Quote:
Originally Posted by Chris D.
I've also wondered if adding a slight lip off the back of a flat bed cover helps or hurts aero?
like this..
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The way I see it the lip is only going to help FE on a (very) short bed, or with an abnormally tall cab. The lip would help improve the angle between the top of the cab to the top of the tailgate. Ideally that angle will be between 12-13 degrees. That angle is the steepest angle at which airflow will remain attached at highway speeds. Obviously, there's no bodywork for the air to attach to behind your cab, but the angle is still important, because the stagnant air trapped between the cab and bed will still have to conform to that angle.
So here we have a stock (current gen) Taco. And you'll notice that the angle between the top of the cab to the top of the tailgate is already 12.5 degrees, quite the optimal angle already. No need for alteration there!
So here's a hypothetical short bed Taco (don't know if they actually have beds this short.) The angle has changed from 12.5 degrees to 14.3 degrees, too steep for airflow to remain "attached."
Now, adding a little lip to the top of the tailgate will help to get that angle back to 12.5 degrees.
This is the same sort of idea that's behind the decklid extensions on Bonneville top-speed racers.
