T-100's still dead so I continue to grind on the calculator:
*I've down-graded the trucks 'high-altitude' 31.894 mpg down to 28.484 mpg at 'standard' air density.
*Working with some weight-penalty curves from RICARDO (Consulting Engineers,Ltd.,England)INC.(online)I've adjusted for the 820-pound travel weight liability,adding back 0.523 mpg,for 29.007 mpg.
*Then,from TABLE 2.10,'Excess Gasoline Consumed per Stop or Slowdown Speed Change Cycle-Automobiles,' by Paul J.Claffey,National Cooperative Highway Research Program,Highway Research Board,Washington,D.C.,1971,and adjusting their 'composite vehicle' values to dovetail the T-100's,@ 0.012518 gallons/stop cycle X 8-stops for the Salt Flats-Carson City-Salt Flats segment;I pick up a 1/10th of a gallon dividend,pushing mileage to 29.189 mpg.
*This mpg reflects a 40.275% Delta MPG.
*Which (extrapolating from Kelley&Holcombe) yields 63.626% drag reduction.
*Or,36.374% of original drag remaining,yielding Cd 0.160.
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Segregating the body from the wheels gives:
*Body frontal area= 27.795 sq-ft (2.688 sq-m)
*Wheel and tire frontal area (allowing for front and rear track)= 1.129 sq-ft
*Total frontal area = 28.925 sq-ft.
*The original turbulent wake of the truck is essentially equal to its frontal area.
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If I begin to 'shrink' the body without changing its shape,while maintaining the wheels as a constant,when I get to the configuration with the 30" boat tail,the wake of the transom and wheels is 10.872 sq-ft,or 37.58% of the original.
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From the drag force and power formulas,by reducing the T-100s 'signature' from 28.925,to 10.872 sq-ft is the same as reducing the Cd from 0.44,down to 0.165.
*This Cd 0.165 is in close agreement with the Cd 0.160 we get from General Motors CdA/mpg relationship.
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Technically,to do a full accounting I'd need to include 'curve-resistance' and 'grade-resistance',calculate losses from cold-restarts in Winnemucca and Carson,City and a myriad of meteorological affects which are just completely beyond the realm of a simpleton like myself.Same goes for coastdowns.
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It does appear that we can use some of the simple relationships to 'rough-in' predictions before we begin mods.
And it looks like some of the 'vintage' numbers,published so long ago acquit themselves quite nicely even by today's metrics.Especially Klemperer's, which turn out lower than when initially published in 1922.
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Cd 0.13-0.12 looks real 'do-able'.
It's going to come down to a corollary of the old racing adage of Q-'how fast can you make my car go?
A-'how much money do you have?,to:
Q-'how many miles per gallon can you add to my car?
A-'how long of a tail can you tolerate?
