Curtis L. Olson wrote: > Speaking of gear modeling in the 747-yasim, have you tried getting the > aircraft up to say 40kts. taxiing and then hit the brakes ... there is > clearly something going on with the 747 gear modeling that is not > physically possible ... best seen when viewed from the chase view.
Without having tried it, I assume you mean that the nose dives straight through the ground when the aircraft pitches down during hard braking? That's actually not a gear issue. What you're seeing is a difference in coordinate origin between the YASim description and the AC3D model file. The YASim origin is at the nose of the plane, while the model places it closer to a nominal c.g. at the back of the hump. So the nose of the plane drawn on the screen is actually ~25m in front of the "real" nose as modeled by YASim, and therefore moves more due to orientation changes. You can see a similar effect with the A-4 model. This is tedious to fix, so no one has bothered. There's also the question of whether it should be fixed in the YASim file or the model file. I contend that the nose is a much better origin, since a "c.g." value is meaningless unless you have the mass distribution handy. YASim recomputes the c.g. dynamically anyway based on fuel load and cargo and whatnot. The FDM configurer and the model author might not be expected to have the same c.g. numbers (in fact, they probably never will -- most 3D artists aren't aero geeks), but hopefully they can always agree on the position of important parts of the airframe. Andy -- Andrew J. Ross NextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com "Men go crazy in conflagrations. They only get better one by one." - Sting (misquoted) _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
