Velomobile Fairing

I was thinking about different methods for building the fairing that might be more easily shaped for an aerodynamic benefit. One method would be to use a foam core that is ruff cut to the desired shape, fiberglass and smoothed. Here is an example that shows someone using foam to shape their bike's exterior in foam. http://www.wisil.recumbents.com/wisil/barracuda/barracudafairing2.htm

Another method would be to build foam ribs and fasten thin strips of foam across the ribs to for the outer shell. A really good example is here: http://www.adventuresofgreg.com/HPB/2006/12/dec-4-2006deck-covering-until-just.html

I think both ideas would work. The rib method would probably be lighter than leaving all the foam in the velomobile, but the extra foam would allow for more impact resistance in the event of an accident. I have to way the difference in safety for weight. The weight penalty should be minimal and this is supposed to be a commuter velomobile.

Velomobile frame drawing

This is what my main frame idea will consist of for the velomobile. Two pieces of plywood that run parallel to one another. Then bulk heads made from 1/4 inch plywood and about two inches thick will be made to construct the shape of the sides. The front will most likely by formed in foam to allow for more curvature. I plan to router 3/4 inch groves out of the plywood bulk heads to run more thin strips of clear pine. The thin strips will be flexible enough to blend around the bulkheads.

After the strips of pine are attached an 1/8 inch thick strips of plywood will fill the void between strips of pine. This will give the final outline of the velomobile. Epoxy and a filler material will be filleted along the bulk heads and finished with a layer of fiberglass.

I am looking for a way to draw to scale on the computer. I am researching google sketchup because it is free. I hope to find something more suitable soon, then paint for the velomobile project.