INTRODUCTION
"Formula Libre", "Unlimited racing", these words are music to the ears and a source of dreams to all motorsport engineers around the world! As I have spent over 20 years working as an engineer in motorsport (mostly in Formula One and in Endurance Le Mans Prototypes racing), I am no exception.
I am passionate about the rich history of motorsport and in particular, I am fascinated by the motorsport era of the 1960s/1970s. During that time, there were some of the greatest technical innovations, from moveable aerodynamic devices, ground effect, fan cars to gas turbine cars and six wheelers, etc... It was the time of technical freedom and it was when racing car design was an art of practical experiments rather than the science like we know today. As a racing car engineer, a question has always been obsessing me ever since I have started my career. "What would be the performance, what would be the look of a circuit purpose built racing car if the technical regulation was entirely free from constraints, with the exception of keeping all contemporary safety devices (halo, reinforced and homologated monocoques, fuel cell installation, etc...), with the obvious target being to achieve the fastest lap times ever known on contemporary racing tracks?"
LE PINACLE is an attempt to answer that question. If you were to ask ten different racing car designers, you would receive ten different answers, which makes it even more fascinating. In particular because with so much freedom, it would be a very hard challenge, even for the most advanced simulation tools that we have nowadays to cover all the design scenarios. It may be possible that there would never be a clear winner in such competition as it would push the physical limits of the drivers to the very edge of human capability. In this respect, I must pay tribute to Peter Wright's article "A Christmas Reverie" from 1998 which shares his own vision of an unlimited racing car and which has been a great source of inspiration for me. Peter Wright was one of the engineers responsible for the Team Lotus Formula One wing cars of the late 1970s, I can very much recommend that read!
In this page, I will explain the logic and the technical choices behind the concept. I hope you will appreciate some of the unique features of the car. Even though my partners and myself bring to bear some serious, solid engineering and CFD effort into the project, the car has to be taken as what it is, it is an early concept of a circuit record purpose built racing car and would obviously evolve with more ressources allowed to its development. However, it is no fantasy or science fiction, everything presented here is based on contemporary (or past/banned) technologies.
I hope you will enjoy the journey."
Sébastien LAMOUR - 30/03/2023
o 
1
2
3
4
5
6
7
POWERTRAIN
Talking about horsepowers
When defining the key figures and targets of an unlimited car, it is very tempting to go for as much horsepower as possible. However, there is a practical limit to how much power and torque is usable in the quest for absolute performance on a circuit.
We ran lap time simulations (including driver in the loop simulations) to assess what would be the optimum power/torque figures for a circuit lap time record car. Increasing engine power has a lot of impact on a car design. This calls for a bigger engine and associated ancillaries (bigger radiators, stronger drivetrains, etc...), which in return translates into more weight and aerodynamic losses.
The conclusion of our studies was that the optimum power output was reached at about 1600 bhp, which led me to two possible candidates as for the engine architecture, small capacity turbocharged piston engine or gas turbine.
Engine and transmission
In terms of power to weight ratio, there is no competition to gas turbine engines as used on helicopters for example. They are very powerful (although this comes with a very high fuel consumption), very reliable and lightweight. However, they are designed and built to deliver their peak power at a constant revolution speed, which means they would only be suitable to a competitive racing car application if coupled with a CVT gearbox (Continuously Variable Transmission). With unlimited R&D ressources, a bespoke gas turbine and CVT transmission combination would definitely be the must have.
I decided to take a more realistic approach though. The concept was developed around a 1.6L V6 engine coupled with two turbos. This is a similar architecture to contemporary Formula One engine specifications but without the hybrid part and without any limitations on boost pressure or fuel flow (and an extra turbocharger). This bespoke engine should allow us to reach our power output target (with high boost pressure) in a very compact and lightweight package.
The car has been designed as a rear wheel driven car. The target being circuit lap time records, it is clear that such achievements would only happen under dry conditions and the car was designed around that idea. Any torque distributed to the front wheels causes understeer in a corner and our simulations have not shown net benefits that would justify the extra weight and complexity. For the same reason, I ruled out any forms of electric or hybrid powertrains. However, I like the idea of using synthetic fuels whose latest developments have proven being very close, even on high performance engines, to the efficiency of their fossil fuel based counterparts.
Transmission is ensured through a bespoke 8 speed sequential seamless gearbox with the possibility of automatic shiftings to help the driver to accomodate with the shorter time responses required in terms of car's handling. To deliver 1600 bhp to the ground through the rear wheels alone will require a lot of low speed grip which will be achieved through our unique aerodynamic configuration.
AERODYNAMICS
Fan-car all over again?
When thinking about unlimited racing car design, fan-cars come first in mind. Do we have another fan-car here? The answer is yes but not only!
Fans are a very efficient way of creating huge amount of downforce starting from 0 kilometer per hour, by creating vacuum underneath the car. However, the amount of downforce generated by the fans remains constant at any speed. Conventional aerodynamics (wings, diffusers, etc...) generated downforce increases with the square of the speed. With a proper ground effect car design, there is a speed for which ground effect generated downforce overshoots a fan-car generated downforce. During our studies, we figured out this speed is reached at about 150 kilometer per hour which means the fan will be more efficient in low speed corners and ground effect aerodynamics will take over in medium-high speed corners.
Producing high levels of downforce at low speed is essential for the success of our powertrain configuration. Achieving even more downforce at higher speeds will be equally important for the car to achieve its performance targets. I decided to get the best of the two technologies, by combining both features thanks to a unique and innovative arrangement of active aerodynamic devices. The car is a fully skirted channeled car with a fan mounted at the back of the diffuser. As such, the car is operating under two modes, a fan mode and a ground effect mode. The switch from one mode to the other is operated in straight line sections (like DRS systems), to avoid abrupt changes in downforce levels and instability in corners. The fan will be drived through the gearbox and thus powered directly by the engine, which will require an extra power boost of about 150 bhp when it is activated.
In fan-car mode, the bottom of the car must be entirely sealed for the air being pumped under the car to create the vacuum. Two active panels, one positioned at the floor entry and one positioned at the diffuser exit, will then close (fan mode) or open (ground effect mode) the floor channels. Those flaps are hydraulically actuated through piston cylinders in a very similar fashion to how DRS systems work. Side sealing of the floor relies on its flexibility and purpose designed aeroelasticity. Kevlar made skirts are directly integrated into the floor lateral extremities. On top of that, the fan blades can be pivoted by an hydraulic actuator in order to reduce their blockage in ground effect mode.
Active aerodynamics
Other aerodynamic active devices include an hydraulically actuated DRS (Drag Reduction System) on the rear wing second element in order to reduce aerodynamic drag.
Sidepod inlets have a unique design featuring a ramp with three oblong shaped intakes, with the intent of feeding air to the cooling systems of the car. Among the three inlets (on each car side), the design was made to allow two flaps to close or open those air intakes. They are actuated through small electric motors. This allows for a wide range of possible strategies and combinations: reducing drag at top speed to get some extras kilometer per hour, more optimal compromise on drag versus cooling in straight lines and corners, etc...
It is very tempting in an unlimited formula to have everything active and moveable. However, each hydraulic, electric actuators generates more weight, more complexity (through motors, control units, lines, etc) and I wanted to get the right balance on that aspect by not getting wild on the number of active devices. And also considering aeroelasticity still offers plenty of "active" opportunities on aerodynamic elements.
Where is the front wing?
The car does not feature a front wing as we know it on contemporary single seater formula cars. Indeed, with total freedom on the underfloor design, we were able to reach our aerodynamic balance target (which for stability reasons needs to be slightly behind the center of gravity of the car) without a full front wing. Our front arrangement with the wheel covers still allows for aerodynamic elements to be added to tune the aerodynamic balance right depending on each track profile. This solution also offers the advantage of attaching those aerodynamic devices directly on the un-sprung mass of the car.
To be an open wheeler or not to be
For most of us, open wheels are the signature of single seater formula cars. During a very long time in motorsport history, the compromise has been going toward not covering the wheels in order to save weight, considering bodyworks were made out of aluminium and aerodynamic was of secondary concern.
There were some exceptions though as full streamlined Grand Prix machineries (including wheel covers) were seen in the past on high speed tracks. The last streamlined Formula One car to hit the track was a Vanwall during the 1957 French Grand Prix. You may have noticed LE PINACLE racing car concept carries number 57!
Later on, wheel covers were banned, definitely freezing in the mind of people, what a single seater formula car should look like. This does not make much sense anymore. Today, carbon fiber technology brings the possibility to build extremely lightweight pieces of bodywork. Moreover, drag penalty of open wheelers is very noticeable with the large wheels being a standard nowadays.
This led me to go for proper wheel covers on this concept. The front wheel covers serve two purposes: reducing drag and out-washing the front tyres wake on the car sides in order to avoid that dirty air flow to interfere with the cleaner flow feeding the rear of the car. Rear wheel covers reduce drag and also serves the handling of the rear tyres wake, at a smaller extent compared to the front. We allowed some open slots on top of the tyres, with the intent to reach the optimum compromise between aerodynamics and weight (tyre wake builds up on the rearward part of the tyres which we have kept covered).
Wheel covers are directly attached to the wheel assemblies and as such, are part of the un-sprung mass of the car. This allows them to be as small as possible, only accounting for the tyres centrifugation and not having to cope with the wheel displacements, travelling or steering. They are integrating the brake ducts and covering includes also the outboard sides of the wheels through separated panels. Those outboard panels are mounted directly to the hub assemblies in similar fashion to the static wheel covers last seen in Formula One in 2009. They are attached to the main wheel covers through fasteners for quick removal of the wheels (please note again this is a circuit record car and as such there is much less stress on fast pit stops).
We need cooling!
Coming up with a 1600 bhp car does not come without incidence on the cooling aspects. Even though the car has been envisioned as a track record purpose built car, without the necessity of lasting a full two hours Grand Prix, we still wanted the car to be able to perform a series of laps in a consistent manner, reliability wise. Also because you don't break track records on one lap shootouts, you need the driver to get used to the car, to explore and find the limits. And obviously, nobody wants to rebuild cars and engines every single lap.
Cooling installation is quite conventional through tubes and fins radiator cores. Cores have a twisted shape for an optimal packaging. On top of that, the sides of the radiators are exposed in an attempt to get an extra bit of surface cooling and saving a touch of bodywork weight (remember this concept is about pushing the design boundaries).
CHASSIS
Safety first!
The chassis was designed around the latest single seater racing safety standards which means the car was designed around a carbon monocoque featuring an Halo structure. Fighter jet canopies were ruled out as it is very much science-fiction for the time being. There has been a lot of research around that kind of concepts the last couple of years but it has been proved very challenging to adapt those to single seater applications, in particular to tick all the boxes concerning weight, strength and quick driver extraction.
Vehicle dynamics of a 7G's cornering car
On our reference simulator test track, the Catalunya circuit around Barcelona in Spain, LE PINACLE is more than 10 seconds faster than current Formula One machineries in qualifyings, with lateral accelerations reaching peaks up to 7G's. This comes with a top speed of above 400 kph in the main straight line. This is basically right at the limits of human capability. G-suits could be an option to help drivers copying with the very high G's. In this case, we would not go for military ones used in fighter jets as they are very heavy but for a bespoke design, something more similar to the racing G-suits being used in the Red Bull Air Race World Championship (their weight is about 7 kg).
The car has been packaged around a smaller fuel cell in comparison to current Formula One cars as, even though the fuel consumption is going to be much higher on an unlimited engine, the car does not need to have the autonomy for a full two hours Grand Prix. This allowed me to design the car around a much favourable wheelbase to track ratio than what we know on contemporary Formula One machineries. The car is architected around generous front and rear tracks, with the intent of maximizing the dynamic and cornering capability of the car. It also maximizes the underfloor area which is a boost for ground effect and increases the fan-generated downforce which relies directly on the underneath sealed area and volume.
Active suspension for the wire!
With the aerodynamic performance of the car relying mostly on a massive ground effect (either in fan mode or in ground effect mode), active suspensions would be the only way to achieve a consistent and an optimum aerodynamic performance, by ensuring ride heights of the car are always being controlled. This would also be a matter of safety, for stability reasons, and to avoid phenomenons like bouncing, which are common on low ride height ground effect vehicles. And finally, this will guarantee a minimum of handling comfort from a driver perspective as otherwise, a conventional spring/damper suspension would have required an extremely stiff setup to handle those kind of aerodynamic loads.
Active suspension technology has been envisioned as very similar to the technologies introduced in Formula One in the early 1990s before they were banned. This will be a fully active suspension system with full ride heights and damping control, operated through hydraulic actuators on each wheels (lengthening or shortening the pushrods/pullrods) and managed by an electronic control unit from wheels load inputs.
On straight lines, the active suspension system will also adjust ride heights to minimize aerodynamic drag on top of the DRS activation.
Mixing with tyres
Ultimately, the car relies on its tyres as its only links to the ground. They are the essential part of the vehicle dynamics of any car. Sustained high G's will put a lot of energy into the tyres, causing them to overheat and bespoke tyre structures and compounds will be needed.
I elected to go for 18 inches wheels at the front, of similar size as new generation 2022 Formula One wheels. This will allow stiffer tyres at the front while allowing the active suspension to cope with most of the front loads to maintain the optimum front ride height and car pitch. However, I decided to stick on 13 inches wheels at the rear, of similar size as the previous generation Formula One wheels (2017-2021). The softer tyres at the rear will allow a better traction, considering the huge amount of torque the rear wheels need to deliver to the ground (remember it is a rear wheel driven car).
On top of that, this will offer a very welcome weight saving in comparison to be using 18 inches wheels on all four corners.
Indeed, the energy being put into the tyres is a function of the mass of the car, the G-levels and the slip angles the tyres run at. The objective being to achieve as high G's as possible and as slip angles and ratios cannot be too low for handling reason, that leaves mass which must be as low as possible to extract as much performance and durability from the tyres.
"Light is right"
The car has been conceptualized as using the latest composites and carbon fiber materials for its construction.
The intent is also to make an intensive use of modern 3D printing technologies and in particular 3D metal printing (aluminium and titanium) which allows to optimize parts design and weight to new boundaries. Our showcase for this approach is our organic single blade roll hoop design. A design we decided to offer to the public eyes through a transparent lexan cover (lexan being on top of that lighter than carbon).
This will be complemented with the use of carbon fiber reinforced thermoplastics. This material in its long fiber form is banned in Formula One although it is widely used in the aerospace, aeronautic and military industry. Components such as uprights or rims could benefit from this technology for substantial weight savings.
As a result and based on our calculations, we are targeting a car that would weight less than 720kg including the driver.
TECHNICAL SPECIFICATIONS
Chassis: Carbon composites monocoque with Halo structure
Engine: Twin turbos V6 1.6L (1600 bhp, extra 150 bhp boost for fan activation),
synthetic (carbon neutral) fuel
Transmission: 8 speed sequential seamless gearbox (longitudinal cluster).
Automatic up/down shiftings possible or semi-automatic through paddle shifts.
Targeted Weight: < 720 kg including driver (45/55 %front/rear ratio)
Dimensions: Wheelbase 3,300m
Track Front: 1,77m ; Rear: 1,78m
Lenght: 5,14m
Width: 2,33m
Height : 1,02m
Brakes: Purpose built carbon discs and pads. Purpose built lightweight aluminium calipers
(6 pistons front/4 pistons rear).
Aerodynamics: - Wing shaped sidepods with full lenght aeroelastic side skirts
- 390mm diameter fan, gearbox driven (hydraulically actuated variable blades pitch)
- Front and rear floor sealing panels (hydraulically actuated in fan mode)
- DRS (Drag Reduction System) through hydraulically actuated rear wing second element
- Variable sidepods cooling inlets (flaps actuated through small electric motors)
- Downforce: 4500kg @ 300kph; 40/60% front/rear aerodynamic balance
Suspensions: Double wishbones front/rear. Fully active suspension system with full ride heights and damping.
control (hydraulically actuated through pushrods at the front and pullrods at the rear).
Wheels and tyres: Wheels Front: 18 inches wheels ; Rear: 13 inches wheels
Tyres Front: Diam. 710mm, Width 390mm ; Rear: Diam. 660mm, Width 450mm