At 22:28 09 June 2008, Mark Dickson wrote:
If both gliders were flying at about 51 kts, doesn't this give the
Cirrus
an advantage? 51 kts probably gives best l/d for the Cirrus, but it
will
be well below best l/d for the diana.

Mark,

That is a good question and one that I have not taken the time to look
deeply into.

According to the polar Johnson measured, the Diana 1 has a sink rate dip
at 53 kts calibrated that gives it 45:1. We were trying to fly 51 KIA on
my ship which is about 51.25 calibrated, or 1.75 kts slower than the Diana
likes. At that speed Johnson gives the Diana about 115 fpm sink rate for
an L/D of 44.1. This would still be 10.6 points higher than my ship
measured. However, especially on the cloud-street run, both ships were
flying though turbulence that bounced the airspeed all over the range that
covered my performance peak and the Diana’s too. So, we’re dealing with
ball park numbers here.

JEH