Rimac C_TWO - World Beater
New ground is about to be broken, as the new Rimac C_TWO is getting closer and closer to final release. Daniele Giacji and Gustavo Andrade give us an in-depth look at the latest stage of prototype crash testing, before moving onto final production crash testing.
We are literally months away from the release of one of the worlds most exciting and groundbreaking cars.
What is Rimac?
You’d be forgiven for asking this question, given their small size and single car portfolio. However Rimac are a force to be reckoned with. Rimac Automobili, as they are formally known, are an all electric hypercar maker based in Croatia.
Founded in 2009 with the simple vision of creating THE definitive 21st century sports car, their first model, the RImac Concept One has already achieved the accolade of being the worlds fastest supercar. The new C_TWO is destined to smash these existing records, and become a true world beater.
There is no question then, Rimac aren’t going to disappoint with the C_TWO. With the original Concept One already producing 1287 hp, possible of 0-60 mph in 2.6 seconds and a range of up to 600km. What could we possibly expect from the new C_TWO?
The Rimac C_TWO
Initially being unveiled at the 2018 Geneva Motor Show, the new C_TWO has been completely re-engineered from the ground up to be the most powerful vehicle in the world.
Timeless, elegant styling, with form respecting function, the C_Two is completely new and yet unmistakably Rimac. It incorporates the company’s signature ‘tie’ design on the flanks, finessed to suit the car’s dramatic proportions. A feature that is also functional, acting as an air-intake for the rear cooling systems.
A method of entry and egress designed to be as dramatic as it is pragmatic. New butterfly doors not only deliver endless kerbside drama, they also elegantly carve away at the C_Two’s wide sill when open, giving a generous space for sophisticated entry and egress.
With its wide, architectural rear end, the C_Two could never be mistaken for the ordinary. Despite incorporating a wealth of active aerodynamic elements, it remains a coherent graphic, combining both the drama and beauty of a hypercar seamlessly with the cutting edge – shaped by the air itself, forged with technology.
Lightweight, forged alloy wheels feature a unique aerodynamic design that channels cooling air to the carbon-ceramic braking system and ensures smooth airflow down the flanks of the car. The C_Two’s tyres are a bespoke design and compound developed in conjunction with Pirelli, designed to make best use of the car’s characteristics.
High-intensity LED light units front and rear provide the very best in terms of illumination. Each headlight contains a hand-built squadron of 58-LEDs choreographed by a Rimac control unit, equipped with its own ventilation system. And even the rear lights also contain integrated air-outlet tunnels.
A broad, sculptural hood design emphasises the Rimac C_Two’s strength and intent and includes active flaps that modify the car’s aerodynamic profile. This provides the kind of low coefficient of aerodynamic drag that allows this hypercar to slice the air like a silent knife, aiding both efficiency and performance.
The Rimac C_Two’s front splitter features active elements to both modify the car’s aerodynamic profile and help maintain optimum operating temperatures for electronic and battery systems. By utilising these mobile flaps, the C_Two can remain cohesive and beautiful, and yet still exceptionally functional.
Despite its appearance as fully-integrated into the back of the car, the rear wing adopts varying positions according to dynamic loads – maximising cornering downforce and also allowing for a high top speed – and instantly operates as a full air-brake to stabilise the car under heavy braking.
A fully flat floor and optimised venturi-effect rear valance accelerate airflow underneath the car and remove positive pressure from beneath. Active flaps modify this effect to make the C_Two exceedingly efficient at managing the air it moves through, while channeling cool air to the battery pack cooling systems.
Chassis and Drivetrain
The Rimac C_Two features a full carbonfibre monocoque with bonded carbon roof, integrated structural battery pack and rear carbon subframe, with crash structures formed from aluminium and carbonfibre. The result is that it is both light and extremely strong.
With its Lithium/Manganese/Nickel chemistry, 6,960 cells and cylindrical 21700 form-factor, the Rimac C_Two’s liquid-cooled battery pack holds 120kWh and produces an astonishing 1.4MW of power. Encased in layers of safety and protection systems, the pack is configured to offer the best possible weight distribution to optimise dynamics.
Four electric motors power each individual wheel, giving both four-wheel drive and unprecedented dynamic control. The bespoke dual permanent magnet, oil-cooled electric motors offer instant response, more than 97-percent efficiency, a near-limitless and maintenance-free operating life and maximum torque from zero rpm.
While a pair of single-speed gearboxes apply drive to the front wheels, a pair of two-speed gearboxes – again, one for each rear wheel – allow the C_Two to make use of its prodigious torque to produce both mind-blowing acceleration and a true world beating top speed.
The Rimac C_Two can load selected racetracks into its on-board systems via the ‘Driving Coach’ function, offering clear and precise guidance on racing lines, braking/acceleration points and steering inputs. A virtual driving coach with a very practical application and learning experience.
R-AWTV replaces traditional ESP and TCS and enables infinitely variable dynamic responses by finessing the amount of torque to each wheel. This configurable drivetrain allows for minute calibration of behaviour, from rear-biased, driftable sportscar to a machine that can meter traction perfect on slippery surfaces.
From advanced ADAS features, facial recognition in lieu of a key, voice control and beautifully animated graphics, the car also features an M2M system monitors over 500 channels of telemetry – which can then be accessed and interrogated in real time via mobile app or laptop.
All of this is possible thanks to eight on-board cameras, a pair of lidar, six radar emitters, twelve ultrasonic sensors, as well as an exceptionally precise global positioning system and IMU sensor for autonomous driving. Indeed, the C_Two may well be the most sensitive and connected series car in the world.
A unique and bespoke set of interfaces have the ability to monitor every aspect of the car’s performance via live telemetry animations or graphs, or simply browse through a library of music, Rimac’s systems provide convenience and intuative usability.
The C_Two features a triplet of high-definition TFT screens, which present as much, or as little, information as the driver decides is relevant. As well as the convenience of touchscreens, an owner can nevertheless complete every function of the car via billet aluminium rotary controls and switches.
A secondary screen displays the car’s current functionality direct to the passenger via a dedicated ‘co-driver’s display’, overlaying on-board datalogging to the screen graphics – a sophisticated semi-gaming experience not seen before in a production car.
Gorgeous billet rotary controls for major and most-used functions: switching through driving modes, controlling the amount of torque sent to the back wheels in ten percent increments, gear selectring start/stop.
Designed for the Open Road
With generous space for two occupants and their luggage, the Rimac C_Two is designed as a true grand tourer. A situation made possible by the car’s generous range of 550 km (WLTP Cycle). With every wheel and button milled from billet aluminium, the experience of interaction in the C_Two is profoundly satisfying.
Wide, generous doors provide an easy access space for any type of driver and passenger – even when wearing racing helmets. The doors take with them part of the car’s sill structure and roof – meaning the C_Two’s occupants are able to sit into the car, rather than clambering in over an awkward sill.
With fully electrically-adjustable sports seats and steering column as standard, the C_Two is more than capable of accommodating any type of driver or passenger with ease, whether touring or on track.
The C_Two comes equipped with everything you may need for longer trips: oddments storage, wireless phone charging and luggage space. The generous trunk in the rear of the vehicle can even be configured in a variety of specifications, according to the customers wishes.
Rimac C_TWO Specification:
Power: 1914 hp
Torque: 1696 lb-ft
Top Speed: 258 mph
0-60 mph: 1.85 seconds
Range: 402 miles
Now that we can appreciate the amazing feat of technology that stands before us, continue reading for more of an insight into how small volume manufacturers like Rimac have to manage and organise crash testing in order to obtain the worldwide approval for sale.
Daniele Giachi is the director of vehicle engineering at Rimac, and Gustavo Andrade is a CAE engineer.
“We wanted to build a car ahead of its time, and this is really a big challenge from the engineering point of view. But it’s also rewarding.”
One of the main challenges is the global homologation from passive safety, and this task is really huge. We want the car to be safe for the customer, and legal worldwide. But it’s a task that is really big for a small volume manufacturer. Especially when you do that for the first time starting from scratch.
Developing a globally homologated hypercar is a completely different level. The successfully design, develop, test and produce a hypercar, we have to go through several steps of research and development.
We have been developing this car for three years now, and I have seen these simulations thousands of times on our screen. One of the main tasks is to create a very detailed model that describes each layer of the carbon fibre, each core, the connection and all the various subsystems of the car.
Our super computers are running 24/7 to improve the performance of our car for safety and stiffness. All in a virtual world.
The goal is to have the most perfect correlation between real and virtual testing, in order to minimise the risk you go to crash a prototype that costs one million euros. The design process is quite complex and long. If I want to explain it in simple worlds, it’s like this; We start from a very rough concept. This concept is simulated with virtual analysis. Then, once we find a good result, we start to refine it, and this refinement goes to several loops between design, engineering to try to find the best compromise.
When we are happy with the virtual results, we start testing. Initially, the component level. Then the system level, and finally, full vehicle level.
Also vehicle testing goes through three different stages. We started with the experimental prototypes, we will do a prototype testing, and then pre-production testing. In each stage, to find a solution is more and more difficult, because the level of restrains increase.
Nobody can promise one hundred percent success for the first time. Sometimes things go wrong.
During the first round of testing on the crash structure subsystem, we had an unexpected behavior. The rail peeled off like a banana, then the team needed to understand immediately what happened, and why we had that behaviour that was not represented by the simulation.
We had to react really fast to understand what happened, to propose a new design, to produce new prototypes. To test it again, and then finally, success.
Because things can go wrong, is the reason why we do so many rounds of testing, and because of this the team needed to be ready to react to this negative result with proactivity, finding the new solution and solving the issue that we encountered.
The scope of the C_TWO project is huge for a small volume manufacturer.
I was scared before the crash testing, and the people that were with me know that. Because, in my experience, I have contributed to the design of several cars, I went to several crash tests, and I know that things can go really wrong. For this reason we tried to look to every detail, to have a robust methodology. At the moment, because the first round of crash tests was really good, the results are paying off.
For the first round of high speed crash tests with the experimental prototype, we used the same monocoque for five crash tests. It was so good, it was so strong, that we decided to one more. Roof crash.
The next step in development is to further improve our design and correlation with CAE simulation , to permit us to develop even more the perfection that we want to achieve with the Rimac C_TWO.
Now that the first round of crash tests finished with great results, we have full confidence in our work.
Final production vehicle tests are planned soon.