ASW 20 SPIN CHARACTERISTICS

Chris OCallaghan wrote:
Owned an A for 17 years. Spun it many times (never inadvertently). If
you abuse the controls at stall, it will spin promptly from positive
flap positions. The more positive, the more dramatic. However, as long
as you use coordinated controls, it handles predictably, though
sometimes sluggishly, with a tendency to spiral dive after stall
break.

The handbook recommends not applying landing flap until on final and
clear of last obstruction. Based on experimenting with recovery from
spins initiated with flaps in landing, this is a very good practice to
maintain.

I think my C model prohibited spinning in Landing flap, so I didn't try
spinning. Attempts at incipient spins were futile, as it took so much
coarse mishandling of the controls to even stall it, I didn't really get
to the start of a spin. The negative angle (up about 5 degrees when the
flaps were down 40 degrees) of the ailerons in landing flap seemed to
give them good authority even as the glider bucked and rocked with lots
of back stick. My CG was about 75%, I think.

How did your A model respond? It had more Landing flap available than my
C model (60 degrees vs 40).
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Eric Greenwell
Washington State
USA

Eric,

I don't recall if my A had a prohibition against spinning in landing
flap. However, to avoid overspeeding the flaps I would immediately
move the flap handle forward after the first half rotation. I had
assumed when I bought the glider that the upturned ailerons in landing
flap position would prevent dramatic autorotation, but this wasn't the
case. I think the 20 developed a bad reputation because pilots were
setting the landing flaps on downwind rather than waiting until final
approach. The 20 definitely handles less pleasantly, especially in
turns and turbulence with the landing flaps down.

With full flaps on the A, the nose angle at stall was below the
horizon. Just another thing to get used to.

I have to say I think George T. went a little overboard in
charcaterizing the 20 as a dangerous glider. Like all fast glass, it
requires additional energy management skills and a respect for the
altitude it will need to recover if abused. I see it as no less safe
or dangerous than a Discus. Perhaps more complex, but that's a
training issue. That's not nostalgia talking. I prefer newer
gliders... they are better harmonized, easier to put together, climb
and glide better. But the 20 (2nd gen) has the same management issues
as third generation flapped ships (V2, ASW-27) and newer gliders are
no less disposed to bite their masters if mishandled. There's nothing
inherent in the glider that would presdispose it to accidents. But
like all fast glass, it will accentuate pilot ignorance.

As for George's complaints against manual control hookups, well, this
is a fact of life. I would guess that 3/4 of all ships in service have
manual hookups. Again, a training issue. Pilots who follow the
manufactures' assembly instructions and best practices (double
inspection, critical assembly check, positive control check) don't
have problems. Control failures can almost always be traced back to
poor maintenance or a mistake in the assembly and inspection sequence.
There are some inherently poor designs, but the 20's hotellier
fittings are not among them. And after market safety devices are
available to address their known weaknesses (or more correctly,
weakness in the assembler). Are automatic control hookups better...?
You bet! But that doesn't make manual hookups inherently unsafe. They
simply require more attention.

On 4 Jul 2004 17:54:39 -0700, (Ventus B) wrote:

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,

Assuming you haven't seen the handbook yet, the following may answer
some of your questions:

http://www.gregorie.org/gliding/asw2..._handling.html

It was written by Andreas Maurer for a pilot who was converting from a
Pegasus: in fact the guy I bought my '20 from. I've found it very
useful, especially as I, too, was converting from a Pegasus. IMO it
tells you most of what you need to know about the '20 that isn't in
the flight manual.

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

This comment is not quite on point - but relevant. I met a pilot yesterday
who flew B-26s during WWII. He mentioned that the B-26 had a reputation for
killing pilots during training. In particular, the pilots were afraid of an
engine out on takeoff causing a spin. Vice President Truman heard these
stories and considered the B-26 a financial waste, so he sent Jimmy
Doolittle down to test the characteristics of the plane.

Doolittle spoke with the pilots, read the operations manual, then flew the
airplane. He then assembled the cadets and brought along one of the
instructors as a check pilot. On the first takeoff, he pulled an engine,
then did a 360 degree turn and landed safely. On the next takeoff, he
pulled the other engine, then did a 360 and returned to land safely.

He then assembled the cadets and stated that he had flown the aircraft and
when the engine was shut down during takeoff, he flew it exactly like the
operations manual directed. His conclusion was that there was nothing wrong
with the airplane, but that the pilots had not been trained properly.

What is important is to understand the characteristics of the aircraft and
give great deference to the operations manual - unless you are smarter than
the guy who wrote it.

Colin


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Very thoughtful of Andreas to put this together. Based on 17+ years
and 2000 hours in a 20, I would add only the following thoughts...

You may move the flap handle from position 2 to position 4 on take off
as soon as the pass the start point of the tow plane. This is where
wings typically drop, in the wake turbulence as you enter it at low
speed. Once past it, you will find plenty of control authority. I
prefer flap position 4 since it lowers the nose, allowing a much
improved view of the tow rope.

When thermalling, use flap position 4, or drill a hole between
positions 3 and 4 if you want less drag. If you need to shift your
circle or correct for gusts, move the flap handle to 3 as you make
aileron inputs. This will give you a better roll rate. As soon as you
have established the desired angle of bank, pop the handle back into
positive (3.5 or 4).


Martin Gregorie wrote in message . ..
On 4 Jul 2004 17:54:39 -0700, (Ventus B) wrote:

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,

Assuming you haven't seen the handbook yet, the following may answer
some of your questions:

http://www.gregorie.org/gliding/asw2..._handling.html

It was written by Andreas Maurer for a pilot who was converting from a
Pegasus: in fact the guy I bought my '20 from. I've found it very
useful, especially as I, too, was converting from a Pegasus. IMO it
tells you most of what you need to know about the '20 that isn't in
the flight manual.

Chris OCallaghan wrote:
....
When thermalling, use flap position 4, or drill a hole between
positions 3 and 4 if you want less drag.

Thank you, Chris. My 20B had a 3.5 hole drilled when we bought it but I
had no advice on its purpose or use. I was puzzled when I couldn't
relate the Flight Manual descriptions to what my glider had. Eventually
I worked it out.

I would be interested in any advice anyone can give on the use of 3.5.
I tend to use it for nearly all thermalling and only use 4 for landing.
Am I right? Is a 3.5 hole common? Did Schleicher's get it wrong?

GC

On Sat, 17 Jul 2004 00:36:28 +1000, Graeme Cant
wrote:


Thank you, Chris. My 20B had a 3.5 hole drilled when we bought it but I
had no advice on its purpose or use. I was puzzled when I couldn't
relate the Flight Manual descriptions to what my glider had. Eventually
I worked it out.

I would be interested in any advice anyone can give on the use of 3.5.
I tend to use it for nearly all thermalling and only use 4 for landing.
Am I right? Is a 3.5 hole common? Did Schleicher's get it wrong?

It depends what you use 4 for: For thermalling at normal bank angles
(20-30 degrees) 3 is the better setting (the 20 converst excessive
speed into height a lot better in 3 than in 4), but very tight turns
combined with high wing loading (or forward CG) need 4.

Many 20 owners drilled the 3.5 hole, but I have to admit that I tested
this setting and I never felt 3.5 to be an advantage over 3 (I hold
the flap handle at 3.5 before I decided not to drill a hole there). At
3 the nose is significantly higher than in 3.5, but I think the 20's
airfoil loves high AoA's. If the AoA of the 20 is too low (in other
words: Flap setting too positive for current airspeed/g-load
combination), the drag rise is drastic - very easy to feel the
deceleration.

One more thing why I love the 20: The flap handle tells you which
position it wants to be in - it moves itself into the optimum position
(if you help it overcome the friction with your hand).

Bye
Andreas

(Ventus B) wrote in message . com...
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,

Just catching up with this thread and no-one seems to have mentioned
the effect of the flexible wings. I don't have experience in the 20
but I do have a series of photos of a fatal accident that started
with a contest finish pull-up and quickly ended up in a spinning
impact with the ground. I believe that the increased angle attack
caused by the wings returning to normal deflection contributed to the
accident.

Andy

Andy Durbin wrote:
(Ventus B) wrote in message . com...

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,


Just catching up with this thread and no-one seems to have mentioned
the effect of the flexible wings. I don't have experience in the 20
but I do have a series of photos of a fatal accident that started
with a contest finish pull-up and quickly ended up in a spinning
impact with the ground. I believe that the increased angle attack
caused by the wings returning to normal deflection contributed to the
accident.

Boy, does this sound highly speculative! How did you conclude it was the
wings, rather than the obvious possiblities, like:

-pilot pulls too hard and stalls glider
-glider hits thermal/gust that stalls a wing
-pilot gets too slow, then skids turn or uses abrupt aileron input

?
--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

On 13 Jul 2004 14:33:53 -0700, (Andy Durbin)
wrote:

Just catching up with this thread and no-one seems to have mentioned
the effect of the flexible wings. I don't have experience in the 20
but I do have a series of photos of a fatal accident that started
with a contest finish pull-up and quickly ended up in a spinning
impact with the ground. I believe that the increased angle attack
caused by the wings returning to normal deflection contributed to the
accident.

Flexible wings do NOT change their AoA while they are bending -
otherwise flutter would start immediately.


Bye
Andreas