Today’s Concept: Connective Airflow.

Quite a few additional aero-mods: let’s look at the nubs along the roofline.
The windshield’s transition to the roof is a major point of lift/drag. Connecting airflow back to the truck is the issue. These rip at-speed above the windshield-stalled air, activating the airflow above the truck mixing out the stalled/reversing air. Big pickups sometimes have a forward jutting roofline “visor” with slots acting like a front wing, arresting the upward flow and directing it over the roof. This is my removable innovation for a similar result. >update= we had a slushy snow of a few inches that froze overnight, then used the truck for a few errands with the ice/snow on the top…about a foot behind the nubs the snow/ice was obliterated by the connective airflow, with a bit of a “windfence” roll of snow just behind the nubs. So it works!
These are special magnets with rubberized feet for cars, used for applying vinyl car-wraps. I cut the handle down to just emerge from the area of stalled air, and shaped it to cut into the air at speed above the truck and spin it down to reactivate the stalled airmass. I hoped it would keep the air flowing far enough to jump to from the cab to the shell, and it seems to have done so as the air-noise from that gap is gone.
The line at the windshield is complemented by the line of Air Tabs at the back of the shell.
These little gizmos were created with Nasa and the U.S. Department of Transportation back in the 1980’s for Semi-Trailers. Each one creates a paired vortices spinning in unison toward each other. Placed forward on a vehicle they create connective surface airflow, acting both as a lubricant against stalled air or “dirty” air (weird flows created by forward movement, tirespin, engine heat, etc). Placed at the rear edge they help create a clean break for air from the square back end, helping lessen lift, and also (there is some questioning by online aero-experts of the next part) interrupting the pocket of drag and stabilizing the rear end.
Many people note that their rear windows stay clean with the air tabs, demonstrating that the stalled/backflow of air has been broken and pushed away from the truck This may even improve gas mileage at highway speed, as some light truck owners anecdotally confirm. As speed increases, drag becomes exponential, squaring at every 5mph increase past 65, and getting crazy from 75-80. This is where they should really perform, and 75/80mph is where my mpg usually tanks, so it should be an obvious difference on our MT trips.
I’m only putting them on the shell for now, and they need a 5″ long flat space that is at most 12-16 inches from the rear edge. I had to jump from the shell to the windows. I ordered them black, and painted some of them to match the truck. On today’s test drive we headed out into a stiff headwind toward the Great Salt Lake, passing semis with no “blowby” from the windshear (one of the air-tab benefits), and experimenting with acceleration, coasting, and alignment/tracking. All were notably improved.
Placing them on the front bumper ahead of the front tires helps the unstable air at the tire and wheel well, and may reattach air to the side of the truck as well. New trucks and cars have this built into the bumper.
The airflow under pickups is always problematic- a “dirty air” mess where the stall force at the back of the vehicle can move all the way to the front, and any back-flowing air is disrupted by all the big under-hanging parts and gaps. In my imagination, these front air tabs will help. I also did something that is actually proven to help: I set foam (black) to block out any front facing gaps- with the magic of magnets! Prior to this at 70mph a roar started, became a clear low note at 75 that I could set my pace by, and faded out after 80. Gone now. I used magnets so I can remove them in the heat of summer if the lessened airflow effects the radiator’s efficiency. If I’m not hauling anything, the current opening should be fine.
This is a gap looking down on the bumper, which weakened air-ram to the radiator.
I removed the three foot whip antenna for the radio and replaced it with this 7″ stubby.
Someday, we’ll head back to the ranch and find out the full benefit. I’m hoping our 130 miles of 80mph interstate section of UT-ID sees better gas mileage. I hardly have to touch the gas now to keep her around 80. I know from today that even driving into a stiff headwind it is more stable, smoother, faster on acceleration at speed, and much quieter. E notices all these things as a passenger as well.

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