Last Tuesday, Alpine launched its first Formula 1 car since the transition from the Renault name over the winter months. The A521 carries over much of the architecture of the Renault RS20, but aerodynamically there are some significant changes. The launch renders and shakedown videos show a basic floor configuration, with the team likely optimising this area around the revised 2021 rules and releasing parts to the track as late as possible in time for the first test this weekend.
Starting at the front of the car, the cape underneath the nose now features a slot along much of its length, in what was a flat area on last year’s car – the additional element will have an aerofoil shape when taking a longitudinal section through it. Due to its position, the Y250 vortex will impose a downward and outward velocity vector upon this element, and hence load it in the same way as a conventional wing. There are a few reasons why this design might have been introduced, one being to improve the yaw sensitivity of the position of the Y250. Ideally, the Y250 will have a consistent position across the aerodynamic map as it propagates downstream, allowing the bargeboard and forward floor region to be optimised. Under yaw, on one side of the car the Y250 vortex will move inboard, thereby loading up the cape at its leading edge, and strengthening the vortex it sheds. This vortex induces a downward and crucially outboard movement on the Y250, moving it back towards a more desired position. With the flap on the cape edge, this loading of the cape under yaw could be accentuated, and hence the Y250 position would also be adjusted further.
Looking further rearward at the bargeboard region, the configuration looks much the same as the end-of-2020 one, with some revisions to the smaller elements evident. Firstly, the mini-bargeboard elements are now both taller and more aggressive in terms of the outwash they induce. This should increase the outwash into the lower wheel wake, improving forward floor performance. Note how the top part of these elements is significantly offloaded relative to the lower part – this reduces the strength, but more importantly the losses, of the vortices shed, improving the onset flow to devices further rearward/outboard.
The other modification to the bargeboard region is a small increase in the height of the forward two thrusting elements far outboard. These elements take the outwashed flow from the bargeboard pressurisation and turn it back towards the longitudinal axis. In doing so, suction is created on the forward-facing surfaces, reducing drag. Looking further rearward, one of the larger changes on the A521 concerns the forward sidepod region. The width of the lower part of the sidepod in particular has been reduced significantly, with a more pronounced undercut. As mentioned in the Aston Martin AMR21 analysis, there are two ways of delivering high energy flow to the rear corner – over the top of the sidepod, or through the undercut – and Alpine have moved more towards the latter route with their new car.
The sidepod inlet itself is also narrower, which improves the mass flow that can be used to generate rear downforce rather than for cooling. Note that the vane extended down to the floor from the sidepod inlet has been removed for 2021. This element would have pressurised the region inboard of it, thereby increasing the downwash on to the front of the floor. However, now that more mass flow is desired through the undercut for the revised sidepod concept, removing this pressurisation will help this cause. Finally, the mirror’s outboard stay has been extended down to the upper side impact structure shroud, and the vertical sidepod vane has been shortened. Looking at the side-on comparison below, the change in sidepod shape is clear for 2021, with less early downwash on the top surface confirming the change in philosophy.
The more aggressive sidepod undercut would also have been enabled by moving some of the car’s internals high up, behind the driver’s head. From an elevated view, the engine cover behind the airbox is now incredibly wide, a clear step compared to recent years, when this area was already bigger than competitors. This will trade off increased delivery of high energy flow to the rear corner (through a smaller sidepod) against worse onset flow for the rear wing. There is also the centre of gravity aspect, with this extra volume being right at the top of the car. Note that the airbox inlet has been revised, despite being the same size overall, perhaps related to the change of internals in this region.
An aerodynamic detail has been added to the halo, in the form of a vertical extension to the rearward part. This will aim to shed a vortex, formed due to the high pressure within the confines of the halo from the blockage of the driver’s helmet creating the pressure difference. This vortex will then help pull high energy flow down the top of the sidepod and towards the rear corner. Last year, when it was able to run without the louvres by the cockpit, Renault ran a small upwashing winglet that may have served a similar purpose. However, this was not a universal solution as it could not be run at many races, whereas this is not an issue for the halo fin.
Finally, the slots in the rear wing endplate have been revised. For 2019 and 2020, the team used a design with staggered vertical elements and upwashing elements in between, whereas for 2021, four vertical elements have been grouped at the rear of the endplate. ‘Unfolding’ the endplate into these elements loads up the outboard part of the rear wing, with less support from the horizontal surface of the endplate.
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