John Murphy wrote:
I've got a Grob 102 Standard Astir III. The manual that came with the
plane has one flight polar diagramed. The diagram contains flight
polars for 3 different configurations of the G102. Because so many
lines are drawn in close proximity to each other, its not a diagram
that can be used for calculating speed to fly. Does anyone know have a
clean flight polar for the 102 Standard Astir III being flown without
ballast, or know where I could get one? Thanks, John Murphy.

Precision isn't needed to have a useful result, as flying 5 or 10 knots
off the "perfect" speed hardly affects the theoretical cross-country
speed. Generally, people fly slower than the "ideal" speed anyway so
they don't get low so quickly and have more opportunity to find a good
thermal. Good thermals is what gives you the good cross-country speeds.
Be sure to read Reichmann's book if you haven't already.

So, picking points off the chart you have will be fine, or using a polar
from a similar glider will work just as well.

--
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Eric Greenwell
Washington State
USA