TECHNOLOGY – AEROBYTES
Simon McBeath offers aerodynamic advisory services under his own brand of SM Aerotechniques – www.
sm-aerotechniques.co.uk. In these pages he uses data from MIRA to discuss common aerodynamic issues faced by racecar engineers
Produced in association with MIRA Ltd
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The fi rst iteration of front wheelarch aperture tested
facilitate the release of pressure within wheelarches and also kill off some lift over the top of wheelarches, both to the betterment of downforce. These had been regulated for some time in terms of the area required, so it was something of a surprise when the ACO announced that from 2012 there would be mandatory apertures rather than louvres in the tops of front and rear wheelarches, with minimum and maximum areas stipulated and limits on location. The data in fi gure 1 compares with and without wheelarch apertures, with the mandatory- for-2012 engine cover fi n fi tted in each case. Whereas the engine cover fi n seemed to make negligible difference to drag, even at the maximum yaw tested (six degrees), the wheelarch apertures did make a difference, increasing drag by around 2.6 per cent at zero yaw, and making a similar difference across the yaw range tested here. This is reasonably signifi cant in terms of straight-line performance, but it must be said that this fi rst attempt at creating the apertures simply involved cutting holes to the prescribed maximum size in the existing wheelarches, with no attempts at shaping to mitigate the effects. The effect on total downforce
The hole truth O
bservers of Le Mans Prototypes will be aware of wheelarch louvres, which
A fi rst look at the effects of mandatory wheelarch apertures
Figure 1: wheelarch apertures altered drag
Figure 2: the fi rst iteration wheelarch apertures made only small differences to total downforce
Figure 3: the wheelarch apertures also altered aerodynamic balance Le Mans •
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