Wind direction and true airspeed calculation

[schwbo]

Dear Support

I used the method described in the NTPS website to calculate various parameters and compared them to the screen (standard pressure day. First two measurements were done at 1100 ft at 19 centigrade and last two at 1200 ft and 18 centigrade) . There are some differences between the calculated Vtrue values and screen values but the mean is close to zero. There are bigger differences in the calculated heading and indicated heading. However, there are huge differences between the calculated wind and indicated wind component. Also, I notice that the indicated wind calculation varies a lot between observations. This is very surprising. Can you please explain.

I've attached the results in the file.

 

[dynonsupport]

What is "calculated heading"? You displayed winds will never be right if your magnetic compass isn't calibrated well and doesn't read the right direction all the time.

 

[SuperCub]

I am having a similar problem and found out that my IAS is not correct. So the Skyview system calculates the wrong TAS and with other values like track and heading it calculates the wind which then is also not correct - this is what I assume.

 

[dynonsupport]

Yes, you must have dead on accurate IAS, static, OAT, and magnetic heading for us to calculate winds correctly. Winds are the difference between your true airspeed, magnetic direction, ground speed and ground track, and it takes only very small errors in that source data to create huge errors in displayed winds.

 

[skydancer]

Time to check your ADAHRS compass heading.

 

[schwbo]

Looking at the data it seems that the Dynon calculated airspeed is not too far from the calculated true airspeed calculated by the track and groundspeed. What seem to deviate is the heading versus the calculated heading.

I'll try to reset my ADHARS.

 

[skydancer]

Check your ADAHRS before you reset or re-calibrate your ADAHRS, and compare the heading difference between the two if you have dual ADAHRS.

Your finding will help every one to resolve the similar issue. Please get back to us with the finding, will be appreciated.