New Scarbs video about why low rake cars may be losing out more than high rake because of the new regulations that forbid holes in the floor and trim both a triangular strip of floor before the rear wheels and part of the lower rear brake duct aero winglets (inboard, aka between the wheels).
I’m out of my depth discussing aero, but here goes.
As I understand it (i.e., not well, based off one listen), Scarbs posits that the bottom of those brake duct winglets would seal or interact with the floor and rear diffuser to mitigate tire squirt (the low energy air bouncing off the rear tire and messing up the nicely accelerated and massaged air being sent to the rear diffuser). The rear brake duct aero is attached adjacent to the inner wheel rim. Low rake cars used the (now reduced) bottom of the brake duct aero to form a sort of ceiling for the tire squirt bouncing off the tire and then the road because their floor/difffuser aligned with the lower part of the wheel rim. High rake cars can still use the (unaffected by the ‘21 regs) top of the brake duct aero to seal with the floor/diffuser to combat tire squirt.
The holes in the floor and that extra strip in front of the rear wheels helped manage tire squirt.
I’m not entirely sure where the floor ends and the diffuser begins. I believe the strakes pointing down from the diffuser play a part in combining with the brake aero, so whatever McLaren’s done with their strakes while using a token to change their gearbox may help with this.
Even if I don’t fully understand it, it does help me connect with the discussion about the differing outboard/inboard Mercedes/Ferrari front wings to divert air around the front tires. I believe Ferrari went inboard because they wanted to send more air under the car because of their shorter wheelbase. I’m going to have to reread that BBC secret aerodynamicist article again.