Puchaz Spinning thread that might be of interest in light of the recent accident.

On Thu, 29 Jan 2004 17:49:53 UTC, (Caracole) wrote:

: There is no doubt that more instructiors have been killed
: in spins in the Puchacz than any other glider.

Is there? Do we have some worldwide statistics to show it?

And how does the Puchacz compare with other spinnable two-seaters?
After it, it makes no sense to look at the number of spinning
accidents in K21's ...


Ian

--

In article , Dave Martin
writes

snip

it must be realised that the pilot caused the inadvertent
stall in the first place by inappropriate use of the
controls. He is unlikely to start making skilful or
precise movements now. Do not attempt to use the secondary
effect of the rudder to restore the wings to the level
position. This would introduce yaw which could result
in the glider spinning. The priority must be to unstall
the glider by moving the stick forward.'

I agree 100% with the above and some years ago had a short article
published in the BGA magazine Sailplane and Gliding on this precise
subject. I repeat this article at the end as it is still relevant.
Timeless, even.

Question: What is the use of lots of rudder near the stall likely to
induce?

No prize for the answer!

The answer is the same whether the use of rudder was well-intentioned or
not.

In the 1950s I was taught to "pick a wing up near the stall by using
rudder", but this often led to a low speed situation being converted
into the first stages of a spin, and sometimes a fully-developed spin
with a tragic conclusion if near the ground.

By the time I became an instructor in the UK Royal Air Force (1965),
instruction had changed to "in an inadvertent slow speed situation,
first reduce angle of attack using forward stick. When at a normal
flying speed, level the wings by gentle use of aileron". Incidentally,
at this time in the RAF, spinning was no covered pre-solo, only stalling
and recovery from inadvertent slow-speed situations. Fully-developed
spinning was covered at about the 30-hour stage as part of training for
aerobatics. Food for thought in the gliding world? There have been
quite a few glider spinning accidents during spinning training. I used
to be a Canberra (US B-57) flying instructor and we killed more people
in training for engine failures than were killed by engine failures
themselves. There is training and there is training, and when the
training itself becomes lethal we need to analyse carefully what we are
doing it for.

Anyway, here is the old S&G article, a bit long but it has many
significant points:

-------------------------------------------------------------------------
-------------

From Sailplane and Gliding, October 1989 edition, page 221

SPINNING TRAINING - A CAUTIONARY NOTE

My basic point is very simple - The automatic application of large
amounts of opposite rudder in slow-speed "wing-drop" situations will,
for most gliders and powered aircraft, make the situation worse. This is
particularly important near the ground, where rudder applied
unnecessarily at slow speed can actually cause a crash.

I know of several accidents where this occurred, in each case the
machine being written off and the pilots badly injured.

1. In one case a stall was being deliberately practised and a
mild wing-drop occurred. Full rudder was applied and the machine quickly
entered a spin from which the pilot was unable to recover before the
ground intervened.

2. A similar case was where an inadvertent wing-drop at low
speed was turned into a full spin by coarse use of rudder, the machine
also crashing into the ground.

3. Another case that I witnessed happened at the launch point
and was even more ironic; a wing-drop occurred at about 200ft on the
approach which the pilot diagnosed as due to a stall but almost
certainly was simply due to turbulence. He had been taught to apply
opposite rudder in this situation, he duly did and the glider crashed
into the ground with its wings almost vertical.

The instinctive reaction to detecting an inadvertent low speed situation
should be to move the stick rapidly forward by an amount proportional to
the severity of the situation and then away from the dropped wing (if
there is a wing-drop). But please be very careful with the rudder until
a fully developed spin is diagnosed. It is a powerful control at the
stall and must not be abused.

I well recall gliders with horrendous stalling characteristics where a
stall was virtually an incipient spin. They would not nowadays be
granted a C of A by the National Regulatory Bodies (CAA/BGA in the UK,
FAA in the USA, LBA in Germany). I vividly remember stalling the Kite 2
(most were spun in) and Geoffrey Stephenson's Gull 1 (also eventually
spun in). A large wing-drop was usually implicit even in an attempted
"straight stall. Fortunately, stalling characteristics have improved
considerably since those days and automatic application of large amounts
of rudder to correct a wing-drop is no longer necessary, if indeed it
ever was.

Having also flown over 50 types of powered aircraft I can assure you
that, at the wing-drop stage, using forward stick for recovery followed
by normal control actions to level the wings, works equally well in a
Harvard (the 1930s piston version, not the Harvard 2 turboprop of
today), Hawk, Hunter, Canberra, Nimrod, Provost/Jet Provost, Vampire and
indeed all aircraft and gliders I have stalled except perhaps the said
Kite 2 and Gull 1 which, unfortunately, are not now available for
experiment.

As an example, the piston Harvard usually has a nasty wing-drop at the
stall, and a "classic" full spin, losing about 60Oft per turn. Many have
been "spun in", with fatal results at low level. In this context I quote
the current Boscombe Down Pilots' Notes (Boscombe Down is the UK
equivalent of Edwards and Eglin AFB in the USA, and used the Harvard for
slow speed photo-chase): "At the stall, the nose and either wing may
drop. With flaps up, the wing drops more rapidly than with flaps down.
If the stick is held back, the aircraft will spin. To recover from the
stall with minimum loss of height, apply power and simultaneously move
the control column sufficiently far forward to unstall the aircraft.
Ailerons then become effective and wing-drop should be corrected with
lateral stick. Ease out of the dive into a gentle climb ..."

Note the absence of any instruction to use rudder (that comes later in
the recovery drill for a fully developed spin), and the emphasis on
smooth handling with no automatic use of coarse or full control
deflections - "Sufficiently far forward", "Ease out", "Gentle climb".

In gliding, what we need is instruction which clearly distinguishes
between a fully developed spin, which should now be very rare except for
deliberate training at a safe height, and the earlier stages such as
wing-drop at a stall which are better recovered by quickly reducing the
angle of attack and then levelling the wings in the normal way, and not
by inducing autorotation the other way by unfeeling boots of rudder.

Stalling and spinning characteristics also vary with the C of G
position. At forward C of G all aircraft tend to be very stable in pitch
and some may not spin at all, just exhibiting a sideslipping spiral dive
in response to full pro-spin control. But as C of G moves aft, pitch
stability reduces and the tendency for a wing-drop at the stall, and to
enter a full spin, increases.

Light pilots, beware!

The Janus is an example, which I had to test for the UK Military (the
Air Cadets, anyway). It will only exhibit a true spin at fully aft C of
G, at all other C of Gs it enters a rather horrendous sideslip in
response to boots of rudder. It has very low directional stability and
is unstable in sideslip below about 55kt. Perhaps this has something to
do with some other Janus accidents (see S&G 1998 page 97). It is also
extremely twitchy in pitch control at fully aft C of G, which shows up
particularly on an aerotow in turbulent conditions and indeed sets the
aft C of G limit. These considerations should be borne in mind when, for
instance, stalling or spinning two-seaters when solo, where C of G will
generally be further aft than when dual.

Instructors have their uses, even if only as ballast!

Wind Gradient.

Stalling and spinning training is carried out at a safe height, whereas
the "worst case" inadvertent slow speed situation is probably the final
turn in a field landing in conditions of turbulence and wind gradient.
Airfields are generally flat (there are some notable exceptions) whereas
the topography around fields may not be, and wind gradient will
therefore be more severe. A slow speed situation could easily get
out-of-control (due to the lower wing being in a lower wind speed, and a
glider with benign characteristics when practising stalls at height
might bite you if you are less than careful near the ground.

There are two rather pessimistic "old adages" which may, on field
landings, be relevant -

1. "If you are going to crash, crash with your wings level".
Particularly relevant in the case of asymmetric thrust on aircraft such
as Camberra/B57, Boeing 707 etc. But also applicable to a glider on an
awkward approach to a field.

and

2. "Always hit the far hedge rather than the near hedge".

Think about it!

I am sorry this article is so long, but my overall conclusion is that we
want more practice in slow-speed situations which we may meet
inadvertently, such as a slow, badly flown turn with thermalling or
landing flap, rather than over-concentration on the deep stall or the
full spin.

And we should practise a recovery technique which is both
straightforward and that will not get us into more trouble.

Lots of us do not have either the regular flying practice of the
professional pilot, or the intuitive handling ability of a Chuck Yeager,
Neil Armstrong, John Farley or Brian Trubshaw (the latter two are
distinguished Brit test pilots, on Harrier and Concorde respectively,
Brian departing to the great test flying "cloud in the sky" a couple of
years ago).

Glider stalling characteristics will, of course, vary with type, flap
position, C of G an even wing condition (bugs, rain etc). Practise
recoveries regularly at a safe height to optimise your technique. But
generally, short of a fully developed spin, the best technique will be
to rapidly move the stick centrally forward to unstall the wings (just
enough to do this, not mechanically fully forward), and then recover
from the ensuing attitude by normal use of controls. Beware the
unnecessary use of coarse control, particularly rudder and particularly
near the ground!

IAN STRACHAN
Lasham Gliding Society

Ian is a qualified Service test pilot and an A1 category RAF flying
instructor as well as being a glider and motor glider instructor. It is
understood that Bill Scull, BGA director of operations, and Bernie
Morris, chairman of the BGA Instructors' Committee, are in agreement
with the main points of this letter.

------- end of quote from S&G ---------

--
Ian Strachan
Lasham, UK

Bentworth Hall West
Tel: +44 1420 564 195 Bentworth, Alton
Fax: +44 1420 563 140 Hampshire GU34 5LA, ENGLAND

"Ian Strachan" wrote in message

There are two rather pessimistic "old adages" which may, on field
landings, be relevant -

1. "If you are going to crash, crash with your wings level".

OK

2. "Always hit the far hedge rather than the near hedge". Think about
it!

This one has me stumped. Does it refer to a circumstance when one is too
high on final and an overshoot is unavoidable, in which case you want to
burn up the most energy before the inevitable?

If someone is low and they try to stretch the glide, it seems like this is
an invitation to stall prematurely and really do some damage and/or cause
injury.

What's the context for this advice?

Pete Brown

Bang on! If it isn't stalled it can't spin!

Allan

Glider stalling characteristics will, of course, vary with type, flap
position, C of G an even wing condition (bugs, rain etc). Practise
recoveries regularly at a safe height to optimise your technique. But
generally, short of a fully developed spin, the best technique will be
to rapidly move the stick centrally forward to unstall the wings (just
enough to do this, not mechanically fully forward), and then recover
from the ensuing attitude by normal use of controls. Beware the
unnecessary use of coarse control, particularly rudder and particularly
near the ground!

IAN STRACHAN
Lasham Gliding Society

From the Ventus 2b Flight Manual:

Section 3.4 Stall Recovery

"On stalling whilst flying straight ahead or in a turn, normal flying
attitude is regained by frimly easing the control stick forward and,
if necessary, applying opposite rudder and aileron."

From The Student Pilot's Flight Manual (Kershner)

"Planes type-certificated under the FARs (as all US general aviation
planes are now) must meet certain rolling (ailerons) and yawing
(rudder) criteria throughout the stall. The FAA, therefore, now
encourages the use of coordinated controls to keep the wings level
during the stall."

Kershner goes on to echo your advice. Move the stick forward first. I
couldn't agree more. But the point is that the FAA is recommending
against the use of rudder only, that is, the way we are still taught
(in glding). In fact, simultaneous movements should be sufficient,
though a slight hesitation after releasing back pressure is the better
habit.

A one size fits all solution is fine in the context of protecting a
student from his ignorance. If the student, due to his inexperience,
fails to recognize and react properly early in the stall and even
possibly abuses the controls, spin recovery actions are beneficial.
But it serves the experienced pilot little if it perpetuates his
ignorance. And far worse if it becomes a crutch for an instructor who
cannot or will not effectively teach and demand flawless execution of
stall recognition and appropriate recovery skills from his students.

Modern aircraft will maintain control effectiveness (even if much
decreased) into the stall. The danger we all understand: exponentially
increasing drag at the wing tip as angle of attack increases. Add to
that the weakened effect of the vertical stab and rudder due to low
airspeed, and the primary concern becomes keeping the glider from
autorotating.

A strong rudder movement at low airspeed is an absolute necessity to
keep the yaw string straight even for small aileron movements. But its
purpose is to compensate for asymmetric drag at the wingtips. This may
or may not have the effect of checking a rolling motion, but this
effect
is secondary. Roll is not the primary reason we use the rudder. And
shouldn't be taught as such. Granted, this goes against much of what
we've been teaching in gliding for many, many years. But that doesn't
make our way right. It deserves some attention.

I'll finish this note with a quote from the FAA Flight Training
Handbook:

[after brief discussion of use of aileron during stall...]

"Even though excessive aileron pressure may have been applied, a spin
will not occur if the directional (yaw) control is maintained by
timely application of coordinated rudder pressure. Therefore, it is
important that the rudder be used properly during both the entry and
recovery from a stall. Thus, the primary use or the rudder in stall
recoveries is to conteract any tendency of the airplane to yaw. The
correct recovery technique then, would be to decrease the pitch
attitude by applying forward elevator pressure to break the stall,
advancing the throttle to increase airspeed, and SIMULTANEOUSLY
maintaining direction with COORDINATED use of aileron and rudder."

(First emphasis is mine. Second is the FAA's.)

It may be disputed if the use of the rudder for picking
up a dropping wing near stall may be or not called a
coordinated action. What I was taught and am going to
teach is that proper coordination is highly dependant
on speed (AOA if fact), slower flight implies more rudder
for the same aileron action. At the stage where the aileron
loose their efficiency or even begin to exhibit
the reversal symptom, you are reaching the limting
case where proper coordination implies action on the
rudder only. However I agree that the proper action
to do in this case is to exit from this high AOA
domain by first easing the stick forward.

I was taught this 'pause' between full opposite rudder
and stick forward and the wind 'shadow' effect was
the reason; However, since it has been proven that
even a Puchacz, which has a low(ish) tailplane, will
recover faster without the pause (Dick Johnson) and
most gliders have 'T' tails to which it doesn't apply
at all, I for one will not be teaching the 'pause'
to my students.
Rob John
Duo 'Si' K6 '350'

In a fully developed spin the tail surfaces can see
an
airflow that has a significant component coming from
underneath the tail surfaces. If the tail surfaces
are
'conventional,' (i.e. not a T-tail), and the elevator
and
horizontal stabilizer are on the fuselage, below the
rudder,
then forward stick produces a 'shadow' in this airflow
which
can block the lower portion of the rudder near the
elevator.
This 'shadow' is reduced when the stick is back. If
you
stand below the elevator and look upward (difficult,
I know)
and move the stick forward in a 1-26, for example,
this
'shadow' effect can be seen. Thus, I was told there
are
some POH's for conventional tail aircraft that recommend
using rudder *before* forward stick in the full spin
to
maximize the effectiveness of the anti-spin rudder.


At least this is what I recall as being the explanation
received from my first flight instructor. Does anyone
else
recall this 'explanation?'


Todd Pattist - 'WH' Ventus C
(Remove DONTSPAMME from address to email reply.)

"Robert Ehrlich" wrote in message
...
It may be disputed if the use of the rudder for picking
up a dropping wing near stall may be or not called a
coordinated action. What I was taught and am going to
teach is that proper coordination is highly dependant
on speed (AOA if fact), slower flight implies more rudder
for the same aileron action. At the stage where the aileron
loose their efficiency or even begin to exhibit
the reversal symptom, you are reaching the limting
case where proper coordination implies action on the
rudder only. However I agree that the proper action
to do in this case is to exit from this high AOA
domain by first easing the stick forward.

Well put, Robert.

Bill Daniels

On Mon, 02 Feb 2004 14:41:14 +0000, Robert Ehrlich
wrote:

It may be disputed if the use of the rudder for picking
up a dropping wing near stall may be or not called a
coordinated action. What I was taught and am going to
teach is that proper coordination is highly dependant
on speed (AOA if fact), slower flight implies more rudder
for the same aileron action. At the stage where the aileron
loose their efficiency or even begin to exhibit
the reversal symptom, you are reaching the limting
case where proper coordination implies action on the
rudder only.

A side light on this and confirmation of your limiting case: last
winter we had a talk at the club from Andy Sephton, who is chief pilot
at The Shuttleworth Collection. A major part of his talk was on flying
the 1911 Bleriot. He said that on take off the Bleriot, with its
highly cambered curved plate wing, has so much adverse yaw plus
aileron reversal that *any* use of ailerons to level the wings on
take-off will cause a ground loop. The only way they found to manage a
take-off was to keep the stick laterally centered and to do all
yaw/roll correction with the rudder. BTW, both main wheels and the
tail wheel are on castoring suspension. He seemed to think this didn't
make things any easier.


--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

A spin means both wings have too high AOA and
one wing has more AOA than the other.

If you can change the AOA of both wings so they are unstalled,
using elevator only, and the stress from the now entered spiral
doesn't make the aircraft wings twist and shatter during recovery dive,
then fine, do that.

If you can't, then it would be great to have both
wings at the same AOA, then reduce the AOA. Rudder is
a possible way to do this (make both wings have the
same AOA by making them both the same airspeed, by
countering the yawing motion). In the ensuing dive
recovery, the wings are level. In some aircraft
these stresses are different than turn/spiral stresses
and the wing structure handles them better.

I suspect this is the reasoning behind
the PARE mnemonic, where rudder is used before elevator.

Power off (for them motorglider thingies)
Aileron Neutral
Rudder Opposite
Elevator forward enough to break stall

Of course, even this mnemonic doesn't work all the
time (sometimes extra power to make the tail surfaces
more effective is better, etc.).

So results for any generalization may vary...