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


Fin, flaps and yaw… W


The effects of 2012 rule changes on an LMP2 racecar


e continue our studies this month on the 2011 Le Mans 24 Hours and


Le Mans Series-winning Zytek Z11 SN LMP2 Sports Prototype of Greaves Motorsport. The most obvious addition this coming season to the LMP2 cars will be the engine cover fin, bringing them in line with their bigger siblings in LMP1. At short notice, Greaves Motorsport managed to manufacture a prototype engine cover fin to the new regulation definition, and the plan was to evaluate its effects at a range of yaw angles. All the configurations


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examined were tested across a representative range of four yaw angles from zero degrees (straight ahead) to six degrees (equivalent to the slip angle at which the tyres generated maximum grip). The effect of the engine cover fin was also evaluated at three different rear wing flap angles in order to derive a matrix of figures that gave a better understanding of the fin’s effect over a relevant working range. The data are presented initially here in three graph plots, one for each flap angle tested, designated maximum, medium and minimum. Comparing these plots


reveals how total downforce reduced with reducing flap angle, although the one exception to this is the data point at maximum flap angle without the engine


cover fin at zero yaw, which generated a lower –CL (total downforce) figure than at zero yaw with medium flap angle. It would appear that the rear wing


Figure 1


Figure 2


The 2012-mandated fin extends rearwards quite close to the rear wing


Figure 3 Le Mans • www.racecar-engineering.com


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