Just as Ferrari have joined Sauber in trying to catch up with McLarens F-duct blown rear wing, Mercedes also appear to be in the early stages of testing their own solution. While not as conclusive in proving there is an f-duct as with Ferraris bodywork, Mercedes do have a duct that links the main plane of the wing to the Flap. However this may not be the complete solution, as there does not appear to be a duct linking this rear wing fin to the chassis.
Mercedes are one of the few teams (and Brawn before them) not to have raced a shark fin engine cover. It could that either Mercedes are awaiting the shark fin cover to run the fully ducted flap and that this test was just a structural test for the now largely hollow slotted rear wing flap. Or that their solution will duct the airflow up through a central wing support strut (currently absent on this car) or less likely through the wings endplates. As this would mean the beam wing would also need to be hollow and some how connected to the F-duct. As Mercedes run a fully exposed beam wing there is little connection between it and the chassis.
It also been noted that the Mercedes ran pipework from the front of the sidepods backwards towards the rear of the car and then up inside the rear wing endplate. These are more likely to be wiring or pressure for sensors, than the duct itself as they are very narrow in gauge and unlikely to pass enough airflow to alter the rear wings aerodynamics.
Mercedes do have one advantage, their monocoque has usefully placed apertures by the side of the pedals, these holes have already sported scoops for driver cooling, these could be modified to be the driver interface with the duct to the rear wing.
It is not likely we will see the full Mercedes F-Duct solution until the other major updates arrive at the next race in Spain.
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