One of the most important aspects that limits the fidelity of the driving simulator compared to a real racing car is the steering wheel. If, for example, you have a Direct Drive wheel capable of delivering 16 Nm of torque output, torque peaks above this value cannot be reproduced in the simulation. The impact of this limitation, in particular, is that torque peaks well above 16 Nm are cut off and manifest as a constant output of 16 Nm (this phenomenon is known as “clipping”). This reduces, for example, the driver’s ability to feel the alignment torques and consequently the indication of the grip level beyond a certain torque threshold.
But what are the torque values in dynamic conditions of a racing car steering wheel?
It is not easy to answer this question, first of all because the forces involved depend on multiple factors such as size and type of tires, geometry and characteristic angles of the suspension, downforce, weight distribution, presence or absence of power steering, etc … and secondly due to the scarce availability of information on the subject; manufacturers and teams are in fact reluctant to share this type of information externally.
However, the Dutch racing team Van Amersfoort Racing, in collaboration with the Delft University Of Technology, conducted an in-depth experimental comparison study between the simulator, based on one of the most advanced modeling software on the market (also used by several Formula 1 teams) and a real Formula 3 Dallara car.
Note: the VAR team is one of the most renowned racing teams in Europe, for which drivers of the caliber of Max Verstappen, Charles Leclerc, Anthoine Hubert, Callum Ilott, Mick Schumacher, Giedo van der Garde, Jos Verstappen and Christijan Albers have raced. Over the last few years, the VAR team has started major investments for the creation of a new state-of-the-art headquarters, in order to strengthen its involvement in two important development programs: the FIA European Formula 3 and ADAC Formula 4 championships.
The study in question focused attention on comparing the sensations transmitted by the steering wheel of a real Formula 3 car, therefore not equipped with power steering, and those transmitted by the steering wheel of its virtual counterpart.
In order to compare the torque calculated by the simulation software and that of the real car steering wheel, appropriate measurements were made using torque sensors. The tests on board the car and the simulator were conducted on the same track, namely the Barcelona-Catalunya Circuit, at the wheel of a Formula 3 Dallara F312. Before doing this, the physics of the car (thanks to data provided by the Dallara car manufacturer) and Hankook tires were implemented in the simulation software.
The aforementioned study has provided various indications but we, however, will focus on the most interesting and functional ones for our evaluations:
- the steering wheel torque, measured in the real car, varies from 10 Nm measured at chicanes and slow corners, to 20 Nm in fast corners;
- the torque values, required to obtain a certain lateral acceleration, calculated by the simulator software are in all situations higher than the actual torque values measured on the steering wheel of the real car;
- in the simulator, the driver has to rotate the steering wheel in general at a greater angle than the real car to generate some lateral acceleration.
The information obtained from the real Formula 3 car was used to update the vehicle model used in the VAR team simulator and to start the development of a new model (through the Multibody Dynamic simulation system), specific for open-wheel cars in this category.
Similar tests were also conducted by the Kunos Simulations team (in collaboration with Honda) and on its official forum reveals that he has found, through the use of torque sensors, that in modern cars the stresses at the wheel are much lower than previously assumed (without however providing the forum users with any numerical value). These tests were used to learn, during the development of Assetto Corsa, the behavior of the “steer assist” and how it is used to modulate the forces according to the driving phases (when traveling through low-speed and high-speed curves and high aerodynamic load, in impacts on the curbs) and make driving comfortable (especially in endurance races) but at the same time provide the rider with sufficient feedback in the race.
With regard to the most extreme situations, such as collisions between two or more cars or collisions with walls and barriers, these types of forces are implemented in the FFB of Assetto Corsa Competizione in a reduced form. The only forces behind the wheel come from the contact area between the wheel and whatever is on the track surface. However, when the car is out of control, such as in the case of a spin, your steering wheel can turn violently left and right; in these situations it can be dangerous to let go of the wheel and try to catch it as it swings out of control.
But what are the torque values that develop on the steering wheel of a modern GT3 racing car equipped with power steering?
We of the Trinacria Simracing team asked our friend Matteo Cairoli, official driver at the GT World Challenge Europe Endurance at the wheel of the Porsche 991 GT3.
“As you can imagine, I cannot give you detailed information firstly for confidentiality reasons and secondly because the steering wheel settings are constantly changing. In fact, for each circuit we change power steering and steering gear. To give you an idea, the power steering of GT3 racing cars, before being tuned, is the same as the cars on the market. As for the Porsche, most of the time our power steering looks a lot like the Porsche GT3 sold in the world in race configuration. Basically, it takes strength in the arms but this can be more or less depending on the layout of the track. In Monza, for example, the steering is harder due to the speed of the track and the chicanes, and the purpose of a harder turn is to be more precise in fast corners. The Porsche, in the GT world challenge, is the car with the hardest steering, the opposite of Mercedes which is the easiest to handle ”.
Even if we have not been able to accurately quantify the amount of torque that produces a modern GT3 car equipped with power steering, we can say that the purist simracers of the simulation (also attentive to the wallet) with some compromises can get a lot of satisfaction even with steering wheels that develop not very high torques, starting from from about 4 ± 1 Nm of a steering wheel with belt transmission. On the other hand, an entry level Direct Drive, capable of 8 Nm of torque, may already be more than enough to reproduce all the peak torque of the steering wheel of a true modern GT3.
After all, if Leclerc rides the Suzuka 130R with one hand…🤔
Trinacria Simracing 