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.
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Will be interested to see what method you choose. I've been pondering building an improved enclosed lid for the Quest. I've been thinking of doing a foam master, like your first link. But then doing a negative mold off that; lay up with a thick layer of fiberglass with reinforcements. Then use that as the actual mold.
ReplyDeleteFiguring this might be an easier way to get a good smooth external surface. Also, there's a chance I may end up making more than one (if other Quest owners get interested), so the negative mold would do nicely for that.
However, not so practical for the larger shell of a velo, and for only making one piece.