ASW20 or LS6

On 2/4/2011 8:04 AM, David Salmon wrote:


I haven't read all 42 postings so perhaps someone has already said this,
but my understanding is that the 20 is very reluctant to spin, except in
landing configuration, ie flaps and wheel down. However in 4 years of
flying one, nearly always at 16.6 meters, it never once attempted an
inadvertant spin entry.

My understanding and experience with my ASW 20C is it is very spin
resistant in the landing configuration, i.e., LANDING flaps selected and
wheel down. That's because the ailerons move up to a negative position,
giving the wing a lot of wash-out.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

On Fri, 04 Feb 2011 16:04:31 +0000, David Salmon wrote:

I haven't read all 42 postings so perhaps someone has already said this,
but my understanding is that the 20 is very reluctant to spin, except in
landing configuration, ie flaps and wheel down.

Look at what Andras Maurer has to say - he thinks '20 are very sensitive
to small changes in wing profile to the extent that almost every '20 has
different handling. Mine would sometimes spin without warning while
thermalling at 45 kts in a 40-45 degree bank and zero flap (did it twice)
but this was probably related to micro-turbulence in the thermal since I
was unable to reproduce that departure in still air later in the day, and
usually it was perfectly happy to thermal at that airspeed and bank
angle. OTOH mine was a perfect lady in zero and thermal flap at speeds
where others have said their '20 would certainly have spun.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Feb 4, 5:05*pm, Martin Gregorie
wrote:
Look at what Andras Maurer has to say - he thinks '20 are very sensitive
to small changes in wing profile to the extent that almost every '20 has
different handling. Mine would sometimes spin without warning while
thermalling at 45 kts in a 40-45 degree bank and zero flap (did it twice)
but this was probably related to micro-turbulence in the thermal since I
was unable to reproduce that departure in still air later in the day, and
usually it was perfectly happy to thermal at that airspeed and bank
angle. OTOH mine was a perfect lady in zero and thermal flap at speeds
where others have said their '20 would certainly have spun.


I've owned a 20B, plus had several flights each in a couple of
different 20s and a 20C. The 20B and 20C both had beautiful handling,
no tendency to spin unless forced, and were well mannered in all
configurations. One 20 (low serial number, IIRC) would spin without
much warning in thermal or landing flap and always in the same
direction (over the top if I was turning the opposite way), the other
would do so only in landing flap, both seemed a bit twitchy at times.
I suspect Schleicher was still learning how to build glass gliders in
a repeatable fashion during the 20 production run, the 20B/C show the
benefits of experience (plus reduced landing flap travel)...

Marc

On Fri, 04 Feb 2011 18:31:23 -0800, Marc wrote:

I've owned a 20B, plus had several flights each in a couple of different
20s and a 20C. The 20B and 20C both had beautiful handling, no tendency
to spin unless forced, and were well mannered in all configurations.
One 20 (low serial number, IIRC) would spin without much warning in
thermal or landing flap and always in the same direction (over the top
if I was turning the opposite way), the other would do so only in
landing flap, both seemed a bit twitchy at times. I suspect Schleicher
was still learning how to build glass gliders in a repeatable fashion
during the 20 production run, the 20B/C show the benefits of experience
(plus reduced landing flap travel)...

Curiosity: have you any idea what the serials were for those 20s?
Mine was 20034, so fairly early...


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Feb 5, 8:16*am, Martin Gregorie
wrote:
On Fri, 04 Feb 2011 18:31:23 -0800, Marc wrote:
I've owned a 20B, plus had several flights each in a couple of different
20s and a 20C. *The 20B and 20C both had beautiful handling, no tendency
to spin unless forced, and were well mannered in all configurations.
One 20 (low serial number, IIRC) would spin without much warning in
thermal or landing flap and always in the same direction (over the top
if I was turning the opposite way), the other would do so only in
landing flap, both seemed a bit twitchy at times. I suspect Schleicher
was still learning how to build glass gliders in a repeatable fashion
during the 20 production run, the 20B/C show the benefits of experience
(plus reduced landing flap travel)...

Curiosity: have you any idea what the serials were for those 20s?
Mine was 20034, so fairly early...

Other significant sources of variability are rigging of flaps &
ailerons, type & condition of seals... and of course now more than
half the 20 fleet flies with winglets of one sort or another, these
make a difference too (especially the odd installation with more toe
on one side than the other).

You really do need to treat these ships as individuals. My 20B is a
pussycat in #4 and L, it's a little sharp in #3. I fly it at 90% aft,
with winglets. It flies straight, the spin behavior is symmetric...
but it does have a eccentric lift pin that someone installed to get it
that way.

Question for Dan: when you swapped ships with the 20B pilot, how much
different were you two in weight? Your story could be explained
rather neatly if you were a bigger guy than your friend. I haven't
flown a 6. Tried to buy one, but the owner wasn't ready to sell. I
ended up with the 20B a few weeks later, have not regretted this.
Cockpit, controls, landing flaps, landing gear and wheel brake are all
better or a lot better on the 20B. However it's certainly true that
the 20 flies best if you keep the roll rates about 1/2 of maximum. At
high aileron deflections, she gets a little draggy. Not sure if I
want to fly a 6... I'm pretty happy with my ship, want to stay that
way!

-Evan Ludeman / T8

On Feb 5, 9:29*am, T8 wrote:
On Feb 5, 8:16*am, Martin Gregorie
wrote:

On Fri, 04 Feb 2011 18:31:23 -0800, Marc wrote:
I've owned a 20B, plus had several flights each in a couple of different
20s and a 20C. *The 20B and 20C both had beautiful handling, no tendency
to spin unless forced, and were well mannered in all configurations.
One 20 (low serial number, IIRC) would spin without much warning in
thermal or landing flap and always in the same direction (over the top
if I was turning the opposite way), the other would do so only in
landing flap, both seemed a bit twitchy at times. I suspect Schleicher
was still learning how to build glass gliders in a repeatable fashion
during the 20 production run, the 20B/C show the benefits of experience
(plus reduced landing flap travel)...

Curiosity: have you any idea what the serials were for those 20s?
Mine was 20034, so fairly early...

Other significant sources of variability are rigging of flaps &
ailerons, type & condition of seals... and of course now more than
half the 20 fleet flies with winglets of one sort or another, these
make a difference too (especially the odd installation with more toe
on one side than the other).

You really do need to treat these ships as individuals. *My 20B is a
pussycat in #4 and L, it's a little sharp in #3. *I fly it at 90% aft,
with winglets. *It flies straight, the spin behavior is symmetric...
but it does have a eccentric lift pin that someone installed to get it
that way.

Question for Dan: when you swapped ships with the 20B pilot, how much
different were you two in weight? *Your story could be explained
rather neatly if you were a bigger guy than your friend. *I haven't
flown a 6. *Tried to buy one, but the owner wasn't ready to sell. *I
ended up with the 20B a few weeks later, have not regretted this.
Cockpit, controls, landing flaps, landing gear and wheel brake are all
better or a lot better on the 20B. *However it's certainly true that
the 20 flies best if you keep the roll rates about 1/2 of maximum. *At
high aileron deflections, she gets a little draggy. *Not sure if I
want to fly a 6... I'm pretty happy with my ship, want to stay that
way!

-Evan Ludeman / T8

I'm curious to know how the eccentric lift pin works. How much
offset can introduced (expressed as an angle or linearly). How is it
possible to get any significant offset unless there is excessive play
in the main spar pins?

Surely the only way that an eccentric lift pin can be used to adjust
wing incidence is if it it done before the spars are bored for the
main pin bushings.

Andy

On Feb 5, 11:59*am, Andy wrote:
On Feb 5, 9:29*am, T8 wrote:



On Feb 5, 8:16*am, Martin Gregorie
wrote:

On Fri, 04 Feb 2011 18:31:23 -0800, Marc wrote:
I've owned a 20B, plus had several flights each in a couple of different
20s and a 20C. *The 20B and 20C both had beautiful handling, no tendency
to spin unless forced, and were well mannered in all configurations..
One 20 (low serial number, IIRC) would spin without much warning in
thermal or landing flap and always in the same direction (over the top
if I was turning the opposite way), the other would do so only in
landing flap, both seemed a bit twitchy at times. I suspect Schleicher
was still learning how to build glass gliders in a repeatable fashion
during the 20 production run, the 20B/C show the benefits of experience
(plus reduced landing flap travel)...

Curiosity: have you any idea what the serials were for those 20s?
Mine was 20034, so fairly early...

Other significant sources of variability are rigging of flaps &
ailerons, type & condition of seals... and of course now more than
half the 20 fleet flies with winglets of one sort or another, these
make a difference too (especially the odd installation with more toe
on one side than the other).

You really do need to treat these ships as individuals. *My 20B is a
pussycat in #4 and L, it's a little sharp in #3. *I fly it at 90% aft,
with winglets. *It flies straight, the spin behavior is symmetric...
but it does have a eccentric lift pin that someone installed to get it
that way.

Question for Dan: when you swapped ships with the 20B pilot, how much
different were you two in weight? *Your story could be explained
rather neatly if you were a bigger guy than your friend. *I haven't
flown a 6. *Tried to buy one, but the owner wasn't ready to sell. *I
ended up with the 20B a few weeks later, have not regretted this.
Cockpit, controls, landing flaps, landing gear and wheel brake are all
better or a lot better on the 20B. *However it's certainly true that
the 20 flies best if you keep the roll rates about 1/2 of maximum. *At
high aileron deflections, she gets a little draggy. *Not sure if I
want to fly a 6... I'm pretty happy with my ship, want to stay that
way!

-Evan Ludeman / T8

I'm curious to know how the eccentric lift pin works. * How much
offset can introduced (expressed as an angle or linearly). *How is it
possible to get any significant offset unless there is excessive play
in the main spar pins?

Surely the only way that an eccentric lift pin can be used to adjust
wing incidence is if it it done before the spars are bored for the
main pin bushings.

Andy

There are two standard offsets available from Schleicher, 0.5 and
1.0mm. These can be installed in "up" or "down" positions in place of
any of the standard pins. The standard clearance on the pins is
(iirc) 0.006", but practically speaking I think (I'm not a Schleicher
mechanic) these are intended to be either up or down. The distance
between the pins fore to aft is on the order of 30", so the incidence
change is truly tiny. 1mm gives less than 0.08 deg incidence change.
Nothing with as much hand labor involved as an ASW-20 comes out
identical in every copy, so having a way to get every example to fly
straight despite manufacturing variance is a good thing.

-Evan Ludeman / T8

On Feb 5, 11:59*am, Andy wrote:
excessive play
in the main spar pins?

Sorry, reading comprehension challenged today...

I don't know what the standard clearance is on the main pins, but it
isn't particularly tight. 0.08 deg over a 2" span (the center spar
stub, center to edge) is about 25 _ten_thousandths, so no problem at
all.

-Evan Ludeman / T8

On Feb 5, 5:16*am, Martin Gregorie
wrote:
On Fri, 04 Feb 2011 18:31:23 -0800, Marc wrote:
I've owned a 20B, plus had several flights each in a couple of different
20s and a 20C. *The 20B and 20C both had beautiful handling, no tendency
to spin unless forced, and were well mannered in all configurations.
One 20 (low serial number, IIRC) would spin without much warning in
thermal or landing flap and always in the same direction (over the top
if I was turning the opposite way), the other would do so only in
landing flap, both seemed a bit twitchy at times. I suspect Schleicher
was still learning how to build glass gliders in a repeatable fashion
during the 20 production run, the 20B/C show the benefits of experience
(plus reduced landing flap travel)...

Curiosity: have you any idea what the serials were for those 20s?
Mine was 20034, so fairly early...

The worst of the two was in the single digits, it was destroyed
several years later in a fatal stall/spin accident with a low time
pilot at the controls. The other one I have no idea about. I'll also
mention that the most important reason I had at the time for buying a
used 20B instead of a 20 was the automatic elevator hookup, I've had
two soaring friends die as a result of disconnected elevators, and
both were far more diligent pilots than I...

Marc

On Feb 5, 11:59*am, Andy wrote:

Surely the only way that an eccentric lift pin can be used to adjust
wing incidence is if it it done before the spars are bored for the
main pin bushings.

Sorry, I am both reading comprehension *and* math challenged today it
seems (I have a medical excuse, it's temporary, fortunately!).
Previous answer to this deleted.

The clearance on the main pins I don't know. I'd guess it's around
0.003" judging by feel, but that's a guess, I've never paid too much
attention. The change in clearance due to an incidence offset is easy
to calculate though, and it's about 0.0005" total on the depth of the
center spar stub for a 1mm offset pin. Those are all armchair
numbers, but the conclusion (supported by experience) is "No Problem".

-Evan Ludeman / T8