Despite upgrading its front wing heavily at the end of last season, and again for the launch-spec C37, Sauber made another major development in this area for the second pre-season test. The only area which is unchanged is the cascade/R-vane set-up, with the most significant alteration coming in the form of an arch which now starts from the leading edge of the wing.
Since the start of the 2017, Sauber has been reluctant to pursue this concept, favoured by every other team for a number of years, instead starting the arch much further back. A solution halfway between what it had and the conventional idea was employed for the launch-spec design, before a full conversion for the test two edition.
This arch works by capturing some of the circulation shed by the wing, as high pressure flow above it rolls over to the low pressure underside, thereby forming a vortex which is then directed either around or over the front tyre, for lower rearward Aerodynamic disturbance. In this regard, the new design should be more aggressive, entrapping more circulation, potentially at the expense of some outright downforce.
The outboard circular footplate, which works in a similar way, albeit with the vortex it contains heading inboard of the front tyre according to an ex-senior F1 Aerodynamicist, has also been reshaped. Lastly on the main part of the wing, the flaps have been revised, with the tips being upturned on the lower two, while the upper one features a more conventional design. Additionally, the chord of the tips appears to be greater than previously.
This will alter the position, and increase the strength, of the vortices shed at the inboard part of the flaps, potentially with bargeboard performance in mind. Like Red Bull last year, and Renault this year, the higher flap tips appear to segment the vortices they shed from the Y250 roaring flow, at least initially, although they may roll up into one large vortex further downstream.
The wing’s endplate has also been heavily revised, with the canard being shortened significantly, as well as featuring a lower angle of attack. As a result, the vortex it sheds, which is then used by the curvature of the endplate (also updated at its trailing edge) to turn flow around the front tyre, will be weaker.
However, this is not necessarily a bad thing, as this has perhaps been traded off against the introduction of a mini-endplate at the back of the wing, inspired by the designs on the Haas and Ferrari, which will have a similar function to the main one. Finally, note that the trailing edge of the wing has been modified, now being much straighter, a modification most likely made in line with the new arch shape, to optimise the flow around the front wheel.