2011 STRATEGY - RACE REPORT
on the car while it was in the pit. As has already been explained, no extra time was lost doing this, but Pagenaud could simply not match Tréluyer’s times on the track. Worse, the Peugeot was back to triple stints, from 07:45 to 10:09 with Pagenaud and from 10:10 to 12:17 with Bourdais. At 11:17 Tréluyer came in
and handed over to Lotterer, Audi deciding that the German had slightly more pace than Fässler, who was due to drive next. The plan was for Lotterer to drive to the flag, if possible, meaning a monster stint of three hours and 43 minutes. For Peugeot, Simon Pagenaud would drive the final stint, getting into the car at 12:18,
Lap Time Audi No 2 Peugeot No 9
with no prospect of new tyres. By now, the Audi could
preserve its lead through the pit-stop sequence and, provided all other things remained equal, it looked as though things were beginning to fall in Audi’s favour. However, the skies were darkening and at around 12:15 it started to rain. Figure 8 shows the
Figure 8: lap times during period of light rain Comments
310 12:16 03:33.544 03:53.463 No 9 pits 311 12:19 03:43.438 03:53.463 No 9 time includes pit stop - driver / tyres 312 12:23 04:03.202 03:47.045 313 12:27 03:52.737 03:37.656 314 12:31 03:35.863 03:37.084 315 12:35 03:38.724 03:42.015 316 12:38 03:53.390 03:39.217 No 2 pits 317 12:43 04:38.661 03:45.164 No 2 time, includes refuelling pit stop 318 12:47 04:02.382 03:56.897 319 12:51 04:18.580 04:01.811 320 12:56 04:03.231 03:49.261 321 12:59 03:46.694 03:47.533 No 9 pits 322 13:03 03:35.641 04:27.576 No 9 time, includes refuelling pit stop 323 13:06 03:34.975 03:37.767 324 13:10 03:35.219 03:34.419 325 13:14 03:35.194 03:32.829
Figure 9: Audi’s final pit stop calculation
• We need: 15 seconds for fuel – take on 20 seconds for safety. • Peugeot needs: 28 seconds for fuel
• We can change tyres in 24 seconds
• Our projected pit stop time: 20 + 24 = 44 seconds • Peugeot projected pit stop time: 28 seconds • Our current lead: 24 seconds. • Projected lead after pit stop: 24 - (44-28) = eight seconds!
Pit work and strategy were key in deciding the outcome of the race. Audi played the tactical game to perfection, while Peugeot failed to split the strategy between its three cars
details of the lap times of Lotterer and Pagenaud as the track became wetter, dried slightly and then became wetter again. Now, if you subtract the time spent in the pits for both cars from the total of the lap times for the 16 laps, then Pagenaud’s average is 3m 45.1, compared to Lotterer’s 3m 47.5. And both cars were on slicks, remember. (Only Gene, in Peugeot no 7, went onto cut Michelin slick tyres.) By 13:30, the rain had
stopped, and the leading cars were separated by just 15 seconds, with the Audi ahead. Both cars would have to make two more stops for fuel, but whereas the Peugeot would need two full tanks to get to the finish, the Audi would be able to get away with a ‘splash and dash’ final stop. Audi also had the flexibility to decide when to make that stop. As they started their 344th
lap, Lotterer was 24 seconds ahead of Pagenaud. The Audi needed around 15 seconds of fuel, the Peugeot about twice as much. Sensibly, Audi decided to come in for fuel at the earliest opportunity, and Lotterer headed up the pit lane at 60kph at 14:22. Pagenaud followed the Audi into the pits, refuelled, and as he set off up the pit lane, saw the Audi coming down off the jacks having had the tyres changed! As they crossed the timing beam at pit out, the gap was 7.8 seconds, marginally less (perhaps) than Audi had calculated (see fig 9), but enough. From here on in, nothing could stop Lotterer – he had fresh tyres, a clear road ahead and sportscar racing’s biggest prize waiting for him. Except that the road ahead wasn’t quite clear. Marc Gene, in the no 7 Peugeot, four laps behind, still needed to be lapped. An hour and a half earlier, Gene had proved particularly difficult for Lotterer to pass, and there was head shaking in the Audi garage and Gallic shrugs chez Peugeot. It was the last hurdle for Lotterer, though he was on fresh tyres and was battling for the biggest prize in endurance motor sport. Deep breaths were taken and Lotterer squeezed through, reeling off the final six laps to take a memorable victory.
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www.racecar-engineering.com • Le Mans
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