> IMHO it'd make the most sense to put the offset (from the nose or > tail) to the > 3D model origin location into the FDM's aircraft config xml file. This > location should be on the leading edge of the wings and z axis > centered on the > nose as described above. The 3D modeler's could refer to that data for > getting the model right, and the fdm should simply report lon/lat/alt at > *that* location. This is how the YASim 747 currently works and > it seems fine.
Maybe I am off=base on this, or misunderstanding the problem, but in my previous experience with 3D modeling and IRIXGL some years ago one had to be careful where the origin of the 3D model was, and the order of rotation/translation. This is what I interpret your concern to be about. In the past day or two Tony, David, Andy, and myself have moved close (I think) to what the FDM can do to help 3D modelers place the model properly. If we can come up with a standard reference frame for the an aircraft model (insofar as it deals with the FDM), would this help? And since the CG can move during flight, we need a way to have a common "anchored" reference point for both 3D modelers and FDMs. The suggested standard reference frame for FDMs is: =========================== X positive out the tail Y positive out the right side Z positive to complete the system, upward origin as desired or as specified in the manufacturers structural frame, or whatever ... but: KEY: The farthest forward point on the aircraft, i.e. nose, or prop hub, must be specified in the FDM config file, so the relationship between the FDM origin and 3D model origin can be obtained. Also, all measurements are in inches. =========================== I have seen posts to the effect that there IS a problem with properly communicating the origin, and that this problem deals with rotating the 3D model as specified by the FDM Euler angles, but NOT accounting for the fact that the FDM assumes rotation about the CG, and the 3D model rotates about a different point, such that the CG moves improperly and perhaps puts the gear underground or something. Is this correct? Jon
smime.p7s
Description: application/pkcs7-signature
