The question marks over Mercedes' drastic changes

Change is a constant of Formula 1. Across the two pre-season tests, there have been plenty of updates and new additions to dissect on the surgeon's table, as the trackside engineers carefully analyse their designs' benefits, determine whether they operate as they should or whether more work is needed.

And in the past, teams with less resource have had to roll out the previous year's car for one last time, making the requisite modifications and using it as a test mule before the actual car hits the road.

But rarely has a top team launched a new car, milked it for all it's worth, and then turned up for the second week with a completely revised package. Reigning champion team Mercedes, with its W10, has done just that - and, quite understandably, it raises quite a few questions.

The front end of the car is completely new. While it might not - at first glance, at least - look like a huge departure from the previous-spec wing, the philosophy is different. Essentially, it has traded inwash for outwash in the endplate design, deciding to fall in line with the consensus rather than forge its own path - which may or may not have yielded dividends.

Giorgio Piola's illustration of the redefined wing endplate showcases the movement of the trailing edge, which is now much more conscientious in directing airflow around the tyre. Although the effective wing span has been shortened slightly, the illustration also displays a marginally different footplate.

The illustration below shows the specification Mercedes brought to the opening test, with an update shape much more in keeping with what the rulemakers would've been hoping for when they designed the 2019 regulations.

So why go with the previous design when it seemed to be so counterproductive? Clearly, when the design was first conceived and trialled in the myriad simulation tools modern F1 teams have available, there was some tangible benefit in breaking the trend and deviating towards an inwash philosophy.

The sum of the new parts tallies up to about 1500 components. It's not just a case of switching philosophy, it represents a wholesale change

But it's such a departure from what's been one of the biggest focuses in performance over the past few seasons - and the new regulations were formulated to specifically cut the amount of outwash produced by the new front wings, aiming to stop drivers behind another car being buffeted by the ensuing mass of turbulence.

Over the off-season, everybody else has been putting great effort into trying to reclaim that outwash, in spite of the 2019-spec regulations. Mercedes itself has gravitated towards that with its week-two package, which features a whole smorgasbord of new aerodynamic addendums.

The nose is also changed, smoothing off the edges at the point where the 'cape' attaches to the underside to help flow spill below and enhance the low pressure zone underneath. That's to dial out any lift from the underside, ensuring the car is not liable to any sudden shifts in downforce level.

In addition, there's a new sidepod package to further shrink-wrap the internals and help airflow drop off towards the rear more easily, tying up with a new set of floor fins that encourage the delivery of air through the slots in the floor to bolster the underbody's effectiveness.

The sum of the new parts tallies up to about 1500 components, including all the fixtures and fittings needed. But that raises a further question - it's not just a case of switching a small bit of philosophy, but instead represents a wholesale change in what's actually going to be run at the start of the season. Why run two distinct aero packages in testing?

One thing we know is this: it's not reactionary. Each component takes time to design and build, and must go through the requisite crash tests before it makes its way to the circuit. There's no way that Mercedes could get that much turned around in such a short space of time. It suggests that the initial specification of car was one finalised quite early on in the process, giving Mercedes more time to develop its next package.

Whatever the situation, the change has alleviated the handling issues that afflicted Mercedes in week one. The updates prompted the approval of Valtteri Bottas, happy with the steps made with the new package - if only as just a starting point.

"From last week to this week, definitely we have been able to improve the overall balance of the car, differences in the balance we had through the speed range," he says. "We've been able to improve overall grip, downforce, stability.

"But all those areas, we can still do better. It's not the perfect car yet. Definitely I feel the potential is there; maybe [it's] another car that has quite a small sweet spot but once you hit it, it can be very quick.

"I feel like it's been a good step. Every time I get back in the car it gets better."

Regardless, there's still plenty of rumour swirling around the decision to run two dramatically different packages in the two weeks. Suggestion is rife that the week-one set-up may still make an appearance through the season, and that Mercedes has essentially tailored two different packages to span a larger gamut of circuits.

But that would be at great expense, and it makes little sense to split resources into two different iterations when Mercedes could focus its 1000-strong workforce towards honing one package - in other words, why change tack after so much success?

Bottas remarked that the week-two package was a much stronger option than the first, but his uncertainty over which decision Mercedes will make doesn't quite render that theory moot.

"Definitely we have some balance issues we still need to solve, many things in the car we can still improve" Valtteri Bottas

"I would say everything we put on the car, at least from my side, feels better," was his take. "My guess would be to stick with that. But I don't know the meetings that have been going on this week at the factory on the future, so I can't confirm anything."

The most likely reason is that Mercedes embarked upon one direction, the net result being the launch-spec W10. Then in the simulations carried out to validate the theory behind the new car, signs pointed towards various issues with the handling characteristics behind it. Teams today have highly-sophisticated simulation tools for vehicle dynamics, and can define a range of inputs to force the suspension members into action.

Furthermore, teams use plenty of CFD (computational fluid dynamics) to develop their aero packages and Mercedes presumably found that, with some tinkering, it could help dial out any negative characteristics with a few reworkings of the bodywork. Development remains ongoing, even after a 'design freeze', and the benefits of getting the new package built early were evidently too much of a draw.

There's still more for Mercedes to unlock, says Bottas; even with the new package, the champion team finds itself adrift of Ferrari - and potentially embroiled in a fight with Red Bull if it can hit the ground running with its new supply of Honda engines.

"It's better," says Bottas, "but if it's enough, that's the big question mark. But I definitely feel improvements since last week with the stability of the car, with the overall downforce of the car, but we definitely feel we haven't unlocked everything that there is to unlock.

"So even though we are approaching the end of testing, we are still learning massively in each run and each day; so we do still need to make improvements, but at least we have some time after testing to again learn more for Australia.

"The package we had here has been developed for a long time like the first package. It was not like after last week we realised we needed to change something and brought something new. It was well planned a long time ago."

Although 2018's W09 was a strong all-rounder, the 2017-spec W08 was famously labelled a "diva" by team principal Toto Wolff - and Bottas suggests that the new car might also be a little difficult to work with.

"Definitely we have some balance issues we still need to solve, many things in the car we can still improve. I have faith in the team.

"We have been in difficult situations before with the car, we've had race weekends where we've been underperforming with the car, so any obstacle I feel it's possible to overcome."

What shape will the car be in by the time Melbourne rolls around? With just under two weeks before the teams have to set off for Australia, Mercedes still has a lot of work to do to understand its new package.

Of course it's still certainly possible that when the race at Albert Park is over, Mercedes will turn out to have been having us on and will streak to an irrepressible one-two finish. This team has just been too successful in this era to rule anything out.