USGP- an engine’s point of view

AUSTIN OVERVIEW
RÉMI TAFFIN, RENAULT SPORT F1 HEAD OF TRACK OPERATIONS

The Circuit of the Americas has already established itself as a classic track, featuring exciting corners, high speed sections and tight, technical hairpins. It’s actually a very challenging circuit and will give every component of the Power Unit a good workout. The PU will operate in the mid to high range throughout sectors one and two, but the final sector will focus on energy recovery and stability under braking.

The start of the lap is one of the hardest sectors for the ICE and turbo. The pit straight will see the ICE work at close to its maximum rev limit, while the altitude change to the first corner strains the turbo as it rotates at a higher speed to generate the same amount of power at the top of the hill. After the first corner, the driver then negotiates the sweeping series of Esses through to turn eight. Like Suzuka and Silverstone’s Esses and Becketts complexes, the ICE will be working at close to its maximum capacity through this section. After all this, the long back straight then sees the cars flat out for over 1km, with speeds in excess of 320kph.

The third sector is a lot more stop-start, but the hairpins and tight corners will give the MGU-K a chance to recharge. At each corner, the driver will stamp on the brakes, putting large forces through the K and filling the battery once more.

Now we enter the final three races, reliability starts to become an overriding concern so having such a challenging circuit at this point in the year makes everyone a little nervous. Mileage on each part is high and putting each through its paces means we’ll have a very busy weekend to check everything over and safeguard against any issues. In most cases we have enough flexibility to play around, plus we also have the confidence of knowing our performance and how to fully exploit it.

Renault Energy Fast Facts

Altitude is an important consideration in Austin as the track rises and falls as it follows the contours of the landscape. This change of gradient means engine speeds and turbo rotation vary over the course of the lap, and settings must be constantly adjusted to give optimal performance.

The low ambient humidity of the Texan grasslands has a big effect on the Power Units. The air will contain more oxygen and the ICE will generate more power, but the aridity is very taxing on the internals. We will watch ignition timing very closely.

Austin can be quite chilly in November, which will increase fuel consumption over one lap. When this factor is added to the stop start character of the last sector, it makes the consumption per kilometre one of the highest of the season. The energy recovery systems will have ample chance to recharge the battery, however, so we will be able to manage the race on the 100kg permitted.

The back straight is 1,016m and the car will be at full throttle for almost 20secs. It will also spend over two seconds at maximum velocity at the end of the straight. The driver will brake heavily at the end of the straight for the hairpin so rear-end stability and stability under braking will be crucial.

Just under 60% of the lap is taken at wide open throttle, rising to over 60% in qualifying. After Spa, Monza and Suzuka, it’s the fourth ‘power’ track of the second part of the season. The average speed will be a touch under 200kph with top speed peaking at over 320kph.

Both pole positions and fastest laps at the Circuit of the Americas have been claimed by Sebastian Vettel using Renault power.

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