Thanks Marc. this is helpful.

In article ,
Marc Ramsey wrote:
Mark James Boyd wrote:
I'm trying to think about this from the Sports Class perspective too.
If I understand it, in Sports Class one chooses their own TPs,
so the pilots can come in from any direction, and a cylinder around the
airport wouldn't seem to solve much in terms of head-on
surprises.

The finish cylinder is basically a circle with (minimally) a 2 mile
*diameter*. A typical one will have a floor of 500 feet and no top.
Once the edge of the cylinder is crossed, one pulls up from the final
glide speed, which may well in excess of 100 knots, to a more reasonable
55 or 60 knots for pattern and landing. Following the pull up you are
usually at a minimum of 600 to 700 feet, and there is plenty of time to
sort out traffic, and sequence for landing. People finishing from the
same direction are no more of a problem than they are with a finish
gate. People finishing from the opposite direction are also not a big
deal, as both you and the head-on glider have normally slowed to 60
knots or less by the time you are within a mile of each other. Most
people by that point have started a series of gradual clearing turns, so
they can assess the traffic situation.

By contrast, with a finish gate, you have gliders converging on the same
point in space (thanks to GPS) at final glide speed of 100+ knots (if
you're under 100 feet, you better be going at least that fast), pulling
up to 200 feet or so (unless they have too little energy), then having
to sort themselves within a few moments and land. Now throw an MAT
(modified assigned task) into the mix, and things get interesting, as
you get some gliders running straight into the gate, and others
approaching the gate from one side or the other (and every once in a
while some bozo goes through the gate in the wrong direction), then
having to make a last minute high speed turn to go through the gate in
the proper direction. Now yes, things are easier with a required final
turnpoint (control point), several miles away from the finish gate, to
get everyone finishing in the same direction, but not all (or even most,
in my experience) contest directors bother to use them.

Marc


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Mark J. Boyd