Rapid-prototype work for the Traxxas project is done with paper-modeling techniques. Paper is a relatively low-cost way to validate the LMP body design as well as the underlying chassis model and all its various hard-points and clearances. Getting the chassis model right is important as it will serve as the basis for additional design projects.

Pepakura helps unfold 3D CAD geometry into the flat forms of a paper model across several letter-size sheets. Pepakura takes the data, recognizes reasonable panel splits for shapes to map into a flat paper form, and provides tools to adjust and manipulate the tabs and joints.

[ screen cap from pepa, with meta in background ]

The build takes some time but quickly reveals any errors in dimensioning or fitment issues. As I'm just working with paper, I can easily modify parts and translate the changes back into the CAD model. And actually seeing a model in real 3d provides a perspective on the design that just don't appear in the abstracted world of CAD.

The rear bodywork split to allow for the wing struts is quite complicated. I'm not confident this could be done well enough in Lexan to be both structurally sound and fiddle-proof.

There are a few fitment issues to work out... Front tires rub the fenders at full steering lock and the battery wires are still a problem. The bodywork will need to be raised up above the rear suspension to clear the wires, requiring a roof re-profiling. If I'm going to do all that, I may as well continue moving the cabin forward of center to add some visual 'length' to the ultra-short wheelbase.