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Old February 15th 18, 05:54 AM posted to rec.aviation.soaring
Matt Herron Jr.
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Default strange ASI readings on LXNAV s80 vs Winter ASI

On Wednesday, February 14, 2018 at 6:39:45 PM UTC-8, Paul Remde wrote:
Are they connected to the same pitot and static sources? Some gliders use a triple probe in the tail for the soaring flight computer and vario and the pitot in the nose and statics on the fuselage for the airspeed and altimeter.

Also, make sure the S80 is set to display airspeed in knots, not mph.

Best Regards,

Paul Remde
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On Wednesday, February 14, 2018 at 7:38:38 PM UTC-6, Matt Herron Jr. wrote:
looking for some instrument debugging help.

I have a steam gauge ASI (winter) and an LxNav S80 sharing the same Pitot and static lines. In the air, the two gauges read ASI differently. The S80 reads about 10 knots higher than the Winter at 70 knots, and 5 knots higher at 40 knots. The error seems to scale with higher airspeeds

Back on the ground we used a syringe to pressurize the pitot line. Both instruments read within 2 knots of each other for the full speed range. they also held steady at the desired airspeed with the syringe, indicating no leaks in the Pitot system.

Back in the air, I tried opening and closing the vent, scooping air into the cockpit to pressurize it, etc. Neither instrument changed its reading, but the offset in speeds remained.

Ideas? Leak in Static?

Matt


yes, they are connected to the same pitot and static sources. That's what is so weird about this