After enduring a difficult 2020 season, Ferrari has made significant changes to its car in a bid to return to a respectable level of competitiveness. The team appears particularly pleased with the gains made on the power unit, the weakest area of the SF1000, and this should be evident this weekend at a power-sensitive track. Many of the developments from 2020 were covered in the SF21 launch analysis, so this short article will focus on those areas the team did not show in detail at the new car’s launch.
Firstly, the rear brake duct inlet has been swept into a horizontal winglet at its base, which sits within the wider part of the legality box for the rear brake duct elements. The main lower wings now sit further back and are trimmed, with the team not opting for the approach of raising the tips to enable full span elements (evident on the Red Bull, Alpine, AlphaTauri and Williams cars). The onset on to this new horizontal element will have some downwash, and therefore the element should generate some local load, as well as aligning the flow better for the rearward elements. Note that a similar design was tried in Friday practice at Abu Dhabi last year.
The upper three winglets have been lowered a little (also visible in the below comparison) which, combined with a raised rear upper wishbone outboard, should reduce the blockage from the wishbone and increase their loading. Looking at a rear view of the rear brake duct elements, the slot gaps in the upper, rearward elements are noticeably bigger than last year, which will offload them. Ferrari has publicly stated that reduced drag was a target for its 2021 car, and this change would have helped in this regard, as these elements are very rearward facing. There would also be some downforce loss, but if the change was above the target aerodynamic efficiency for development, this would be a positive development.
Looking at the top surface of the diffuser, Ferrari has three vertical elements along the Y450 edge. The flow here is out washing, so these elements will have their suction side on the outboard-facing surfaces. Typically, there is a single vortex that is shed along this edge that promotes downwash to control the ingress of tyre losses. The Ferrari design should result in more vortices being shed, improving vortex losses, as well as keeping the centre of vorticity higher, perhaps to work better with the narrow span rear brake ducts wings at maximising the downwash between the edge of the diffuser and the rear tyre.
Finally, looking at a rear view of the diffuser, there are a number of developments from 2020. Last year, the team ended the season with a diffuser that was very similar to the end-of-2019 spec, but the 2021 version looks to be based off a mid-season design from 2020, and hence that is shown here. The centre ramp of the diffuser has been widened significantly, with the vertical expansion increased, evidenced by a raised trailing edge. It appears as if the team is trading off lateral expansion in favour of vertical expansion with this design. Note that an extra vortex generator has been added on each side to work with the wider ramp. Also, the first two flaps above the centre of the diffuser have been combined for 2021 due to the reduced chord required from the raised trailing edge.
Both the first and third fences from the inboard have curved trims to their trailing edges, with the inboard fence more aggressive in terms of incidence than last year. Together with the greater ‘ground effect’ from the close sidewalls, this fence should recover much of the load lost from trimming it by regulation, and aid in smoothing the pressure recovery of the centre ramp. Finally, the most outboard (fourth from inboard) fence from 2020, which defined the outer part of the diffuser, has been removed and the surface smoothed out, something now present on many cars, while the third fence trailing edge has been moved inboard.
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