Re: [Flightgear-devel] Turbulence should affect YaSim and JSBSim the same way
On Sun, 16 Jun 2013 19:09:40 -0600, Jon wrote in message 005a01ce6af7$58b69470$0a23bd50$@net: ..my oversimplification: http://wiki.flightgear.org/YASim guesses how it flies from how it looks, while http://wiki.flightgear.org/JSBSim knows how it flies and tries to show us how that looks, e.g. stalls are assymetrical in YASim but (still?) symmetrical in JSBSim. ..if I guess FG progress correctly, we need to model downwash correctly, and if you want assymetrical stalls in JSBSim, you need 2 halved JSBSim models per plane so each wing etc surface calculation is run independently. I have not tried modeling a piston aircraft in quite some time. [Hal Engel's P-51D does stall in either direction, does it not?] ..I haven't tried the P-51Ds much, but yeah, my stalls went both ways on both FDMs AFAIR, but here I'm going on what I remember from when YASim was introduced here, and whatever I've picked up on how they differ, and on my WAG these things have changed since I last checked the P51Ds 3 or 4 years back. My big problem was always too low framerates on T/O. ;o) In any case, it should be possible to model aerodynamic effects from the propeller in the XML model file for any JSBSim aircraft (in the aerodynamics section) - effects that would affect stalling, I suspect. It's not that JSBSim doesn't support asymmetric stalls - JSBSim doesn't *not* support it. ..my (flawed?) understanding of JSBSim is both wing halves sees the same wind because they are calculated together as one wing, where YASim cuts up the wing and calculates the wing sections independently and adds them up together, AFAIRI from the discussion way back here. But, I'm not sure anyone has crafted the aerodynamic/propulsion interactions that would effect that. This isn't necessarily the fault of users, either. We (JSBSim development community) would ideally make available more examples and documentation. JB -- ..med vennlig hilsen = with Kind Regards from Arnt Karlsen ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. -- This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
[Flightgear-devel] Turbulence should affect YaSim and JSBSim the same way
Hi, I have been looking over the FG code for sometime and would like to start contributing to the project. I just browsed through the open items and figured out Turbulence should affect YaSim and JSBSim the same way issue in 3.0 backlog. As the first step, I am trying grasp YaSim and JSBSim approaches. I just would like to ask if anybody else is working on this. And if not, can anyone help/guide me through drafting a solution. Regards, -- Umut DURAK, Ph.D. http://www.metu.edu.tr/~udurak/ -- This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Turbulence should affect YaSim and JSBSim the same way
On Sun, 16 Jun 2013 23:03:21 +0300, Umut wrote in message candytvdfry0hsmpts0+ul4yvhgagtb2ggzpenpbml8kci7k...@mail.gmail.com: Hi, I have been looking over the FG code for sometime and would like to start contributing to the project. I just browsed through the open items and figured out Turbulence should affect YaSim and JSBSim the same way issue in 3.0 backlog. As the first step, I am trying grasp YaSim and JSBSim approaches. ..my oversimplification: http://wiki.flightgear.org/YASim guesses how it flies from how it looks, while http://wiki.flightgear.org/JSBSim knows how it flies and tries to show us how that looks, e.g. stalls are assymetrical in YASim but (still?) symmetrical in JSBSim. ..if I guess FG progress correctly, we need to model downwash correctly, and if you want assymetrical stalls in JSBSim, you need 2 halved JSBSim models per plane so each wing etc surface calculation is run independently. I just would like to ask if anybody else is working on this. And if not, can anyone help/guide me through drafting a solution. Regards, -- ..med vennlig hilsen = with Kind Regards from Arnt Karlsen ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. -- This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Turbulence should affect YaSim and JSBSim the same way
..my oversimplification: http://wiki.flightgear.org/YASim guesses how it flies from how it looks, while http://wiki.flightgear.org/JSBSim knows how it flies and tries to show us how that looks, e.g. stalls are assymetrical in YASim but (still?) symmetrical in JSBSim. ..if I guess FG progress correctly, we need to model downwash correctly, and if you want assymetrical stalls in JSBSim, you need 2 halved JSBSim models per plane so each wing etc surface calculation is run independently. I have not tried modeling a piston aircraft in quite some time. [Hal Engel's P-51D does stall in either direction, does it not?] In any case, it should be possible to model aerodynamic effects from the propeller in the XML model file for any JSBSim aircraft (in the aerodynamics section) - effects that would affect stalling, I suspect. It's not that JSBSim doesn't support asymmetric stalls - JSBSim doesn't *not* support it. But, I'm not sure anyone has crafted the aerodynamic/propulsion interactions that would effect that. This isn't necessarily the fault of users, either. We (JSBSim development community) would ideally make available more examples and documentation. JB -- This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
