ASW 20 SPIN CHARACTERISTICS

Although George Thelen doesn't name the sailplane that is the subject of his
July 2004 Safety Corner column in Soaring magazine, he seems to be talking
about the ASW 20A. Perhaps someone familiar with that particular accident
could elaborate.



Bryan




"Ventus B" wrote in message
om...
I have been considering buying an ASW20, ASW20B, or ASW20C. I knew
they were champions in their day and still have a lot of admirers.
However a few folks from my club say they have some nasty spin
characteristics. Specifically, that they have a tendancy to not only
immediately spin when stalled, but will go inverted as they spin. Can
anyone eloborate or corroborate? I normally only hear good things
about the 20.
Respectfully,

When I got my first 20A, I was nervous as hell about the spin characteristics
as there had been a whole bunch of spin accidents, world wide. For the first 50
hours I tried to gently provoke her, but she wouldn't depart unless severely
manhandled. After that I settled down and enjoyed the bird. Nothing will climb
like a 20A and those floppy wings, smooth out the ride.
After 10 years or so, I formed the opinion that some 20's would spin at the
drop of a hat and others wouldn't. A friend had a *good* 20, that wouldn't spin
under normal conditions. One day he adjusted the flaps, so that the flaps and
ailerons were all exactly at neutral with the flap handle in zero and the stick
exactly in the middle. You guessed it, after that he had a *bad* 20 that would
spin at the drop of a hat. It could have something to do with the flap
adjustment, but I'm not sure what, because they are flap-erons and move with
the ailerons.
BTW, the accident at Air Sailing was a 20A.
JJ Sinclair

"JJ Sinclair" wrote in message
...
When I got my first 20A, I was nervous as hell about the spin
characteristics
as there had been a whole bunch of spin accidents, world wide. For the
first 50
hours I tried to gently provoke her, but she wouldn't depart unless
severely
manhandled. After that I settled down and enjoyed the bird. Nothing will
climb
like a 20A and those floppy wings, smooth out the ride.
After 10 years or so, I formed the opinion that some 20's would spin at
the
drop of a hat and others wouldn't. A friend had a *good* 20, that wouldn't
spin
under normal conditions. One day he adjusted the flaps, so that the flaps
and
ailerons were all exactly at neutral with the flap handle in zero and the
stick
exactly in the middle. You guessed it, after that he had a *bad* 20 that
would
spin at the drop of a hat. It could have something to do with the flap
adjustment, but I'm not sure what, because they are flap-erons and move
with
the ailerons.
BTW, the accident at Air Sailing was a 20A.
JJ Sinclair

JJ,
Interesting, do you remember what the factory flap setting should be?
On first thought I would think the aileron would be slightly more negative
to the flap setting with the flap handle in neutral. Only when in the high
speed setting would both flap and aileron line up.
Just a thought.
Udo

I believe the LS-6 does it that way (flaps and ailerons all even in full
negative flap position) my recollection of the 20 is that everything is even at
zero flap and zero stick. One can set it up as one wishes, but one may be
dialing in undesired consequences.
I remember the Boeing engineer who told me, "Aircraft are designed by geniuses
to be operated by idiots".
JJ Sinclair

On the 20, everything is flush in the full negative position.

--
Bert Willing

ASW20 "TW"


"JJ Sinclair" a écrit dans le message de
...
I believe the LS-6 does it that way (flaps and ailerons all even in full
negative flap position) my recollection of the 20 is that everything is
even at
zero flap and zero stick. One can set it up as one wishes, but one may be
dialing in undesired consequences.
I remember the Boeing engineer who told me, "Aircraft are designed by
geniuses
to be operated by idiots".
JJ Sinclair

There was some discussion about ten years ago that a contributing
factor in the early '20 accidents might have been the type of sealing
tape used on the flaps and ailerons. Specifically, before the
wholesale adoption of Mylar seals, many of the older ships had white
cloth tape on the lower surface that could bulge out at the hinge line
under certain airflow conditions, presumably triggering some sort of
undesirable behavior.

Anyone recall this or know if it was true?

Chip Bearden

(Chip Bearden) wrote in message . com...
There was some discussion about ten years ago that a contributing
factor in the early '20 accidents might have been the type of sealing
tape used on the flaps and ailerons. Specifically, before the
wholesale adoption of Mylar seals, many of the older ships had white
cloth tape on the lower surface that could bulge out at the hinge line
under certain airflow conditions, presumably triggering some sort of
undesirable behavior.

Anyone recall this or know if it was true?

Chip Bearden

Reply: Quite true. '20 is very sensitive to the quality of sealing on
both top and bottom of the wing. Remakable affect on both performance
and handling.
UH

It's true that many ASW20A's were/are sealed with cloth tape on the
underside of the flaps and sometimes the ailerons. It is needed for
the flaps because of the 55 degree (jesus)down flap setting for short
field landings. Mylar would just peel off when trying this flap
psoition during your control checks.

Mine is sealed with cloth tape and I intend to leave it on the
underside of the flaps. I have looked at how it is installed. It would
appear it was put on with full negative flap applied and even then a
small amount of "slack" has been left and pushed up into the gap by a
small amount. No matter what flap setting I use this "slack" always
stays up in the gap.

I would think it unlikely that cloth tape contributed to spinning
accidents. More likely poor energy management and/or the use of
landing flap before speed has been set and final turn complete.

Always complete your final turn, check your speed, make sure you are
going to make the field, check your speed, then select whichever
landing flap position you want, check your speed and use further
airbrake if required, continue checking you speed. Sorry if this seems
like teaching Granny to suck eggs.

Andy Henderson
ASW20FP


(Chip Bearden) wrote in message . com...
There was some discussion about ten years ago that a contributing
factor in the early '20 accidents might have been the type of sealing
tape used on the flaps and ailerons. Specifically, before the
wholesale adoption of Mylar seals, many of the older ships had white
cloth tape on the lower surface that could bulge out at the hinge line
under certain airflow conditions, presumably triggering some sort of
undesirable behavior.

Anyone recall this or know if it was true?

Chip Bearden

(JJ Sinclair) wrote in message ...
I believe the LS-6 does it that way (flaps and ailerons all even in full
negative flap position)

LS6 has effectively one piece flaperons, so there is never any split
between the flap and the aileron (which is probably why it slows down
so much with landing flap!).

Interestingly, the wing is faired (wingroot and tip) at full negative
(-5) flaps, not at 0. Makes sense, when you think about it.

Since this is a spin thread, the 6 will kinda spin, if forced, but at
my somewhat forward CG only in landing flap.

Kirk
66

JJ,

The 20's flaps and ailerons are split. They move differentially. The
ailerons alot, the flaps a little. They are flush with stick neutral
in fist positve, "0," and negative flap positions. And, of course, in
landing flaps, the ailerons go up causing the distinctive anhedral bow
on approach.