A couple percent error in static/pitot is considered to be pretty good. A couple percent error in ASI instrument is pretty good. A couple percent error in sink rate however measured is pretty good. Now we have 6% on an unlucky day, even with good data. Dick Johnson's test data is probably as accurate as can be practically done. It has a lot of noise and scatter, like +/- 5%. Not many people have that equipment, or patience.

You aren't going to get anywhere with handicapping the gliders by degrading performance directly or indirectly, as you know. In this day of turned in IGC log files though, one could analyze them post race to determine conditions, and apply corrections to handicaps. For example average climbs each hour for the top 5 pilots could define conditions. According to pilot poles, rules and scoring are already too complex, so acceptance of such a large step in complexity might be an uphill battle.

On Saturday, December 23, 2017 at 1:13:37 PM UTC-8, wrote:
10% error means a 10% change in L/D ... and that would sure be embarrassing as test data.

Your comments about individual A/C performance are "owner's responsibility" ... it's actually pretty easy to do basic testing on your own sailplane -- the real issue is a good static.

If you could just solve the problem of correctly handicapping for wing loading in known conditions, that would be a much greater advance than fitting the polar curve better.

Hey, it's as if I fed you this question! There is in fact a pretty straightforward solution to this BUT no possible solution ends up with a single "handicap number" independent of the soaring conditions ... and in fact that's obviously true just about sailplane handicapping in general.

In very weak soaring conditions low-performance sailplanes fly "much better than their handicap" ... it's obvious, just look at the speed-to-fly optimization. Any "one-size-fits-all" handicap factor implies a known headwind/tailwind and mean rate-of-climb, even from simple McCready speed-to-fly.

Handicap schemes that can deal with changing gross weights are really the same issue as dealing with changed assumptions about the conditions enroute.

Beyond that, one of the biggest real problems is risk optimization, and "transitions."

One of the biggest problems of handicapped contests is that the lower-performance gliders may be simply incapable of a transition that the better ones make, and DNF. A great deal of this lies on the CD and forecaster, to pick tasks that don't have impossible transitions for the weaker sailplanes.. Obviously ... sometimes this screws up.

The broader problem is more subtle ... when you are gliding there is always some risk you won't find the next thermal ... how does that risk depend on the gliding range you will have? Pretty obviously the lower-performance gliders face a higher risk of not finding a next thermal ... how do you handicap that? What can be done about it?

Stay tuned (but don't hold your breath) ... that is the problem I am working on. The math of this is pretty straight forward but the problem of the risk model isn't. We don't actually know that much (statistically) about this issue, particularly how to estimate it from met forecasts.

Just to mention two snarky ideas that I am sure would cause a riot if actually implemented

* risks could be equalized by height-limit handicapping: if you know the predicted lift ceiling then the lowest-performance gliders get to climb that high, and all the higher-performance gliders are given lesser altitude limits that equalize the gliding distance (at predicted speed to fly for the conditions) down to 1000' AGL (and like some contests a safety DNF is enforced at just a little below that, from your flight recorder)

Betcha all the pilots who show up with the low-handicap gliders would really love that one ... right?

* and then for a really wacky one ... it would be technically really easy to build a little "auto-spoiler" device that measures your airspeed and degrades the performance of your glider to some pre-programned polar ... the polar of the worst glider in the contest! Yowza! Now everybody in the contest is flying an equal glider! Dontcha think people would just love that one? NOT!