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#21
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Bryan wrote:
Although George Thelen doesn't name the sailplane that is the subject of his July 2004 Safety Corner column in Soaring magazine, he seems to be talking about the ASW 20A. Perhaps someone familiar with that particular accident could elaborate. Yes, that was Ruben's fatal ASW-20A accident at Air Sailing. Jeremy |
#22
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#23
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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. |
#24
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JJ,
The 20's flaps and ailerons are split. They move differentially. The ailerons alot, the flaps a little. They are flush with stick neutral in fist positve, "0," and negative flap positions. And, of course, in landing flaps, the ailerons go up causing the distinctive anhedral bow on approach. |
#25
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(Chip Bearden) wrote in message
.com... . Specifically, before the wholesale adoption of Mylar seals, many of the older ships had white cloth tape on the lower surface that could bulge out at the hinge line under certain airflow conditions, presumably triggering some sort of undesirable behavior. Worse yet is that this cloth tape will shrink over time and can restrict control surface travel. If you have not replaced your cloth tape in several years you could have less travel than you should. You can of course pull or push real hard to get to the stop but that is not a good thing to have to do. Robert Mudd |
#26
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It's true that many ASW20A's were/are sealed with cloth tape on the
underside of the flaps and sometimes the ailerons. It is needed for the flaps because of the 55 degree (jesus)down flap setting for short field landings. Mylar would just peel off when trying this flap psoition during your control checks. Mine is sealed with cloth tape and I intend to leave it on the underside of the flaps. I have looked at how it is installed. It would appear it was put on with full negative flap applied and even then a small amount of "slack" has been left and pushed up into the gap by a small amount. No matter what flap setting I use this "slack" always stays up in the gap. I would think it unlikely that cloth tape contributed to spinning accidents. More likely poor energy management and/or the use of landing flap before speed has been set and final turn complete. Always complete your final turn, check your speed, make sure you are going to make the field, check your speed, then select whichever landing flap position you want, check your speed and use further airbrake if required, continue checking you speed. Sorry if this seems like teaching Granny to suck eggs. Andy Henderson ASW20FP (Chip Bearden) wrote in message . com... There was some discussion about ten years ago that a contributing factor in the early '20 accidents might have been the type of sealing tape used on the flaps and ailerons. Specifically, before the wholesale adoption of Mylar seals, many of the older ships had white cloth tape on the lower surface that could bulge out at the hinge line under certain airflow conditions, presumably triggering some sort of undesirable behavior. Anyone recall this or know if it was true? Chip Bearden |
#27
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Andy Henderson wrote:
"Mylar would just peel off when trying this flap psoition during your control checks." Sorry, but I must disagree: my PIK 20B is sealed on the underside of the flaps with Mylar and Teflon, and they go down to 90 degrees! - the Mylar doesn't peel off, it works just fine if you put it on right. And if the grip of the mylar you have fitted to other places on the airframe is that tenuous you should be worried about it peeling. Rgds, Derrick Steed |
#28
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Andy Henderson wrote:
It's true that many ASW20A's were/are sealed with cloth tape on the underside of the flaps and sometimes the ailerons. It is needed for the flaps because of the 55 degree (jesus)down flap setting for short field landings. Mylar would just peel off when trying this flap psoition during your control checks. *Only* 55 degrees? We do 90 degrees in HP-Land. I use wide Scotch plastic tape applied to the outside surface to seal. Yes, using mylar may be feasible but it is very difficult to keep stuck in place on these ships. Regards, -Doug Mine is sealed with cloth tape and I intend to leave it on the underside of the flaps. I have looked at how it is installed. It would appear it was put on with full negative flap applied and even then a small amount of "slack" has been left and pushed up into the gap by a small amount. No matter what flap setting I use this "slack" always stays up in the gap. Yup. Same here. |
#29
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Good post Andy,
When the 20 first came out we had a rash of accidents, like 20 or more world-wide. Then things settled down and the carnage stopped. Why? I have an opinion, lots of guys climbed out of the 301 libelle and bought the hot new toy. Think about the differences; The 301 had automatic elevator hook-up, the 20 didn't. Hence, a bunch of us forgot to hook things up. The 301 flaps only went down about 15 degrees, the 20 flaps went way down. Hence a bunch of landing accidents. On the 301, the stick only moved the ailerons, whereas in the 20, everything out there moved and therefore a bit of heavy-handed input could get one in trouble a whole lot faster. The 301 was nimble and quick, try to be nimble and quick in your 20, with the flaps down, and one could end up with rocks in the cockpit. Why didn't we just stick with the good old 301 libelle? JJ Sinclair |
#30
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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 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.713 / Virus Database: 469 - Release Date: 6/30/04 |
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