Originally Posted by gap

You can export UV projections by selecting any 3D model chunk in S3d: in the UV map preview section, match the Width and Height fields with the size of the desired texture, and then click Save and choose one of the saving options. You should repeat this process for all the sub-meshes composing the aircraft.
Altenatively, you can do the same in Wings3D: export the meshes one by one, import them in Wings, select them either in body or in face selection mode, right click on the subsequent AutoUV window and choose "create texture" and edit Draw Options at wish. When finished, look for the generated texture in the outliner window, Images section, right click on it and choose "Make external" to save it in the format you prefer