A comprehensive guide to F1's preseason testing

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Imagine if a football team had just three days to do all of its physical and tactical training ahead of a new season. Or if a tennis player was given a new type of racket the week ahead of a Grand Slam tournament and allowed just a day and half to get accustomed to it (assuming the strings didn't break on the first day and limit that time further).

That's pretty much what Formula One's teams and drivers will face this week as they are granted just three days of preseason testing at the Bahrain International Circuit to understand how their brand-new cars work in the real world. And because F1's regulations dictate that each team can have only one car on track at any time during those three days, the two drivers will have to share that single car, reducing their track time to less than 12 hours each (minus time in the garage fixing issues and changing setups).

But unlike a football training session, F1 testing generates a huge amount of excitement among fans. Often the lap times are at best inconclusive or at worst misleading, but after a winter starved of track action, how can you not get carried away with Red Bull's pace in the middle sector or the way in which the Ferrari's lap times drop off a cliff after just 10 laps?

Below is a guide to what testing is all about and just how much you should read into the headline lap times from the next three days in Bahrain.

Why do F1 teams go testing?

F1 cars are meticulously engineered and carefully built, but ahead of the first race of the season, they also represent 200 mph science experiments. While a great deal of time and money is spent making sure a new F1 car goes fast in simulations over the winter, there's still the potential for the wheels come off (sometimes literally) when it leaves the garage for the first time in real life.

As a result, F1 teams go through a rigorous debugging and refining process with their cars before the first race to make sure they are as fast and reliable as possible when the lights go out on a new season. In the past, this process was spread over more than 10 days of preseason testing in Spain, but to cut costs, the number of test days has now been reduced to just three and they take place the week before the first race at the same venue.

The opening morning of testing is usually spent running system checks on the car to make sure everything is operating as it should. Although teams have advanced test benches at their factories and will likely have completed a 200-kilometre shakedown prior to arriving in Bahrain, nothing compares to running the car all day in the heat of the desert sun.

Checks on the cooling system, hydraulic system and electrical system are crucial early on the first day to flush out any potential reliability issues. In its race specification, an F1 car carries more than 300 sensors creating up to 90MB of data per lap, but in testing those numbers are much higher so as to harvest as much real-world data as possible.

Sensors on F1 cars are sometimes too small to spot and often are placed under the bodywork to measure temperature, inertia and loads, but when it comes to understanding a car's aerodynamics, the sensors are often impossible to miss. Big metal fences known as rakes are attached to the cars behind sensitive areas of airflow to measure air pressure and understand the flow structures around the car.

The rakes are made up of a series of pitot tubes, and their readings are compared with the work the teams have conducted over the winter in the wind tunnel and via CFD (computational fluid dynamics). If the real-world data matches up with the simulations, a team is already several steps closer to extracting the true potential of the car at the first race. If it doesn't, the team is already on the back foot.

Another method for understanding real-world airflow around a car's surfaces is to douse it in "flow-vis" paint and see how the colourful water-based liquid spreads across the bodywork at speed. This surprisingly simple method allows engineers to see if the aerodynamic surfaces are having their intended impact on the airflow.

Feedback from the driver is also key to understanding a new car. Simple things such as the seating position often need to be adjusted, and long days in the cockpit are the best way to find out what's comfortable and what's not. Steering feedback and brake feel are also early boxes to tick, although it can take more than half a season before a driver is truly happy with the finer details. More experienced drivers can also help engineers understand where lap time is leaking away by describing the behaviour of the car through the corners.

Once it's been established that the fundamentals of the car are operating as they should, teams turn their attention to setup. Finding the right setup is crucial to unlocking performance, and knowing how a car will react to different ride heights, wing angles and suspension settings helps engineers build up a toolbox of solutions to exploit in different situations later in the season.

Engineers will spend large parts of testing sweeping through different setup combinations to find out what works and what doesn't across different fuel loads and tyre compounds. Gaining as much knowledge as possible at this stage of the year can pay dividends later on in the season when handling issues appear in the heat of competition.

A reliable car that responds well to setup changes is the aim by the final day of preseason, along with reams of data to inform the next steps of car development back at the factory.

How to spot who's quick and who's not

The lap times as they appear on the timing screens are rarely an accurate picture of the competitive order. A light fuel load and fresh soft tyres can make an average car look faster than the most competitive car on high fuel and used hard tyres. As a result, the order at the end of each day should be treated with caution.

It's always much easier to spot the teams having a bad time in testing as the clearest sign that a new car is struggling is a lack of mileage. While that will usually indicate a reliability issue, it also means the team is not progressing with the performance of the car simply because it is not getting the track time or data to move forward.

Assuming the car is reliable, the vibe around a team during testing can also indicate where it stands. Engineers and drivers are always keen to play down expectations at this time of year, but in the close-knit F1 paddock, confidence levels become increasingly easy to gauge after a couple of days at the track.

Despite the fastest times for each team being potentially misleading, it is still possible to piece together a vague picture of who's quick and who's not by digging deeper into the available data. By recognising certain patterns in the lap times, you can gain a better understanding of what's really going on and start to make predictions about who has found the biggest step in performance over the winter.

Performance runs

These are the laps where the team is trying to get a better understanding of the car's performance over a single lap. They are easy to spot as the drivers will alternate between "hot laps" and "cool-down laps," creating a tell-tale pattern of fast, slow, fast, slow on the timing screens.

Drivers have to intersperse their fast laps with slower ones to allow the tyres to recover after being pushed hard on the previous lap and to recharge the battery in the car's hybrid system, which will use up most of its power on a qualifying-style lap.

Tyre compounds are key to one-lap performance, and Pirelli offers all five of its compounds to the teams during testing. The compounds are numbered C1, C2, C3, C4 and C5, with the C1 being the hardest and the C5 being the softest. Softer rubber provides more performance but is less durable, meaning the softest compound might be good for only a single lap before it loses its peak performance.

The fastest times in testing are usually set on the softest tyres, but if a car using C2s is only a tenth of a second slower than a car on C5s, it's likely the car on the harder compound has an underlying pace advantage. Temperatures also fluctuate throughout the day, with Bahrain offering its optimum track conditions once the sun has set and the tarmac has cooled. As a result, a time set on C5s in the heat of the midday sun is not comparable with a time set on the same compound under the floodlights late in the day.

These are all factors that need to be taken into account when looking at the fastest laps each day, but even if you know the tyre compound and the time of day at which the lap was set -- which are both public information -- you still know only half the story.

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A car's fuel load is a major factor in performance, and 10 kilograms will add roughly 0.3 second of lap time. Put another way, a car with a full tank at the Bahrain International Circuit will be more than 3.5 seconds per lap slower than a car running on fumes. The reality is that most of the time the teams will run a fuel load somewhere in between, as the extra weight of running on a full tank will damage the tyres after a handful of laps and running on qualifying amounts of fuel will mean the car must return to the pits more often to refuel.

There is no way of knowing how much fuel a car has on board from the outside, and teams are not obliged to hand out figures. As a result, the most impressive lap time in testing might be set by a team running with 40 kilograms of fuel in the tank, while a fundamentally slower car can look surprisingly competitive by running with 20 kilograms or less. Loading the car with fuel during testing is often referred to as "sandbagging" -- F1 speak for a team intentionally hiding its performance -- but the truth is that a fuel load between 60 kilograms and 30 kilograms offers a more practical baseline for understanding car performance over a run of a sensible length.

Unfortunately, the most useful tool to cut through the secrecy and make sense of lap times isn't available to fans and the media. Teams closely monitor GPS traces of rival cars to gather data on both corner speeds and straight-line speed, allowing them to build a clearer picture of true car performance. The speed at which a car accelerates and brakes is useful to guesstimate both its engine mode and fuel load, and at the click of a mouse, that data can be cross-referenced with previous years' test sessions or races to identify trends and spot anomalies.

What's more, F1 teams are creatures of habit and will often stick with a set fuel load for testing from one year to the next. As staff move from team to team over seasons, it doesn't take long for an experienced engineer to build up a bank of data and knowledge to help sift through the times popping up on the timing screens and pick out the true star performers.

Long runs

One way of removing the uncertainty over fuel loads is to look for teams attempting "race simulations." In an ideal test, most teams will aim to complete a race simulation by the end of the three days so that they can gain an understanding of how the car performs over a grand prix distance and to gather data that could increase their points haul a week later at the first race.

In order to complete a race distance without returning to the garage to refuel, cars will need to leave the pits at the start of the run with close to the maximum fuel load of 110 kilograms. And once we know cars are starting out with the same fuel load to complete the same number of laps, it makes it much easier to compare performance.

It's not an exact science because the time of day, track conditions, engine modes and tyre strategies can skew the results, but as a general rule it is the best way to build a more accurate picture of performance by removing some of the questions over fuel load. Race sims can easily be spotted by a series of slow but steady lap times over long runs that are interspersed by race-style pit stops, where the pit crew will practice tyre changes as it would do in a real race. Alternatively, if you see that a driver's pit board is counting down from 57 laps (the length of a grand prix in Bahrain) the chances are the team is attempting a race sim.

By working out an average lap time from each driver's race sim, it's possible to get the best indication of how quick a car really is over a lap compared to its rivals. However, because race sims are usually among the last tasks on a team's job list, it's possible the team simply won't be able to fit them in over the three-day schedule. If that's the case, it will be back to guesstimating fuel loads in an attempt to compare cars like for like.

Add a pinch of salt

While some kind of order usually emerges from testing, it's not always representative of the first race. This year the sole preseason test and the first race are being held at the same venue, Bahrain, improving the chances of an accurate prediction. But even so, a lot can change in a week.

Teams always hope to develop rapidly at the start of a new season as they gain an on-track understanding of their cars to compare with simulation data. A car that starts slowly might be a few setup changes away from unlocking significantly more pace, but the key to that performance might present itself only after the data has been fully analysed at the end of testing. Based on the data gathered over the three days, teams will also be able to refine their setups in the driver-in-loop simulators back at their factories.

What's more, the cars that run in testing this week might look surprisingly basic or underdeveloped when we look back at them at the end of the year. For the bigger teams, some updates will come as early as the first race, and it's not unheard of for performance to be unlocked by an upgrade between testing and the season opener.