Quote:
Originally Posted by Big Dave
Just who I wanted to hear from.
Which do you think is more important: maintaining flow attachment or reduction of wake area? Sure, we'd all like to do both, but I only have 80" of "run" to reduce 24" of "delta-y."
Would it be better to have 10 degrees and 12 degrees and the top of the thing 9" above the top rail of the tail gate or rather going 10/12/14 degrees and the top about 7" above the rail?
This is an interim for me follwing shooting off my mouth. Ultimately I'll make something like Bondo's fiberglass bed cover but I intend to build in a couple of faired in hard points for CCTV cameras. Here in Indiana I may be able to get an exemption from the requirement for side mirrors and my truck's mirrors are huge.
First things first. If the removable tarp thing works out I may do a side business selling to the driveaway guys. Then the hard cover.
The goofy fixed fairing I have (see garage) actually does very well at improving MPG. Its just not bed-user friendly.
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Big Dave,Kamm and Korff and all the other heavy-hitters insist that its more important to maintain attached flow.On his K-cars,Kamm never exceeded 10-degrees of roof slope.He could of,as Mair would later demonstrate.And if you look at pics of the K-cars,the roof does not descend a great deal before its chopped off.The trade-off was good rear visibility,good rear headroom,and a drag coefficient close to that of the full-boat-tail car.If the bed cover slope starts out too radically,the flow will immediately separate.It may re-attach somewhere downstream,however your fuel is wasted feeding that rotational energy which cannot be recovered .I did a post on "Rooflines" as one of my recent installments here in the aero section of ecomodder.I think you'll find it of interest.Much luck with the project,like what your doing,Phil.