When Haas revealed its 2021 car on the first morning of testing, it looked like the team had purely made it legal to the new rear-end aerodynamic regulations, but not changed any other bodywork. This was because the team opted to introduce its plethora of new parts for 2021 over the last two days of testing. Historically, the team has struggled with correlation, particularly with in-season upgrades. As the 2021 car is an upgrade of last year’s, the team decided to assess the performance of the new components individually, and the fact that they all stayed on the car is encouraging for the American team.
Starting at the front of the car, a new front wing was introduced for day three of testing. There are now only two elements connected to the FIA-mandated neutral section, with the three upper elements raised at their tips. This should result in a higher Y250 position which will improve onset flow to rearward devices, most particularly the bargeboards. Elsewhere, the flap adjuster has been moved to the upper element, which will remove the boundary layer losses it generates from the final slot gap, improving flow health on the underside of the final element. Also, there has been some re-profiling outboard, although it is difficult to determine the change in loading here from the images available.
Further rearward, the number of vertical elements under the nose was reduced from 6 to 3, allowing the introduction of a cape, and Haas was the last team to add such a device. As such, this will not be discussed in any more detail here. There were also some developments to the bargeboards, introduced on day 2 of testing.
Firstly, an additional horizontal wing has been added about halfway down the main bargeboard. These wings generate lift in their own right, but they increase the downwash on to the elements below them, raising the load from the foot of the bargeboard and increasing the circulation of the vortices that pass under the floor. This is example of sacrificing load locally in order to benefit overall downforce. Note that the number of elements perpendicular to the bargeboard was reduced from 7 to 6 on the new design, and there have been some further detail changes elsewhere.
The engine cover on the VF-21 is quite different to last year’s, with visually more downwash on the top surface ahead of the rear wing. This should help to load the leading edge of the wing, thereby creating low pressure on a forward-facing surface and reducing drag. Note that the small low undercut on the sidepod has been removed.
Also at the rear of the car, a new t-wing design has been introduced. It features squarer endplates, which allows purely upwashing sections to be retained for a greater span-wise distance, at the expense of sharper corners that might promote wedge separations. The lower element is now horizontal across its span, while the upper element drops in height as it transitions from the rear wing pillar to t-wing legality box, a feature seen on many cars up and down the grid. Note that due to the increased downwash from the bodywork, the onset flow to the t-wing will be different from last year, which would have required re-alignment of the profiles.
Lastly, Haas ran two diffusers that were different to last year’s during testing. The first featured trimmed fences to comply with the new rules, as well as the addition of a new fence outboard. With the trimmed fences, the outwash to support the diffuser outboard corner is reduced (potentially causing flow separation or vortex breakdown), so it is possible that the additional fence aims to recover this outwash.
The second diffuser built off the first one, with a number of changes. Firstly, the trailing edge of the centre ramp was dropped to that of the outboard trailing edge, which would improve flow health on the suction side of the diffuser, probably at the expense of a little overall load, Further outboard, the additional fence on the first diffuser now features multiple slots, again looking to improve flow health, both for the fence itself and the vortex it produces.
Finally, and most interestingly, the outboard vertical trailing edge of the diffuser has been extended outboard of the Y450 plane. Since 2017, teams have migrated to a single solution here, running the trailing edge to Y450, then using additional winglets up to Y525 to further increase the diffuser expansion while avoiding separation from the large adverse pressure gradients at the back of the diffuser. The vertical winglets have not been optimised around this revised trailing edge, with the first one in front of the back of the diffuser, which is not optimal aerodynamically. Given that no other team has gone in this direction, it is unlikely that this is a big performance differentiator and it remains to be seen if it remains on the car going forward.
Racing Tech 