Re: [Flightgear-devel] Turbulence in YASim vs. JSBSim
Am 11.07.2011 14:47, schrieb Jon S. Berndt: >> Note that the JSBSim environment model is in the middle of a major >> overhaul so I wouldn't make too much of it at this point. It would be >> more interesting to see how it compares after the rewrite. >> >> Erik > > The architecture is, but it should not affect the environment modeling. > Also, the new code should not be in FlightGear, yet. > > The turbulence model is an implementation of a widely respected military > turbulence model. It should be pretty good. My guess is that the commanding > of it from the FlightGear side needs tweaking. That's probably a bug, I introduced when I made the turbulence model selectable. I set the Windspeed20ft property to the value of the fg ground wind. Looks like Windspeed20ft is in fps while ground wind is in kts... I'll have a look later today. Torsten -- All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2d-c2 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Turbulence in YASim vs. JSBSim
> Note that the JSBSim environment model is in the middle of a major > overhaul so I wouldn't make too much of it at this point. It would be > more interesting to see how it compares after the rewrite. > > Erik The architecture is, but it should not affect the environment modeling. Also, the new code should not be in FlightGear, yet. The turbulence model is an implementation of a widely respected military turbulence model. It should be pretty good. My guess is that the commanding of it from the FlightGear side needs tweaking. Jon -- All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2d-c2 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Turbulence in YASim vs. JSBSim
On Mon, 2011-07-11 at 14:45 +0300, thorsten.i.r...@jyu.fi wrote: > I've first suspected that something is fishy with the DG-101G, but since > I've flown all sorts of aircraft through the thermals (as a side note, > it's really interesting that the F-16 instrumentation allows nicely to > trace the thermal rise profile - I hadn't expected that). Of course, an > F-16 isn't thrown so wildly around as the DG-101G for the same magnitude > of turbulence , but then it has 100 times the mass .. and the F-16's flight computer compensates for non commanded aircraft movements. Note that the JSBSim environment model is in the middle of a major overhaul so I wouldn't make too much of it at this point. It would be more interesting to see how it compares after the rewrite. Erik -- All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2d-c2 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
[Flightgear-devel] Turbulence in YASim vs. JSBSim
I've recently tested the DG-101G which is (I think) the first JSBSim glider I've been flying in Flightgear. I've noticed a rather strange issue: In Local Weather, I added some amount of turbulence around a thermal proportional to the strength to simulate the fact that a thermal is not a laminar rise as wave lift. In a thermal, the DG-101G turned out to be essentially out of control for magnitude-norm of the turbulence set to just 0.18. Now, I determined the amount of turbulence to be added to a thermal by test-flying with the ASK-13 and comparing with my real flight experience - and in the ASK-13 the value seems about correct. However, the ASK-13 is a YASim FDM. I've first suspected that something is fishy with the DG-101G, but since I've flown all sorts of aircraft through the thermals (as a side note, it's really interesting that the F-16 instrumentation allows nicely to trace the thermal rise profile - I hadn't expected that). Of course, an F-16 isn't thrown so wildly around as the DG-101G for the same magnitude of turbulence , but then it has 100 times the mass - but there seems to be some sort of pattern that JSBSim aircraft are affected much more by the same value of magnitude-norm of turbulence than YASim aircraft. If anyone else could try confirm that? If the observation is real, it's sort of bad, because it means that one can't really draw up a thermal which works realistically for both JSBSim and YASim. Well, one could make FDM-dependent statements into Local Weather, but I feel that's somewhat beyond the scope of a weather system. So maybe a better potential fix would be a Flightgear-wide FDM dependent scale factor such that a given value of turbulence magnitude really means the same for all FDM engines and the weather system can simply set it. * Thorsten -- All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2d-c2 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
