Where 2023 Alfa Romeo F1 car has borrowed from rivals: C43 aero analysis

F1

Alfa Romeo provided the first glimpse of a 2023 Formula 1 car at its launch event. Aerodynamicist Kyle Forster finds plenty of detail to delve into

Alfa-romeo-2023-F1-car-front

Kyle Forster worked as an aerodynamicist at Mercedes-AMG F1 from 2018-2020 and runs the JKF racing engineering consultancy.

The Alfa Romeo C43 is our first look at a launch car that clearly has elements of a 2023 car.

It’s definitely got some carryover elements from last year, as well as some things that are hidden and de-featured, but there’s a lot to discuss that could very well be seen on the real thing.

Alfa front wing

The front wing is not hugely different to last year – in fact looks like it’s completely unchanged – so this is likely just for the reveal unless Alfa Romeo has had a particularly bad off-season in the wind tunnel. I would expect this to change a fair bit for testing

Here’s a quick recap of what it’s likely doing: it’s very heavily centre-loaded, which means Alfa is likely trying to extract a large amount of the front balance of the car from this region and not using it to generate a huge Y250-like vorticity (named after the 250mm neutral area either side of the nose, which featured on cars until last year).

Although it is inevitable that some degree of vorticity will be shed from this inboard section, further outboard there’s a clear coning region where the wing lifts and steps down, this is likely where it is shedding the bulk of its vorticity, which will rotate in such a way to create downwash along the side of the tyre and onto the deflector, which would hopefully help with management of tyre squirt — the turbulent vortex at the junction between the tyre and the ground.

Alfa front wing 2

The rear of the endplate is cut out, this is presumably to help with outwash.

It’s worth noting that the legality on the front wing tip has changed a bit compared to last year to prevent a repeat of the Mercedes design where the bottom rear of the endplate was detached from the flaps.

I don’t think that the Alfa wing would fall foul of the rules this year, but by the same token the legality is complex and to be sure you’d have to fully reconstruct the model, which would be very time-consuming.

Alfa underbody

Most of the underfloor and floor leading edge vanes are pretty generic – I wouldn’t read too much in to them as they look to be in the same sort of style as in the Alfa Romeo launch pictures last year, and are likely heavily defeatured. Particularly the diffuser, where Alfa has historically run a fair amount of contouring in the outboard portions.

Alfa side mirrors

The mirror setup is fairly straightforward: a structural stay then two detached vanes. Legality requires a single section in an X plane (running across the car), but there is no such requirement in Y (front to back) or Z (top to bottom). The rules haven’t changed much here, they’ve just changed the definition of the position a bit.

As with last year, the main intent of this vane is to provide outwash in this region, and the rotation of its vortex will also provide downwash along the top of the sidepod. Splitting it into multiple strakes can improve the vortex health (its power and shape), and also allow the structures to cover a slightly larger area than one single vane.

2023 Alfa Romeo F1 car three quarter shot

The bodywork is very different to what the team ran last year. The sidepod inlets are more like a Ferrari, while the rear takes much more of an Alpha Tauri/Red Bull approach. As we now have teams designing with the knowledge of what other teams have done from last season, I would expect a lot more mixing and matching of concepts, just like this.

The Ferrari-style inlet is significantly wider and shorter than what Alfa was running last year, which allows it to get the inlet much higher for the same inlet area. This has allowed it to get quite a decent downwashing section and big undercut at the front of their sidepod. This should help increase pressure on the forward floor, which should help drive outwash along that section of the floor, as well as downwash on the floor leading edge, increasing suction under the floor and suppressing top surface losses.

Unlike the Ferrari design, it does not fill out so much to the outside of the legality box. This should provide a bit of a smoother path for the flows on the inboard side of the car above the floor, which would help reduce flow losses down the car, although this probably won’t have the bulk wake-shifting power of the stagnation from the Ferrari solution.

2023 Alfa F1 car side view

Moving further rearwards, the top deck of the sidepods follows that philosophy we’ve seen from so many teams of trying to get the clean upper flows down to the floor edge to maximise performance in that region. Higher up though we have a second ‘bazooka’ setup that is really quite chunky and extremely downwashing. The downwash produced by this region often helps to significantly improve the efficiency of the beam wing and the rear wing. You produce lift locally on the bodywork, but the wing power increases so much and the diffuser sees the benefit of this, making the overall performance of the car superior.

2023 Alfa Romeo F1 car top view

One thing to really note here is the sheer amount of cooling on this car – there’s a lot. The rear exit looks huge, and based on previous years should be able to do the job of cooling all by itself. You then have two separate sets of louvre panels. Now if you remember back to last year, Alfa had almost no rear exit at all, and just a big louvre panel on top of the pod that spent a lot of time with blanking panels on it. Bearing that in mind, we are likely looking at an extreme cooling configuration, and I would guess that under normal operation they will either blank or remove the other louvre panels.

2023 Alfa Romeo F1 car floor strakes

When it comes to the floor edge, this has to include the disclaimer that last year Alfa presented an initial model with a highly serrated floor edge, and this never raced or saw testing.

The first thing I would like to point out is that the legality in this region hasn’t changed – sure, in the 2023 rules, the boxes have moved around a little bit to move the outboard edge of the floor around 15mm up but the fundamental wording of the rules here is still the same. So why is it legal and why haven’t we seen it from other teams before?

The floor edge rules allow you to have a ‘Floor Edge Wing’ just like last year. There are quite a few rules around it, the primary ones are that it may only produce a single, closed section when intersected with an X plane, which must be between 5 and 20mm from the main floor at its closest point. It must also produce a single section when intersected with a Z plane, and not have any concave radius smaller than 25mm, convex can be whatever you like. This particular interpretation fulfils all those requirements, however there are a few tricks it needs to pass.

Related article

Due to the convex fillet rule, each vane can be no closer than 50mm to another, as otherwise there wouldn’t be enough space to put in a fillet radius of 25mm on each. You also have to have the vanes pretty much dead straight out: you can’t go too fancy with the shapes or you won’t satisfy the section rules.

In terms of what this means – you have essentially 3 choices with this design. You can  have straight, flat vanes, with a gap of 50mm between each one. This sacrifices a lot of planform for only the benefit of vortex discretisation and mass flow bleed, where clean air is allowed to pass through the floor edge to ender the underbody, often improving its cleanliness versus an unslotted floor — probably inadvisable.

You can have heavily nose-up vanes – this would be clean but the vanes may be so nose-up that they generate local lift, and may bias the load too much to the inboard floor edge system, which could be undesirable.

Or you could have upwashing vanes, which is what Alfa has here. These upwashing vanes will generate local load and take load off the inboard floor edge vortex system, which will clean it up but they will generate a degree of loss off each one that could be ingested further downstream.

The upwashing system, combined with the vertical fence that they connect to would significantly reduce outwash, and the load on the inboard floor edge, which would locally clean it up, even if the rest of the system might be a bit lossy. You would also discretise the outboard floor edge vortex more, which could help with its health and controllability, although it’s a trade against the losses you introduce by adding more upwash and local load on the vanes, as well as the floor fence.

So why do they have it this year when it was legal last year and anyone could do it? Well, the floor edge is now a fair chunk higher, so perhaps this system now works where perhaps before it didn’t.

2023 Alfa Romeo rear wing

The most notable thing on the rear of the car is the beam wing, with its mildly serrated trailing edge. There’s a lot of research on these types of trailing edges, but it’s mainly centred on noise reduction. This makes sense when you consider an owl’s wing which has a similar detail. Of course, an F1 car doesn’t need to worry about this, so what are we doing here?

When we have a serrated trailing edge on a forwards element, it can produce very small vortices that can help energise the boundary layer of the second element and delay separation. However we are right at the back here.

What trailing edge disturbances like this can help do is break up the shear layer coming off the back of the wing. The air on the top is trying to slide outboard while the air on the bottom is trying to slide inboard. This produces an unstable shear layer of vortex-like structures on the back. By giving the trailing edge some degree of discontinuity you can cast these off as discrete vortices instead of an uncontrolled mess, one of the reasons it works so well for noise suppression with wings at high angles of attack. In terms of what benefit this could give from an aero performance standpoint, this might give a better central wake profile from the losses off the beam wing, potentially a more stable wake with less fluctuations, that could have benefits for downforce or drag. However, I would imagine it’s quite subtle, potentially even neutral.

The other option is this is just something they have added into the launch render for looks — a constant consideration when assessing these pre-launch images!