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flight meteorology

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flight meteorology

Postby brathering » Sun Mar 13, 2022 4:14 am

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Re: flight meteorology

Postby Thorsten » Sun Mar 13, 2022 7:15 am

A more realistic treatment of turbulence (i.e. beyond just putting it to a region where you kinda expect it) is generally tricky - turbulence evolution follows a complicated differential equation, it is lost against ground friction, gained by thermals and windshear, changes scale from large eddies to small eddies as it evolves, is advected by the wind and lifted by thermals...

So I basically know how it works in weather forecasting frameworks, but that doesn't mean FG has anything like the computational resources to utilize that information - real weather models use dedicated runs on large computing clusters, not some leftover time on the CPU after FDM and rendering have done their thing.
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Re: flight meteorology

Postby brathering » Sun Mar 13, 2022 8:03 am

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Re: flight meteorology

Postby S&J » Sun Mar 13, 2022 12:17 pm

JSBsim has it's own turbulence code but I'm not sure if it's used.

As for thermals, I'd like to see the use of local thermal 'heat maps' but I suspect it's not something high on the list of things to do, as it's for gliders.
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Re: flight meteorology

Postby Thorsten » Sun Mar 13, 2022 1:34 pm

It is really difficult to move towards 5000ft vibrations to simulated?


I am sorry but I have no idea what 5000 ft vibrations are supposed to be - could you elaborate?

JSBsim has it's own turbulence code but I'm not sure if it's used.


It is- which is why JSBSIm craft react different to turbulence than YASim craft, which is why the weather has the option to dial relative turbulence strength.

I'd like to see the use of local thermal 'heat maps'


Actually they take albedo and daytime into account which is pretty much what determines the local heating rate.
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Re: flight meteorology

Postby S&J » Sun Mar 13, 2022 1:45 pm

S&J wrote in Sun Mar 13, 2022 12:17 pm:JSBsim has it's own turbulence code but I'm not sure if it's used.


Let me correct myself.

Jsbsim turbulence is used in manual weather, and is very good.

Advanced weather, I've heard jsbsim can be over sensitive.
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Re: flight meteorology

Postby Thorsten » Sun Mar 13, 2022 2:15 pm

Advanced weather, I've heard jsbsim can be over sensitive.


As I said, the issue is that setting the same turbulence-magnitude-norm weather side does not produce the same effect FDM side because YaSim uses a generic turbulence code and JSBSim uses its own.

So unless the weather starts working dependent on FDM, there's no way to get it right out of the box. For that reason, you can dial down the turbulence strength in the dialog when you feel it is over-sensitive (for historical reasons, the fleet of YaSim gliders has been much larger, and so the defaults work better for YaSim).

But any pain beyond that point is self-inflicted... if you don't use the option, it's not anyone's fault.
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Re: flight meteorology

Postby brathering » Sun Mar 13, 2022 3:13 pm

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