Giorgio Piola's F1 technical analysis
The 2017 season was the first time in Formula 1 history that downforce was ramped up through regulation, delivering a significant laptime gain and a much closer fight at the front of the grid.
So, as the 2018 season looms, we take a look at the changes that the designers have had to overcome and the various solutions that cropped up during the season that are now either completely banned or placed under heavy scrutiny by the FIA.
Perhaps the most surprising feature of 2017 was the 'T-wing', a solution that was initially passed off as insignificant but quickly became one of the seasons must-haves.
This all came about because the teams noticed a loophole that allowed the use of bodywork in a region ahead of the rear wing. This image illustrates where bodywork may or may not exist, with the excluded zones marked in red and the region where T-wing's could exist highlighted in yellow.
It's understood that these winglets produced a small but efficient amount of downforce in their own right, but also served the secondary function of helping to tidy flow ahead of the rear wing too.
Winter testing is fraught with challenges, especially when such a large regulation change takes place. And while the T-wings used by the teams behaved themselves to a large extent, it was noted that the T-wing mounted on the Haas had a tendency to wag the shark fin when loaded.
It's a trait closely scrutinised by the FIA during FP1 in Australia, leading to a request for its removal for FP2, with the caveat that it could be reinstated if the team could strengthen the shark fin. It duly complied (see above), knowing the performance advantage the winglet could offer.
The FIA subsequently introduced a deflection test for T-wings amid concerns of several high-profile failures, most notably when the structure failed on Valtteri Bottas' car in Bahrain and caused considerable damage to Max Verstappen's car.
The FIA subsequently announced it would be testing the winglets, in order that they not flex more than 5mm when presented with a load of up to 100 Nm.
The designs seemed fairly benign initially, but grew in their complexity quite rapidly, with numerous variations cropping up as the teams maximised the available space.
As the season progressed, the more basic single element winglets were often replaced with multiple elements, featuring their own complexity and slots. Some of the teams, of which Williams was an early adopter, also saw fit to use winglets lower down, influencing the exhaust plume and underside of the rear wing.
As we can see from the introduction of the T-wing, it isn't always about what is written in the regulations but rather what isn't, with these grey areas in between affording pockets of performance that might otherwise be left on the table.
For example, the ability to use shark fins in F1 never really went away, but with the taller rear wing and subsequent loss of the connection to the rear wing, due to the banning of the F-duct in 2011, it fell out of favour.
As such, the return to a lower rear wing structure in 2017 presented an opportunity for their return - and while they aren't exactly aesthetically pleasing, their reappearance provided an uplift in performance the teams couldn't ignore.
The regulations have been amended in order that both shark fins and T-wings will not appear in 2018, with a more conventional engine cover, such as the one tested by Sauber back in Austin (above), expected to be used once more.
The much-maligned safety device, which was proposed in 2015 and features a central spar supporting a hoop around the driver's head, will be raced for the first time in 2018.
The device we have seen attached to the cars thus far has been a dummy, used mainly for sight testing, cockpit access tests and aero evaluation, with the actual device needing to be anchored to the chassis.
Its installation has caused the teams headaches, as the specifications of the static load test came quite late in the day and requires it to fatigue and give way, rather than the chassis or its mounting points.
This has proved problematic for the designers, who are intent on keeping installation weight down, while still being able to pass the load tests shown above.
With the minimum weight of the car having already surged up to 728kg in 2017, accommodating the wider tyres and bodywork and an increase in the size of the fuel tank, the designers have been given a further 6kg to play with in 2018.
However, many of the designers have voiced their concerns about this given installation, including the weight of the halo, comes in around 14-15kg and means the teams will have less ballast to play with and will once again penalise heavier drivers.
The Halo, which can be purchased from three suppliers based in the UK, Germany and Italy, will cost the teams at least €15,000 each, is made from titanium and can be shrouded with bodywork designed by the team.
We've already seen teams running with a more aerodynamically neutral cover throughout 2016 and 2017, but the regulations allow the designers to influence the external airflow with their own fairings.
This is something we've already started to see, as some novel solutions appeared at the post Abu Dhabi GP test.
The most aggressive of these solutions came from McLaren when it ran a hooped three-element winglet atop the halo, as the team looked to mitigate some of the aerodynamic inefficiencies the structure may present, channeling the airflow into less disruptive places.
Having played a significant role in the 'out of the box' performance of some of the more advanced teams last year, another clarification regarding the suspension has been issued ahead of this season.
It's understood that the technical directive issued to teams seeks to limit a change in the ride height of the car while being steered, a technique which when exploited can improve aero performance.
While some changes to ride height are inevitable, it's suspected that some systems have been designed in order that the change is not incidental, improving the car's aerodynamic platform at a point when otherwise it would be compromised.
From now on the teams will have to provide the FIA with relevant documentation that shows that the ride height changes by no more than 5mm when the steering wheel is moved from lock-to-lock.
Of course, anyone that has already enjoyed success with such systems, or planned to, will have to find other ways to simulate the technique.
Ferrari (above) and Red Bull (below) both spent time testing revised suspension layouts during 2017, both of which featured upright extensions that altered the pushrod's location (arrowed) and are thought to target scenarios where the ride height is adjusted when the car is being steered.
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