Andy Ross <[EMAIL PROTECTED]> said: > 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.
It isn't tedious at all, we can offset the origin to where we want without messing with the ac file *and* it won't affect the animation. The reason I put it where it is now is because placing it in the cockpit put the main gear in the water. The A-4 could be changed easily, just hadn't thought of it ;-) Having the FDM origin at the center of gravity should improve the appearance of the 3D modeling since pitching of the model would appear more realistic. That said, I still think there is something not quite right. If you move the 3D model it just flips the tail up higher. It could be that the brakes are too good. If you locked the wheels up at 40kts the 747 _maybe_ would stop that quickly...not sure. It is quite a mass, as you know. Flipping the tail up in the air might be exactly what it would do in that case, but the tire tread would need to have a hell of a grip. Anyone have a real 747 they can try this on? :-) Best, Jim _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
