The spline modeler describes shapes in a vector based format, much like an eps file. The mesh modeler is a data base of x,y,z points in space. You can translate from spline to mesh but not vice/versa. The spline model is a smaller file, is scaleable and better for curvred (or organic) sahpes. You can import your wing drawing for the basic shape and play with the envelope descriptions for curves etc, it takes some time to get the "feel" of it. Best thing to do is re-read the manual on the spline modeler & then open up some of the models that are on the CD, ungroup them and "jump-in" on the elements to see how they were made.