cross wind error

[davestephens]

I have found that i always have a 30-40kt cross wind showing in flight, I have calibrated the compass but will it be an error on this calibration or somthing else causing it? (we do not have a compass rose so i did it to the aircraft compass which is good to our runways so its reasonably accurate) I am using a Garmin 296 as primary GPS and the Dynon as secondary.

cheers

Dave

 

[Ham_Goulding]

I suggest that it might be ASI Position Error. If your Indicated Airspeed is not an accurate RAS there will be a wind error because the system will think that the difference between groundspeed and airspeed is due to wind. I have that situation in my aircraft. See if you can check your indicated airspeed accuracy. Ham Goulding.

 

[davestephens]

I have done the comparison with my Garmin GPS in 4 directions and calculated the airspeed. its fairly acurate (as is my standby steam guage)

it always shows a crosswind, cant remember which direction of about 45 degrees and 40kts

 

[dynonsupport]

The following inputs factor into the Winds display - suggest you confirm that ALL of these are operating as expected:

• GPS
• Pitot
• Static
• Magnetometer
• OAT

Of all of these, the magnetometer is the input that's most suspect. Did you DO the compass calibration after installing your SkyView system? If not, despite your assessment that magnetometer is good enough, it's probably not accurate enough for accurate Winds calculation.

 

[davestephens]

I will check what I can, I suppose i can switch the Garmin off whilst i am flying as it is the primary GPS and it will default back to the Dynon GPS and see if the cross wind value changes. OAT reads about right (possibly a degree or so high) and the airspeed is correct at all speeds as is altitude so i would think the pito and static are ok so my best bet is the compass calibration. i did it when it was all first installed, so it has had updates etc since then so i will do it again. i take it you do not have to do the inclination etc like you have to do on the other EFIS as i could not find where to enter this info?

cheers for the help.

Dave