McLaren MP4-27 Singapore New Rear Wing Gills

Main Drawing: New Gills                     Inset:  Old Gills

McLaren brought a new high downforce rear wing due to the high downforce nature of the Marina Bay track. But with higher downforce comes more drag.

The new rear wing featured more and modified gills in the endplates. 
Those gills are there to increase the efficiency of the wing as the part of the wing close to the endplate produces drag inducing vortices. Those vortices are produced because of the very low pressure air from below the wing, the very high pressure from the top of the wing and the atmospheric pressure air from the outside of the enplates. When these 3 air streams meet at the trailing edges of the wing, a strong vortex is produced. The gills allow high pressure air to leak to the outside of the endplates and mix with the atmospheric pressured airflow, thus slightly reducing downforce produced by the extremities of the rear wing but also reducing the strength of the vortex and the drag associated with it, improving the L/D ratio (Lift to Drag) of the rear wing.
Due to the wing being a high downforce one, it is configured  for a higher downforce and a higher AoA (Angle of Attack) so it is steeper and the number of gills was increased to suit the higher AoA configuration.

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