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#41
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AT, TAT, MAT?
On Oct 13, 4:41*pm, "noel.wade" wrote:
I still don't see how this changes the problem with people coming in under-time, if the raw time (before adding 15 minutes) still has to be greater than the minimum task time... Apples and oranges - the (now defunct) 15 minute rule flattened out the points awarded as a function of time on course OVER AND ABOVE the minimum time. It was an attempt to reverse out an implicit scoring penalty due to the dilution of final glide speed into sustained cross- country speed - longer flights got penalized more as the dilution effect decreased. The second topic has to do with flight management - being on time but not under. The penalty for being under time is much more severe than the hidden penalty for being over - you get marked to minimum time, which is like averaging in zero speed for the time you are under. Hope that makes sense to people. 9B |
#42
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AT, TAT, MAT?
On Oct 13, 4:25*pm, BB wrote:
I don't understand - if you add 15 minutes, what's to stop people from trying to come in 14 minutes and 59 seconds sooner? *Doesn't that just shift the "minimum task time" without affecting the racing (if not, what's the logic I'm missing)? --Noel I'm guilty of being too obscure. A few years ago the US experimented with the following rule. To determine your speed for scoring, we take (Time + 15 minutes)/distance. Time still had to be greater than minimum time. The effect of this change is to offset the fact that you get one fast final glide, or equivalently one fee thermal to the top of the start gate, per flight, and therefore remove the critical importance of finishing close to the minimum time. For example, suppose you fly 50 mph through the air -- top of start gate to top of last thermal -- *and then *do a 15 minute, 100 mph final glide on a 2:00 hour turn area task. If you fly it perfectly and finish in two hours, you go (50 x 1.75 + *100 x 0.25 )/2 = 56.2 mph. If you blow it and do a 2:30 flight, you go (50 x 1.25 + 100 x 0.25) / 2.5 = 55 mph * or 972 points. That is a huge difference in contest soaring, so no wonder pilots invest in thousands of dollars of computers. *If you add 15 minutes to each time, though, you get scored for 50 mph in each case! The 15 minute time addition exactly offsets the one- glide-per-flight effect and makes it unimportant how long you stay out, so long as you end above minium time and fly fast. I wish I could say that this was overturned by the evil conspiracy of flight computer manufacturers. Pilot confusion and poor salesmanship by its advocates *did in a very pretty idea. And I am not trying to revive it -- lost cause! John Cochrane The main argument against this was due to the rate = distance / time formula being drilled into us in junior high school. Many people hated the idea that your speed wasn't distance divided by time. Of course at that time points were proportional to calculated speed. Since we have now (I suspect) increased distance points to 600 and thereby compressed scores so speed points are not necessarily pro-rata to actual speed around the course, it might be acceptable to re-think a form of this. While it was analytically elegant to think in terms of the 15 minutes added in calculating speed around the course I think it might be better to think about it in terms of how points are awarded and leave the speed calculation alone. I realize that there are circumstances where a slower raw speed might earn higher points than a faster raw speed, but my recollection is that the differences are minor and the only way this would happen is if someone took a much longer flight than a competitor flying nearly the same speed. Making the scoring work with the equivalent of 10 minutes added rather than 15 would likely clean up this apparent anomaly. Also, a modest incentive not to go chase a cloud street into the next state may not be so bad. I would add that, while John's logic and math are absolutely correct there is often enough going on with the weather that overrrides how much time you do (or should) spend on course that the logic for being just on time versus a few minutes late gets washed away like good intentions. Now that the government is taking John's advice and recapitalizing the banks rather than buying their bad loans, maybe we should revisit his soaring advice too. My soaring season is done, so I may as well re-hash this sort of thing. 9B |
#43
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AT, TAT, MAT?
Now that the government is taking John's advice and recapitalizing the banks rather than buying their bad loans, maybe we should revisit his soaring advice too. Just to set the record straight, this is a little joke from Andy. Don't blame me for this mess of a hideous bailout and goverment takeover of the banking system! (As if anyone ever listened to my advice in the first place.) Ok, it's not as disastrous as having the government buy out every bad mortgage in the country, but not by a whole lot. John |
#44
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AT, TAT, MAT?
On Oct 16, 8:41*am, BB wrote:
Now that the government is taking John's advice and recapitalizing the banks rather than buying their bad loans, maybe we should revisit his soaring advice too. Just to set the record straight, this is a little joke from Andy. Don't blame me for this mess of a hideous bailout and goverment takeover of the banking system! (As if anyone ever listened to my advice in the first place.) Ok, it's not as disastrous as having the government buy out every bad mortgage in the country, but not by a whole lot. John ;-) |
#45
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AT, TAT, MAT?
On Oct 16, 9:40*am, wrote:
On Oct 16, 8:41*am, BB wrote: Now that the government is taking John's advice and recapitalizing the banks rather than buying their bad loans, maybe we should revisit his soaring advice too. Just to set the record straight, this is a little joke from Andy. Don't blame me for this mess of a hideous bailout and goverment takeover of the banking system! (As if anyone ever listened to my advice in the first place.) Ok, it's not as disastrous as having the government buy out every bad mortgage in the country, but not by a whole lot. John ;-) In a feeble attempt to make this more glider-related: I'd like to see the bailout architects *actually* have to bail out. If they survive, we consider letting them stay in office... But I can't decide if we give them a parachute or not. ;-) Also, I believe that commercial glider operations need to lobby congress. Many are failing or have gone into bankruptcy, and they need the government's help to stay afloat. We keep hearing that consumer spending is the lynchpin of our economy, and glider rides and rentals are certainly an excellent avenue for consumers to spend their money! Furthermore, once launched the glider is a zero-emissions vehicle - and we are all conscious of environmental impacts and the cost of energy/fuel these days; so supporting glider operations is truly an important issue. It is also a wonderful subject for future government study. Can you imagine how much fuel we could save if we could develop a glider-based transportation network? To heck with those noisy and fuel-burning VLJs, why not launch small 3 - 8 person gliders to 30,000' and then glide to destinations up to 170 miles away (hey, 200 miles if the towplane climbs at an angle away from the airport)? That only requires a 30:1 glide-ratio, which is quite doable with today's technology! All we need is some money from the government... --Noel (who has now used his XCSoar PDA simulator to "fly" a couple of TATs and understands them much better) |
#46
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AT, TAT, MAT?
On Oct 13, 6:39*am, Brian wrote:
Just one more comment. The thing that makes the top pilots so good is the ability to adapt the or even predict the conditions. *They know when to go fast and the know when not to. They know when they can get low and when they shouldn't. How they do this is just basic soaring skills but they somehow do it better than the 2nd place guy. I have yet heard anyone explain how they do this consistantly. I suspect it is just years of experience. How to come in at the back of the pack I am a much better expert at, but it is the same things that will put you there. Falling out of the lift band and having to climb back up in the 1 knot thermal after passing up the 4 knot thermal will lose you a lot of time. And staying high and stopping often in really strong conditions with a large lift band will cause you to fall behind as well. As you can see what works one day may not work the next or even from one hour to the next. The pilot that can shift gears at the right time and fly both of these conditions best on the same day will win the day. The pilot that can adapt on a consistant basis will win the contest. The math of getting around the couse fast is pretty simple. Fly the McCready numbers for the conditions and you will do well. You will do excellent if you can fly the McCready speed for the next thermal instead of the last one. Of course there is some art to find the thermals as well. Brian I agree with the first point Brian makes but not necessarily the second. IMHO there are two fundamental and ironclad rules for fast racing: 1) Don't take weak thermals - by this I mean take only the strongest 20% or so on average. 2) Don't get low. Brian's first point speaks to the inherent tension between 1) and 2). Sailplane racing is a game of maximizing probabilities - if you can understand your odds at any given point in the flight you will fly faster than if you can't. By odds I mean things like the probability of finding a top 20% thermal from where you are at any given time. McCready speeds are a nice way to think about whether you should be flying faster or slower for the average lift conditions and through patches of sink, but being off by even 15 knots on cruise speed is going to make only about a 1.5 minute difference in task time over a 3.5 hour task. By contrast taking a single thermal at 4 knots instead of 5 knots for 3000 feet costs you the same time. Fussing around for three turns in zero sink before you core a thermal cost the same time. I fly 85-knots dry most days, 95 knots if it's smokin' and 75 knots if I'm in trouble. That's it. The main skill I see in going fast is knowing when to press on for the better thermal versus knowing that the one you've got is the best you're likely to get before you run out of altitude and ideas. Always feeling the urge to "press on" - and knowing when to resist it - is the main point. I remember taking a start one day last year and gliding, gliding, gliding for something like 45 miles finding nothing great. I passed on a couple of 3 knot thermals and was getting low enough that I was about to turn back towards some fields rather than press on. I pushed into a wind shadow bowl for one last shot at a climb and found an 11- knotter. Within three turns a 100 seeding point pilot rolled in beneath me. I found that thermal at the edge of my comfort zone - I recall he wasn't particularly nervous about his altitude. For both of us an 11-knot climb for 7,000 feet really helped the old average. It's all about managing your odds. 9B |
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