On Tuesday, December 1, 2015 at 9:52:39 AM UTC-8, Andy Blackburn wrote:
On Tuesday, December 1, 2015 at 8:00:23 AM UTC-8, wrote:

Saw FLARM leeching at PAGC. Poor XG couldn't get away to do his own brilliant thing. He expressed his frustrations in passing and very politely at one of the meetings.

I looked at the traces from this race - a couple of days every thermal for every pilot on course. The only guys I could see following XG were his teammates - I assume this was team flying, but maybe that was prohibited? In any case they fell off his trail after a few climbs.


It is not just plain leeching either. Two thermals are ahead on the first leg and marked by other competitors. The guy trailing gets to pick which has a better value and save the time of centering it. Using FLARM, the guy coming from behind uses the talents of the other two and potentially does better than either.

The data just doesn't support the reality of this claim - the VAST majority of the time the climbs achieved by later arrivals decline materially. I'm sure there are occasional cases where it takes you 4, 5, 6 turns to catch the core and annoying to have someone come in right below you and climb with you, but generally using someone else's thermals is a losing proposition - and you can't really pick the ones where the other guy "just found the core after a struggle and will safe you some effort". It's far, far more likely that the strong part of the thermal has passed you buy if you ar trailing by more than a mile or two.

I'll go grind through more contest traces, but I was startled at what a poor proposition "borrowing" thermals is from a long trail position.

Looking forward to flying with you at Nephi - hope you come. You know it'll be fun. We can discuss the various merits of Flarm over beers (I'll be hiding mine though - ;-) )

9B

Andy, I hate it when you bring data to an argument. I suggest that at Nephi, the field be randomly split between stealth and non-stealth mode. It's probably enough gliders to have a valid experiment. Since the theory behind leeching is that it speeds up the slow pilots while not slowing down the fast ones, the aggregate score of the non-steath group should be statistically higher than the stealth group. That could be further refined by looking at the bottom half in each group (presumably, leechers). According the stealth supporters, there is no difference in safety so there should be no objection on that account. Since the fast pilots are going to win anyway (and are not leechers), they should not object to which group they draw.