On Monday, March 4, 2013 1:59:39 PM UTC-5, Craig Funston wrote:
On Sunday, March 3, 2013 8:18:02 PM UTC-8, wrote:

First flight today in glider with LX 7007 and Winter varios. Needles on both the LED vario and the Winter



mechanical would swing wildly from 10 kts up to 10 kts down all thru the flight- mostly in cruise,



but also in the early phase of thermalling. Needle and LED display seemed synchronous. Both would settle down to give reasonable readings once established in a thermal.











I believe both are plumbed to the same TE probe (an unusually long probe with tee at the end-- not the



usual bent up variety).







Can't be a computer or electrical problem as the Winter would not be affected.







Any suggestions as to cause and fix?







Bill



If the receptacle in the fin is designed for Prandtl Tubes, it has two ports. You need to plug the unused port if all you are using is a standard TE probe. Otherwise there's a very big leak.



Best regards,

Craig

I've seen this problem with my mechanical vario (Sage). For that I installed
a gust filter. I'd already done the split back in the tailboom, making use of
tubing that had connected to a flask back there. I moved the flask up near
the Sage where it belonged.

Checking for leaks is always a good practice. There's articles on doing that
using an ASI and a syringe if you hunt around.

Matt