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Old January 8th 09, 12:43 AM posted to rec.aviation.soaring
Andy[_1_]
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Default 2009 Proposed US Contest Rules Changes

On Jan 7, 3:50*pm, wrote:
Okay, *The new numbers for a 40 mile first leg (center to center) are
that the "safe sector" has an included angle of around 85 degrees and
a distance along the circumference of 7.5 miles. If you increase the
first leg to 70 miles the angle goes up to 120 degrees and the
periphery extends to 21 miles. Compare that to a full "front half" for
reasonably long first legs of a bit under 31 miles around the edge of
the cylinder (it's not a full half circle because it's measured as an
arc from the first turn).


Your angles look reasonable to me but you seem to have made the same
mistake as I did in my second post for the length of the front half
circumference. The full circumference is piD or 31.4 miles. The
length of the front half circumference is then about 15.7, and the no
risk arc is about half of that at 7.5 for the task I defined. For the
120 deg included angle of your second task the circumference should be
about (120/360)*31.4=10.5.

I wonder which flight computer software will be the first to depict
this safe start area.

Andy