[hat_man]

Hello again everyone.

I am enjoying reading my new book (Aerodynamics of Road Vehicles) and found the chart we have all seen on the aerodynamics of pickup trucks. I currently have a Ford Ranger with a soft full tonneau. According to the chart, there is a large gain (reduction in drag) to be had from adding a cab spoiler/wing as long as it attempts to fit the template. It only shows this with a half tonneau.

Does a spoiler/wing work just as well with a full tonneau (and didn't need to be drawn on the chart) or is the half tonneau the only want to see that amount of drag reduction? How does the extra cavity behind the cab from a half tonneau affect air flow as opposed to a full tonneau? Does it draw the flow downward to more approximate the template?

I would like to keep my full soft tonneau as it comes in rather handy and it's much better than the open bed.

The other question I have is regarding the type of spoiler/wing on the chart and how it may compare to something like a full aero cap cut in half. Something like this but shaped to better fit the template. For me it would allow better rearward visibility without having to engineer a weatherproof window to keep things dry. And if designed right I could still keep my soft tonneau.