At 08:17 11/07/2007, Anthony wrote: >Are the handicapping models readily available to the general soaring >public?
Yes - they are all published somewhere - but you have to know where to look and then if you want you can use the reference thermal for your own calculations. All the handicappers do usually is to accept a glider polar and apply it to the "reference thermal" - those using a more sophisticated model also apply a "reference wind" to the polar. These are where the SCWAGs come in - choosing an "average" thermal size and strength, and wind, for the location you are handicapping for. The "Standard British Thermal" that the UK handicap system is based on involves a parabolic lift distribution from 4.65 knots absolute vertical velocity at radius = zero, out to zero absolute vertical velocity at somewhere around 400 metres radius (don't hold me to the latter figure). I believe they now include a wind of 10 kt (direction is irrelevant for closed-circuit racing). This is actually too small a wind for the average comp day! The "Standard Australian Thermal" is stronger and larger (ask someone like Graham Brown (Bathurst) or Tobi Geiger for details) and there will be a standard European thermal that is used for FAI Club Class handicaps. However the handicap system cannot predict the average thermal actually encountered by competitors - and it also does not allow for streeting as it uses classical MacCready theory. The aim is to neutralise the effect of glider performance so that whoever uses the strongest thermals on the day will win the race. Another SCWAG! The GFA system also allows the handicap committee to "adjust" the resulting handicaps in the light of experience - which sometimes helps a pilot who is flying a glider type usually flown by inexperienced pilots. Also some people will choose to fly a glider with handling characteristics that they think give them an advantage - or not fly a glider whose handling disadvantages them. (That was one of the reasons for my recent change of glider, but I still have not flown it enough to validate the cost yet. Roll on next summert!) Wombat _______________________________________________ Aus-soaring mailing list [email protected] To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
