Hello, I have posted on this list before but I guess I never introduced myself. I am a Brazilian system analyst with experience in C programming and a little C++. I have no real pilot experience and no physics formation.
I have a crude patch to improve gear friction in yasim using the method cited by Andy if I am not mistaken. It uses a spring and damper around a stuck point to simulate the static friction. This patch started just for fun to see if I could help this sliding problem, that annoyed me a lot since I love flying helicopters. The code isn't very clean and it still have a problem with moving platforms. The problem is that I have to keep the stuck point moving with the carrier but the carrier "update" is not on the same frequency than the FDM "update". I have tried to extrapolate the carrier position using it's speed and the dt but there was too much jitter, maybe because errors in the dt? I couldn't find the source. It is working well on land though. Maybe if someone with a better insight on the internals could give me a hint on how I could get the "updated" carrier position from the FDM, then I could finish this patch. If someone wants to try it I can try to clean it a little bit and send the patch. I will just need some time though since the patch is abandoned in my local copy and I will have to refresh my memory. At least it is working with the latest CVS revision. Regards, Diogo Em Seg, 2009-02-02 às 18:43 +0100, Melchior FRANZ escreveu: > Ever since helicopter support was added to the YASim FDM > there's an annoying bug: even when parked, with rotor off > and braked, helicopters slide happily around on the ground. > > Andy knows about it and explained why it happens, but claims > that there's nothing to be fixed in the FDM code. Instead, > he suggested to place masses and weights "appropriately" in > the FDM config. Then the sliding would stop. > > I've spent many hours on that, without success. And I even > doubt that is works: after all, there are adjustable pilot > and passenger weights, different loads (MG, missiles, etc.), > changing fuel level. So, how could one find a working mass > distribution for all these different states?! > > I've tried a lot of other things -- most of it were ugly hacks. > Different gear (skid) parameters, masses that would only > get activated when the helicopter is parked, thrusters > that would counter any movement, thrusters that would > press the helicopter down. Nothing worked. (Oh, and I tried > to fix the gear code itself -- without success. Not that > Andy would accept a patch, I guess.) > > A few days ago I found the best remedy so far: a thruster > that *lifts* the helicopter when it's parked. This stabilizes > it a lot, though when the rotor spins, all the sliding is > back. > > Has anyone ever found a solution to the gear bug? Something > that's not a hack? (I'd accept an alternative FDM as well. > What about JSBSIM? :-) > > m. > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by: > SourcForge Community > SourceForge wants to tell your story. > http://p.sf.net/sfu/sf-spreadtheword > _______________________________________________ > Flightgear-devel mailing list > Flightgear-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/flightgear-devel ------------------------------------------------------------------------------ This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
