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#51
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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) |
#52
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ASW20 or LS6
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 | |
#53
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ASW20 or LS6
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 |
#54
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ASW20 or LS6
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 | |
#55
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ASW20 or LS6
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 |
#56
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ASW20 or LS6
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 |
#57
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ASW20 or LS6
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 |
#58
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ASW20 or LS6
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 |
#59
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ASW20 or LS6
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 |
#60
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ASW20 or LS6
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 |
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