"Andy Blackburn" wrote in message
...
Bill Daniels wrote:
I've been replaying on-line contest .IGC files with
Henryk Birecki's
'GPS_LOG WinCE'. (This is a training function to
learn Henryk's
software)
It's possible to set the software so auto-select
the McCready number
based
on actual thermal strengths. Other software can
do the same thing.

The average M number is a pretty good way to determine
how good the day
was.
For example, one day might be a M= 6.1 and the result
is some very long,
fast flights. Another might be a M=2.2 and shorter
and slower flights
result.

My thought is that it might be possible to run the
day's contest results
through similar software to determine the average
M number and use that
number to handicap the weather in addition to handicapping
the gliders.
This is a simplistic way to reduce the day's soaring
weather to a single
number.The result would be to make the contest more
equal for different
gliders.

That would interest me because my Nimbus 2C is not
competitive with it's
handicap in strong weather since the US Sports Class
disallows water
ballast. On the other hand, smaller gliders are
not competitive in weak
weather where the unballasted Nimbus is at it's best.
Canceling WX
effects
could make the Sports Class more attractive.

Thoughts?

Part of the problem in accomplishing this is that a
large part the average climb for the day is influenced
by the individual pilot. I've seen two pilots flying
identical tasks one of whom saw an average thermal
strength of 5.5 knots and the other of 9 knots (!).
Picking the best thermals is the key differentiator
in cross-country speed (and hence distance). By handicapping
for it you are in part discounting skill - probably
the opposite of what's intended. If you average over
multiple traces you get into small numbers problems
in most areas because few OLC pilots fly the same tasks
on the same day.

It would be great to equalize for weather (or even
better, for weather/sailplane combinations) - but the
more I think about it the less likely it seems that
there is enough information available to estimate the
'pure' weather effects. If I fly 1 mile away from another
pilot and find a blue street that ups my XC speed (and
distance) by 20% was that pilot skill or a weather
difference that we should equalize for? How about if
I'm 10 miles away, 100 miles away, 1000 miles away?

It's worth further thought, but the basic problem is
the best pilots fly in the upper 10% of the lift strength
distribution while less skilled pilots flying in the
same air are lucky to fly in the upper 1/3 of the distribution.

9B


Of course, no system will be perfect and it's easy to find situations that
would make it difficult. With wave or ridge lift available, the weather
factor could be devalued as most pilots would be able to use the lift
effectively. The biggest problems with weather are at the very strong or
very weak end of the thermal spectrum. For example. Region nine at Parowan
vs. the Sports Class Nationals at Ionia, Michigan.

I've analyzed a number of .IGC files from the On-Line Contest that were
flown in the same general area on the same day. The optimum McCready
numbers were fairly close to each other. I think that most doing the same
could reasonably be expected to say, "That was a 5 knot day".

I was thinking of a real contest where the flying was restricted to a task
area and the pilots were likely to be fairly good at thermalling. To help
get a more accurate picture of the day, the lower 25% of the contestants
could be discarded.

If the upper 25% of the pilots got 5 knots +or- 1knot at the best hour of
the day, that would seem to be a pretty good indication of the best the day
had to offer.

Bill Daniels