The car rolls on forged Advan GT wheels, 18×11 with a 15mm offset in the front and a 18×12 with a 20mm offset in the rear. The front tires are Yokohama soft compound slicks 280 by 650mm, the rear tires are 320 by 650mm.
For the Pikes Peak Limited Class the amount of aero the car can have is limited under the rules so, yes of course the car could go a lot faster with more aero but under the rule constraints there is only so much that can be done. The car is a flat bottom with the belly pan being constructed of carbon honeycomb. NACA ducts are used to get air flow to parts of the drivetrain and exhausts to prevent damage.
The front splitter is under a lot of scrutiny and the size is limited. It is made out of carbon honeycomb.
Efforts were made to seal up all unecessary holes and to seal the splitter to the bodywork to build up the maximum amount of stagnation pressure over the splitter and belly pan.
The front of the splitter has carbon extensions that act as stagnation plates with a vertical element that also functions as a vortex generator. The notch in the side plate helps spillover air to form a side vorticity that helps keep air from curling under the car and interfering with the underbody aero’s air flow.
The underside of the splitter features two diffusers to enhance lower pressure under the nose of the car. Two NACA ducts pick up some airflow for the front brakes.
8 comments
Great build and write up. One small note is that the vertical strakes on a diffuser limit spanwise flow. Without them, the air will tend to move laterally across the diffuser surface. Obviously, that reduces the effectiveness of the diffuser. Of course, there’s a small drag penalty, but it’s more than made up for in the aero efficiency.
Fun fact: These strakes were first developed for the swept wing jet fighter aircraft. Because the ailerons are generally located near the wingtips (for the maximum moment arm) the control surface on swept wings was losing ability due to boundary layer separation. This was because the swept wing caused the air to turn outward (spanwise flow.) By introducing a wing fence (vertical strake projecting above boundary layer) you limit spanwise flow and the aileron remains effective, so even under extreme yaw angles.
We did it mostly to try to keep the flow attached with a less than optimal angle. We used a pre-made diffuser to expedite stuff. We might redo it later if there is time and money.
Yeah, it’s difficult to know if the flow is staying attached or separating. Obviously, you can’t use wool tufts, because gravity.
Maybe you could make your own ‘flowviz’ paint, but I think that gravity would make that difficult, too.
Not many good options without a wind tunnel. And no reason to spend $$$ unless you know it’s going to work.
Also, the front end should always see the bulk of the aero effort. If the front isn’t working properly, then it won’t matter what you do at the rear. The flow will be turbulent by then, anyway.
Best of luck on Pikes Peak.
page 5 pic 1
it looks like there’s what looks like a delrin bushing on the knuckle between where the tie rod and LCA connect to it. From what I can tell its between 2 rigid non-moving parts… and its not in the pics of the kit on the Wisefab website… whats its purpose?
It’s a steering stop.
oh i see, that makes sense…
I was low key hoping to see a double wishbone conversion similar to what the HKS time attack car did
Not legal for our events!
that makes sense… I didn’t really consider that