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Old 08-14-2019, 12:42 PM   #8 (permalink)
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turning vanes

Originally Posted by litesong View Post
Can't say about roof racks. But in the 60's, there were "wind guards" with curved surfaces, that were put on the roof top rear of station wagons, to direct air, downward over the rear window that kept the rear window clean.
One extra aerodynamic plus, was the air directed downward, helped kill the vacuum on the end of the car..... & MPG went up.
Such a device would really help kill the vacuum on square-backs. Also, vertical curved surfaces on the rear sides, directing side air into the rear vacuum area would also help lessen the vacuum & raise MPG.
I don't have the most current literature,but Wolf Hucho,who ran the climatic wind tunnel at Volkswagen for a decade couldn't get any of them to reduce drag.
The only thing he actually ever measured a drag reduction with,were either box-cavities,or boat-tails.
The drag behind the vanes always exceeded any potential benefit of 'filling' the wake.
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