Quote:
Originally Posted by hat_man
I'm not exactly sure it's called a Bonneville spoiler, but I thought I had seen a picture of what I'm thinking about in a thread here years ago. Searching "Bonneville spoiler" didn't turn it up so.........?
This is probably more of a mental exercise, but I don't think I've seen it discussed before. Maybe there's a reason for that?
I understand how the half tonneau and cab wing works, with the low pressure zone being transmitted into the bed and creating a pressure difference on either side of the tailgate. But most tailgates come up short of the "template". I had seen pictures of a bed cover "extension" that went beyond the tailgate and ended where it would intersect with the "template". Some were even curved like a D with the straight part being at the tailgate.
Would this work with a half tonneau, also? A bed cover that starts halfway down the bed and extends to a point where it will meet the "template"? Would it negate the pressure difference because of it overhanging the tailgate? Amplify it? If I could figure out how to attach a cab wing I think it would be interesting to try. One sheet of plywood first long and squared off. Then long and D shaped at the rear. Then cut down to be even with the tailgate.
Would it work without the cab wing, just not as well?
My old vinyl tonneau has seen better days. The Velcro doesn't hold anymore and the vinyl had to be screwed to the rails. The catches that keep it taught have failed and it is beginning to rip at some of the screws. With my work commute being so long (110 miles round trip) and this job being so long term, I was hoping it might make a good test platform for some "outside the box" ideas. It's an old Ranger, and I won't mind drilling a few holes in it here and there. LoL.
Any thoughts on this tonneau idea?
|
1) for the 'Bonneville' spoiler you'll want to look at HOT ROD Magazine's Project Red Hat Camaro, GM's 2006, Chevy Cobalt ECOTEC Bonneville race car, and Ford's 2007, Fusion 999 Hydrogen LSR Bonneville race car.
2) they all use a form of the 'Bonneville' spoiler.
3) all the spoilers terminate along a 'template' contour.
4) the spoilers reduce drag, reduce lift, add high spe4ed directional stability, and provide a more turbulence-free wake in which the drogue parachutes can safely deploy.
--------------------------------------------------------------------------------------
5) GM's patented half-tonneau was based upon the pre-1986 C-10, long-bed pickup. The top of its tailgate happens to coincide with the 'template.'
6) This truck was Cd 0. 535.
7) with the half-tonneau it was Cd 0.491.
8) with full-tonneau, Cd 0.513.
-------------------------------------------------------------------------------------
9) For Texas Tech's 1988 SAE Paper, they used a circa 1987 F-150 long-bed and short bed.
10) As your memory is 'good', the combination cab-wing, plus half-tonneau was almost as good as the GM' 'aeroshell', delta-18% vs delta 20% drag reduction. Around 60% of rear lift was killed.( for the long-bed ).
11) Optimum wing 'size' and angle depended on bed type/ length.
--------------------------------------------------------------------------------------
12) All modern low-drag concept cars are using aft-body contours close to, or dead on the 'template' contours, depending on 'aggressiveness.'
-------------------------------------------------------------------------------------
I don't have a 'blueprint' for your Ranger, so I don't know it's particular architecture.
For a first approximation, you might start with a wing and cantilevered half-tonneau which mimicks the contour of the #3 'template.'
RIVIAN is using it, and until CYBERTRUCK hits the market will be taking top honors for lowest drag pickup.
If you want to get laughed at, you can add a 'blister' on top of the half-tonneau, to fill in some of the vortex void above it. AeroStealth and I tested one back in the 90s on SPIRIT, and it showed the highest mpg increase, short of a 3D aeroshell.
A 'wing' will help by itself.
Same for the tonneau.
Both together is better.
I'll check at home for the wing lengths. Maybe have them Thursday.