Designing the Lightyear One – Suspension and Chassis
Wouter Jansen — Vehicle Dynamics Architect
Being a Vehicle Dynamics Architect at Lightyear means I focus on the mechanical parts of the car. I work on the chassis, the structure of the car, the wheel suspension, the wheels themselves, the braking system and the steering system. The interactions and interfaces between these systems are crucial. The challenge is finding the very best connections in order to optimize the performance of the Lightyear One. I would like to tell you something more about these systems and interactions.
What makes designing the Lightyear One special?
The Lightyear One is fundamentally different from your typical car in many ways. This means we have to find to non-conventional solutions, or look to use conventional solutions for new problems. One of the striking features that really sets the Lightyear One apart from the bunch is the air suspension system. Using this system the Lightyear One can vary its ride height. When set to a greater ride height the Lightyear one has better ground clearance, making driving over rough terrains even easier. We want to make a car that can drive everywhere, and air suspensions pushes those limits just a bit further.
There is much more to the air suspension though. The air suspension helps with the aerodynamics as well. By changing the ride height according to the speed of the car we can minimize drag.
As the Lightyear One will be an exceptionally light car the possibility to compensate for a heavy load is also a great feature of the air suspension system. Normally more weight would lower the ride height, which is not optimal for the aerodynamics and ground clearance. Using the air suspension we can compensate for this extra weight. Moreover, if for instance people sit at one side of the car it would lean slightly to that side. Using the air suspension we can level the car. We measure the position of each damping so we can keep the car perfectly leveled. Not only is the Lightyear One an extremely light car, the weight distribution is also distinct. Regular cars have light wheels and a heavy body containing the powertrain. This is inverted in the Lightyear One, since we have in-wheel motors and brakes, making the wheels heavier while making the body lighter. Lowering the center of gravity like this gives you maximum control over your car, but if not accounted for it could cost you in comfort. Heavy wheels could make the car more sensitive to shifts in weight, but thanks to the air suspension this is well accommodated for.
The weight saving cycle. The lighter the car, the more weight we can still save
This brings us to another special feature: the wheel suspension itself. Aerodynamics are a vital part of designing the Lightyear One. We gain an advantage by streamlining the bottom of the car. Normally you would be able to see the suspension links. That does of course create a lot of turbulence. The suspension links that connect the wheels to the car are placed slightly higher, so that we can create a smooth undercarriage. In doing so we minimize drag. Moving the suspension links upwards does of course bring challenges of its own, especially in the packaging.
Another intriguing part is the braking system. Having four independent motors in the wheels means you can brake using the motor, and using each motor separately. When you brake using your motors you can lead the energy created back to battery. This way, braking will charge the battery. This also reduces the need to brake mechanically, using a brake disc and caliper.
As with each decision there are also some challenges. One challenge is how to make optimal use of the brakes when the battery is completely full. First of all, the mechanical brakes will of course support this, but different battery configurations are also an option.
A nice side effect of using mechanical brakes far less is that these too can become a bit lighter, improving both the efficiency and comfort of the Lightyear One. They are of course still designed to enable a full emergency stop without any help from the electric motors should the need ever arise.
Creating a chassis fit for a racing car – light and strong
Finally, the chassis itself is fully optimized to reduce mass. The low production volumes of the Lightyear One allow us to use cutting edge production techniques and materials, such as aluminium and fiber reinforced plastics. These materials are not just very light, but also incredibly strong. The chassis has ample crumple zones at all sides, so that even in the event of a rollover the occupants are safe. All in all, we work to make sure everything is perfectly balanced for the best possible safety, optimal weight and impressive performance.