Aerodynamic Development of Mackie Adlem's SABAT Mustang

Project Outline

The importance of aerodynamics in high-speed motor racing is easy to understand. The spectacular failure of Raikkonen's rear wing at the German F1 Grand Prix in Hockenheim shows just how critical aerodynamic forces and aerodynamic balance can be. The aerodynamics themselves are however not as simple to comprehend.

South Africa's largest aeronautical institute, based at the CSIR in Pretoria, has extensive aerodynamic expertise and has been involved in various automotive aerodynamics initiatives, utilising its large (7.5m by 6.5m) wind tunnel, its rolling road facility, computational fluid dynamics (CFD) and several smaller wind tunnels.

In a recent initiative, headed by aeronautical engineer Terence Denton, this technology will be applied to Mackie Adlem's SABAT Mustang WesBank V8. Through this initiative, the CSIR hopes to gain exposure to the racing fraternity as well as to the viewers and spectators in the CSIR's target market for aerodynamic flow solutions. To this end, Mackie's car will now be carrying the CSIR logo.

Rally car on the car balance in the CSIR's 7m wind tunnel

Drawing primarily on the CSIR's wind tunnel capabilities, Mackie's car will be tested in the CSIR's 7m wind tunnel early in September, with the aim of improving handling and lap times. Using flow visualisation to identify problem areas in terms of drag, intakes, cooling and general airflow, the car will be aerodynamically "tuned". An instrumented platform known as a "car balance" will be used to measure the lift and drag forces acting on the car and will enable the car to be set-up for Mackie's particular driving style and the specifics of the race circuit. Increasing down force allows better cornering (provided the front-rear balance is correctly set up), but the higher down force results in higher drag, which means lower top speed. The critical balance between drag (top speed) and down force (cornering) can have a dramatic effect on the performance and handling of a high-speed vehicle such as this. Similarly, the force balance between the front and rear of the car is equally critical - less down force for high-speed circuits, more for tight circuits. This balance is closely linked with the suspension set-up and thus the two have to be tested together in a facility such as the wind tunnel.

A scale F1 car in the rolling road facility, low speed wind tunnel

While this wind tunnel does not attain the same air speeds as the actual racing speeds, the aerodynamics can be extrapolated. Thus the wind tunnel provides a similar aerodynamic environment in which controlled evaluation and modification can be performed.

Although the wind tunnel testing is only scheduled for September, the PSIREC and the CSIR are already involved during races to determine the most effective areas in which the maximum improvements can be made in the shortest time. First, a short and intense wind tunnel programme is planned to optimise the current aerodynamic set-up. Thereafter, more detailed aerodynamic analyses will be performed to develop and "tweak" the car aerodynamically as required.

Obviously all the rules of the WesBank V8 Class will be adhered to, but the boundaries will be tested and all constraints will be optimised during this aerodynamic process. Essentially, the rules hold the cars to various dimensions/shapes/angles etc – it is within those parameters that the opportunity to optimise lies.

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