ASW 20 Handling Issues?

A few 20's were produced with slightly different incidence angles in the wings..........yep, the wings were not hooked on straight! I'm sure those ships liked to spin when flown too slow. Schleicher had several "eccentric" rear lift fittings to solve the problem. I'd bet they are all fixed by now, but if your 20 always seems to turn one way, your wings may not be true!
JJ

On Sunday, 5 November 2017 23:45:19 UTC+2, wrote:?

Flutter was associated with seal tapes. Flaps fluttered more than ailerons if I remember correctly.
UH

Mine had aileron vibration (it is not flutter) twice with pristine teflon/mylar seals, so it might not be that simple. I did change flap hinge bearings and new seals just to be sure and never experienced vibration again. (Control play was well within limits before change).

Talking about 20 handling, you would probably compare it to gliders similar vintage. LS4, Discus or Ventus with aft c/g will spin as eagerly and drop wing in most cases in similar fashion. 20 is no different in that respect. I flew 20 for over 1000hrs with few wing drops after mishandling the glider in thermal but I wouldn't call the glider anything but extremely well-behaved. It is the safest glider to land in tight spot. One of few gliders that truly were well ahead of it's time.

On Sunday, November 5, 2017 at 1:55:40 AM UTC-4, wrote:
The ASW 20 seems to have a reputation for bad behavior in some configurations. Is this reputation deserved or overblown? What has been the experience of those who have owned and flown the glider? Are some variants of the 20 better or worse in terms of handling characteristics?

Tom A

600+ hours in a 20B ... one instant over the top spin in a strong small-core thermal ... I did have an extreme aft CG (I had a tail tank with a separate dump control from the wings.) Did some stall testing when I first transitioned to the 20 and thought the transition was pretty normal - although not as benign as the LS-3 which was my prior ship. I then installed elevator tabulators and verified they provided a lot of additional control into the stall. Your experience may differ. kk

On Sunday, November 5, 2017 at 10:28:45 PM UTC-5, wrote:
A few 20's were produced with slightly different incidence angles in the wings..........yep, the wings were not hooked on straight! I'm sure those ships liked to spin when flown too slow. Schleicher had several "eccentric" rear lift fittings to solve the problem. I'd bet they are all fixed by now, but if your 20 always seems to turn one way, your wings may not be true!
JJ

Errata:

Interesting. I recall that a few ASW 19s had the same problem...and solution: i.e., eccentric rear lift pins from the factory. My memory might be playing tricks but the guy who told me about it had a '19, not a '20. I've always wondered how the wing was twisted after that since the spars and main pins weren't altered.

My memory might be playing tricks, Part II, but regarding flap flutter, I also recall hearing that some early '20s had a slight amount of "slop" in the flap drive that was fixed by smearing epoxy on the end of a long wooden stick or dowel, jamming it into the wing root at the appropriate point, waiting for it to harden up, then breaking off the stick/dowel. Apparently a bunch of owners had theirs done on a rain day at a big contest (late 70s/early 80s?). That seemed to address the flap flutter.

I believe Rudy Mozer's ASW 20B was one of four brought over for the Worlds (Hobbs, 1983). When I saw it that spring, it had lower flap seals that were beryllium copper (to accommodate the landing flap deflection?). Pretty nifty looking. Beryllium copper dust is toxic so that might have killed any enthusiasm for using this material.

Chip Bearden

Krasw, I've been thinking the same.
This was a period of pushing performance without as much consideration for things like handling, cockpit ergonomics and safety as there is in current models. Seems there was always something missing. Perhaps Gerhard did better with general handling than Klaus achieved in the Ventus A/B, but the Ventus had auto hook ups while the early 20s required connecting 7 L'Hotelliers.. The elevator became auto hook up in late 20B and all C model, or modification using Tech Note 29.
Rick Wagner had some mods for 20s that improved performance, including shortening of the flap at the root and aileron at the tip, a better wing root fairing, and a wingtip that looked like an LS4. His work was before we had winglets.
Sorry that the earliest Ventus I've flown was the C, which had lovely handling. The A/B without winglets seemed to have a reputation for needing to be flown all the time. The 20 A- B- and C- models I've flown all had great handling (pilot-glider relationship much like any other Schleicher) and personally didn't have any spin entry threat. One of them was a "Hobbs Special", but the high red line was only for the duration of the Worlds. None had winglets, which seem to improve characteristics near to stall speed.
I've been on both sides of this equation: ASW20 flying alongside ASW27. In the midrange there was no difference! One mistake in a 20 and you won't catch up, though.
The LS6 was the easiest to fly well of this vintage in my experience. Climbs full of ballast and outruns a 20. Not enough time alongside Ventus A/B or C at 15m. Once ran all day at Ely with a 15m V2 at the same wing loading.
Once swapped an original LS6B for one with the Flying Nun tips for a few days. Thought the biggest difference was in blocked visibility.
Jim


On Sunday, November 5, 2017 at 11:28:19 PM UTC-8, krasw wrote:

Talking about 20 handling, you would probably compare it to gliders similar vintage.

On Monday, 6 November 2017 19:44:45 UTC+2, JS wrote:
I've been on both sides of this equation: ASW20 flying alongside ASW27. In the midrange there was no difference!

27 is overrated, that tiny wing needs 18m span to work as intended as 29 has shown. I've flown 20 against 27 and sure it runs a little better at very high speeds but you can basically fly all day long side by side and arrive home 5 minutes later. When you put glider price into that equation...

At 05:55 05 November 2017, wrote:
The ASW 20 seems to have a reputation for bad behavior in some
configuratio=
ns. Is this reputation deserved or overblown? What has been the
experienc=
e of those who have owned and flown the glider? Are some variants of the
2=
0 better or worse in terms of handling characteristics?

Tom A

I can only claim about 400 hours in a 20, and almost invariably flew it at
16.6m, and it never showed any untoward handling characteristics. I have
read, though never experienced it, that they can depart easily when in
landing configuration.
Dave

I owned WA - Wally Scott's ASW20 for a number of years. It was a while before I discovered he had secreted large amounts of lead in the wings and tail and that the W&B data was completely fictitious. I can confirm that with a CG well aft of the factory permitted range it can depart into a spin quickly and viciously!

With the lead removed and the CG returned to the permitted range, I never experienced another problem. There were reports of a tendency to spin when the "Jesus" landing flap position of early ASW20s was selected, but this again was not a problem I encountered.

Mike

On Tuesday, November 7, 2017 at 9:59:38 AM UTC-6, Mike the Strike wrote:
I owned WA - Wally Scott's ASW20 for a number of years. It was a while before I discovered he had secreted large amounts of lead in the wings and tail and that the W&B data was completely fictitious. I can confirm that with a CG well aft of the factory permitted range it can depart into a spin quickly and viciously!

With the lead removed and the CG returned to the permitted range, I never experienced another problem. There were reports of a tendency to spin when the "Jesus" landing flap position of early ASW20s was selected, but this again was not a problem I encountered.

Mike

I think the departures that occur in the "Jesus" landing flap position result from pilots realizing too late that they are coming up short and getting too slow in an attempt to make the landing area. My advice to new 20a drivers: If you are going to use full landing flap, don't aim for the near end. Choose a touchdown point in the middle of your chosen landing area!

Anyone purchasing an ASW 20A (actually, ANY glider), should query the previous owner (and assess his/her weight--hopefully without insulting them!), inspect the logbook and placards, and then do a full weight and balance to check the CG before flying it.

Recognizing that this latter time-consuming step may not be done by everyone immediately, at a minimum, inspect the tail for lead weights. In more recent gliders, there's often a battery compartment at the top of the vertical fin. The lead in my ASW 24 lives below the battery there so inspect carefully.

In older gliders, lead was added by removing the rudder and bolting it in the lower fin area. I removed the lead I had installed in my LS 3 when I sold it even though the new owner weighed more than I did. There's a lo-o-o-o-o-ng moment arm all the way back there so a small amount of weight has a fairly significant effect on the CG. It may be difficult or impossible to inspect for this without removing the rudder. Also, weight may have been added to the tailwheel or (in one case I'm aware of) in the tailwheel area itself

Obviously the CG can also be too far forward. I've seen lead weights in the nose installed by lighter pilots. But the too-far-aft CG seems to be more common and insidious.

The rule for CG is: take nothing for granted, even from the factory. I recently spoke with a very careful, highly analytical friend who discovered--after an alarming first flight--that the minimum cockpit weight for his new glider was far higher with the longer wingtips installed than with the short tips.

Taking your CG for granted can be fatal. I am familiar with at least one such stall/spin crash where CG may have been a factor.

Chip Bearden