Following the steps of the previous cars, delivering good engineering, safe and fast racing prototypes, Projecto FST Novabase is proud to present the design of its most advanced prototype up to date: FST 05e. Always wanting to learn and evolve, the team wants to deliver a top performance in the international competitions where the FST 05e will take part in. The FST 05e will be competing in Germany, Hungary and Spain in 2013. Being an electric powered prototype, the team is relying on a lightweight and innovative philosophy to improve its design from the previous and first electric formula, the FST 04e.
SUSPENSION In order to fulfill the team goal, the suspension system is designed to search for the best grip while being light. Suspension is, after all, a group of lines and points that control wheel movements, so our main focus was to design the lighter suspension system up to date.
The FST 05e suspension makes a wise use of material selection in each and every component. Going along with the massive use of composite materials of the team, the rims and suspension links are all made of CFRP. Furthermore, the joining techniques of composite and isotropic materials were taken in account by extensive physical testing due to its extreme importance.
Everything was scrutinized to reduce weight and even a costumized steering system was designed, including the steering wheel itself. Loss in weight usually comes at a cost of less stiffness, but that is not the case. Proper attention was paid concerning the stiffness of the parts so wheel control would not be compromised.
DRIVETRAIN & BRAKE SYSTEM The drivetrain system allows us to combine the power of our motors with how we want the car to perform dinamically. This tandem is better achieved using torque-vectoring and for that matter we make use of two gearboxes, one for each motor, which transfer the power to the wheels. For better efficiency we use a gear system. This gears are made of steel and built using E D M — E l e c t r i c a l Di s c h a r g e Machining. In order to achieve the best drive ratio, a two-stage gearbox was fully designed by the team. The wheels and hubs are now designed in aluminium, saving a lot of weight compared to the more common use of steel.
Our brake system is designed for reliability with all the hydraulic parts purchased from respected brands in the market. The step forward this year is the self-designed brake rotors, made of steel and with perfect dimensions for our specifications.
CHASSIS For the first time in our long tenure the team is designing and building a rolling monocoque chassis. The whole team was highly receptive to this advance, not only in performance but also in know-how in a new area of learning. The chassis team quickly put their hands on the job in 2012, by first designing and manufacturing a full monocoque for competition in FSUK Class 2. The next step is to design a new monocoque chassis with all the knowledge gathered in the previous year.
The FST 05e monocoque is precisely designed to comply with the FSAE rules, make room for all the components and withstand all the loads imposed by the quick accelerations the prototype will achieve. Physical testing was a major concern to ensure safety and every possible case was handled with special attention. The impact attenuator is made of aluminium honeycomb, one of the most suitable designs for a hard front impact of the prototype.
POWERTRAIN & ENERGY ACCUMULATOR Making good use of the knowledge acquired from the previous car, our electric components were selected to follow the team goal of making a lightweight prototype. Safety is a major concern in this area where a small mistake can turn into a big problem very easily. Our team showed consistency in this area with our previous car and, consequently, safety will be a feature of the electric unit of the FST 05e. Our motors were carefully selected from a list of several choices. The motors propelling the FST 05e are the ones which present the best power to weight ratio. From Siemens, this motor is a permanent magnet AC unit, being each motor driven by a control unit of its own, a torque vectoring demand. Providing energy to the motors, our battery cells have the best energy density currently in the market. This LiPo cells are so light compared to the ones used in the previous prototype, that a loss of 60% of weight was possible. The capacity of the accumulator is also increased by the use of regenerative braking at the rear axle.
AERODYNAMICS & REFRIGERATION Not only following the trend of Formula Student nowadays, the team needed proof that the not so long ago a considered exotic design, would be a valuable asset in this kind of competition. This confirmation was achieved through simulations of a winged vehicle and finally the decision was made: the team’s first aero car is now being built. By delivering downforce to the tyres we are able to achieve superb accelerations, helping the car to go faster and also to stop faster. To deliver this kind of performance front and rear wings will be used together with an undertray, all of them optimized by the team’s aero department. The FST 05e aerodynamic devices will be able to provide a downforce of 250kg at 120kph.
Always learning from previous experiences, the cooling problems with the FST04e were addressed and the knowledge gathered was used to design the cooling system of the FST 05e. Two radiators will be used to cool the motors and controllers securing optimum operating temperatures.
VEHICLE DYNAMICS & DATA ACQUISITION Vehicle dynamics is a main area in motorsport and the team wants to evolve as much as possible here, making good use of our knowledge to help the FST 05e go faster. An electric powered vehicle is the optimum target of a torque vectoring system, that controls the torque input to each one of the driven wheels independently. This opens up a lot of scenarios concerning handling control and this is one of the main features of the FST 05e.
A suspension specially designed for the aero loads is what we will see on track combined with an efficient drivetrain, a chassis which is stiff enough to attain such high accelerations and a slip control system acting together will make the FST 05e a treat to drive. The FST 05e will only take 2.85 seconds from 0 to 100 kph and will be able to corner at nearly 2 G’s.
Such control of the situation is not possible without a feedback system and the FST 05e will have the bigger amount of sensors used until now in the team’s long history of chasing quick cars. Equipped with accelerometers, gyroscopes, linear and rotary movement sensors, temperature sensors and even strain gauges to measure the strain on several components, this prototype will be not only a driving machine, but also a learning platform for the future.
SPECS Wheelbase: 1590 mm Track: 1200/1170 mm Weight (including driver): 268 kg Maximum speed: 125 kph 0-100 kph: 2.85 s Chassis: Full CFRP Monocoque Suspension: CFRP suspension links, Double-wishbone. Front pullrod and Rear Pushrod Powertrain/Drivetrain: 2 Electric AC motors with permanent magnets, rear wheel drive controlled by torque vectoring. Energy Accumulator: LiPo cells. Aerodynamics: Undertray, front and rear wing.