[swede]

Thanks for the comment aerohead.

The first real highway run I did was this weekend and I had no way to see air flow over the top of the lid but the drivers side I could see out of my side mirror. I attatched tufts and observed the air flow that followed the contour from the b pillar of the cab and around the leading edge of the cap. I observed a little flow disturbance right at that edge and as the air continued along the cap it had a definite upward flow toward the top of the cap. I'm not sure if this is normal or even desirable on an aerodynamic cap like this. The other factor that may have skewed any real flow observations is the fact that I had a 90 degree crosswind coming from the passenger side of the truck during my drive.

I know that the angle looks steep but when measured from the beginning of the curve to the end at the tailgate with and angle meter, I have 11 degrees of slope. This is well within acceptable limits from what I understand.

The radius of the angle change from the top plane of the cab roof to the slope may be a little on the steep side but tuft testing with a chase/observation vehicle will tell.

One Question:

When tuft testing, are the tufts supposed to flow straight back with no movement along the surface of the substrate, or do they sometimes move side to side along the surface while still laying parallel to the substrate?