[NeilBlanchard]

George,

I understand your question now -- it is my understanding that the template is completely scalable in size; and it "works" up to ~250MPH.

Look at the template. It is one part, and one part is better than multiple parts, all else being equal. Two parts of more mean there is some additional interaction. On the classic Jaray two part body, the lower main part is what initiates the movement of the air, and the second part is then working within a "pre-pressurized" zone, and the air that has already been moved is then forced to move outward more. The air "wants" to return to it's original pressure, so it will flow towards where ever there is lower pressure.

The profile of your two part design is pretty much cab-forward, so in that direction it would act like a one part body. But because the second part is narrower in plan, some of the air that would have gone up over the roof moves instead to the sides of the second part; because the pressure is lower there than it is at the top of the roof.

This may or may not be better than if the roof extended to the sides of the car body, in terms of Cd; though it would add area. It would add interior room, and if the Cd was lower, then this might (more than?) offset the greater area.

Or think of it the other way around -- narrow the sides of the car in towards the passenger compartment. This simplifies the air flow *and* greatly reduces the frontal area.

If you think about the function of a car -- carrying people -- then a two part design like the Maybach Stromlinienkarosserie or the Porsche with their relatively tiny interiors don't make as much sense. Compare the Maybach to the Schlörwagen -- 2 seats vs 7 and you get my point. Neither is a small car, and the Schlörwagen is very wide and probably has the greater frontal area, but it also is better at a car's primary function. If 7 is too many, then scale it down. Most of the Maybach's frontal area is just for the car itself.