ASW-20 spins

On Tuesday, June 2, 2015 at 2:25:00 AM UTC-4, Jonathan St. Cloud wrote:
Saw the quote below in another thread regarding spoilers open while turning (it was actually in the comment section under the video ) and was wondering if anyone could comment? This is the proper spin recovery technique.

"The ASW 20 killed a number of pilots by spinning inverted out of a steep banked turn with positive flaps in thermals. They would go full stick forward and rudder against the apparent rotation in an effort to recover which simply held them in the spin. "

I have never heard of the behavior you describe.
When the '20 was new, a lot of pilots still subscribed to the idea that it was good to fly at the aft CG limit to maximize performance. This seems to have led to a number of unexplained spin accidents when landing. I never heard of an unrecoverable spin, nor going inverted as part of the spin. Someone may well have over done the forward stick and gone negative in the recovery.
My first '20 had some undocumented tail ballast that made it very ugly when I first flew it. I was quite proficient in spins so no bad came of it.
Interestingly the addition of external seals that came along later made the spin characteristics a bit more benign. Obviously some internal flow was going on in the trailing edge area.
'20 recovery is normal. Opposite rudder, neutralize stick, flaps neutral. When winglets are added, it is a bit more resistant to spinning, but slightly more abrupt when it departs, likely due to blanking of the tip by the inboard stalled winglet.
FWIW
UH

Power: idle
Ailerons: neutral (and flaps up)
Rudder: full opposite to the spin and held in that position
Elevator: through neutral

this works inverted as well, and been tested over and over again to work in almost any aircraft (properly loaded)

http://www.aopa.org/Pilot-Resources/...eness-Part-III

"The ASW 20 killed a number of pilots by spinning inverted out of a steep banked turn with positive flaps in thermals. They would go full stick forward and rudder against the apparent rotation in an effort to recover which simply held them in the spin. "

I watched one of those early ASW 20 fatal spins. It was from slow straight and level flight, not thermaling. The wing dropped sharply and the glider entered a conventional, nose-down spin. The recovery began almost immediately (approx. 1/4 turn) but unfortunately there was not sufficient altitude (this began at approx. 300 ft AGL) and the pilot was killed when the glider impacted the ground slightly nose down (i.e., the recovery was almost complete) but still sinking. Undocumented tail ballast was probably a factor, as with UH's situation. Pilot incapacitation due to dehydration may also have been a factor. The final blow, so to speak, was the lack of a headrest in this very early '20 and a battery pack behind the head that came loose. The pilot was an experienced, high-time competition pilot and instructor. All of the contributing factors were avoidable.

Chip Bearden
ASW 24 "JB"
U.S.A.

I was much more lucky in my ASW-27 at 70% CG when I had a windshear induced
stall while moving to flap L at ~300 above threshold. I lost 269' and was
fortunate to recover over lower ground before having to dodge a topsoil
pile in the neighboring gravel pit.

With headwind component = TAS - GS, the flight data shows 3 windshears,
each over a 2 second interval, of -17, +23, -28 kt (application of
Pythagorean sum of squares of a triangle on the final shear yields 6 kt of
apparent headwind giving -34 kt -- TWICE the recorded wind).

Recovery action was flaps negative and stick forward.

The usual stall practice at 3000 AGL with a 1 kt/second deceleration has
little resemblance to a low level windshear stall.

More details on:

https://www.dropbox.com/sh/lq9osn15b...wuYvScXya?dl=0

I watched one of those early ASW 20 fatal spins. It was from slow
straight
=
and level flight, not thermaling. The wing dropped sharply and the glider
e=
ntered a conventional, nose-down spin. The recovery began almost
immediatel=
y (approx. 1/4 turn) but unfortunately there was not sufficient altitude
(t=
his began at approx. 300 ft AGL) and the pilot was killed when the glider
i=
mpacted the ground slightly nose down (i.e., the recovery was almost
comple=
te) but still sinking. Undocumented tail ballast was probably a factor,
as
=
with UH's situation. Pilot incapacitation due to dehydration may also
have
=
been a factor. The final blow, so to speak, was the lack of a headrest in
t=
his very early '20 and a battery pack behind the head that came loose.
The
=
pilot was an experienced, high-time competition pilot and instructor. All
o=
f the contributing factors were avoidable.

Chip Bearden
ASW 24 "JB"
U.S.A.

I'm very glad this worked out.

But I have my doubts about the wisdom of using negative flaps for stall recovery, especially close to the ground. I don't think that this can be said to be a good practice in general and I would recommend heartily against in my own ASW-20B.

-Evan Ludeman / T8



On Wednesday, June 3, 2015 at 11:15:05 PM UTC-4, George Haeh wrote:
I was much more lucky in my ASW-27 at 70% CG when I had a windshear induced
stall while moving to flap L at ~300 above threshold. I lost 269' and was
fortunate to recover over lower ground before having to dodge a topsoil
pile in the neighboring gravel pit.

With headwind component = TAS - GS, the flight data shows 3 windshears,
each over a 2 second interval, of -17, +23, -28 kt (application of
Pythagorean sum of squares of a triangle on the final shear yields 6 kt of
apparent headwind giving -34 kt -- TWICE the recorded wind).

Recovery action was flaps negative and stick forward.

The usual stall practice at 3000 AGL with a 1 kt/second deceleration has
little resemblance to a low level windshear stall.

More details on:

https://www.dropbox.com/sh/lq9osn15b...wuYvScXya?dl=0

I watched one of those early ASW 20 fatal spins. It was from slow
straight
=
and level flight, not thermaling. The wing dropped sharply and the glider
e=
ntered a conventional, nose-down spin. The recovery began almost
immediatel=
y (approx. 1/4 turn) but unfortunately there was not sufficient altitude
(t=
his began at approx. 300 ft AGL) and the pilot was killed when the glider
i=
mpacted the ground slightly nose down (i.e., the recovery was almost
comple=
te) but still sinking. Undocumented tail ballast was probably a factor,
as
=
with UH's situation. Pilot incapacitation due to dehydration may also
have
=
been a factor. The final blow, so to speak, was the lack of a headrest in
t=
his very early '20 and a battery pack behind the head that came loose.
The
=
pilot was an experienced, high-time competition pilot and instructor. All
o=
f the contributing factors were avoidable.

Chip Bearden
ASW 24 "JB"
U.S.A.

Didn't have the time to check exactly where the the flap handle was going.



At 12:00 04 June 2015, Tango Eight wrote:
I'm very glad this worked out.

But I have my doubts about the wisdom of using negative flaps for stall
recovery, especially close to the ground. I don't think that this can be
said to be a good practice in general and I would recommend heartily
against in my own ASW-20B.

-Evan Ludeman / T8



On Wednesday, June 3, 2015 at 11:15:05 PM UTC-4, George Haeh wrote:
I was much more lucky in my ASW-27 at 70% CG when I had a windshear
induced
stall while moving to flap L at ~300 above threshold. I lost 269' and
was
fortunate to recover over lower ground before having to dodge a topsoil
pile in the neighboring gravel pit.

With headwind component = TAS - GS, the flight data shows 3 windshears,
each over a 2 second interval, of -17, +23, -28 kt (application of
Pythagorean sum of squares of a triangle on the final shear yields 6 kt
of
apparent headwind giving -34 kt -- TWICE the recorded wind).

Recovery action was flaps negative and stick forward.

The usual stall practice at 3000 AGL with a 1 kt/second deceleration
has
little resemblance to a low level windshear stall.

More details on:


https://www.dropbox.com/sh/lq9osn15b...wuYvScXya?dl=0

I watched one of those early ASW 20 fatal spins. It was from slow
straight
=
and level flight, not thermaling. The wing dropped sharply and the
glider
e=
ntered a conventional, nose-down spin. The recovery began almost
immediatel=
y (approx. 1/4 turn) but unfortunately there was not sufficient
altitude
(t=
his began at approx. 300 ft AGL) and the pilot was killed when the
glider
i=
mpacted the ground slightly nose down (i.e., the recovery was almost
comple=
te) but still sinking. Undocumented tail ballast was probably a
factor,
as
=
with UH's situation. Pilot incapacitation due to dehydration may also
have
=
been a factor. The final blow, so to speak, was the lack of a headrest
in
t=
his very early '20 and a battery pack behind the head that came loose.
The
=
pilot was an experienced, high-time competition pilot and instructor.
All
o=
f the contributing factors were avoidable.

Chip Bearden
ASW 24 "JB"
U.S.A.

So far, I've been intentionnaly spinning almost all flapped gliders I flew (about two dozends), and putting flaps to full negative *always* helps to end the spin earlier. Especially close to the ground this is very important, as every fractions of a second counts. Many years ago, when I did an unintenional spin for stupid reasons close to the ground, the negative flaps saved my live.


At 12:00 04 June 2015, Tango Eight wrote:
I'm very glad this worked out.

But I have my doubts about the wisdom of using negative flaps for stall
recovery, especially close to the ground. I don't think that this can be
said to be a good practice in general and I would recommend heartily
against in my own ASW-20B.

-Evan Ludeman / T8