[aerohead]

1) ' The optimum amount of streamlining then, is that for which the sum of friction and pressure drag ( profile drag ) is a minimum.'
Fluid Mechanics With Engineering Applications, page- 297
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2) ' The smallest values of the coefficient of parasite drag so far observed are those of well-designed bodies of revolution.'
Theory of Flight, page- 104.
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3) The lowest friction and pressure drag sum and lowest coefficient of aerodynamic drag for a streamlined body of revolution occurs with a fineness ratio of 2.5:1, and Cd 0.0379.
Figure 4.119, page- 200, Hucho, 2nd-Edition ( Re: Hoerner, 1965 ).
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4) If fineness ratio is smaller, pressure drag increases.
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5) If fineness ratio is larger, friction drag increases.
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6) '[L]ow drag can only be achieved when separation at the rear is eliminated.'
Hucho, page- 16, 2nd_Ed.
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7) '[P]ressure drag is the largest component in the aerodynamic drag. Its minimization is the true objective of motor vehicle aerodynamics.'
Hucho, page- 119.
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8) '[T]he optimum shape in terms of drag is a half-body, which forms a complete body of revolution together with its mirror image - produced through reflection from the roadway.'
Hucho, page-15.
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9) The lowest coefficient of aerodynamic drag for a streamlined half-body is realized when based upon a streamlined body of revolution of fineness ratio of 2.5:1, and Cd 0.0758.
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10) The ASTs are each based upon variations within the confines of a 2.5:1 fineness ratio streamlined body of revolution, as contributed from different sources.
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11) A novel feature of the ASTs are that they all remain within their original 'reflection' , with ground clearance 'removed' from the reflected body, rather than through bifurcation and lofting above the ground plane.
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12) Overall drag of the half-body with the addition of wheels will be determined by tire width.
( see ' Tire Width Impact on Fuel Economy,' by MetroMPG, #3 permalink, 3-15-2018, ( Re: BMW 318 ).
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13) By some reporting, contemporary wheel drag of passenger vehicles is on the order of Cd 0.10.
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14) ' A closer approach to the value of the basic body without wheels is only achievable through further integration of the wheels into the body,'
Hucho, page- 201, 2nd-Edition
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15) Integration of the wheels beyond what can be accomplished through active suspension / ground clearance, is addressed in 'The Leading Edge, by Goro Tamai.
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16) Up to a 70% wheel drag reduction via Tamai's presented technology is reported.
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17) The most current AST represents, schematically, the 70% wheel drag reduction technology.
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18) The AST wheel drag reduction technology respects all SAE' approach, breakover, and departure clearance angles.
( Please see SAE Handbook ).
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19) Paul Jaray demonstrated that the peculiar quasi- axysymmetricality of the half-body is not a mandatory condition of low drag, as long as cross-sectional area-per-unit-position along the body profile does not vary, which allows for semi-circular-to- more rectangular section, as long as critical edge radii and tumblehome are respected; facilitating improved space utilization.
( and exo-duct analogue to A.S.H.R.A.E. common practice )
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20) Vehicular length requirement for ultra-low drag, with respect to 'practical' length consideration has already been investigated and active aerodynamic solutions presented, since, circa-1939, by Baron Reinhard von Koenig-Fachsenfeld and others.
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21) As off-the-shelf technology, with the attribution as an 'optimum' architecture for low drag ( Refer to (8) ) , and when applied as a simple comparative tool, it may not be inconceivable that AST profiles could be capable of generating low drag modifications without need of additional R & D, as long as body porosity, or any underbody or wheelhouse corruptions of the basic, simple conditions are accounted for; and chosen AST profile properly integrates into the vehicle's initial aft-body profile.
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22) Results from on-road, Chrysler Proving Grounds, Bonneville Speedway, and full-scale / 1/3- scale wind tunnel testing imply such capability.