Key tech talking points from test two

As Formula 1 entered its second and final four-day test of winter 2016, the development of the cars remained low key, with no teams scheduling massive upgrades in this year's compressed testing schedule. Programmes generally focused on long runs and simulations for the new qualifying format.

But there were some technical novelties to be found, with nearly every team having something new and the most notable updates brought by Mercedes and Toro Rosso. Teams also relaxed the tight pit security of the first week and we were able to see some of the hidden technical detail on other cars.

MERCEDES' EVER-MORE COMPLEX BODYWORK

Paddy Lowe described Mercedes' multiple sidepod vanes as the "innovation of the first test" and the champion team continued to bring new parts throughout the second week.

Again its focus was on long runs and race simulations, so the true pace of the W07 has been covered up, but the car leads the pack in design terms.

Using its second race chassis for week two, Mercedes ran two new different rear wing specifications, a new 'monkey seat' winglet and yet more revised sidepod vanes - each with a great degree of complexity and segmentation.

The first rear wing was relatively simple with a slight 'V' groove in the centre of the profile. This wing was tested with the stick-on serrated trip strips on its underside evaluated during the Abu Dhabi Grand Prix weekend last year.

The wing was bounded by new endplates, which featured a taller slot in their leading edge, again a solution tested in late-2015. On the final day another rear wing profile was tried, with the trailing edge of the main plane cut into a zig zag serrated pattern. This was similar to that run on Mercedes' front wing last year and on the McLaren rear wing in 2014.

It's thought these serrations help keep the airflow attached under the rear wing, which may additionally help the airflow reattach when DRS is used.

Below this a more complex monkey seat was tried with further slots made into its multiple elements.

Lastly the tall vertical vanes mounted beside the sidepods were revised. What was one tall vane is now split into an upper and lower vane, with the lower one being mounted to the floor and not connected to the upper vane.

With all of this added complexity, it's clear the Mercedes is working the bodywork harder to pass the airflow around the car, rather than relying on longer curved bodywork, as on the Ferrari for example.

These little add-ons no doubt add not just complexity but drag. With its performance advantage Mercedes may find itself in the same position as Red Bull did during its dominant years, where the car can run more downforce and drag because pole position is near-certain so it's not expecting to be challenged by rivals along the straights in the races.

FERRARI'S REPACKAGED POWER UNIT

Upgrades were less notable on the Ferrari, with the car outwardly being the same as that launched the week before. A few minor details on the front wing and diffuser were changed, but no big upgrades were seen.

Instead we have seen more of Ferrari's repackaged power unit, which has taken the next step after the winter of 2014/15 brought the engine up to near Mercedes levels of power and energy recovery. Now the focus for Maranello has been to slim and shorten the power unit for better chassis packaging.

It's known that the old power unit had its MGUs mounted behind the engine, with the MGU-K being beside the clutch and the MGU-H between the two parts of the turbo. Now these have both moved further forward on the engine into more conventional positions, the MGU-K being beneath the left cylinder bank and the MGU-H inside the 'V' of the engine.

This has allowed the carbon gearbox case to be slimmed and raised to allow more space under the rear of the car.

It's also now known that the Ferrari gearbox follows Mercedes' 2014 trick of being a carbon outer structural casing, with the gearbox itself then fitted in a self-contained titanium cartridge inside.

Along with the repositioned MGUs, Ferrari has also repackaged its intercooler and inlet plenum. Last year there was a water cooled intercooler mounted in the V of the engine, then a 3-into-1 inlet plenum on each cylinder bank.

This set-up was neat but precluded the use of a large inlet plenum with variable length inlets. So now there is a single large inlet plenum undoubtedly fitted with variable inlets mounted above the engine.

What's clever is that Ferrari has then split up the turbo intercooler into two elements. The turbo compressor feeds the compressed charge air straight up into a triangular air-to-air intercooler above the gearbox. The partly cooled air then exits the intercooler and pipes alongside the engine into a water-to-air intercooler in the back of the chassis. This further cools the air that then enters the engine.

This split set-up cools the charge air effectively, both with a light air intercooler and with the consistent cooling of the water intercooler, while keeping a relatively short inlet path which is good for reducing turbo lag.

TORO ROSSO'S MULTIPLE UPDATES

Toro Rosso did not bring a 'B-spec' car as some anticipated, but there were more updates to the base STR11 along with its revised livery.

Two key updates were the new floor and front wing, while several versions of the monkey seat wing were also tested.

The new floor's key alteration appeared to be the recessed space below the gearbox and the slots ahead of the rear tyre, both of which were much larger than the initial test spec.

The recess means the upper floor area dips down 50mm into the step plane below the car. A slim gearbox and sidepods allow more airflow to pass along this lower floor to the diffuser, meaning more downforce can be produced.

In front of the rear tyre the series of slots first exaggerated by Ferrari last year have been taken to a new count by Toro Rosso, with some 15 of them in the edge of the floor.

These divert air to below the floor where the rear tyre meets the side of the diffuser and prevents the tyre's wake upsetting the diffuser's efficiency.

Lastly on the front wing the common outwash approach is formed into the wing tips. Now the front edge of the wing is narrower and then widens out towards the front wheel to direct airflow around the tyre. Much of the wing's general shape and the cascade winglets remain the same, so this is a simple reworking of the old spec front wing.

SAUBER'S NARROW REAR END

In its first week of testing the new Sauber looked to have changed very little, but some of its finer details can now be appreciated.

What appeared to be a twin pylon rear wing support is in fact a single gearbox mount, split into a 'V' to meet the old specification rear wing's twin mounting points.

As with Ferrari and McLaren, the rear wing pylons pass through the exhaust tailpipe, a trick first employed by Toro Rosso last year.

The exhaust has a teardrop shaped duct welded into it, then the split mounting pillar passes through this duct. Surprisingly heat is not an issue and this clever set-up keeps the rear aerodynamically narrow.

McLAREN'S AERO OVERHAUL

Now running the second specification Honda power unit, the MP4-31's reliability and pace has improved.

After ending day seven of testing with a near full-car flow-vis application, McLaren then appeared on the final day with a revised aero package, featuring a new floor, front and rear wings.

None of these updates were dramatically new, though the front wing did differ visually with a revised cascade element fitted, now featuring a three element winglet and curved inner vane,. Overall the revised set-up followed the concepts seen on the launch car.