Define penetration.

Well, since you brought it up, the stronger the tailwind, the more
important your minimum sink rate becomes in establishing the greatest
possible distance over the ground. With a headwind, you are turning
the speed ring clockwise... speeding up. With a tailwind,
counterclockwise... slowing down. So to answer your question, NO, you
don't "penetrate" downwind. High speed glide angle is less important
than the total time you can remain aloft, allowing the wind to carry
you along.

Withdrawing? Only if soaring is a particularly sensual experience.
Hmmm, penetrate rapidly, withdraw slowly. Not a bad perscription all
the way around.

Drifting might be a better label, though it too is loaded with
connotations.


"whbush" wrote in message ...
So you can't penetrate downwind? So going down wind is withdrawing?
"Chris OCallaghan" wrote in message
m...
I'll give it a try....

Penetration: a measure of sailplane performance as a function of Lift,
Drag, and Airspeed such that increase in drag is disproportionately
small compared to increasing airspeed throughout the sailplane's speed
range.

Since penetration is most often used to describe a sailplane's ability
to make progress against a head wind, a "penetration factor" of a
sailplane could be measured by establishing L/D at speeds of 60, 80,
and 100 knots, or, conversely, at some fixed rate of sink. The 300
feet per minute sink rate speed has been used as a de facto
penetration factor in the past. The higher the measured airspeed at
-300ft/min, the better the penetration.

Chris OCallaghan wrote:
Well, since you brought it up, the stronger the tailwind, the more
important your minimum sink rate becomes in establishing the greatest
possible distance over the ground.

The interesting part about this for me is that the min sink rate
of so many modern gliders is so similar (on paper).

But I suppose this doesn't take into account ballast, which I expect
one would drop if in a tailwind and just barely
able to glide back to an airfield. How many of you folks have
dropped ballast at the end of the day when the air goes still
except for a tailwind home?

I was recently challenged to define Penetration.

Kobe Bryant was also asked the same question, check with him for the details.


JJ Sinclair