Hi all, When putting the default c172p on a 'gravel' runway, like say YGIL:33, after a number of seconds the aircraft 'tilts' slowly backwards...
And it will also happen on a reset... and can happen after applying heavy breaking on the gravel. And there seems no particularly relevant output to the console when it happens... It is very hard to get a good view of it, but in studying what I can, it looks like maybe the two rear wheel 'sink' into the gravel, while the (nasal controlled, I think) front wheel either just touches the surface, or even comes to rests 'above' the surface. While the tail of the a/c sinks down, the tail does not appear to actually touch the ground - I suppose about a 5 degree nose up attitude... I have never seen this on other runway surfaces... even on the default YGIL:08 which is 'Dirt'! Starting the motor, and moving forward a few feet will right the plane - bring it back to an even keel... if you are careful with the brakes... It looks like the nasal that controls the front wishbone type suspension, is over straightening the wishbones, for some reason, but not sure... especially when it looks like the wheel is above the surface... When in the 'normal' flat position, the black wishbones look to be at about 60 degrees, while in the tilt-back state, it looks closer to 90 degrees! Perhaps the best screen shot is this one - http://geoffair.net/tmp/tilted-001.png and this is after moving forward... http://geoffair.net/tmp/tilted-002.png back to level... And it does not happen if I drive the plane off the gravel onto the grass beside the runway, so it does seem related to the 'gravel' runway surface. http://geoffair.net/tmp/tilted-003.png This started some time back, I think around the time of the last JSBSim sync... but not sure. I do not think it was in 2.0 for example, but will recheck this... It happens in both my own Ubuntu build, from a recent git 2.2.++ update, and in Fred's WIN32 setup 20110207.exe, where the above images were taken. (Fred, thanks for a great simple WIN32 installer by the way ;=), and the terrasync pre-fetch is fantastic!) The only likely place I can find is in c172p/nasal/action-sim.nas, where it comments # Compute the scissor link angles due to \ nose strut compression which looks to be the problem, but have not tried changing anything, mainly through lack of understanding on what is done here... especially how the type of 'surface' comes into it... Not really a 'big' problem, but quite annoying just the same... it makes the Cessna feel like a tail dragger ;=)), but as mentioned, the tail does not actually touch the ground. You can not see if any kangaroos are crossing in front of you... Any help to get the plane to rest 'properly' on this gravel surface would be much appreciated. Regards, Geoff. ------------------------------------------------------------------------------ The ultimate all-in-one performance toolkit: Intel(R) Parallel Studio XE: Pinpoint memory and threading errors before they happen. Find and fix more than 250 security defects in the development cycle. Locate bottlenecks in serial and parallel code that limit performance. http://p.sf.net/sfu/intel-dev2devfeb _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
