TECHNOLOGY – AEROBYTES All change please… A new project, and a comparative look at the initial set up
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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e commence a new project this month and find ourselves working on the 2011
LMP2 Le Mans 24 Hours-winning and 2011 LMP2 Le Mans Series- winning Zytek Z11 SN-Nissan of Greaves Motorsport. As usual with a new project,
we’ll begin with a look at the car and its baseline data, and make comparisons with the nearest racecar we have previously tested. In subsequent issues we’ll take a look at the effects of some of the mandatory modifications imposed for 2012, including the engine cover fin, wheelarch top
apertures and larger mirrors, with the car straight ahead and at meaningful yaw angles. In the photos, most of the
main aerodynamic appendages are readily visible, with the large, regulation-governed splitter, double dive planes and louvred wheelarches. Not visible, of course, is the curvaceous, broad front diffuser under the front bodywork. Behind the front wheels are apertures in the side panel to allow some of the air to exit from under the front diffuser, and these apertures are fitted with turning vanes just outboard of the apertures and attached
Table 1: baseline aerodynamic coefficients of two LMP cars in the MIRA wind tunnel
CD -CL -CLf -CLr % front -L/D
Radical 0.565 1.631 0.607 1.024 37.20 2.89 Zytek
0.582 1.910 0.796 1.112 41.72 3.28 Difference +3.0% +17.11% +31.14% +8.59% N/A +13.49%
to the running boards. At the rear, the wheelarches are again louvred, and the regulation boxes behind the wheels outboard of the controlled but still fairly voluminous diffuser can be seen. The wing is a well cambered dual-element device supported on ‘swan neck’ mounts. A large Gurney sits on the trailing edge of the rear bodywork. The car came into the wind tunnel in its 2011 ‘preferred specification’. By way of comparison, the data for the Eco Racing LMP1 Radical SR10 in its highest downforce, best balanced configuration (as seen in V19N1- 3) are also given in table 1. The coefficients are based on
estimated frontal areas, and have been ‘normalised’ to enable direct comparison, so we can say that the Zytek generated three per cent more drag than the Radical,
The Le Mans-winning Greaves Motorsport LMP2 Zytek Z11 SN waits for the wind in the MIRA full-scale facility
The potent front end featured the regulated splitter and double dive planes, as well as a curvaceous diffuser below
Side vents were supplemented by turning vanes Le Mans •
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