TAS online calculator tool
Posted: Tue Jun 03, 2025 2:36 pm
Hi,
Scott posted about indicated and true airspeeds. I've attached a link to Wolfgang Polak's online tool to derive TAS from your observed GPS ground speed. He is a member of EAA Chapter 62.
It requires you to fly a minimum of three legs that are 90 degrees difference to each other. I suggest setting up a autopilot course. There is also a link to a Kit Planes article with a link to a spreadsheet. In the spreadsheet you can fly 4 legs (a square track) for a bit more accuracy. However, this National Test Pilot School link appears to be broken.
The link to the Polak calculator page has an embedded link to the mathmatics behind it which is also posted below.
Your mileage may vary and you might not like what you find. Which may point to some needed fine tuning of your avionics or pitot static system plumbing.
As a generic rule of thumb you can look at your IAS, GS and indicated/computed wind data and see if the TAS ballpark-wise makes sense.
https://www.eaa62.org/technotes/speed.htm
https://www.eaa62.org/technotes/speed.pdf
https://www.eaa62.org/
Also Doug Gray and the NTPS method is cited in this Kit Planes article
https://www.kitplanes.com/flight-testin ... -gps-data/
Scott posted about indicated and true airspeeds. I've attached a link to Wolfgang Polak's online tool to derive TAS from your observed GPS ground speed. He is a member of EAA Chapter 62.
It requires you to fly a minimum of three legs that are 90 degrees difference to each other. I suggest setting up a autopilot course. There is also a link to a Kit Planes article with a link to a spreadsheet. In the spreadsheet you can fly 4 legs (a square track) for a bit more accuracy. However, this National Test Pilot School link appears to be broken.
The link to the Polak calculator page has an embedded link to the mathmatics behind it which is also posted below.
Your mileage may vary and you might not like what you find. Which may point to some needed fine tuning of your avionics or pitot static system plumbing.
As a generic rule of thumb you can look at your IAS, GS and indicated/computed wind data and see if the TAS ballpark-wise makes sense.
https://www.eaa62.org/technotes/speed.htm
https://www.eaa62.org/technotes/speed.pdf
https://www.eaa62.org/
Also Doug Gray and the NTPS method is cited in this Kit Planes article
https://www.kitplanes.com/flight-testin ... -gps-data/