On Apr 19, 1:51*pm, wrote:

When I push hard forward to increase airspeed.....the cambridge VSI
goes up to 10knots positive.

Then when I pull back to bleed off airspeed.....the VSI goes down to
10 knots negative.


To answer you question directly - I don't believe you can fix the
problem you describe with electronic compensation. Here's why:

If I remember correctly an uncompensated vario reads climb when you
bleed off airspeed and sink when you accelerate. This is because with
static pressure only as the pressure source (no compensation) your
vario will indicate the altitude change irrespective of any associated
change in kinetic energy. Your description reads like the opposite, or
OVER-compensation.

I believe there also is an effect from the initial drag of adding lift
in a pullup (and presumably the opposite from reducing lift in a push-
over maneuver). That causes the uncompensated vario to show some small
altitude loss at the very beginning of a hard pullup (think of the
glider "mushing" a bit when you pull hard). This means that on a hard
pullup the vario would read momentarily down by 1 knot or so, then
read up until the speed stabilizes - all in still air, of course.

Putting this second effect aside for now, a pullup from 100 knots down
to 60 knots will gain you about 250 feet in about 10 seconds -
depending on the steepness of the pullup. That translates to 15 knots
average climb rate. You will see more climb rate early in the pullup
than at the end. If you were reporting 10 knots of positive climb rate
on a pullup then it would lead me to believe that you are getting
little or no total energy compensation and you should set the CAI 302
to 70% or so. This has two problems: First, you are reporting behavior
that indicates 70%+ OVER-compensation, not under. Second, I'd be hard-
pressed to recommend to someone that they put that much electronic
compensation on top of a TE probe since you are likely masking a big
problem.

Finally, you are asking for a specific answer to an insufficiently
defined problem. Without knowing the pullup profile the fact that you
are showing 10 knots on the vario doesn't really give enough
information to know how to set your instrument. I generated an answer
by assuming a profile - but I don't really know what kind of pullup
you used to generate this result. The glider matters too, but my
analysis ignores this detail in favor a of a simple energy conversion
relationship.

Hope that's helpful.

9B