TAT +34C at FL330

[Fatback 84]

I uploaded the new version today and I'm I'm getting a TAT of +34C at FL330. It's knocking my AP off and affecting my airspeed and cruise level and I'm wondering if it's the upgrade or something else? Here is my flight plan:

 

SCEL DILOK1.ASALO LAR UA307 SIS UR554 VAS UM403 BSI UW10 FRM UZ27 PTL MSS UN866 APASO UN871 VJF UN10 HIJ TLD UN858 DGO UN867 BLV UP87 MOKOR UN741 KEPER KEPE5P LFPG

 

I'm approaching VAS and the Opus Upper Atmosphere Weather Report is showing the temp as -48 for FL340 but that is clearly not what I'm getting. Any help appreciated. Thx!

 

 

[Opus Software 84]

The targeted temp is of course a SAT or OAT and not the TAT which is a calculated temp that factors in your airspeed. It's actually proportional to the square of your airspeed as a Mach number. So the TAT will always be a great deal warmer.

 

The Local or Destination report will show you what both the actual SAT and current TAT (inside the sim are), did you check to see if the actual SAT in the sim was behaving itself.

 

Also if you are using Selective Updates then try turning them off and use the default Dynamic Weather Themes. DWTs are far more detailed and accurate, SU mode relies on the sim to interpolate the weather as it only updates selective stations in the distance. On the other hand, DWTs define the weather AND all wind/temp targets everywhere, it does a much better job of weather interpolation and does not use the sims rubbish interpolation at all.

 

So make sure you check the on screen reports and keep an eye on both the targeted SAT and the actual SAT, the recorded TAT will always be much warmer than these Outside Air Temps ... due to the compressional (of the air molecules) heating of the air as you fly through it. I believe it's normally 20 to 30 degrees warmer at normal cruise speeds. You can work it out for yourself ... have to Google the formula as I'm on holiday at the moment.

 

My guess is it's the rubbish sim weather interpolation as the temp is not controlled only targets are set for the sim to follow, but after a while those targets in SU mode are set at remote locations and the sim does the rest.

 

You could also try forcing a weather update which will inject a DWT and hence update the weather and all targets everywhere again. That might kick the sim back.

 

Stephen : -)

[Fatback 84]

Thank for the detailed reply Stephen!

[Opus Software 84]

You're welcome.

 

I would advise you keep an eye on the 'on screen' Opus Destination or Local Weather report and compare the actual ambient temp (SAT Or OAT) with the current targeted temp. If you notice the sims ambient temp drifting too high, away from the desired target value, you should force an Opus weather update. This will load a Dynamic Weather Theme, defining the weather and all wind/temp targets everywhere and stopping the sims code from doing its own interpolation. Personally, I always fly using default DWTs and don't use Selective Updates. In OpusFSI the DWT weather updates are quite infrequent (every 30 mins) and the weather is far more detailed and realistic, especially with the new Cloud Associations option set and the new mid and high level forecast data.

 

Stephen :-)