Race Strategy explained

Hi everyone, we are back on track with another exciting and exclusive installment of F1 Framework related topics. Judging from the stats, you have really enjoyed the insight on Engine Maps brought to you by Maurizio Bollini - he worked as engine engineer for Michael Schumacher when he was the Ferrari F1 driver, during 1996 to 2006 period.
Today, he goes strategic to explain what are the main considerations behind Race Strategy - an imminent element of every single start in Formula 1.

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When explaining the basic concepts of the F1 Race Strategy, let’s consider two of the factors contributing to race pace: the tyre behavior (and degradation) and the weight effect of the car on the lap time. We are going through a very simplified demonstration.

Tyre behavior

A given set of tyres is used in a race stint. During the utilization in the stint, the tyres go through four phase of life:

• warm-up phase (the firsts one or two laps)
• performance phase (depending on the compound, from 10 to 20-30 laps), 
• degradation phase (depending on several factors, it can be very few laps), 
• Give-up (in very short time).

During the warm-up phase the tyre reach the optimal working temperature in its working range. The working range depends on the compound and other factors. Pirelli tyres for F1 2013 season have the following working ranges:

Low Working Range

• Super Soft, 85-110 deg
• Medium, 90-115 deg
• Hard New, 90-115 deg (from Bahrain 2013 onward in the season)

High Working Range

• Soft, 105-125 deg 
• Hard, 110-135 deg

The performance phase is a window whose duration depends on the compound, the track characteristics and the car. For the softer tyres it could be somewhat like 10 laps, for harder tyres it could be in the range 20-30 laps. In this phase the tyres gives the best performance and so the lowest lap time.

The degradation phase occurs for wear, abrasion, graining and blistering and the lap time start to increase. It is time to make a pit-stop to change tyres.

The give-up occurs when the cyclic stress reached the maximum acceptable level for the compound and construction. The combination of stress and heating generate mechanical and chemical changes in the rubber causing the lap time increasing sharply. Usually the car is called at the pit stop before this phase because it can cause tenths of retard on the pace.

Weight effect (on lap time)

The weight-effect is a value that expresses how faster the car run while the weight decrease because of the fuel burned. It is measured as seconds/lap/10 Kg.

It can be estimated at the Lap Time Simulator (LapSim), an application running on a PC, with experiments at different level of fuel or just by fitting real data public available from FIA.
The LapSim gives, for Australia 2013, a value for Weight Effect of 0.22 sec/lap/10kg.

As alternative, the Weight Effect can be easily estimated by fitting real data. Let’s consider the real lap times from Australia 2013 F1 race from three drivers.

For comparison, if we take the best of the fitting cases above we get a Weight Effect of 0.0722 sec/lap. Knowing that the fuel consumption in Australia is somewhat as 2.5 kg/lap, the fitted Weight Effect will be 0.29 sec/lap/10kg, not so far from what we get from the more accurate simulation and not so bad considering the “noise” affecting the second measure.

Going through a normalized value per 10 Kg is not really needed for this purpose but it is important to compare the weight effect of different race circuits.

Race Strategy example

As a race strategy example, we want to compare two tyre management options for the Australia race, called Option-A and Option-B. Both options use the same sequence of tyres, SuperSoft/Medium/Medium.

Option-A do pit at lap 13 and lap 35. Option-B do pit at lap 17 and lap 38. The pit-stop time is the same in both cases (20 seconds) and the tyre model, very simple and just for the purpose of this demonstration, is based on the Weibull degradation formula.

We calculate the lap time lap-per-lap for both options on the race distance including the weight reduction effect and the tyre behavior effect.

Then we sum the lap times in order to have a cumulative curve for Option-A and Option-B and we make the difference, lap by lap, of the last two cumulative curves. Results are plotted on the next chart.

By reading this chart, the conclusion is that at the end of the race, Option-A is slower of about 3.61 seconds respect to Option-B.

Using this procedure, it is possible to play with different scenarios. During the race, simulated lap times are updated, lap by lap, with the real lap time and the scenario update in accordance.

This is, in a very simplified way, what is behind a dynamic race strategy application.

This tool is used trackside by the Performance Engineers with the support of the Strategy Engineer at remote garage, the facility located at the Team’s Headquarter. Such example is Neil Martin from Scuderia Ferrari, who has been known to update the team in terms of strategy via remote link from Italy. 

Making the right strategy call is, of course, very important. The recent example was Mark Webber in Hungary, 2013 - he had to start P10, running for a long period on Medium compound and eventually making it to P4 with very late usage of the Softs. 

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Maurizio Bollini is the owner of MET Milano (www.met.it), a consultancy firm involved in motorsport. In the past he worked as engine engineer for Michael Schumacher when he was the Ferrari F1 driver, during 1996 to 2006. He can be contacted at maurizio.bollini@met.it.

F1 Simulators

In F1 world simulators are expensive set of hardware and software, whose aim is to resemble as closely as possible the real car feeling while driving on a certain track. Consider F1 simulators as the massively expensive version of the small simulators you may have at home or driven at some public car shows and events. Add to that equation the variable "sophistication" and you'll be closer. Still not convinced? Proceed below :)
The prime drivers to have that article are, as usual, sharing information inside F1 world, and the increasing emphasis on simulations overall, as testing on track becomes more and more limited, following recent news that teams have not agreed to open doors to in-season testing.

In details

Image: Youtube.com

Woking, Mclaren factory - this is what you are going to face on the front door of this secret place, fortunately, we have something to share.

Mclaren

Mclaren is perceived to have the most advanced installation at the time of writing this article. These words come from the person who has spent lots of time inside it - Pedro de la Rosa, who used to be Mclaren test and reserve driver, currently doing the same at Ferrari. The work at Woking factory started back in 2003, which according to the Spaniard gives them (Mclaren) few years advantage.
Gary Paffet, their test driver says: "Certainly, inside the tub you get very similar feedback to what you feel in the real car". Jonathan Neale adds: "What separates the $2000 home installation and the multi-million dollar F1 simulator is the engineering and the science models that lie below. We do want to know what is happening with the tire contact patch, what the forces are, fine tune the engine modes, as they affect the downforce. We do want to know where the downforce is working when you have steer angle, roll and yaw".
"We have committed", Neale continues, "thousands of man hours in software models, tire matrices, engine modes in order to give the testing driver the best feeling about the car".
Chris Goodwin, chief test driver, admits that the simulator has been irreplaceable and essential part of their projects, which also helped Mclaren road cars division to integrate lots of knowledge in production.
This is how it looks like:

Ferrari

Our next stop is at Maranello, where Ferrari are enjoying the simulator installation done by company called Moog - a process which has started back in 2008.
Some of the technical aspects of the simulator are:

• Viewing angle - 180 degrees
• 10 multiprocessor computers 
• 60 GB of RAM
• Around 5 GB of data per day
• 3,500 Watt Dolby Surround 7.1 sound system

All this looks like this:

And finally, if you want to see it working:



Thanks to Axis of Oversteer for both photo and video.
It's not all roses for Ferrari, though - back on the connection between Mclaren and them - Pedro De la Rosa - when the Spaniard made an examination of the current status quo upon its arrival at Maranello, he explained that steps need to be taken, first in terms of hardware and then software built upon it, if Ferrari want to chase the rivals in that area.

Red Bull

Certainly, the reigning world champions, Red Bull Racing, are not just magically winning races and are surely complemented by similar system.
Before we proceed to the technical details, a short word on why such machinery is important.
The time stamp says 24.05.2013, Friday, Red Bull are noticing that they need about 1 second prior to going into qualification mode in Monaco. The information gathered on the streets of Monte Carlo is sent back to their base and Sebastian Buemi does about 400 laps in the simulator, which reportedly resulted in new parts / modifications being done to the front wing of the car (RB9) for the race.

The Main man behind the simulator is Andy Damerum. The cockpit is from the original Red Bull RB1 of 2005, yet it is programmed with the aerodynamics and engine specification of the current car.
Pedals and driving position are exactly the same, steering wheel works in full, all buttons, and is exact copy of the one that gets used on race weekend.
This cockpit is on top of a platform, which is mounted over six hydraulic “legs” - they are somewhat high, so the driver is almost 2 meters above the ground. Roll, pitch and yaw are there, as you can imagine - people with motion sickness better stay out.

Since peripheral vision is weak with us, humans, compared to animals, we need more time and resources to identify the surrounding objects, thus, the simulator wants to try to emulate the environment closely and stimulate the brain’ Occipital lobe, which is mainly responsible for processing vision. Hence, there’s a single 180 degree vision screen to match the moving pictures of the track and objects that you leave behind.

Short note about senses stimulation: a while ago Williams F1 team had a technical partner, Qinetiq, who has done a research on how the nerve endings are sending info to the Cerebellum (smaller region in the lower part of the brain) about perceptions of yaw, pitch and roll. The research claims that if stimulated at early age, these perceptions are being developed much faster than at later age. Sorry for the medical distraction, I strongly believe, however, that physics and human body, most notably including the brain, are one of the most important aspects of the beloved sport.

Back on the simulator, any type of setting and parameters that can be altered during the race, such as angle of attack, toe-out, suspension, etc, can be changed in the simulator, too.
Something which is usually not changed is the grip levels, as they will produce different feeling for the driver, hence the grip is usually a constant parameter.
The engine sound is, well, fake, but certainly the sounds match the sound frequency of the gears. Feedback through the steering wheel is definitely there.

One of the most frequently asked question is how tracks are defined within the simulator. New tracks are added in database model first via raw data (coordinates, numbers), then video footage to polish the sharp edges, then input and potentially real data from car tested over there.

Andy Damerum or other team personnel is monitoring the live data: the same parameters are available there, as on the track, even named the same for full match: pDiff, nEngine, NGear, rThrottlePedal, MDiffDemand, etc.

This is a typical screen that a simulator engineer is looking at:

Finally, short word about Merceges AMG F1 team - back in 2010 the Brackley-based squad has complained a lot about the lack of proper simulator. Today, 2013 in the summer, the team are already seeing positives in having Robert Kubica helping them with simulator work and feedback. The Pole has already had multiple sessions in the simulator, but his main task for now is rallying and there's no long term plan for him.

Once again, thanks for attending, questions are welcome!