Piola on test two's eye-catching aero developments

Between the first and second tests of the 2019 pre-season, the Formula 1 teams made varying degrees of changes to their new cars. Some were happy to focus their developments on making sure the internals were fully optimised, which meant that external changes were minimal.

But others cast their eyes towards tweaking more visible portions of their cars as the engineers continue to get their heads around the demands of the 2019 rule changes.

Mercedes returned for the second week of testing with a heavily-upgraded aero package, attempting to address a number of problem areas with the new W10. But elsewhere on the grid there were plenty of other areas of intrigue, as the teams made the most of the final opportunity to test their new cars before the season begins in Melbourne. Here are the main items that caught Giorgio Piola's eye in the final days of winter running.

Alfa Romeo's fins of fury

Positioned either side of the S-duct are a quartet of fins at the front of the chassis bulkhead, just above the inboard suspension mounting points. Presumably Alfa Romeo had been detecting some airflow inconsistencies in that area, having opted for a dramatic outlet for the S-duct to bleed into, and the fins offer a little more control over the flow in that area.

Picking up the airflow from the top, the idea here is to pull it downwards towards the flanks, guiding it around the suspension wishbones and then firing it at the bargeboard and sidepod geometry. This is just to make a little bit more use of the airflow passing over the top of the car, while remaining legal as it slots into a small zone around the front tyre in which bodywork is allowed.

Setting the angle at which the bulkhead begins to slope back creates a larger zone for the team to play with for that kind of development. It's something that Mercedes has taken advantage of too, fitting two winglets at a similar point, and it seems like something that could be ripe for further development elsewhere on the grid.

Alfa Romeo also runs an array of winglets in front of the sidepod inlets, so these could also be used to activate these to a greater extent in managing flow around this area.

Ferrari hits the floor

Ferrari is really pushing the envelope with its floor design, featuring a multitude of cut-outs and slots to help protect the underbody from the effects of the rotating rear tyre.

Airflow is brought outwards and around the face of the tyre, minimising the effect of what's known as tyre squirt.

Tyre squirt is when a small pocket of air rotates in front of the tyre and, as the car moves, it bursts. This is then sent inboard into the diffuser, reducing its effectiveness as the clean expansion of airflow from the underbody is stunted by the mass of turbulence from the wheel.

These slots have become a popular addition to the floor, taking advantage of a 10cm section at the edge of either side of the floor to introduce a range of cuts and perforations. Last year, Ferrari added three banks of small fins to further enhance the outward motion of the airflow, but having tested them in practice sessions it decided these weren't worth including as standard.

But it seems that they weren't completely discarded, just placed on the backburner; the final bank of fins attached to the corner of the floor were brought back for testing to boost the outwash in this area a little more.

The pressure is now on for those with a slight deficit to make the most of any final updates

Ferrari also continues with its raised rear suspension pick-up point, opening up the space around the top of the diffuser to clean up the airflow, as well as creating a little more breathing room for the rear hub-mounted winglets to develop further downforce.

Mercedes' bargeboard charge

Another component of Mercedes' large aerodynamic overhaul for the second week of testing was the bargeboard and chassis flank area, which received plenty of attention between specifications. It's now one of the most important areas of the car, thanks to the reduced impact of the front wing, and there's been a number of changes there on the W10.

Along the top edge of the main bargeboard piece, the horizontally mounted winglets have changed in geometry. The original specification had two small fins on the second and third 'teeth', but these have been extended to salvage a little more tyre wake, convert it into something useable and send it down the sidepod flanks, just to enact a little more clean flow towards the rear of the car.

The sidepod-mounted slats have also changed, reducing the chord length of the first slat to reduce the odds of separation and lead into a redefined second piece. This has now been fitted with a squarer leading edge, offering a more pragmatic transition further downstream into the curled extension piece, which rolls up a small vortex to be carried down along the sidepod undercut.

There's more, as the flanks above the bargeboard geometry now have two winglets, which link into one another.

Aggressively shaped to point downwards, these parts assist with turning any unpredictable airflow patterns away from the suspension components going downwards, opening up the sidepod inlets to a greater supply of clean airflow.

Turbulence here can produce a detrimental effect on the mass flow rate of air entering the cooling systems, so controlling that ensures that the internal components are at a reduced risk of overheating.

These additions complete the Mercedes upgrade package, which is closer in line with what the team will actually run in Australia. With a deficit to the Ferrari package, which showed strong performance out of the box, the Silver Arrows squad may need to find a little bit extra if it's to close the gap to the Scuderia. Lewis Hamilton estimated the current gap to be up to half a second per lap.

There's now under two weeks for the teams to get any final updates together before the season begins, and the pressure will be on for those with a slight deficit to make the most of them.