Yeah, think everyone is over the dimples, just put it up as I thought they had some interesting comments on why they sometimes don't seem to work.
If you just want to push a box through air, then the detail isn't that important, but if you want to streamline that box, then minor details are crucial.
That seems obvious to me with the number of discrepancies in drag reduction from different mods by different individuals, so for my part I am trying to understand the detail. Better to waste my time on the computer in comfort than waste it along with fuel doing A-B-A testing on a poorly designed modification.
Anyway, regarding the Cortez, didn't mean to be disrespectful, I do get "foot in mouth" occassionally.
Don't know what your greater plans are, but it probably comes down to considering what your options and goals are, purchase price is irrelevant as that is history and is wrapped up in emotion which doesn't make for good financial decisions.
If you want an RV, then restoration may be a viable option, if you need a utility vehicle, then conversion may be viable, but this should be costed fully, most of the time it will go well over costed budget and may be more than just buying a truck, etc. etc.
As for the shapes, yes that was the list I was refering to.
Pity they don't have the half sphere backwards to compare it, but the cylinder forms further down indicate some of this effect,
Flat circular plate = 1.17
Cylinder ratio <1 = 1.15
Cylinder ratio >2 = 0.82
So same frontal and rear profile and a reduction of 30% roughly in the Cd just because of the extra length. The only thing that I can put that down to would be the developement of a thicker boundary layer and hence a subsequent reduction in wake size.
Or maybe the extra length allows for reattachment of air blown out by the bow wave, resulting in the creation of turbulent lobes that are contained either side of the forebody and virtually simulating a teardrop shape?
Most vehicles are way short, so if you improve frontal flow, you just tighten the boundary layer, you don't have the length to get the benefit of reduced skin friction, but you suffer the penalty of a stronger wake.
With a longer vehicle you do have the potential to gain a benefit from reduced skin friction, but the question is whether the thinner boundary layer will result in the same negative impact with the wake.
Irrespective, it seems to me that they may need slightly different approaches to gain the maximum benefits.
I found the post below which also had a little bit of info in the diagrams posted.
http://ecomodder.com/forum/showthrea...pes-11183.html
Now, overall there is no denying that most of the information indicates that there is a far greater benefit in tapering the rear, and in most cases the front effect is minimal, but in some cases I think the front has a much greater bearing on the overall outcome particularly with longer vehicles like vans.