Touge Spyder - Electric Racing Concept

The apex predator of serpentine tarmac

The romance of the car has always revolved around freedom. The freedom to travel at will, but also the freedom to transcend natural human abilities of movement; to move faster than any animal. As cars gradually develop into fully autonomous vehicles of pure utility, the primary role of the car designer will shift gradually towards developing interfaces for in-car experience and entertainment. Touge Spyder is an electric racing concept designed for touge racing. Touge are narrow ribbons of tarmac that wind through steep Japanese mountain passes. This project explores what would happen if the evolution of the vehicle was divergent, one path optimised for efficiency and sustainability, the other optimised for raw thrills. Touge Spyder addresses the latter route, it’s an exploration of the emotive, visceral possibilities of electric motoring. Touge Spyder highlights and builds upon the natural advantages of an electric powertrain. This was driven by a belief that the current cohort of electric cars focuses on trying to overcome their weakness, namely energy density, to make them more like fossil fuel cars. Range is a luxury that we cannot afford in electric vehicles in the long term, we must design around it. Hillclimb cars only run for seconds or minutes, so range isn’t an issue. Electric motors can have a much higher specific torque than petrol engines and they make all this torque at 0 RPM for breathtaking acceleration. They can generate and store energy when braking and actively vector torque to assist cornering, allowing agility far beyond that of a traditional combustion driven car. The batteries and powertrains can be packaged with far more freedom of design to facilitate ultra low centres of gravity, or very aggressive ground effect aerodynamics. As combustion engines need to breathe air, they are subject to power loss at altitude. This not a problem for electric motors. These positive attributes have been utilised to create a car that is highly specialised for its environment. The apex predator of serpentine tarmac.

Sustainable Electric hillclimb Racing in Nature

Touge Grand Prix is the concept racing series that the Touge Spyder was designed for. Touge GP allows people to race in the forests and mountains of Japan while still maintaining deference for their purity. To this end Touge GP is an all electric racing series, no fumes, no noise, just speed and excitement. Touge GP tours Japan, almost as an emissary for its natural beauty. It runs in all seasons from Hokkaido to Kyushu, sun, rain or snow. It is designed to be recorded using drones so that the racing operation is low impact on the environment, but the content is still world class. The Touge GP is not a racing series where one type of car competes, the entrants are free to design and build their own electric racing cars. The series is designed to attract more people towards STEAM (Science, Technology, Engineering, Art and Maths) concepts by building their own racers. Touge Spyder is an exploration of what an optimised Touge GP car might look like. Touge GP takes the core values of the European motorsport culture of ‘Bergrennen’ (mountain running) and translates it to suit Japan’s mountains and forests. This translation is evoked by the word ‘Spyder’, a pan-European word of uncertain etymology that refers to open top sports cars. The aim was to create the spiritual successor to the ultra lightweight Porsche 909 Bergspyder that dominated European hillclimb racing in the 60’s , while paying visual homage to the Honda RA272, the first Japanese car to win an F1 Grand Prix. This is why the Touge Spyder isn’t festooned with aerodynamic addenda. It explores the limits of pure mechanical grip without downforce for a pure driving experience and clean aesthetic. Touge GP would also include an ‘Unlimited Aero’ category to really push the boundaries of hill climb racing.

Biomimetic Tensegrity Structure

Touge Spyder is not a styling project. Proven components were used wherever possible such as the suspension, motors and batteries in order to maximise the feasibility of the project. The suspension geometry has been computer simulated to ensure real world performance. The batteries and motors have been calculated and chosen through research and engineering formulae.  A huge amount of time was spent refining the design so that it could actually be built and raced. The chassis was designed to be woven from carbon fibre on a rotary loom. Dual tube rotary loom technology has only been used once in an automotive application. This was developed in Japan by Lexus for the LFA supercar, however geometry restrictions limited them to implementing the technology solely on the A-pillars. Typical chassis geometry rules out this weaving process and requires that the carbon be painstakingly hand laid, which is time consuming and expensive. This chassis is quite unique in that its topology has been optimised to facilitate the tubular weaving process in its entirety. This allows the non-contiguous longitudinal elements to be incredibly strong and light by borrowing tensegrity concepts from nature. The subframes are 3d printed from Titanium using electron beam fusion. This process was chosen so as to reduce heat affected zones in the metal while avoiding the oxidation that Titanium is prone to when welded. 3d printing allows the complex geometry of the subframe to be fabricated without relying on costly jig manufacturing.

Competition proven components

In order to ensure the feasibility of the project, many powertrain components are off the shelf. The motors and controllers are designed and built in Slovenia, by Emrax and Emsiso respectively. These were chosen for their exceptional power density (>10kW per kg) and compact packaging dimensions. Each motor produces 80kW of peak power and after being transferred through the custom 3:1 takedown gearbox, 450Nm of torque is available at each wheel. GKN Cosworth spec constant velocity joints were chosen as few other systems can stand up to this kind of abuse. The suspension geometry was developed using Vsusp, an open source suspension simulation design software. Suspension design is always a compromise, this setup has been optimised to minimise rollcentre migration in roll for a stable, consistent driving characteristic. The roll centre only moves 0.5mm in 6 degrees of roll, so that goal has been achieved. Inboard Ohlins TTX springs and dampers from a Ducati Panigale have been chosen for their lightweight and external damper reservoirs for greater damping consistency. Custom aero profile wishbones, pushrods and tie rods are all designed to be woven on the same loom as the chassis.

Modular Battery swapping technology

The chemistries were optimised for power density as opposed to energy density, so that as few batteries as possible could used while still discharging them at safe rates. LG He4 chemistry was chosen for this application, in industry standard 18650 format. Touge Spyder uses 4 packs of 655 cells each, one per motor. Each pack is made up of 5 parallel banks of cells in series, this provides 470v at a safe discharge rate for the 80kW generated by each motor. The battery packs have been designed to facilitate ‘hotswapping’ so that freshly charged batteries can be swapped in less than a minute. Oddly this feature is not yet commonly seen on electric racing cars. The brakes are mounted using an unconventional inboard layout. While this makes designing the subframes very complex and time consuming, it has a number of advantages. The brake disc diameter is no longer limited by the wheel size, allowing much larger diameter, thinner discs to be used. This decreases the rotating mass while increasing the mechanical advantage of the calipers. It also decreases the unsprung mass, allowing the damper to more finely control the wheel bound and rebound on undulating surfaces, very beneficial on a rough hillclimb. Continuing the theme of using lightweight motorbike parts wherever possible, Brembo WSBK calipers complement 320mm Brembo Steel discs. Steel was chosen over carbon-carbon discs for its braking consistency and faster warm up times demanded by the sprint nature of hillclimbing.

Performance and Specifications

Touge Spyder’s number one priority was light weight. Weighing in at 320kg (705 lbs), this has been achieved. This ultra low mass, combined with 320kW of power (420 bhp) and 1800N⋅m of torque (1327 ft-lbs), allows the Touge Spyder to accelarate from 0-100kph (0-62 mph) in less than 1.6 seconds. That should be breathtaking indeed.

Touge Spyder was awarded the Red Dot Award for Mobility 2019.