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The Impact of Non-Linear Aerodynamics on Racecar Behaviour and Lap Time Simulation
ISSN: 0148-7191, e-ISSN: 2688-3627
Published December 02, 2002 by SAE International in United States
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Despite massive research efforts carried out by racing car manufacturers aerodynamics is probably the most unexplored field in the design of high performance vehicles. Scale wind tunnel testing is still the most effective way for the development of a new car, CFD codes being at the experimental stage.
Wind tunnel engineers produce what is called an “aero map”: a simple graph expressing aerodynamic forces versus ride height. That means, drag, downforce, and relative distribution are measured on an array of front and rear different ride heights.
The same concept can be applied to track testing with the use of proper sensors on the real vehicle, such as ground height laser sensors and suspension force transducers.
Reading such a map and relating it to static and dynamic suspension characteristics is a vital task for performance optimisation. In the perfect world the centre of pressure would always be in the ideal position anywhere on the track, thus enabling the driver to make the most out of the car.
As a matter of fact any unwanted, back and forth movement of the centre of pressure due to pitch and/or heave (e.g. under power, in braking, or on road bumps) affects cornering behaviour: the car can be perceived as difficult and tricky for the driver thus jeopardising performance.
A module dedicated to non-linear aerodynamics (called “Aerolap”) has been added to the RCS software for lap time simulation, working in close co-operation with the Minardi Formula 1 and BMS Scuderia Italia teams. The vehicle model can now take into account the effects of ride height variations on aerodynamic forces, as well as non-linear suspension and tire ground stiffness. The user can therefore simulate the impact of set-up modifications on aerodynamic balance along the track as well as on overall performance.
The RCS project (presented at the 2000 SAE Motorsports Engineering Conference in Detroit) was conceived as a pit lane support tool for the race engineer, who usually works under pressure in a noisy, stressing environment were things happen -and decisions are taken- all very quickly. Therefore a particular effort was devoted to interface and graphics. Regarding the Aerolap an innovative method was devised for map visualisation as an alternative to the usual contour plot. This seems to enable a far more intuitive correlation with performance results.
On the math side two different methods were used to approximate the aero map surface: a Gaussian array and the so-called Akima's triangles, the former giving more reliable results where extrapolation is required.
CitationGadola, M., Candelpergher, A., and Adami, R., "The Impact of Non-Linear Aerodynamics on Racecar Behaviour and Lap Time Simulation," SAE Technical Paper 2002-01-3332, 2002, https://doi.org/10.4271/2002-01-3332.
- Candelpergher A. Gadola M. Vetturi D. Developments of a method for lap time simulation SAE paper 2000-01-3562 . Proceedings of the 2000 Motorsports Engineering Conference and Exposition Detroit 2000
- Milliken W.F. Milliken D.L. Race Car Vehicle Dynamics SAE International 1994 1-56091-526-9
- Guiggiani M. Dinamica del Veicolo CittàStudiEdizioni 1998 88-251-7248-6
- Katz J. New Directions in Race Car Aerodynamics Robert Bentley Publishers 1995 0-8376-0142-8
- Hucho W.H. Aerodynamics of Road Vehicles IV SAE International 1998 0-7680-0029-7
- Ferrari A. Gadola M. Mensi A. I sistemi di acquisizione dati Appunti del corso di Meccanica del Veicolo, Università di Brescia 1999
- Resconi G. The Morphogenetic Neurone Proceedings NATO ASI, Soft Computing and its Applications 1996
- Cambiaghi D. Gadola M. Maffezzoni P. Tire modelling with the use of neural nets for vehicle dynamics studies SITEV - Automotive Industry International Week Turin, Italy November 1994 ATA Journal - Ingegneria Automotoristica March 1996
- Akima H. A method of bivariate interpolation and smooth surface fitting for irregularly distributed data points ACM Transactions, Mathematics Software 1978
- Floyd R.S. Law E.H. Simulation and analysis of suspension and aerodynamic interactions of race cars SAE paper 942537 . Proceedings of the 1994 Motorsports Engineering Conference and Exposition Detroit 1994
- Bonetti R. Ottimizzazione della strategia di gara in veicoli da competizione: elaborazione di un modello orientato e validazione sperimentale University of Brescia 1996
- Cambiaghi D. Gadola M. Manzo L. Vetturi D. A tool for lap time simulation SAE paper 962529 . Proceedings of the 1996 Motorsports Engineering Conference and Exposition Detroit 1996
- Peri A. Modellizzazione del comportamento di una autovettura da competizione. Sviluppo di software applicativo orientato alla determinazione delle prestazioni limite University of Brescia 1998
- Candelpergher A. Sviluppo di ausili informatici per l'ottimizzazione delle prestazioni di un'autovettura da competizione University of Brescia 1999
- Adami R. Vielmi S. Analisi e simulazione del comportamento di autoveicoli ad alte prestazioni con caratteristiche aerodinamiche non lineari University of Brescia 2001