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Old 02-02-2012, 07:15 PM   #38 (permalink)
aerohead
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radius

Quote:
Originally Posted by ChazInMT View Post
No, this to me is like showing how the rear window on a Model T might work, almost all modern cars (after 1990) have a radius there at the top of the rear glass, this looks like a study in roof to rear glass with no radius. Could care less about Pinto Aero....

But fer sure thanks a ton for finding this bit here, it just wasn't the thing I remember. The diagram had Radius as the variable, not angle.
In Hucho's book he has eleven graphics depicting Cd as a function of 'sharp' angle roofs.
The last,Fig.4.59 shows optimum angles as a function of length of rear portion of the car.The table shows five different optimum angles for five different lengths.So if you're unfortunate enough to have a roof like this,then you could construct a curve from this scatterplot,and using your own dimensions,find your best angle.
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Directly following the sharp-edged roof section is Buchheim et al ' work on rounded rooflines.It is this work from which Hucho selects 23-degrees as the maximum recommended slope angle,as is depicted in Fig.4.60.
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