I have added support for a new format to ModelConverterX today, this new format is the AC3D format. It is commonly used by FlightGear for aircraft and scenery models. In the next development release you will find a reader and writer for the AC3D format. There are a number of limitations at the moment:

• Shaded objects are not being read or written correctly. This is because the format does not directly store the normals of the polygons, but only if it is smooth shaded or not. I am still figure out how to interpret this correctly in ModelConverterX.
• Only geometry is read or written, so no animations at this moment. I think FlightGear uses an extra XML file to specify animations, I will have a look at this later.
• When exporting to AC3D I think the axes system used is wrong for FlightGear, so it could be the object is on its side if you import it now. I am still checking this.

Besides that I must say that I tested it with a number of FlightGear models, but I am sure that there are models that have different features and will not work directly. Please let me know if you have trouble, so that I can improve the tool.

I also haven’t tested the AC3D output in FlightGear itself, but OpenSceneGraph can visualize it. I guess I should head off and install FlightGear…