Re: Re: Comparitive spin characteristics was Re: Puchacz fatal accident 18 Jan. 2004 at Hus Bos

[stephanevdv]

In the previous post, I read the classic

> 2. Short pause,

However, EASA's CS-22 (the new European glider design norm, replacing
JAR-22) gives the following standard spin exit procedure:

> AMC 22.221(c),(d),(e) and (f)
> Spinning
> General
> The standard procedure to recover from a spin is as follows:
> Where applicable, close throttle.
> Sequentially:
> (1) Check ailerons neutral.
> (2) Apply rudder opposite to the direction of the spin.
> (3) Ease the control column forward until rotation ceases.
> (4) Centralise rudder and ease out of the ensuing dive.
>

The "short pause" is not included in this procedure (it wasn't included
in the JAR-22 norm either, at least not in the last version I
downloaded). I called it "classic", however, because I read it in most
glider pilot training handbooks. The question is: where does it come
from, what is it's purpose, why isn't it included in the design rules,
what will be the difference in the spin behaviour, and last but not
least, how long or short is a "short" pause? Could it be that this
short pause was a factor in some spinning accidents, given that it is
in contradiction with the official design requirements?

When learning to instruct, I was also told the "short pause" bit. I
never really applied it, as far as I can remember. I never had any exit
problems (on Ka-2b, Ka-7, ASK-13, Blanik, Puchacz) when the pupil
correctly gave opposite rudder first, and eased back on the stick
immediately after. I had some cases, however, where the Puchacz refused
to exit if the rudder was not sufficiently pushed in the opposite
direction. That's why I never start instruction spinning with an
"unknown" pupil below 3 000 ft. I always stop the the exercise above 1
500 ft.

When I read in June 2004 that the BGA was dropping the requirement for
low spinning exercises, I was astonished to learn there was a country
where they routinely teach such a thing (I fly in Belgium).
> The recommendation in the BGA Instructors Manual, page 19-3, to
> initiate a 'brief' spin at 800 feet during pilot training will be
> removed by appropriate amendment action in due course.
If something goes wrong, 800 ft seems very low indeed! Perhaps we
shouldn't wonder too much about the frequency of spinning accident with
instructors on board if such rules are applied. Plus, spinning being
habit forming, the more you practice, the less dangerous it seems: some
instructors are really "spin happy", requiring prolonged spinning "so
that you can really identify the phenomenon". Personally, I much prefer
my pupil to apply the correct exit manoeuvres as soon as spinning
starts. That will possibly save his life in the event of a last turn
incipient spin. Waiting to "identify the phenomenon" will surely get
him killed in this instance.


--
stephanevdv
------------------------------------------------------------------------
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[Tony Verhulst]

> The "short pause" is not included in this procedure (it wasn't included
> in the JAR-22 norm either, at least not in the last version I
> downloaded). I called it "classic", however, because I read it in most
> glider pilot training handbooks. The question is: where does it come
> from, what is it's purpose, why isn't it included in the design rules,
> what will be the difference in the spin behaviour, and last but not
> least, how long or short is a "short" pause?

The following is what I was taught about that. I am not sure of it's
correctness and further discussion is welcome.

The purpose of the opposite rudder is to stop the spin rotation. The
pause is to allow time for the rotation to stop. The stick forward
unstalls the glider - at which point the glider accelerates and you
recover from the dive. If you unstall the glider before the rotation
stops, you are then in a spiral dive - which is preferably avoided.

It has worked very well on the dozen or so glider types that I've spun.

Tony V.
http://home.comcast.net/~verhulst/SOARING

[Z Goudie]

At 15:30 16 January 2005, Tony Verhulst wrote:

>> The 'short pause' is not included in this procedure
>>(it wasn't included
>> in the JAR-22 norm either, at least not in the last
>>version I
>> downloaded). I called it 'classic', however, because
>>I read it in most
>> glider pilot training handbooks. The question is:
>>where does it come
>> from, what is it's purpose, why isn't it included
>>in the design rules,
>> what will be the difference in the spin behaviour,
>>and last but not
>> least, how long or short is a 'short' pause?

I was always of the opinion that the 'short pause'
first came about because it was thought that with a
low mounted tailplane (which most aircraft then had)
use of the elevator first could cause turbulence which
would blank the effect of the rudder and thus slow
down or even prevent the yaw correction.

If that was a good reason, with T tails does it matter
a jot?

My first instinct with any sign of sudden departure
is to thrust the stick through the instrument panel
and UNLOAD THE WING (not necessarily to keep it their
until VNE arrives) along with the appropriate rudder
as required.

Generally I find that the spin stops PDQ.

[W.J. \(Bill\) Dean \(U.K.\).]

Z,

If you read the handbook for your K21s, as amended by Schleicher Tech. Note
23 of Jan. 91 (your handbooks have been updated I hope?) you will find
something about the pause, and something about thrusting the stick straight
onto the forward stop.

The amended ASK 21 Flight Manual page 13 reads:

"III.1 RECOVERY FROM SPIN

"According to the standard procedure spinning is terminated as follows:

"1. Apply opposite rudder (i.e. apply rudder against the direction of
rotation of the spin).

"2. Short pause (hold control inputs for about 1/2 spin turn).

"Warning: Disregarding the pause will result in slower recovery!

"3. Release stick (i.e. give in to the pressure of the stick) until the
rotation stops and sound airflow is established again.

"Warning: Full forward stick may retard or even prevent recovery!

"4. Centralise rudder and allow sailplane to dive out.
The altitude loss from the beginning of the recovery until the normal flight
attitude is regained is about 80 meter (260 feet).

"Note: During spins the ASK 21 oscillates in pitch. From a steep nose
down spin recovery according to the standard procedure is up to 1 turn, from
a flat spin less than 1 turn."

On page 15 we find:

"III.4 WING DROPPING

"The sailplane stalls extremely benign. Nevertheless one always has to
face the possibility of wing dropping because of turbulence. In that case
push stick forward immediately and apply opposite rudder against a
noticeable turn _at the same time_ to regain a normal flight attitude. If
the rudder deflection against the turn is forgotten, a spin may occur even
if the stick pressure is released."

There is more on page 25 and 26 (also amended by TN 23), in particular the
effect of different C. of G. positions is discussed.

There is also the question of whether the minimum placard cockpit weights
are actually based on C. of G. position and moments. Frequently the glider
is placarded with a standard minimum weight, usually 70 kg. (154 lbs.); the
true minimum based on moments may be that figure, or much less, the pilot
has no way of knowing which.

Z, how many of the K 21 pilots at your club know all this?

Regards,

Bill.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.

"Z Goudie" > wrote in message
...
> At 15:30 16 January 2005, Tony Verhulst wrote:
>
>>>
>>> The 'short pause' is not included in this procedure (it wasn't included
>>> in the JAR-22 norm either, at least not in the last version I
>>> downloaded). I called it 'classic', however, because I read it in most
>>> glider pilot training handbooks. The question is:
>>> where does it come from, what is it's purpose, why isn't it included in
>>> the design rules, what will be the difference in the spin behaviour, and
>>> last but not least, how long or short is a 'short' pause?
>>>
>
> I was always of the opinion that the 'short pause'
> first came about because it was thought that with a
> low mounted tailplane (which most aircraft then had)
> use of the elevator first could cause turbulence which
> would blank the effect of the rudder and thus slow
> down or even prevent the yaw correction.
>
> If that was a good reason, with T tails does it matter
> a jot?
>
> My first instinct with any sign of sudden departure
> is to thrust the stick through the instrument panel
> and UNLOAD THE WING (not necessarily to keep it their
> until VNE arrives) along with the appropriate rudder
> as required.
>
> Generally I find that the spin stops PDQ.
>

[Z Goudie]

At 14:07 17 January 2005, W.J. \bill\ Dean \u.K.\.
wrote:
>If you read the handbook for your K21s, as amended
>by Schleicher Tech. Note
>23 of Jan. 91 (your handbooks have been updated I hope?)
>you will find
>something about the pause, and something about thrusting
>the stick straight
>onto the forward stop.

Point taken Bill; I was perhaps exaggerating somewhat.

The point I was trying to get over was that unloading
the wing rapidly is probably the best way to prevent
a full blooded spin happening in the first place and
an instinctive stab forward on the stick accompanied
by a dab of opposite rudder has probably saved me severe
embarrassment on several occasions.

Every glider has its own characteristics and, though
Ian Strachans's point about the majority of us not
being test pilots is well put, I would like to think
that anyone who is going to thermal below 1500AGL (i.e.
all of us in the UK) has investigated at a safe height
the spin entry and (quickest) recovery techniques for
whatever they are flying.

Incidentally I don't instruct these days so I'm not
passing on any bad habits!