[aerohead]

Originally Posted by ByDesign

Fun to see the bantering here . . . some of you have a fun sense of humor. Thanks for making me smile.

On aerodynamic shapes, size and speed are really important factors. RC cars were mentioned -- but the speed and size make aerodynamics far less important. (Basically if you have no frontal area, the CD becomes moot.) Similar with Solar vehicles -- at least classically -- they travel at much slower speeds than you'd design for in an automobile. Their big thing is trying to make every last watt count -- and from what I've seen, the biggest advantages are in the mechanics and internal electronics, even the cells -- not the 1/2% difference in aerodynamics. (That's not to trivialize it, just to emphasize there are so many important factors.)

As we compare to production vehicles, there are production and economic and all sorts of other considerations that enter in. Even as trivial as customers that want to see out the back window so they lower the trunk even though it's not ideal aerodynamically. Or, a 7 passenger vehicle -- hard to drop the rear roof line when someone needs to sit back there -- and no sense in making a long tail if a customer can't park in the garage. For one-offs, like us, yea, but not for production.

Generally, you can take any smooth foil shape and use it -- stretch it proportionally -- to meet the need. Longer for higher speed. Any smooth, continuous, convex surface will be better than one with interruptions, discontinuity or concavity. So many times I've seen results of weird stuff just works in the isolated situation and logical stuff fail. If you want to be very exact, there is no substitute for wind tunnel testing.

Per ChazInMT, what are you doing? That will make a big difference with respect to shapes and templates.

Here is a road load horsepower curve Honda published for one of the WSC -winning solar racers.You can see that at highway velocity,the majority of power is going to overcome aero drag.And this is a 'car' with Cd 0.10