Garmin G3X Airspeed Calibration

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htx

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Ted
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I recently took delivery of a brand new Sling NGT (S-LSA) and the indicated airspeed seems to be faster than it should read. For instance, I'm stalling at an airspeed about 5 knots faster than the POH indicates (for both full flaps and clean config). Also, I'm almost always flying into a "headwind" if you compare TAS to ground speed. I've verified that my ground speed is accurate (it matches ForeFlight) and true airspeed is calculated correctly given the inputs (so, it's only wrong because IAS is wrong).

Is there a menu in the G3X that would allow me to calibrate IAS? I found zero-airspeed calibration, but I'm almost certain that's not what I'm looking for.

Any ideas would be welcome. Thanks.
 
I would go out on a calm day and do some fast taxiing, compare G3X airspeed vs GPS ground speed.
 
Good idea. I'm going to try that in the morning, in addition to flying a triangular course on autopilot to cancel out the affects of wind at altitude. My altimeter is exactly equal to field elevation with the AWOS barometer setting, so that leaves my pitot tube as the possible culprit.
 
Probably static system not exactly to plans. Builders always think they can do it better than what the plans call for. Any changes such as an aftermarket static port or slight change of position will effect accurately measuring static pressure. Ram pressure is the easy part. edit. nevermind s-lsa
 
My G3X does the same thing with headwind in every direction: meaning the IAS reads too high at cruise speed. It’s only about 3-5 mph but it’s annoying. I talked to the avionics shop that does my pitot static inspections and they said they’ve heard that a lot of them do that but mine checked out Ok. I can only speculate that the position of the pitot tube is causing it to pick up prop blast in many situations. Since I can get indicated airspeed over 20 mph during a static engine run up that would seem to be true.
 
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Narwhal said:
My G3X does the same thing with headwind in every direction: meaning the IAS reads too high at cruise speed. It’s only about 3-5 mph but it’s annoying. I talked to the avionics shop that does my pitot static inspections and they said they’ve heard that a lot of them do that but mine checked out Ok. I can only speculate that the position of the pitot tube is causing it to pick up prop blast in many situations. Since I can get indicated airspeed over 20 mph during a static engine run up that would seem to be true.
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Your propwash theory is interesting. My Sling has a much more severe left-turning tendency than the other two Slings that I've flown; I believe it's because of the angle at which the propeller blades are mounted. Maybe that also changes the slipstream enough to affect the pitot tube.

I won't have access to my plane for a couple of weeks, but I'm going to test out that theory when I get it back.
 
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