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