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Old 06-11-2015, 04:34 PM   #66 (permalink)
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Originally Posted by Sneakybassturd69 View Post
Should the sides of the bad cap taper towards the end , if so how much, a foot by the time it gets to the end ?
That's a very good question,and after the wind tunnel experience I'm not sure what to recommend anymore.
If you're NEVER going to add boat-tailing,then my opinion is to go ahead and give plan taper to the sides.This would be a safe contour for the sides

VW went ahead and tapered the roof on the XL1 and it ends before the back of the car,so an owner could,conceivably add a little elongation if they wanted

IF you plan to ever add boat-tailing,then I think the plan-taper of the shell only might 'wrinkle' the flow.You'll have a downwash off the 'roof' which is opposed to what's happening around the rest of the bed.You can see what I mean in this photo.

For the trip back to the wind tunnel in 2016 I'm going to kill the plan-taper of the bedcover,and instead,starting from the rail tops,allow a new fairing to just 'tumble',from the cab rear,increasing tumblehome as it proceeds rearward,spanning from the rail to the upper edge of the bedcover.
When to the rear,I'll have a more uniform flow pattern for the onset flow over the new tail.
I don't have a drawing.Sorry! Here's the idea.

The ideal aft-body would be a new truck bed which begins plan taper just behind the cab,beginning the camber necessary for real drag reductions even without a boat tail extension.
On your VW you wouldn't be able to do this easily,as it's unibody.whereas I can just unbolt my bed and toss it.
Photobucket album:

Last edited by aerohead; 06-11-2015 at 04:43 PM.. Reason: add image
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