I'm in the process of starting to Un-confuse (family friend word) the electrical wiring on my glider and I'd thought I'd bring the tubing into the 21st century as well. Pretty much everything looked as I expected it to other than the hook-up for my
Winter mechanical vario.

(1) The glider has 4 static ports, the fwd two (T) together, then split apart to feed both the Cambridge unit and the airspeed indicator. So far so good?

(2) With that said, the winter mechanical vario has two inputs, one is dedicated to the vacuum flask(s) .9l as required, and the other input gets what I thought was the aft two static ports combined via a (T) connection. Upon closer inspection, the TE
probe line is (T) connected with these static lines feeding the Winter vario. (The TE probe also feeds (via a T) the Cambridge unit.

My silly question of the week is... should the TE probe line tie in with the two aft static ports feeding the Winter vario, or not? If so, why? My guess is that it shouldn't.

D

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On Tuesday, May 31, 2022 at 6:57:05 PM UTC-4, wrin...@gmail.com wrote:

My silly question of the week is... should the TE probe line tie in with the two aft static ports feeding the Winter vario, or not? If so, why? My guess is that it shouldn't.

For mechanical variometers:
If the variometer is connected to the static and flask, you will get stick thermals.
If the variometer is connected to the TE and flask you will not.

I have never heard of connecting a static to a TE for any variometer use, but I am not familiar with a Cambridge variometer.

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For the mechanical variometer, see what rakel says.

What Cambridge unit do you have? This is what the L-Nav manual says:

L-NAV Installation
6.1 Pneumatic tubing
Using PVC or silicone tubing of 3/16" inside diameter, connect the 4 pneumatic inputs to the instrument. Use the same sources of Pitot and Static pressure as those for the glider's mechanical airspeed indicator. Use tubing "tee" fittings as appropriate.
Use another "tee" fitting to connect the glider's Total Energy (TE) probe to both the L-NAV TE input and the mechanical variometer. The supplied 0.45-Liter variometer flask is connected to the L-NAV Flask fitting.

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On Wednesday, June 1, 2022 at 4:12:42 PM UTC+8, Stéphane Vander Veken wrote:

For the mechanical variometer, see what rakel says.

What Cambridge unit do you have? This is what the L-Nav manual says:

L-NAV Installation
6.1 Pneumatic tubing
Using PVC or silicone tubing of 3/16" inside diameter, connect the 4 pneumatic inputs to the instrument. Use the same sources of Pitot and Static pressure as those for the glider's mechanical airspeed indicator. Use tubing "tee" fittings as appropriate.

Use another "tee" fitting to connect the glider's Total Energy (TE) probe to both the L-NAV TE input and the mechanical variometer. The supplied 0.45-Liter variometer flask is connected to the L-NAV Flask fitting.

The Total energy probe should not be connected to the statics in any position. your maintenance manual should tell you which statics (front or rear) that the ASI should be connected to to minimise position error
if you are using flow type devices (varios) like the winter mechanical varios and also are using pressure technology ( most modern electonic varios) T off the Total energy as far aft as possible and then feed the two different type devices from the
split TE line, this minimizes "cross talk" between the two technologies
the statiics should only be used for altimeter, ASI and flight computers that require static connections
Chris Runeckles
Western Australian Sailplane products

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On Wednesday, June 1, 2022 at 7:46:09 AM UTC-4, cmrun...@gmail.com wrote:

On Wednesday, June 1, 2022 at 4:12:42 PM UTC+8, Stéphane Vander Veken wrote:

For the mechanical variometer, see what rakel says.

What Cambridge unit do you have? This is what the L-Nav manual says:

L-NAV Installation
6.1 Pneumatic tubing
Using PVC or silicone tubing of 3/16" inside diameter, connect the 4 pneumatic inputs to the instrument. Use the same sources of Pitot and Static pressure as those for the glider's mechanical airspeed indicator. Use tubing "tee" fittings as

appropriate. Use another "tee" fitting to connect the glider's Total Energy (TE) probe to both the L-NAV TE input and the mechanical variometer. The supplied 0.45-Liter variometer flask is connected to the L-NAV Flask fitting.

The Total energy probe should not be connected to the statics in any position.
your maintenance manual should tell you which statics (front or rear) that the ASI should be connected to to minimise position error
if you are using flow type devices (varios) like the winter mechanical varios and also are using pressure technology ( most modern electonic varios) T off the Total energy as far aft as possible and then feed the two different type devices from the

split TE line, this minimizes "cross talk" between the two technologies

the statiics should only be used for altimeter, ASI and flight computers that require static connections
Chris Runeckles
Western Australian Sailplane products

If it's difficult to T off the TE line far enough back, you can coil the tubing and put it behind your panel. I did this (about 10') and it cured cross-talk between a PZL mechanical and an LX7007 Pro IGC. Not elegant, but it works.

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On Wednesday, June 1, 2022 at 4:12:42 AM UTC-4, Stéphane Vander Veken wrote:

For the mechanical variometer, see what rakel says.

What Cambridge unit do you have? This is what the L-Nav manual says:

L-NAV Installation
6.1 Pneumatic tubing
Using PVC or silicone tubing of 3/16" inside diameter, connect the 4 pneumatic inputs to the instrument. Use the same sources of Pitot and Static pressure as those for the glider's mechanical airspeed indicator. Use tubing "tee" fittings as appropriate.

Use another "tee" fitting to connect the glider's Total Energy (TE) probe to both the L-NAV TE input and the mechanical variometer. The supplied 0.45-Liter variometer flask is connected to the L-NAV Flask fitting.

I honestly don't recall which model it is, it is being replaced in the near future anyway. Thanks for posting this bit of information. It does match exactly to what I have to include the .45l flask.

D

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