertia, the sailplane was slowing
down very slowly to the speed corresponding to its attitude, and needed
while slowing down more and more action on controls to counter induced
roll and induced bank up to the point where I had almost full out stick
and a lot of inner rudder when the inner wing dropped. Of course the controls
were badly crossed, but some amount of cross control is normal in order
to counter induced roll and induced yaw, this is not an uncoordinated
flight, the yaw string is is the middle. The excess in cross control
was due to the fact that both induced effects increase when speed decrease,
not to a lack of coordination.

Another experience I had, which is also in contradiction with this opinion
(i.e. spin can only occur by lack of coordination) was when I was
preparing my instructor rating. As there was no other spinable glider
available, we had to demonstrate spin entry and recovery in a Fox, an
aerobatic glider. My instructor was Katona, a well known aerobatic
pilot, and he explained that in order to spin this glider I should
slow it down just very close to the stall and then have stick and rudder
to the same side. I objected that I had always be taught to push the
rudder to the side I want to spin ans the stick to the opposite side.
He said that in this case the Fox would do a flat spin, which is difficult
to exit and was not the objective of the present exercise.