I've got an assembly of an RC aircraft. I've already removed unncessary (for CFD) parts like the servos, motors, etc., but the internal ribs are part of the parts associated with the airframe. I've saved this assembly as a part file, saving all component geometry, resulting in a part file containing a series of body entities. I'd like to turn this overall geometry into a solid, watertight model for grid generation. Does anybody know of a straight-forward approach to accomplish this? I've often used various tricks to do this (do a section view, delete internal faces, knit exterior faces and form solid, etc, use the Combine tool...), but this geometry is too complex to do this using the methods I'm familar with. Ideally, I would form a solid block that contains this aircraft geometry, then use Combine->Subtract to remove the geometry from the block, save the resulting faces, and knit them into a solid, sans exterior block. Any suggestions on how to do this? Unfortunately, I cannot provide the files.