I'm going to begin this thread and see if Al can get free to scan 5-drag tables I've put together over the last three weeks.
Walter E. Lay,of the University of Michigan,Ann Arbor,investigated road vehicle aerodynamics in 1933,publishing,"Is 50 miles per gallon possible with correct streamlining?",SAE-Journal,Volume 32,1933,pp 144-156;177-186.
I'm acquainted with Lay's work through Fachsenfeld's book,Karl E. Ludvigsen's SAE Paper# 700035,SAE Transactions,Volume 79,Part 1,1970,p.108-109,and Hucho's 2nd-Edition book.
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Lay used a multi-biometric wooden model of 1137mm overall length,230.7 mm height,and 238 mm width which could be configured with different lead and trailing architectures,allowing up to 16-different configurations
for automobiles alone.The models had softened noses,but other than that,parallel walls,front to back,top to bottom,no longitudinal edge radii according to Hucho.No wheel-houses,only simple wheel simulation. Depending on nose/tail combinations,the models drag would vary from Cd 0.35,to Cd 0.12
Three for 'vans',with drag of Cd 0.86,0,59,and 0.46,depending on edge radii,or lack thereof.
Lay's 'van' research led to a full-scale body with interchangeable components incorporated onto a 'normal,body-on-frame', Cd 0.61,1933 automobile of which the drag could be altered between Cd 0.86,and Cd 0.46,simply by softening or hardening the leading and longitudinal edges.Some contemporaries considered it a practical joke,just as with Fachsenfeld's/Kamm's 'Kamm-back' which 'followed on'' Lay's research.
In 1951,Professor M'o'ller at Germany's Braunschwieg Polytechnic came up
with almost identical values during his experiments with the Volkswagen Microbus.
Lay may have been using the wind tunnel of which the Ford Motor Co. would later use in the 1950s,a low turbulence,1/10-scale model tunnel of 5-ft by 7- ft test section,less than 1% blockage,wall-to-wall ground board,and up to 170-mph airspeed.(50-to-150 mph velocity provides satisfactory measurement accuracy).
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Of interest to EcoModders is the similarity in drag between the 'ideal' nose car,and 'contemporary' windshield cars of virtually identical Cd.This resonates with Hucho's comment of the mid-1980s,that the front ends of cars by this time were sufficiently good,that they would respond favorably to boat-tailing.The "technological feasibility" was not a question,but rather market acceptance,and the value placed upon low drag.This is why I keep doggin; the 'Template.'
Only a 1972 JEEP or HUMMER H-1 windshield could keep a car from achieving Cd 0.12 or lower.
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Al's printing books like a mad man,maybe he can shake free before closing time,hope so.
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PS For the last table,Lay only provided the Cd 0.08 streamline body of revolution in ground proximity.I've shown it in free flight away from the ground at the top,then moving into ground-reflection/mirror-image,then as an attached half-body,a half-body at similar ground clearance as other test models,and finally,with simple wheel simulation,as per Paul Jaray/Ludwig Prandtl,Edwin Rumpler,Fachsenfeld,Kamm,Read,Heald,Klemperer,etc. .)
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