For months, experts, media and technically minded F1 fans had hoped that the Monaco Grand Prix would finally shed light, as it did in 2022, on the most important aerodynamic component of the sport’s modern ground effect cars – the underbody.
Indeed, Monaco did not disappoint, with cars from all three top teams suspended from a crane high above the street circuit revealing the underside that is so vital to the performance of these cars.
Again, it was noticeable that Red Bull’s floor is very different from Ferrari’s and Mercedes’, as Red Bull’s floor looks much more complex. This prompted many people to say that you could see from the photos alone why the RB19 is running circles around its rivals from Brackley and Maranello, whose floors, as Sky F1’s Ted Kravitz said, are ‘prehistoric.’
But it’s far more complicated than that, and this statement ignores much of the important nuance of what makes the Red Bull so much faster. Of course, Red Bull’s complex floor shows the advanced stage of the development of its underbody, although it’s important to remember that complex doesn’t necessarily mean better, even if it certainly seems that way in the case of the RB19.
To understand what is actually at play here, we need to dive a lot deeper.
Contents
Red Bull’s Floor Concept
A look at the Ferrari and Red Bull floors clearly shows that they have two fundamentally different concepts. Ferrari’s underbody is much lower than Red Bull’s floor and aims to be close to the ground with much more of its surface area.
No conclusions can be drawn about the exact flow structures and performance of an F1 underbody from images alone (we’d need CFD analysis and simulations to paint the full picture), but certain inferences can be drawn about the concept and the approximate mechanisms a team is working with.
It is precisely these conclusions that suggest Red Bull’s approach regarding the new regulations is very unusual, as it is based on less downforce, which is then recovered in a very complicated and elaborate way.
Where Red Bull Differs
The ‘roof’ of the underbody of the Red Bull is unusually high in places. Red Bull’s underbody, with its molded, high roof of the floor resembles less of a wing and more of a bluff body (a shape that doesn’t generate as much drag when close to the ground as a traditional inverted wing shape does).
Meanwhile, the underbodies of Mercedes and especially Ferrari more resemble classic ground effect floors that were shaped like inverted wings, with a single throat section (the area with the smallest ground clearance) and an overall smooth surface shape.
The diagrams below illustrate the differences between wing shapes and bluff bodies.
The diagram on the left shows the values for downforce (CL) and drag (CD) of a wing in relation to the ground. As you can see there, the lower the distance of the wing to the ground (further to the left on the graph), the higher the downforce (green line). This is indeed the so-called ground effect, which means nothing more than that a body near the ground can generate additional downforce, or “negative lift.”
On the right you can see what is known as a bluff body, in this case a diffuser, where of course the same phenomenon can be observed. What is striking here, however, is that the drag value (blue line) increases significantly less with higher downforce than it does in the diagram on the left.
This partly reveals Red Bull’s first secret, having an advantage in drag and being so fast on the straights. However, it should be noted here that Honda’s PU is probably the strongest, as the brutal acceleration seen when the RB19’s DRS is open cannot be explained only by reduced drag.
The fact that Red Bull’s floor is partly more like a bluff body and less like a wing means that it should develop less drag.
The Compromise
But no advantage comes without a disadvantage in aerodynamics, which is why Formula 1 analysts always talk about the ‘best compromise.’ The higher distance of the Red Bull floor also means that it benefits less from the ground effect and therefore generally generates less downforce.
The almost classic Venturi ducts used by Ferrari and Mercedes utilize a constriction after the inlet, which causes the air to accelerate strongly and its pressure to drop. This pressure drop causes the well-known suction effect that we always talk about when dealing with F1 cars.
The shape used, as I’ve already mentioned, is more like an inverted wing profile that you want to bring as close to the ground as possible to achieve the maximum ground effect and therefore the greatest possible downforce.
This difference alone makes it clear that Ferrari and Mercedes have taken a completely different approach to Red Bull. While the RB19 gives up some downforce on purpose, the other two aim for maximum downforce (even if Mercedes has already given up some ground effect with the new floor and even back in 2022).
But since it is downforce that allows F1 cars to go so fast through the corners and achieve lap times that are so much quicker than other race cars, Red Bull obviously needs to reclaim this downforce in some other way.
How The Red Bull Recovers Downforce
When you look at what Red Bull has done in the underbody area and what the impact could be in the areas where their floor differs from Mercedes and Ferrari, the first thing you need to know is that the four so-called ‘strakes’ in the underbody inlet area create strong vortices. A vortex is a rotating low-pressure structure that can be used to generate downforce on the underside of the car.
One of the basic requirements for generating downforce is air with ‘high energy,’ where energy here is the sum of static and dynamic pressure. Using as much air with this high energy as possible, while avoiding losses as much as possible, increases downforce.
Using Vortices
Vortices can be used for this purpose. The following picture from Willem Toet, the former chief aerodynamicist of Benetton, Ferrari, BAR and Sauber F1 teams, clarifies that.
This image from Toet’s hill climb car show high energy air in red. Note that a lot of high energy air is still on the inside of the floor (at the bottom of the image). A vortex could ‘grab’ that air and make it useable for downforce production. But vortices need space to ‘roll up.’
Red Bull’s high and sculpted roof gives them more space, which means they can roll up and grow more, harnessing as much high-energy air as possible to generate downforce.
With the Ferrari and Mercedes underbodies, downforce losses are likely to be significantly lower because they are closer to the ground. This could explain why they don’t have high-roofed floors that allow for this extra rolling up of the vortices.
But wouldn’t this mean that Red Bull is simply avoiding further downforce losses here, rather than making extra gains over their competitors?
It could, but stronger vortices have two other effects.
The Other Effects Of Vortices
A stronger vortex has a lower pressure, and it also ensures stronger ‘suction’ of the air, especially further back in the diffuser, which should ensure that some of the downforce is recovered. But that alone shouldn’t be enough. This is where the complexity and other elements of Red Bull’s floor come into play.
The high roof of Red Bull’s floor no longer runs all the way to the so-called ‘kick point’ of the diffuser (the part of the diffuser where it starts to rise). Instead, Red Bull has added a second kick point, located very far forward, and a transition between the high roof and the diffuser’s kick point.
This transition has several small kicks that are not unlike small diffusers, so they create a local load there in addition to the two kicks. This helps to recover some downforce.
The diffuser has a strongly concave surface after the kick point, probably made possible by a specially designed gearbox with a step to free up this space for such a feature. This helps recover even more downforce.
The resulting greater extraction of air allows for greater pressure recovery, which in turn provides more downforce by driving the floor harder.
In addition, there is a flick under the beam wing that creates additional negative pressure. This increases the negative pressure already generated by the beam wing, which creates an even stronger suction effect that accelerates the air under the floor more strongly and further lowers the pressure there.
The areas that generate the most downforce are the diffuser kick point, the roof of the tunnel, and the rear corner of the floor. The latter two areas are loaded by two strong vortices that move and can vary in strength, as is evident in the CFD simulations by Shubham Sangodkar and his channel F1 Aerodynamicist on YouTube (7:42 onwards in the video below).
Red Bull has arguably already regained a lot of downforce just by manipulating and controlling key vortices towards the rear of the car.
The Mouse Hole On The RB19
But the recovery of downforce doesn’t end here, because Red Bull has also done a vast amount of development work in another area. Red Bull has repeatedly sprayed flow-vis paint on the rear area of the sidepod, but also on the undercut and the sides of the underbody.
A lot of hard work was done in that area, which strongly suggests this part of the car is performance-critical, and many teams copied Red Bull’s approach. Red Bull directs some of the air flowing above the sidepod to the side, while most of it is directed as downwash (induced by the edge vortex) towards an opening called the diffuser’s mouse hole.
The air in the undercut is also directed there, while some of the air in the back is also directed outward and is pulled by the edge vortex under the floor, where these increase in strength. Here the edge wing plays a large role, as the CFD comparison by F1 Aerodynamicist from earlier shows.
The strength of this vortex and the vortex created at the top edge of the outer of the four strakes are important to control the ‘tire squirt,’ which occurs when the contact area of the tire pushes the air outward. This has a detrimental effect on the diffuser’s downforce generation, especially in corners, as its turbulent air interferes with downforce production.
Directing Air Into The Mouse Hole
The remaining air that runs from the undercut to the back and the air that comes from the top of the sidepod as downwash is directed into the mouse hole of the diffuser, where it further energizes the vortices that meet there, amplifying and accelerating them even more.
It is remarkable how even these airflows are on the Red Bull and how they manage to direct them exactly where they want to use them. Ferrari still mostly uses inwash and did not change to downwash, even with their new sidepods
With these mechanisms, Red Bull recovers the downforce that their underbody concept ‘loses’ compared to Ferrari. But why does a team choose a concept that promises less downforce only to regain it in a very complex way? The reason can only be that this concept promises further advantages.
One of these benefits was the reduction of a phenomenon known from the so-called ground effect cars of the late 1970s and early 1980s – porpoising.
Porpoising & TD039
One of the reasons for this aerodynamic ‘bouncing’ of the car was the downforce itself, which pulled the car down so far that the airflow under the floor stalled, causing the downforce to drop dramatically. This reduced downforce caused the car to rise, but when the airflow reattached, downforce became stronger again, which again pulled the car down, starting this bouncing cycle all over again.
There were various triggers for this, but basically ‘too much’ downforce under these conditions was always the main cause because that was what pulled the car down. One of the possibilities, logically, was to eliminate some of this downforce, which Red Bull did with the high ‘roof’ of their floor.
Another equally logical effect of the high roof was that it avoided the very low ground clearance of the tunnel roof that caused the stall in the first place. These advantages then led to even more advantages!
Softer Suspension
The first was that it was not necessary to stiffen the suspension to avoid those very low ground clearances. This meant that a softer suspension could be used, which in turn increased mechanical grip and was advantageous in terms of tire longevity. Likewise, it is easier to drive over the kerbs and therefore use a more advantageous racing line.
Lower Ride Heights
Another advantage of the high roof is that you can run lower ride heights, because the ground effect just doesn’t reach the point where the airflow separates with the high roof. So, you have the edges of the floor closer to the ground in high and medium speed corners, which allows less ambient air to enter the tunnel because it is better sealed.
This is also where Ferrari’s problem becomes clear. They have had to use a very stiff suspension setup since the TD039 technical directive was issued in 2022. TD039 suddenly introduced a new load test for the underbody. At the time, Ferrari’s underfloor was very flexible. This prevented problems with the wear of the plank of the floor (maximum of 1 mm) and allowed Ferrari to use very low ride heights.
Ferrari’s approach of using the ground effect as much as possible with the low roof had therefore been a great solution before TD039. It had excellent underbody sealing and enormous downforce production, and the suspension could also be tuned softly enough, as the flexibility of the floor reduced the wear of the plank accordingly.
Porpoising was controlled by a special edge of the underbody that allowed air to escape if the body bounced too much, reducing ‘excess’ downforce.
The Introduction Of TD039
But TD039 rendered this concept obsolete. The floor had to be stiffened and was no longer able to bend and flex appropriately, resulting in increased ride height. In order to still be able to drive as low as possible, the suspension now had to be stiffened to avoid losing even more downforce from the floor.
Ferrari’s concept, which until then had virtually guaranteed higher downforce, suddenly had a lot of disadvantages. It is also important to know that F1 cars are designed to work in a certain ‘operating window’. Only within these windows will the cars produce maximum (and importantly stable) downforce. Ferrari’s concept suddenly lost its advantages while the ‘weakness’ of the Red Bull concept became another advantage.
This also makes Red Bull’s dominance in 2023 completely logical and almost inevitable. Ferrari was faced with the choice of either developing a completely new floor that had a higher roof like Red Bull’s – which would have set them back a year – or trying to cope with the problems that arose and probably lose less time (the same goes for Mercedes, who have since made a half-step towards Red Bull though). But Red Bull could simply keep developing.
Why Couldn’t Ferrari Just Copy Red Bull?
A year later, Ferrari is still struggling with the impact of TD039 on their concept, and in hindsight it might have been better to go the Red Bull way. However, there is a problem here. Red Bull’s floor, as I’ve explained, is very complex, which it has to be in order to recover the lost downforce.
Otherwise, it would always be inferior to Ferrari’s underbody in terms of pure downforce production. However, this complexity also entails a correspondingly high development effort, which is often difficult to realize in times of the budget cap and also entails the risk of losing even more ground. The question here is how Red Bull came up with such a completely different concept than all the others in the first place.
The Aston Martin Valkyrie
Formula 1 cars are so fast because they generate a lot of downforce, which pushes and sucks them onto the road, making them incredibly fast in the corners where other cars may be much slower. So, pursuing a concept that generates as much downforce as possible always seems advantageous.
Pursuing a concept that generates less downforce, which then must be made up for at great expense, appears to be less advantageous, despite all the other advantages (softer chassis, etc.). This is especially true in the era of the budget cap, because in Formula 1 you can easily get caught in a development backlog.
Red Bull could not know that a technical directive would strongly affect the concepts of their main competitors and strengthen their own, but they did choose which route to go down ahead of the 2022 F1 season. What made them make these choices?
Adrian Newey Strikes Again
Many will remember that Adrian Newey helped design the Aston Martin Valkyrie hypercar when Aston Martin was still a sponsor of Red Bull. The Valkyrie is a hypercar with a ground effect floor that is designed for road and track use. To be able to use the ground effect, the underbody must also be as close to the ground as possible.
Since normal roads aren’t as flat and uniform as racetracks, such a car must also have correspondingly softer suspension than an F1 car and a higher ride height. Also, the problem of porpoising had to somehow be avoided, because ‘normal’ (albeit ultra-rich) motorists won’t pay a seven-figure sum for a bouncy car.
Even if Newey was not subject to the restrictions on active suspension and was allowed to install it on the Valkyrie, it is very possible that Red Bull’s underbody philosophy began with that car. Interestingly, the Valkyrie’s underbody does indeed feature high, shaped tunnels, albeit far less complex than the ones on the RB19.
Even then, some competitors criticized the possibility of Red Bull conducting aerodynamic research here and gaining an advantage, especially since their F1 engineers were leading the way here, above all Adrian Newey. This could not be prevented because it was an offshoot company of Red Bull, which was not active in F1 at the time. Finally, Ferrari also builds supercars, as do Mercedes and McLaren, and no such advantages seem to have been gained there.
In retrospect, however, this project may well have given Adrian Newey the opportunity to gain important insights that ultimately gave Red Bull a certain advantage, especially since it was already clear during development that the new F1 cars would be ground effect vehicles. Newey will have undoubtedly gained some aerodynamic knowledge during development that he could not be expected to just forget.
Final Thoughts
In 2022 and 2023, Red Bull managed to do something that other teams couldn’t do or hadn’t thought of. That has always made the difference between victory and defeat in Formula 1 since the beginning of the World Championship back in 1950. Until the other teams catch up with how Red Bull have succeeded in their floor designs, the Milton Keynes-based team is likely to continue to dominate the championship.
Andi writes technical F1 articles and analysis for German media, and is in constant contact with current and former Formula 1 engineers. He shares his insights to help Formula 1 fans gain more understanding of the technical side of the sport.