Looks like the edge of the collector transition. All the cars have essentially the same shape piece there: a shell around the brake disc that transitions into round duct which empties at the outflow "scoop".
AR3-GP wrote: ↑21 May 2025, 19:10
A closer look at the brake duct layout from the video. Is anyone able to explain why the brake disc cover looks the way it does? It is unlike the other teams.
https://i.postimg.cc/SNMRdfjt/image.png
It's a carbon fiber cage around what looks like a shell of formed mineral/ceramic fiber insulation. A cage and not a continuous shell of carbon because... either to simply lightweight it or speculatively allow some heat to dissipate through the insulation. If the latter then of what use would a small amount of thermal radiation allowed beyond the collector duct be? Prevent heat buildup under the CF shell to help it keep its shape, otherwise have to consider what use there is in heating the inner cake tin/drum. If the insulation can breath then you'd be dissipating a little less heat through the main disc outflow collector and a small amount through the collector insulation along with the drum cooling.
General arrangement on the current cars is: Disc collector<inner drum<outer drum with ducts feeding into and out of the first two layers.