Ferrari launched its 2021 Formula One car yesterday, and it is undergoing a shakedown in Bahrain today ahead of pre-season testing. Much of last season’s disappointment was caused by an power unit deficit, with the team losing around 1s/lap to competitors, compared to 2019, on this front alone. Given the severity of the horsepower deficit, good progress should have been made which, together with some potential aerodynamic gains, might enable a top three position in the constructors’ championship.
Starting at the front of the car, the front wing is an evolution of the one with which Ferrari ended last year. Outboard, the leading and trailing edges of the wing have been raised noticeably. This should reduce the ride height and roll sensitivity of the wing by increasing the static ground clearance. With the current generation of wide cars and front wings, the outboard of the wing has a very low ground clearance when under roll, most pronounced in high speed corners. This results in the outboard of the wing loading up considerably, and the multitude of vortices shed outboard (e.g. from the strakes and the footplate) become very strong. When these are subjected to adverse pressure gradients, as they propagate downstream, they can then breakdown, which worsens control of the flow around the front tyre. This should be improved with Ferrari’s 2021 design.
It should be noted that raising the elements in this way does lose some load, so it is necessary to recover this elsewhere on the wing to enable the car to be set-up with the optimal balance. This might explain why the flap adjuster has been moved outboard, allowing more of the wing to be affected when the flap angle is changed. Additionally, the 2021 tyres, when run at the end of 2020, induced an understeer balance on the cars, so some extra front wing balance might be helpful. Towards the end of last season, Ferrari favoured running with a trimmed flap, potentially for reduced drag (as long as it had the required balance range), but for this year, a more conventional final element has been presented.
Inboard, there are now 2 elements connected to the FIA-mandated neutral section, up one from last year’s wing, with the first element shortened locally to allow this change. This leading element was quite aggressive on last year’s car, so perhaps there were some issues with stability at low front ride height, motivating a forward move of the first slot gap.
It should be noted that Mercedes and Red Bull have only one element connected to the FIA section, but it is not as long the central section. They then have four ‘free’ elements, a design which has potential advantages in terms of tip detailing, and a higher Y250 vortex. This will, however, have some structural disadvantages compared to the Ferrari concept. Finally on the front wing, the endplate no longer features a cut-out in side view, but instead the trailing edge has been brought forward, following a trend on a number of other cars. Further to this, one of the vertical vanes sitting above the footplate channel has been removed.
The most significant change visually on the car comes from the new nose design. Due to its desire to use the two permitted development tokens at the rear of the car, on a new gearbox design, the team could not change the front crash structure, and therefore had to retain a wide nose. Within these limits, Ferrari has still managed to incorporate some of the benefits of the designs of other teams.
The spacing of the two front wing pillars has been reduced, allowing for the introduction of a drooped leading edge to the cape which Ferrari only had a short version of last year, instead favouring seven vertical elements under the nose. This drooped leading edge is a feature on a number of other cars, and may help improve the yaw sensitivity of the Y250 position. Under yaw, one of the Y250 vortices will move closer to the nose, away from its optimal position for rearward devices. However, this flow under yaw will reach the drooped leading edge of the cape with incidence, loading it up on one side, and strengthening the cape vortex more than would be the case purely from the Y250 being further inboard.
Four vanes have been added to the top of the nose, an area where most teams have an aerodynamic device. These vanes should help promote a little outwash into the wheel wake and some downwash ahead of the bargeboard/forward floor region. The tips are clearly offloaded, which would suggest the team is trying not to shed a vortex that might interfere with the sidepod inlet further downstream. Note also how the S-duct outlet is now embedded within the shell of the nose, rather than protruding out, which should help reduce losses at the roots of the additional vanes.
Looking at more of a side-on view of the nose, it is clear the cape has been lengthened considerably, while the first five vertical vanes under the nose have been removed. Both of these devices aim to manipulate the position of the Y250 vortex by shedding a vortex of their own, and there are both advantages and disadvantages to each, although the general grid trend of the past few years has favoured the cape.
During its launch, Ferrari discussed drag reduction as a priority for the design of the SF21, working with the power increase to address its straightline speed deficit, and favouring a cape over the vertical elements may facilitate this. The vertical elements reduce the pressure in the region between them, which includes the rearward facing surface of the nose, and therefore will increase drag. By contrast, loading the cape results in a low pressure region facing directly downwards, and therefore contributes less to drag. Note that the final two vertical elements have been retained and these extend forward at their base to interact with the end of the cape.
After keeping its front brake duct inlet shape relatively similar over the past two years, Ferrari has changed this significantly for 2021. The inlet is much squarer overall, and has been narrowed at the top. This should help reduce losses from the junction with the upper wishbone for two reasons. Firstly, the locally narrower inlet reduces the expansion of its external surface, and therefore minimises the adverse pressure gradient seen by the flow’s boundary layer, while secondly, the angle between the lower surface of the wishbone legs and the inlet is now much larger, minimising the merging of the boundary layers from each of these three surfaces.
The bargeboard region is very similar to the end-of-2020 specification, with the main change being the reduction in height of the three forward elements, and a deeper third slot. These tall forward bargeboard elements are possible as they fit within a regulation box defined from the edge of the chassis, and are not considered in the bargeboard legality box. However, this means their spacing from the chassis side is very small, and under yaw, they load up significantly as they are effectively in ground effect. This can produce significant losses which harm the floor’s leading edge performance, as they are pulled downward as they move rearward by the suction of the forward floor. The benefit of these tall elements is they raise the centre of vorticity shed off the top of the bargeboard, reducing the impact on the floor leading edge. Therefore, it is possible that the team is trading off these two effects on the front of the floor’s onset flow.
Further rearward, the sidepod vanes have been revised, with six horizontal elements replacing two L-shaped devices from 2020. The wide vertical vane at the rear of this cascade has been lowered, and its upper trialing edge trimmed. Moving to a series of horizontal elements will produce some additional local load, at the expense of a little increased drag, as the forward-facing suction of the vertical elements is lost. While Ferrari’s overall philosophy has been to reduce drag, there would also have been a minimum efficiency for development in terms of downforce:drag for each device added to the car. Typically, this ratio lies in the region of 2-3, and if higher than this, a part is positive for overall laptime, on average over the season. A further possible downside of these horizontal vanes is the junction losses they generate where they join to the vertical element ahead of them.
Looking at a front view of the sidepod vanes, the element extending up from the floor’s top surface now runs right up to the underside of the upper sidepod vane, and its upper part has been moved outboard. This is a clean solution, and terminates the shroud around the upper side impact structure, allowing an independent vane to be designed outboard. Note also that a slot has been added into this vertical element, allowing a more aggressive design while maintaining attachment. This will further pressurise the region inboard of this element and increase the downwash on to the forward floor, loading it up.
The forward floor edge has been developed subtly from 2020, with the upwashing curl reduced in height and a double-flap arrangement now used to keep it attached. This has been seen on many cars and is due to the removal, by regulation, of the slots inboard of the floor edge for 2021, worsening boundary layer health on the curl underside. Additionally, the front of the winglet has been extended forward to meet the bargeboard trailing edge.
The image below compares the sidepod inlet design for the SF21 to the SF1000. The difference in the outboard mirror stay should be ignored as the 2020 image is taken from launch for a better comparison of the sidepod. The inlet has been significantly reduced in size, which will increase the volume of high energy flow propagating over the top of the sidepod and down into the gap between the floor edge and the rear tyre, improving control of rear tyre squirt/wake.
The horizontal vane above the inlet has been lowered as it extends outboard, allowing the introduction of two out-washing elements above. These elements will produce vortices that aim to keep the mid-lower tyre wake outboard, and they can be quite aggressive because they are short so their tip vortices will help keep the flow attached on the suction side.
The smaller sidepod inlet mentioned above has been partially enabled by a larger airbox, with two additional inlets added here. The previous inlet would likely have fed the engine, while the additional ducts will provide airflow for coolers. Most other teams on the grid have a large airbox, and Ferrari had been an outlier over the past two season in this area.
Finally, looking at the sidepod design, there is a more clearly defined downwash ramp over the top surface. This will aim to bring high energy flow down on to the top surface of the floor, before this feeds the gap between the floor edge and the rear tyre, improving control of the losses emanating from the tyre. This is a direction many teams have taken over the past few years, with Alpine being the odd one out of the cars launched so far, favouring a larger sidepod undercut.
In summary, it is clear that Ferrari has made significant changes to its SF21 car and more of these (such as the rearward floor edge and the diffuser) will become apparent during pre-season testing. A lot of visual change is no guarantee of improvement – indeed, sometimes the cars which look outwardly similar to their predecessors are the ones that progress the most. However, if the correlation from the wind tunnel is strong, and the promised power gains are delivered in reality, the team should move forward in 2021.
Racing Tech 