calibrating IAS

[Dyn@cavok]

Hello, I try to ask a help, with a Dynon Sky view D700; I can see a difference about 10 km/h about the IAS, between the analog indicator and the Dynon; checked with GPS in calm air, the analog works well, so I think that the issue is on the SkyView; how can I fix ?

Thanks

Paolo

 

[Carl_Froehlich]

Assume the analog is wrong until proven otherwise. Most are off, brand new out of the box.

Make a simple manometer using the attached template to convert inches of water to knots (make sure you print it out at 100% scale). Connect to your pitot and see which is reading correctly.

Analog airspeed instruments can be calibrated, but if you have not do this perhaps you should ask for help.

Carl

 

[skysailor]

Check that the Dynon reads zero when parked. A Zero Airspeed Calibration is easy and will fix this if not.

 

[Dynon]

Also, SkyView can be configured to display either knots, mph, or kph. Make sure they're all in the same units.

 

[Dyn@cavok]

Dear all, thanks for your previous help; Unfortunately I checked the unit measurement (same units), the Zero Speed calibration (Zero when parked) and in flight - wind calm, the GS and analog IAS matches; Dynon D700 IAS is always 10 Kph lower.
Kindly
Paolo

 

[swatson999]

What about the altimeter (assuming you have a separate, second altimeter installed)?

 

[GalinHdz]

As Carl Froehlich said; "Assume the analog is wrong until proven otherwise. Most are off, brand new out of the box."

FWIW; I went through this same issue several years ago and can say Do not rely on plain GPS speeds for these numbers. You can't establish where the error is until you do a 3 leg in-flight check. Only then can you determine which instrument is correct, which is wrong and how to fix the issue.

Here is a link to a .pdf document with my situation and how I corrected the problem. If you need a copy of an Excel Spreadsheet I made up to do the calculations, let me know and I will eMail it to you.