At Monza Sauber debuted a new front wing cascade set up, discarding the 2012 Japanese design for a simpler Lotus-esque design with integral turning vanes.
After being flushed with success in 2012, Sauber’s year has not been as fruitful. Rear end instability plagued the car for the first part of the season and while this was resolved, other aero development has been put on hold.
Mid season saw the team continue with its more normal path of development, the car’s super slim sidepods front being mated to a Red Bull style tunnelled coanda tail section.
Having been tested at Spa, Monza saw the new cascade arrangement race, with other changes specific to the needs of these two low downforce tracks. This is the first major change the Japanese specification wing detailed in this blog last year.
With the new wing the main wing and endplate arrangement remain the 3-4 element design, with its curved slot gaps and underwing vane. The three complex cascade elements have now been replaced with a single device.
This takes the form of a two element winglet with a relatively straight profile, mounted to the endplate. At its inner tip the winglet’s endplate forms a curved (in plan view) shape and this outswept vane-like shape is echoed in the small vane mounted above the winglet. For these races the inner “r” shaped vane mounted inboard of the cascade hasn’t been fitted, this is likely to return for more conventional tracks.
The main purpose of the cascade is managing the airflow around the front tyre. Both by the general outsweep of the airflow around the wheel, but also in controlling the vortices formed by the rotating tyre and the separation of the airflow behind the tyre. The cascade creates vortices which are aimed at the top outer corner surface of the tyre; these counteract the unwanted turbulence created by the tyre, which greatly improves airflow back along the car, to prevent the tyre’s vortices being ingested by the low pressure formed in the coke bottle area.
Sauber have usefully provided a CFD video on their excellent YouTube channel, where they show the effect of a car rotating 360-degrees in the airflow. In the straight ahead position, the streamlines from the cascade winglet and “r” vane can clear be seen to be hitting the top surface of the tyre. As explained above, these offset the tyre squirt-like effect of the airflow deflecting off the rotating tyre at speed.