By svartbjorn - 4/6/2014 12:17:41 PM
SD constantly seems to calculate a far too high GS. That is my conclusion after caøculating dozens of scenarios.
Here is what i have done:
Android version only supports Static Pilot Log, so I had to create something to have an Operating Flight Plan (=Live Pilot Log). I have asked for support of Live Pilot Log in another thread, but SD answered they can't tell when to support that.
So I created a spreadsheet where I have implemented Live Pilot Log (+ more features than Live Pilot Log). In the spread sheet I enter IAS, temperature, altitude, wind etc. I calculate TAS taking the following into account:
- adjust TAS as a function of temperature and altitude using this formula: http://en.wikipedia.org/wiki/True_airspeed
- increase TAS by 2% per 1000'
- decrease temperature by 2 degC per 1000'
This gives me TAS spot on with the manual E6B (checked with examples on the web). I also compared with the Android app "FlightTools E6B", which is within 1%. So seems my equations are very accurate.
However, SD is constantly giving TAS too high. I compared SD with E6B and my equations by creating routes on SD at different places with different altitudes, temperature and wind conditions. I adjusted the track to get straight tail or head wind (no xwind) such that GS=TAS+/-head wind. Then I looked at the PLOG to get the wind, altitude, TRK and GS data.
Could SD explain why the results differ and how SD calculates TAS taking altitude and temperature into account?
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By svartbjorn - 4/15/2014 6:06:47 PM
Thank you so much for clarifying this and sending me the link. Great service! Highly appreciated!
I will need some days to go through the details. I'll let you know how it works out.
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