Friday 27 March 2015

Sebring 12 hours - the anatomy of victory

The 63rd Annual Mobil 1 Twelve Hours of Sebring Fueled by “Fresh from Florida” provided a perfect opportunity for the Action Express Racing Team Coyote Corvette DP to demonstrate its superiority over the rest of the 43 car field in the classic race around the runways and service roads of the historic airfield circuit last weekend. It must have been a particularly satisfying win for Bob Johnson and his team, following their failure to capitalise on a similar performance advantage at the opening round of the Tudor United SportsCar Championship at Daytona at the end of January, when Chip Ganassi used a well-timed full course caution period to snatch victory for his more economical turbo Ford-powered Riley from the GM-branded car.

The second of the traditional Floridian enduros ran with just 28 laps behind the Safety Car - out of a total of 340 completed - which left more than ten hours for some proper racing, including one green flag period of 3h 47m 59s. And it was this long green period that enabled the Action Express car, ably piloted by João Barbosa, Sébastien Bourdais and Christian Fittipaldi, to establish a lap’s advantage on the rest of the field and allowed the team to run the final two hours to the flag without any real concerns.

No race of this length is ever easy, but once the fragility of the LMP2 challengers proved their undoing, there never seemed much doubt that the Mustang Sampling sponsored car would come out on top of the Corvette DPs. If the relatively smooth surface of Daytona was too much for the Le Mans-rules cars, what hope did they have over the bumps of Sebring?

So how was it done?

Well, in the first place, it was a fault-free run. The car completed the race with just fourteen pit stops, the longest of which was 1m 14.684s - and the Safety Car was out then in any case, nullifying any time lost in the pit lane: Fittipaldi resumed and simply latched on to the tail of the queue of cars. Every other stop for the car was less than 1m 04s. The length of the stints was dictated, to some extent, by the timing of the Full Course Yellow (FCY)periods, but during green periods, the car could run for 23 laps between refuelling stops.

The full list of pit stops looks like this:

Stop no. Activity Time in pit lane
1 Barbosa stays 1m 01.557s
2 Barbosa to Bourdais (FCY) 1m 01.295s
3 Bourdais stays (FCY) 0m 58.029s
4 Bourdais to Fittipaldi (FCY) 1m 14.684s
5 Fittipaldi stays 1m 03.265s
6 Fittipaldi to Barbosa 1m 01.899s
7 Barbosa stays (FCY) 0m 49.623s
8 Barbosa stays 1m 01.695s
9 Barbosa to Bourdais 1m 02.148s
10 Bourdais stays 1m 00.833s
11 Bourdais to Fittipaldi 1m 01.039s
12 Fittipaldi stays 1m 03.303s
13 Fittipaldi to Barbosa 1m 03.969s
14 Barbosa stays 1m 02.977s
Total 14m 26.316s

As usual, the time spent includes the time spent driving down the pit lane itself. Needless to say, the time spent in the pits by the Action Express car was less than any other prototype that finished the race. And of course, the actual time spent stationary is considerably less than the time spent in the pit lane.

Under IMSA rules, the time spent stationary consists mainly of getting fuel into the car, so the length of time in the pits depends largely on how much fuel is required, which is in turn dependent on the length of the previous stint. As the table above shows, Barbosa got the most time behind the wheel, as he managed to get three shifts to the two each for Bourdais and Fittipaldi. Here's the full breakdown of the driving periods:

Stint no. Driver Laps Time
1 Barbosa 22 42m 19.467s
2 Barbosa 27 1h 04m 21.575s
3 Bourdais 22 54m 00.786s
4 Bourdais 28 1h 02m 44.283s
5 Fittipaldi 25 52m 12.941s
6 Fittipaldi 22 42m 27.064s
7 Barbosa 12 25m 53.412s
8 Barbosa 25 53m 04.216s
9 Barbosa 22 42m 04.219s
10 Bourdais 23 43m 56.789s
11 Bourdais 22 42m 03.538s
12 Fittipaldi 23 44m 42.196s
13 Fittipaldi 26 58m 23.241s
14 Barbosa 18 34m 43.108s
15 Barbosa 23 44m 16.664s

The totals for each driver were:
Driver Total Laps Green Laps Time
Barbosa 149 137 5h 06m42.651s
Bourdais 117 84 3h 22m 45.396s
Fittipaldi 118 90 3h 17m 45.442s

Endurance is always a team effort, and it is important that the drivers work well together; but I am always interested in comparing the lap times of the drivers of a car, to see if there is any evidence of a weak (or sometimes a particularly strong) member of the team: after all, many of the driver's excuses can be ignored if one is able to drive the same car more quickly in the same conditions than the others...

Having said that, team managers may give specific instructions to their driver: setting a target lap time, for example, to which some drivers may be more obedient than others. The tables above give you practically all the information you need to work out average lap times for each stint, for each driver, for yourselves, but to save you the trouble of that, I’ve laid it out on a stint by stint basis in the table below.

Stint no. Driver Stint Average Lap Green Lap Average
1 Barbosa 1m 55.430s 1m 55.246s
2 Barbosa 2m 23.021s 1m 54.803s
3 Bourdais 2m 27.308s 1m 54.852s
4 Bourdais 2m 14.439s 1m 54.951s
5 Fittipaldi 2m 05.318s 1m 55.699s
6 Fittipaldi 1m 55.776s 1m 55.810s
7 Barbosa 2m 09.451s 1m 55.128s
8 Barbosa 2m 07.369s 1m 55.505s
9 Barbosa 1m 54.737s 1m 54.634s
10 Bourdais 1m 54.643s 1m 54.560s
11 Bourdais 1m 54.706s 1m 54.751s
12 Fittipaldi 1m 56.617s 1m 56.528s
13 Fittipaldi 2m 14.740s 1m 55.848s
14 Barbosa 1m 55.728s 1m 55.471s
15 Barbosa 1m 55.507s 1m 55.396s

The column showing the Green Average lap is the average lap time for the green laps in the stint: ignoring laps into and out of the pits.

Consider this: Fittipaldi drove 90 green flag laps. On average, as can be seen above, his laps were a second slower than those of his team-mates. In that case, the car could have been a further minute and a half ahead: nearly a lap!

Perhaps that is speculation a little too far. But how did engineer Iain Watt and Crew Chief Bill Kueller get their car to be so much quicker?

The answer, if one looks at the sector times (Sebring is split into 10 sectors by the IMSA timekeeping team), lies in the fact that in only two of Sebring’s sectors was the #5 car quickest. It was not fastest through either of the two speed traps. And yet, of the three Corvette DPs around at the end of the race, it had easily the fastest average lap time. It may not have been as fleet of foot as the Ligiers, but nevertheless it strikes me that the team was quickest by virtue of the optimum compromise. And if that meant that the car wasn’t quite to Fittipaldi’s taste, it was certainly better than anything else at Sebring.

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