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Old 06-01-2013, 03:48 PM   #560 (permalink)
aerohead
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Testing

Wind tunnel testing for the 'Template' was originally conducted by Wolfgang Klemperer in 1921 at the Zeppelin Werkes.
It's been re-tested by various aerodynamicists throughout the decades since,including Hucho.
This 'original' 'Template' is the Jaray half-body,derived from an airship hull.
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Hucho uses Jaray's roof contour as a benchmark for boundary layer integrity and separation-free,attached laminar flow.
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Roof contours steeper than Jaray's roofline are what Hucho refers to as 'pseudo-jaray'.These roof contours produce separation and very strong attached longitudinal vortices of remarkably high drag.
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The 2.5:1 'teardrop' from which the AST-I&II are derived are well-tested and produce Cd 0.04.
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The 5:1(effective fineness ration) half-body derived from the teardrop is well-tested and produces a body of Cd 0.08 in ground proximity.
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When wheels.tires are added to the half-body,the drag increases to Cd 0.12-13,depending on tire width.This has been well-tested.
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When wheel fairings are employed,the drag can fall well below Cd 0.12.This is well-tested.
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In light of the fact that so much testing and re-verification testing has been accomplished since 1921,it's extremely unlikely that the aerodynamicists involved have missed anything significant.And so,the 'Template' could pass for off-the-shelf technology,nothing theoretical about it anymore.Just waiting to be exploited.
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Any members with Hucho's book(s) will already know that he'll tell you that there a plenty of ways to get to Cd 0.15.If you want to go any lower,then you must extend the back of the body,while reducing its cross-sectional area such as not to produce separation.And Jaray's profile guarantees success here.
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Of course,no production car is circular in cross-section.They don't need to be.As long as any elongation of the body produces only the progressive reduction in cross-sectional area as with the 'Template' there shouldn't be any separation,nor vorticity of any significance.It's structurally impossible.Sectional density is respected to the highest degree.
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And so it's my humble opinion,that we've had enough testing.We've tested the thing to death.And it always delivers the lowest drag (for a car you can walk up to,open a door,and get in or out of,without a bunch of teammates to help).
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