Sauber rushed to optimize further the rear end of the C31 and raced at Melbourne a ducted floor in front of the tyre profile . Ducted rear floor is not a new idea in Formula 1 and was a common feature a couple years ago . The duct is within FIA technical regulations because it is situated outside of the area of the 900 mm wide floor continuous surface , something that article 3.7.6 imposes . It is believed that the duct feeds the diffuser with air coming above the floor level , air that is strengthened further by exhaust gases that bent downwards due to the special shape of the bodywork behind the exhaust pipes (down-wash effect) .
A logical step forward to enhance the effect of the design would be the following
– two channeled sculpted bodywork ,behind the pipe , with the outer channel to expand further outwards .The expansion of the channel without dividing it into two would ruin somehow the direction control of the dpwnwash effect
– new vertical floor fence with a benting inwards leading edge
Finally Sauber paid extra attention to the car’s cooling efficiency at very hot and moist Sepang circuit and added two slits close to the exhaust area , pointed with a yellow arrow in first illustration .
- Sauber C31 – Rear end improvements at Jerez test (formula1techandart.wordpress.com)
To strengthen the stiffness of the diffuser and rear floor , Sauber connected the later to the rear crash structure via a pair of cable supporters . Their task is to eliminate possible vibrations that would potentially harm the aero behavior of the rear end . To even increase rear end stability an extra mini plane was added on the beam wing ( in yellow) .
- Sauber C31 – Rear beam wing (formula1techandart.wordpress.com)
C31 diffuser may lack any eye-catching innovations but is nevertheless full of interesting details . The roof tab is slotted to allow portions of air bleed through hence reducing drag, a trend carried over last season and pioneered by Toro Rosso STR6 . There are three vertical fences , two of the same height and an outer shorter , at both diffuser sides symmetrically placed to allow not any interaction between the air flows travelling through the channels formed by the fences . The centre part ( magnified ,in the inset above ) looks very interesting and totally different than that of C30 -2011 car . It clearly exploits aerodynamically the motor access hole to gain extra downforce . The flow travelling around sidepods bottoms reaches the slim rear end and penetrates through the starter hole to rich the diffuser zone to increase diffuser ability to pull air from under the floor. The contribution is enhanced by the warm air escaping from holes in the area of the gearbox and aided by a little flap . That flap apart from its aerodynamic role reduces the overall size of the engine starter entrance to comply with the article 3.12.7 of the FIA technical regulations . Not far in the past that hole raised significant protests against Mc Laren which forced FIA to further clarifications about the size of the hole .