The 2009 regulations were the biggest shake-up the sport had seen in a generation, with almost every aerodynamic surface refined to curtail downforce levels, while a switch back to slick tyres was intended to change the relationship between aerodynamic and mechanical grip.

The rules had been shaped around research done by the Overtaking Working Group (OWG) to slow the cars down and help improve overtaking by changing the shape of the wake generated by the lead car and the trailing car's susceptibility to it.

2009 rules package overview Photo by: Giorgio Piola

The main changes centered around the distribution of airflow around the car, with the front wing set to match the car's span, allowing the designers scope with which to push more flow outboard.

However, the central 500mm of the wing was designated a no-go zone for the designers, with a neutral section mandated by the regulations. The intent was to control how air moving over the front wing generated downforce when in the wake of a trailing car and lessen the aerodynamic balance shift that occurs as the car closes in.

Ferrari F60 (660) 2009 diffuser comparison with F2008 Photo by: Giorgio Piola

The rear wing height was increased and the diffuser reduced in height and length, the idea of which was to change the shape, trajectory and ferocity of the upwash with the intent of making it easier for the trailing car to close in.

Changes were also made to the rest of the bodywork around the car in order to limit the various winglets and flick-ups that had appeared in the preceding years.

The drivers were also to be given several weapons to improve their arsenal in wheel-to-wheel combat, the first of was trimming the car's aerodynamic balance - the front wing's upper flap could be moved by six degrees, twice per lap, which would further balance the car as it trailed in another's wake.

McLaren MP4-24 2009 KERS packaging Photo by: Giorgio Piola

Secondly, KERS was introduced, allowing the driver to dispense up to 400kj of electrical energy previously recaptured under braking at a rate of 60kw or roughly 80bhp (or less) which equated to 6.66 seconds of full power per lap.

It was a start, a far cry from the ERS system deployed by the sport in 2014, but one that came with compromises too. The system weighed in around 30kg and, if inoperative, would be dead weight to carry around, meaning you needed to gain 6.66 seconds worth of laptime out on track to make it worthwhile.

KERS proved to be hit-and-miss in its maiden year with neither champion team Brawn, nor runner-up Red Bull using the technology, putting the weight to better use elsewhere and leading to a one-year sabbatical for the the manufacturers to refine it in 2010.

Changes were also made to the minimum weight of the car on its return in 2011 in order to make it a must-need system, rather than something that could even be used at a given circuit, as McLaren and Ferrari sometimes opted to do in 2009.

BGP001

The Brawn GP story is the stuff of folklore, a phoenix rising from the ashes that could have turned out very differently if it wasn’t for the support of Mercedes, who supplied its V8 in lieu of the Honda unit no longer being available.

As we know now, the Mercedes unit was a far better fit than the also-offered Ferrari engine. It was supplied without KERS, as it didn’t fit with the same criteria and integration that would have been possible in the RA109 - but this did give Brawn GP the scope to work with the weight that would have been used with KERS and place it in more convenient locations.

Brawn BGP 001 2009 ballast in splitter Photo by: Giorgio Piola

The splitter became home to a large chunk of the ballast, placing it in a low down and forward position to aid CoG, improving the car's balance. On top of this, the team opted to run with a snowplough device, which with the loss of bargeboard length in the new regulations helped to gather the airflow under the nose and redistribute it into key areas on the leading edge of the floor.

Brawn BGP 001 2009 cutaway engine installation detail Photo by: Giorgio Piola

The change of engine could have easily turned the BGP001 into a dog but was one of the many areas of the car that actually helped it overachieve. Honda made an early start on the 2009 regulations, essentially sacrificing the 2008 challenger as the marque knew how big the gains could be if it got it right.

The project worked outside the scope of the regulations we face today, with multiple wind tunnels operating flat out to design several iterations of what was to become the RA109. This expansive and longer gestation period allowed the team to look at various options and become more precise in the delivery of key areas of the car.

Brawn BGP 001 2009 front wing flap adjuster detail Photo by: Giorgio Piola

Clearly the fully-integrated double diffuser stood Brawn in good stead compared with those that had to retrospectively adopt it. But Bran's front wing design was also looking at things differently, compartmentalising the adjustable flap to a smaller inner section, allowing the outer portion, including the endplate of the wing, to be used to shape the airflow passing over and around the front face of the tyre.

Brawn BGP 001 2009 front view detail comparison Photo by: Giorgio Piola

The lower positioning of the front wing’s mainplane when compared with 2008 also made the team think differently about the positioning of the front suspension and steering arms. They now had a role to play in controlling how airflow spilt by the front wing would impact structures downstream and so were placed one behind the another, lengthening their overall surface.

Brawn BGP 001 2009 sidepod turning vane Photo by: Giorgio Piola

Unimpeded by the additional cooling requirements of running a KERS system, the BGP001’s sidepods were also very slender, allowing for a deep undercut in the front face, maximising the airflow's path to the rear of the car.

One of the oddities of the BGP001 is we never saw it in its full Honda trim and so we don’t know where it would have sat in the pecking order but the car does serve as an example of how teams can triumph over adversity if enough planning has already been done.

2010-2013

Red Bull RB6 low-line exhaust to blow the diffuser Photo by: Giorgio Piola

The changes made for 2009 were vast and opened up several channels for innovation, the first and most contentious being the double diffusers. The F-Duct that followed in 2010 and the subsequent emergence of exhaust-driven diffusers midway through 2010 were just the tip of the iceberg as teams sought clever interpretations of the regulations in order to improve their car's operating envelope - be it increasing downforce or reducing drag.

Brawn BGP 001 2009 diffuser exploded overview Photo by: Giorgio Piola

The double diffusers that caused controversy in 2009 helped to unravel the changes initially installed, with the wake generated by the lead car significantly different to the one studied by the OWG.

This neutralised the intent of the moveable front wing, which unceremoniously disappeared from the regulations in 2010 as it wasn't being used by the drivers, who weren't having the balance shift that was expected when the regulations were devised.

McLaren MP4-25 2010 rear wing with f-duct Photo by: Giorgio Piola

McLaren changed the game in 2010 with their rear-wing 'stalling' device, known in-house as RW80 but subsequently dubbed the F-duct by the media. The team had found a way to dramatically reduce rear downforce and drag through the use of a fluidic switch system.

McLaren's initial concept was swiftly copied by the rest of the grid but the Woking team deserves a special mention for its tenacity in designing what was a relatively simple system, yet one that elegantly circumvented numerous regulations to achieve its goals.

The FIA was not fond of the driver interaction needed to deploy the system though, with various ways of deployment invariably impeding the driver's ability to operate the car.

Elements of the regulations that permitted its introduction were rephrased but the FIA learned a valuable lesson about how to resolve the issue of overtaking, with the Drag Reduction System introduced in 2011.

During this phase of the regulations, it became clear that some of the teams were using aeroelasticity to their advantage, primarily on the car's front wing.

The FIA was forced to make numerous regulation changes between 2009-2013 in order to curtail the flexi-wing practice, as the teams sought ever more ingenious ways to circumvent the load tests that the cars undergo in scrutineering.

2014 - The hybrid era

For years those that were involved or followed the sport believed that there was too much emphasis on aerodynamic performance in Formula 1.

And so, when the FIA looked set to introduce new regulations, initially expected for 2013 but pushed back a year, the intention was to bring the engine back under the spotlight.

Early discussions with the teams, manufacturers and the governing body highlighted a need for Formula 1 to drive future development within the road car industry, aligning the manufacturer spending with what consumers may see a little further down the line.

Numerous solutions were tabled, including an in-line four-cylinder engine, ERS capability on the front wheels and an array of turbocharging solutions.

Renault 2014 power unit exploded view Photo by: Giorgio Piola

The final decision was a 1600cc engine, with a single turbocharger that must be installed on the car's centreline and paired to to a motor generator unit (MGU-H), which can be used to slow the turbocharger and recover energy or speed it up and reduce turbo lag.

A larger-capacity motor generator unit than the one used in KERS would also be attached to the crankshaft and a much larger energy store (battery pack) would be used, too.

Engine revs would be reduced from 18,000rpm to 15,000rpm, although fuel flow restrictions would see that the power curve dissipated just above 12,000rpm in any case. A maximum of 100kg of fuel could be carried under race conditions, with a maximum fuel flow rate of 100kg/h.

As was the case with KERS, the new ERS was scalable depending on the prevailing track conditions, with the driver able to adjust how much energy is recovered and deployed with adjustments made on the steering wheel.

Unlike KERS, the deployment of the ERS dispenses energy based on the current mode selected and the throttle pedal position applied, as it's intrinsically linked to the car's total output.

The MGU-K, connected to the crankshaft, can dispense a maximum of 120kw or roughly 160bhp, of which 4mj can be used from the energy store per lap, it can recover and store 2mj per lap while the energy recovered and dispensed by the the MGU-H is unlimited.

However, the most interesting aspect is that energy can flow between the MGU-K and MGU-H through the control system without needing to be stored, allowing one MGU to power the other, creating a more efficient energy system, as there are only negligible losses compared with an AC/DC power conversion when storing energy.

2014 Regulation change overview, using Red Bull RB9 to compare Photo by: Giorgio Piola

Aerodynamically, the 2014 regulations sought to continue the downward trend in downforce that could be extracted, with the front wing reduced in width by 150mm, the height of the nose tip and the transition between the nose and chassis subjected to a much lower positioning, not only for safety reasons but also to reign in the aero gains that had been made during the last regulatory phase.

The supposed aerodynamically-neutral camera pods that were being exploited by the teams for aero gains were now moved into what was considered a more neutral position.

A universal side-impact protection spar was introduced to combat the variance of solutions that had cropped up and down the grid to suit each team's aerodynamic and weight targets.

The lower beam wing was removed entirely, whilst the upper box area for the mainplane and top flap was reduced by 20mm, impacting on DRS too.

The centralised exclusion zone at the rear of the car that permitted items such as the monkey seat was increased from 150mm to 200mm as it had to also facilitate the exhaust, which had been positioned centrally in order to limit any aerodynamic implications, such as the exhaust blown diffusers that had populated the sport during its last phase.

The changes for 2014 were therefore extensive, but perhaps went a little too far, erasing downforce from the car at a point when they'd suddenly become 60kg heavier, owing to the additional power unit components.

Everyone immediately seemed dismayed at the relative loss of pace to the car's predecessors and just how close the laptimes of the smaller teams were to other series, such as GP2.

The issue was that too much downforce had been eroded at a point when it was needed to accelerate the additional weight through the corners. Furthermore, the understanding of the power unit technology was also very immature.

As we've seen in subsequent years the situation has righted itself, with the 2016 cars a handful of seconds quicker than their 2014 brethren and breaking lap records in some instances.

While the change was needed to stabilise the field, especially in terms of reigning in Mercedes, the 2017 regulations were somewhat of an expensive knee-jerk reaction that will likely lead to fewer overtaking opportunities.