On Apr 19, 1:51*pm, wrote:
I've have a Cambridge 302 in my glider. *I have the setting at 0%
since I have the total energy probe fed into it, along with the pitot
tube and static port. *The te tube is split just behind the cockpit as
recommended. *The static and pitot are split or "t'd" behind the
instrument panel.

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.

The manual says to increase the % , but doesn't say how much.

Another option is to not use the te tube and put it at 100%.

The te probe in my glider is located about 6 feet behind the wing spar
on the top of the fuselage. *It's not the conventional spot on the
rudder.

Any thoughts? *Recommendations?

Yep, pretty easy. Normally you would just change the % compensation
until it behaves as you want. But then normally you would need little
if any electronic compensation.

You say it's a fuselage mounted probe, there is nothing wrong per se
with fuselage mounted TE probes, Dick Johnson spent time trying to
point that out.

Presumably you have a mechanical vario and capacity flask on the other
side of the split TE line. Does that mechanical vario seem to behave
correctly? If so the problem is at the Cambridge 302, and that 302
should not need huge compensation adjustments (normally none).

Check the plumbing carefully, it might be as simple as you actually
have the static and TE lines crossed at the Cambridge (that would be
the first thing to check - don't rely on the color or the tubing etc.
(it might be spliced wrong you cant' see) really check there is a air
pressure connection by blowing gently onto (not into!) the TE probe).

Also simplify the problem. Block off any ports you really don't need.
Check all connections carefully, etc. Block the other side of the TE
line where it splits. Double check that the IAS and pressure altitude
on Cambridge all look OK (long shot but it may show up a problems).

If you start to suspect the Cambridge, try just sticking it on the
static line with 100% compensation and see what it does. But this
really should not be needed.

Darryl