Interesting read on pickup truck aerodynamics.

[Frank Lee]

Originally Posted by Big Dave

This would militate toward the sloped sidewalls of the GM Avalanche.

Huh?

[Ryland]

Originally Posted by Frank Lee

I suspect they did not get high for aero; they are high because of the ginormous wheel/tire packages driving the entire chassis up. The cabs are higher too.

Right, the bed is not deeper if you are standing in the bed of the truck and I don't think that the sides are all that much higher if you look at the ratio of cab hight to bed side hight, it's not like trucks are getting cattle panel sides.

[t vago]

Originally Posted by Frank Lee

I suspect they did not get high for aero; they are high because of the ginormous wheel/tire packages driving the entire chassis up. The cabs are higher too.

It's possible for that reason, too. Certainly, larger tire/wheel packages do not help with aerodynamics. I suspect, too, that these new trucks also have lousy undercarriage visibility that contributes to a higher than necessary C(d).

However, the new truck profiles appear to fit more neatly into that teardrop stencil as a result of their higher bed heights. While the cabs themselves are higher, the truck fronts also look like the trucks gorged out on sheet metal and plastic over a holiday season.

[Frank Lee]

Let's see the overlays...

[Big Dave]

Solving the trig problem on my 24" deep bed with the cab top sitting another 24" above the bed rail, I came up with a 11 degree slope that stayed 8" above the tail gate.

My old bed cover was too steep (17 degrees) hitting right at the top of the tailgate, but it sure beat a flat tonneau.

If the bed were 8" deeper, a straight angled cover would have been just right.

[Frank Lee]

Ahhh, here is why they keep getting taller:

I wish the F-150 weren't so tall. I recall when I first saw the face-lifted F-series a year ago at a Ford event in Dearborn, one of the engineers boasted that they had increased the ride height by an inch, because dealers told them that many buyers were paying the dealers to put lift kits in their trucks anyway. You know, sometimes car companies should not cater to stupid people. You want your truck to ride an inch taller for no good reason other than that you want to tower over the guy next to you at a stoplight? Then pay your dealer's service department to install the lifts. Let the rest of us drive trucks that are a little easier to get into and out of and that have the aerodynamic efficiency advantage of a lower ride height. Jeez, the optional bed step with the recessed grab handle in the tailgate is cool, but it shouldn't even be necessary.

2009 Ford F150 - Nicely Tailored Cabin - New Ford Pickup Truck Review | 2009 Ford F-150 Review at Automotive.com

[Frank Lee]

I put some of that gobbledegook into real units:

If model was real it would be a truck 196" long (short box), 208" long (baseline), 219" long (long box) x 72" wide x 66" high.

Baseline bed height (I think it should be called bed rail height because the bed floor height does not change) = 18"; low rails are 10"; high rails are 26" above the floor.

Bed floor is 28" off the ground thus making bed rails 38", 46", and 54" off the ground.

Baseline bed length is 81" (6.75'); short bed is 69" (5.75'); long bed is 92" (7.7').

I have to admit, I don't completely comprehend the figures that purport to show flow vectors. The units and proportions don't make sense to me- is the tailgate a foot thick or what? The flow patterns don't all follow the "rotating box vortice" that in the past I was led to believe all pickups had. The oil tracers all look the same to me as well.