Bugatti Bolide; An Engineers Take
Updated: Jan 20, 2021
I’m a little late to the party, but I finally got round to having a good look at some of the details on the Bugatti Bolide concept. Happy to say I was inspired enough to write my thoughts down into a short article!
As a motorsport engineer and motorsport fan, i was quite excited when the early renders made their way out into the public domain. Bugatti recently supported us with a press pack containing some really high resolution shots of the exterior - a perfect opportunity to understand some of the engineering - externally at least.
Read on for some of my initial observations...
The first thing i was happy to notice follows the recent industry focus on using increasing amounts of negative space in the aero package.
By negative space, what is meant is ‘empty’ volumes within the bodywork; carefully designed inlets and outlets to manipulate the aerodynamic flow within the surfaces of the car. Traditionally this space would be closed to form the body shell.
With tightly packaged modern carbon monocoques, it makes perfect sense - ‘Shrink wrap’ the monocoque around the driver to create the survival cell and whats left is four wheels and a powertrain package.
In basic form, the resulting platform resembles open wheel formula cars which are inherently horrible from an aerodynamic point of view - so what is the best way to use bodywork to guide airflow around these 3 essential sub-systems of the car in the most efficient way?
The result is something resembling the Bugatti Bolide.
The aerodynamic philosophy of this car is clear - gently ‘nudge’ and guide the air around the structure of the car.. Work with the air rather than bursting through it. This approach makes me happy.
As we often see in the natural world, design which works in symbiosis with the system of physics around us rather than fighting it doesn’t just perform better than design which doesn't, but is always aesthetically beautiful.
If my work around biomimetics has taught me anything - whether it’s something to do with the golden ratio or perhaps certain naturally occurring surface treatments and contours, efficient engineering is always pleasing to the eye.
These design sketches courtesy of Bugatti illustrate this point perfectly.
All of the aero is so well integrated. I’d love to see some CFD showing pressure coefficients around the body. I’m willing to bet they’re pushing industry standards forward. You have to congratulate the aero team on this one.
What else do i see of note..?
The front wheel arch vents are noticeably large - appearing to serve function in both exhausting air travelling around the front of the monocoque and likely a portion of the hot flow from front radiators.
Relatively novel in road cars but perfectly fitting with the overall architecture of the Bolide’s body, there are bargeboard style devices located at the trailing edge of the wheel here too.
In a similar way to the wheel covers, this bargeboard acts to keep flow exhausted from the wheel arch area civilised, minimising turbulence and promoting attachment to the body. This benefits the downstream aero platform such as wings and intakes.
The whole body of the Bolide has clearly been well engineered to generate favourable pressure coefficients around all of the various exhaust vents. By minimising pressure drops through a particular radiator or duct, the general airflow around the body works with each vent to allow it to perform optimally.
Sandwiched between the low pressure diffuser exit flow and within the low pressure field of the rear wing, the position of the engine bay vents not only looks dramatic but allows flow to be ‘sucked’ through the engine bay - reducing drag by minimising the pressure drop, and improving mass flow of air. Cool.
There’s also a three layer diffuser here to help in the extraction of air through the underbody. I’ve not seen something like this before and from the pictures it’s not clear whether these curved vanes have an aerofoil profile or they simply contribute to keeping diffuser flow disciplined upon exit. Maybe i’ll get to answer the question one day.
Although not new, aerodynamic wheel covers seem to be making a more common appearance in motorsport recently as their benefits are starting to become more important.
Shielding the wheel spokes from air flow reduces the propensity of air passing the side of the vehicle to become turbulent. Air flowing past the wheels (especially fronts) interacts with wings and intakes further downstream, so ensuring flow from the wheels is tidy only supports the performance of the rest of the platform. Neatly done.
Depending on the rest of the inner package of the wheel, generating a low pressure outside of the wheel with cover geometry can also act to draw a higher mass flow of air past hot brakes to improve cooling.
By far, the masterpiece of the show has to be the ‘dimples’ located downstream of the engine air scoop on the roof.
This is a really innovative idea. Perhaps inspired by golf balls, perhaps inspired by the Shortfin Mako Shark, the dimples are located in the boundary layer of air flowing over the roof and are electronically adjustable, either by the driver or by the control strategy.
In the same way as plane wings, rally cars and other automotive applications, these dimples act in the same way as vortex generators. In inflated form, the dimples create turbulence in the boundary layer. In turn, this draws in undisturbed air from above and ‘energises’ the flow over the surface. Ultimately this helps to maintain attachment.
The benefit of attachment is context specific. But for the Bolide, the ability to disturb or promote attachment directly impacts flow towards the rear wing which of course will ultimately influence downforce. In this sense, it has a function as a DRS (Drag Reduction System, i.e. F1)
Reducing the volume of messy, recirculating air behind the scoop also reduces viscous drag behind the cabin, a double benefit.
What a great project to be involved in.
From an engineering point of view, this kind of design philosophy has the great benefit of reducing frontal area and viscous drag. The pressure coefficients around the Bolides body are likely very well managed in the sense that they work to minimise drag, aid cooling performance and maximise negative lift leading to a really efficient design!
As far as i’m aware, there are no announcements for this car to enter the new Le Mans Hypercar (LMH) category, but it's my opinion that it’s a project designed exactly in the spirit of the new category. it would be a shame if it didn’t appear.
If anyone from Bugatti sees this and would like to invite me to evaluate the concept in the flesh - i would only be too happy! :-)
*All media in this article is courtesy of Bugatti.