|
If I remember correctly, and I can't recall or find the proper thread, Phil has said that the template was a safe conservative way to lay out the taper. He never spoke to the amount of deviation that would produce significantly degraded drag. It is pretty clear to me in looking at many modern cars that even the dedicated manufacturers are using slightly steeper rears than the template predicts. Examples are the Insights(both), the Prius, the Fit and any number of others.
I think that what may be happening is that manufacturers have wind tunnels, and we don't. They are testing their shapes in detail and we can't. From an earlier tuft test on my Insight 1 it is clear that there is some slightly turbulent flow across the rear hatch, but the flow is still attached. Honda obviously made a compromise that they felt was not overly costly, and probably produced the lowest drag vs. dozens of other factors such as total length, interior room, weight, visibility, aesthetics, styling, etc. - all factors that a "real" world car manufacturer must consider. Who can argue with their results? They produced a street car that had the lowest Cd available for many years.
I suppose the real question, the one that interests me, is not where perfection lies, but rather, what is the aerodynamic cost of deviationg from the ideal, and how quickly does that cost mount?
|