Chuckjr wrote:
With all due respect, how are you sure it creates "all that extra drag"? I don't think we can assume they are as draggy as they may appear. Heck there's not even agreement on their shape yet! I don't think we know nearly enough to make any assumptions about these things and what they may do/cause.
The devices themselves
will be relatively draggy.
(Basic physics: Rho/2cwAv^2).
Lets have a look at the OoM:
Cw for a Body with the given shape will be somewhere in the ballpark 0,3 - 0,5. A ~ 0,25m x 0,6m.
At 300km/h this would mean roughly 20kW for increased drag (at assumed cw 0,4).
So not devastatingly hig but noticeable.
Re not knowing the exact shape: The exact shape of the devices is largely irrelevant since most of the drag will come from the pressure loss due to the almost vertical rear side. Front shape will only minimally influence that via the direction of the streamlines when moving past the vertical part. This can increase the size of the low pressure area and thus increase drag of the device itself.
What is not known is the exact effect it has on the diffuser and thus any possible reduction in Rear Wing Drag.
Since the horizontal velocity in the low pressure area is probably not extremely high, I'm not sure the overall effect of the device itself on the diffuser will be terribly big. That is why LMP cars try to minimize the height of the rear end over the diiffuser as much as possible. It causes inefficient DF.
The difference and thus (main) benefit here is that it will help 'connecting' the diffuser to the lower side of the Rear Wing, thereby increasing the extraction volume behind the diffuser. This, however is most beneficial at high AoA of the rear wing. Therefore lower Angles of the Rear Wing might not be where this solution will shine.