Russell Suter > David Megginson wrote: > > > Andy Ross wrote: > > > >> I'm not sure exactly what this is for. I can (and > probably should) > >> export the C.G. position for the view code to use > appropriately. But > >> the VRP stuff seems like a double-correction. It's basically > >> identical to the view center offset stuff, isn't it? > > > > > > It's the location on the plane where the FDM reports the > lon/lat/alt. > > It's kind-of a nifty idea, actually. > > True, but... This is a chunk of calculations running every > frame. In > the olden days, the cost would be > too high. Our Aerodynamic modelers always seemed to know where the > empty weight CG was every > frame without additional calculations. That said, we made > the graphic > artists translate the visual model > such that the 0,0,0 point for the model was the empty weight > CG.
That's what I did for the Hunter model - seemed to make sense, and I could readily derive the CofG from the YASim calculations. I was aided in this decision by the fact that the CofG of that aircraft does not move much as fuel is consumed. That said, it's marginally easier to draw the model with the origin at the nose, and then move it. (not offset - just moving it in the drawing package). It seems, from a visual point of view, equally valid to leave the origin at the nose and to offset the views. Is the a technical reason to prefer one or other choice? What is clear from all this discussion, that to use the nose of the 3d model as the origin, and not to adjust the views to the CofG will produce the visual impression that rotations are taking place about the nose, even though the FDM's are of course rotating about the CofG. I remain disconcerted that the visual model appears to roll through 180 degs vertically on the up and down legs of a loop when in chase or helicopter view. Not the end of the world, but lacking realism. If you are not confused by now, you don't understand the problem. Vivian Meazza _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
