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#11
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Bob Greenblatt wrote: Aren't we trying to puncture the edge of the cylinder very near its bottom at maximum speed? Got to thinking about your question, Bob and actually we shouldn't try to hit the edge of the cylinder at red-line. Why? Because our sailplanes are very inafficient at red-line, in fact they start coming down like a stone at anything over 90 knots. We should climb the last thermal to 500 over home + a smidgen and then fly the indicated M/C to the edge of the cylinder. You should get there between 60 and 90 knots, depending on conditions on the glide. If you get there at red-line, that means you climbed too high in the last thermal and it cost you (time). The finish line, on the other hand, requires a finish at red-line, so that we can exchange our excess speed for pattern altitude. I'm even tempted to say the cylinder is the most efficient way to fly the final glide, but if I did, OC would just fly off in another snit, and I would be forced to look up all those big words, again............... :) JJ |
#12
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OC, You never did answer my question, "How many contests have you flown
using the finish cylinder?" Your skepticism leads me to believe you havent flown that many. I know you flew it at Montague, anywhere else? How about giving it a fair try before condeming it? JJ |
#13
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Optimum is the same for either finish. Most of us just don't have the
guts to cut it that close with a line finish. With a high cylinder finish, you can cut it close. You're risking points if you end up a bit lower than you hoped. But your margin for momma and the kids is built in to the optimum answer. Its then more a contest of skill than nerve, at least for the final glide. Since most pilots will try to fly efficiently, the range of speeds at the cylinder is reduced, and lowered compared to the gate. Makes for a nice orderly follow the leader to land, with a tad more time after the race is over to sort it out. That can degenerate when everyone finishes way too high and hot or just squeaking in a rolling finish, but it does the same thing with a gate. With a line everyone shoots for the sweet end of the line. There always is one. With a cylinder, finishers will naturally be much more spread out. Maneuvering will be less predictable, but also more uniformly gentle. Given the blind spots in all our gliders, and the tendency to fixate on the targets you see and know about, we really count on the big sky theory more than we like to admit. A little more natural spacing makes the sky bigger. But the cylinder is an instrument approach since it is completely invisible, which has to pull some of your attention into the cockpit. Cutting the edge of the gate is, too, since its really defined by GPS coordinates, not a ground feature. Not very comforting for either finish in traffic. If you think either one is really safe, you're nuts. Both can be executed successfully, but the margins flying that close to so many other gliders and the ground are just not that big. I think the cylinder is a bit less risky, but a lot less fun. A perfect final glide to the edge of the cylinder at 75 kts is so anti-climactic after an epic adventure out on course. Nothing compares to the good old assigned task and no minimum height gate. But I can change... If I have to... I guess. -Dave Leonard ZL wrote: Bob Greenblatt wrote: Aren't we trying to puncture the edge of the cylinder very near its bottom at maximum speed? Got to thinking about your question, Bob and actually we shouldn't try to hit the edge of the cylinder at red-line. Why? Because our sailplanes are very inafficient at red-line, in fact they start coming down like a stone at anything over 90 knots. We should climb the last thermal to 500 over home + a smidgen and then fly the indicated M/C to the edge of the cylinder. You should get there between 60 and 90 knots, depending on conditions on the glide. If you get there at red-line, that means you climbed too high in the last thermal and it cost you (time). The finish line, on the other hand, requires a finish at red-line, so that we can exchange our excess speed for pattern altitude. I'm even tempted to say the cylinder is the most efficient way to fly the final glide, but if I did, OC would just fly off in another snit, and I would be forced to look up all those big words, again............... :) JJ |
#14
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#15
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JJ, I'm thinking back. Half a dozen sanctioned contests? We use the
cylinder at M-ASA for our Club tasks as well. You miss my point though... It's not condemnation of the finish cylinder as a concept. Whatever the rules, I'll follow them and use them to my best advantage. It's an assessment of the forethought that has been applied to its implementation. Many of the concerns you aptly apply to the finish line can be transferred to the finish cylinder. While it answers some concerns, it ignores others and raises still more. In my opinion, the finish gate is most dangerous when sailplanes of different performances and speed ranges are finishing together. This is why the cylinder is an appropriate solution for the sports class. Under such circumstances, there can be significant differences in the patterns pilots must fly after the finish. And the cylinder raises greatest concerns during TATs and ASTs, especially in weak or blue conditions, when gaggling is most likely. I've talked about the heads down aspect of the cylinder, the de facto reduction of finish line width during ASTs, the reduced separation of high and low speed traffic and the variables we're likely to encounter once we enter the cylinder and proceed to the IP. I keep asking for some regulation at the cylinder that will make it easier for me to anticipate likely hazards. And the constant response is density. I've flown the 1-mile "turn cylinder" for several seasons now, and I've come to the conclusion that it does little to alleviate congestion. There is some improvement under certain conditions, but by and large there's typcally only one "best" way to round the turnpoint at any given moment, and that's where sailplanes operate. It comes down to this: I understand the finish gate. I know its hazards and can anticipate them. The cylinder presents unaddressed variables. And unlike some pilots, I prefer the advantages of going into a hazardous environment with as much knowledge as I can. Right now I am admitting my ignorance of how best to manage the cylinder. And I'm not taking much confidence in the recommendations of those who purport to understand its dynamics. Racing is not inherently safe. And experience leaves me dubious about rules changes that are predicated on improving the inherent safety of any aspect of the sport. The density argument rings untrue. There is clearly some value in elimination of head on traffic, but this can be addressed in other ways as well, many of which have been offered but not thoroughly explored because the cylinder is assumed to trump them all. You have to give me some credit here. I'm not addressing this as a blunt-skull only. Sports Class... use the cylinder. MAT... the cylinder might be appropriate... for the CD and his advisors to decide. Single class of experienced pilots flying AST or TAT (Nationals), the line serves very well. Perhaps even better. In either case, the safety of cylinder versus line is determined solely by the knowledge and practices of its users. I'd like to be knowledgable in both. If nothing else, you've turned me pragmatist, JJ. The line serves me fine, but I know I'll be presented with the cylinder more and more. So let's get on with the business of putting some regulation on it. wrote: OC, You never did answer my question, "How many contests have you flown using the finish cylinder?" Your skepticism leads me to believe you havent flown that many. I know you flew it at Montague, anywhere else? How about giving it a fair try before condeming it? JJ |
#16
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Morning Andy,
On the last day of the 18 meter nats at Montague, a few years back, the fire base was activated and the County required us to arrive at or above 1000 feet. Several pilots came to me and said, "If you don't raise the finish cylinder to 1000 feet, some guys will drive hard and then call a rolling finish, we need a big penalty for that". So, I raised the 1 mile cylinder to 1000 feet and announced a 10 minute penalty for making a rolling finish. Two top pilots did exactly what wou described and BOTH missed the cylinder! They got their rolling finish time + 10 minutes. There was ****ing & moaning & nashing of teeth the like of which the world has seldom seen, complete with threats of taking their protest to a higher power. I don't recommend the procedure you described for several reasons, but the big one I see is; It brings back the pull-up. I would be in favor of a rule prohibiting hard pull-ups in the cylinder. Easy to enforce, we have your GPS trace. JJ I did an analysis of this and it would appear that the minumum time solution is to dial in a finish altitude equal to 500' minus the altitude you can gain in a pullup from your McCready speed to minimum sink speed. Just before the cylinder edge you pull up and hit the bottom outside edge of the cylinder. Depending on your McCready setting you will approach the edge of the cylinder at somewhere between 0 feet (Mc = 6 or higher, full ballast) and 350' (Mc = 2, dry). It's easy to calculate that you save about 45 seconds over flying the McCready speed to the cylinder at 500'. |
#17
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I don't recommend the procedure you described for several reasons, but the big one I see is; It brings back the pull-up. I would be in favor of a rule prohibiting hard pull-ups in the cylinder. Easy to enforce, we have your GPS trace. JJ But the rules DO recommend the procedure. It's the fastest way to finish ! For any rule prohibiting hard pull-ups, how will the pilot know in the cockpit, how hard can he pull up without violating the rule ? Will g-meters be required equipment ? I personnally have no fears of hard pullups, as long as I don't have to do them below 1000 ft AGL. Todd Smith 3S |
#18
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Hi Todd,
The rule could say something like, no sudden increase in altitude at or near the finish cylinder, not to exceed, say 300 feet. I'm sure our clever scoring programmer could measure time vs. altitude in the pull-up and flag the trace for penalty consideration. But the rules DO recommend the procedure. It's the fastest way to finish ! For any rule prohibiting hard pull-ups, how will the pilot know in the cockpit, how hard can he pull up without violating the rule ? Will g-meters be required equipment ? I personnally have no fears of hard pullups, as long as I don't have to do them below 1000 ft AGL. Yes, but this is where the near mid-air occurred at this years Seniors. Several posters have pointed out the same potential exists in the cylinder as in the line, hence my recommendation to basically prohibit the pull-up in or near rhe cylinder. It's the guy in your blind spot that gets you (or you get him) JJ Todd Smith 3S |
#19
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#20
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Ah, much better. Now we're going in the right direction. Is there some
way we can raise these from site specific to general practice? And in the process, refine them to address conceptual (versus reported) problems with the cylinder. And then do the same sort of thing for the line. Let's make them both as safe as possible, then measure their relative worth under the variety of finish scenarios we see. Your contests will use the cylinder exclusively. That's fine. Others will prefer the line. Each will attract its adherents, but in the long run, there's no reason they can't co-exist, especially if each in its own way contributes to improvements in traffic management at the finish (I won't say safety in this case, because being safe is largely dependent on individual practice and compliance with accepted procedures). The good news, JJ, is that you're at least partly right. Maybe all right. ;-) Time will tell. And it needn't be based on casuality figures... just pilot preference. Cheers, Chris OC |
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