Barcelona F1 test technical overview

Typically the last test of Formula 1's pre-season is about the teams learning their cars and working through race and qualifying simulations.

It's the chance to fit the majority of the upgrades ready for the first race, and we've seen developments on every car this week.

There is a chance that some teams might add a few surprises on the final day, but it's just as likely the better resourced teams will bring new aero parts directly to Melbourne, safe in the knowledge their simulations will be accurate.

Mercedes

The W06 has had a number of subtle modifications this week, and more detail of the power unit has also emerged.

The car's front camera mounts have been modified to meet the letter of the current regulations, resulting in rather odd vertical struts supporting the camera pods. This design keeps the pods in the same high position, but keeps the housing that mounts them outside of the 150mm centreline restriction.

At the rear end of the car the 'coke bottle' exit and diffuser have had a few detail modifications, and the bodywork forming the tail of the sidepod now wraps downwards to form a vane connecting to the floor. Presumably the vane directs airflow through the coke bottle area more accurately over the diffuser.

Mercedes W06 rear end has sported minor tweaks during this test

In the centre of the diffuser the ramped extension that connected the diffuser to the rear impact structure has been removed, replaced with an even steeper ramp, connecting nearly vertically with the impact structure. This appears to be a logical progression from the team's late 2014 switch away from the U-shaped central diffuser arrangement.

The simple winglet that replaced the 'monkey seat' as part of a new rear wing mounting system at the first Barcelona test has remained on the car for this week. However, two flicks added to the crash structure below suggest the team's trademark larger winglet may return.

Detail images of the Mercedes power unit are yet to emerge, but it's apparent that the team has moved away from the very tightly packaged log-style exhausts in favour of a more conventional tubular 3-into-1 exhaust.

While this is bulkier than the old format exhaust, the tubes are still tightly packaged against the engine and unlikely to be a hindrance for the aerodynamicists. Also adding some bulk to the package is the new inlet system, which is slightly larger than before in order to package the movable inlet trumpets in the plenum chamber above the engine.

Ferrari

For this test Ferrari ran a new front-end package, which may be the last update we see before Melbourne.

The long nose is the same, but the front wing is fundamentally new. The multiple wing elements are divided differently between the main wing element and flaps behind it. Now the wing is clearly split into three sections: the main plane, the flaps and the outer tips.

More of the inner span of the wing is formed by the main plane's two elements (red painted), with the flaps reduced to just two elements (white painted). Outboard of this the black painted tips are split into a cascade of seven elements.

This design means most of the wing's aerodynamic load is created by the aggressive outer sections.

Allied to this change were slightly revised front brake ducts, with the fence protruding forward of the wheel now extending further than the old design. Much like Mercedes, Ferrari had to alter its front camera mounts, making them more like vertical vanes spaced far enough away from the car's centreline to meet the regulations.

Williams

Williams is nearly in its Melbourne specification, and this week the FW37 gained its final upgrades (bar three or four parts), most notably a new rear wing mount.

For 2015 the opportunities of diffuser design outweigh the risks of rear wing disturbance from a mounting pillar. Thus the Williams now has the on-trend 'Y' mounting pillar, known in the paddock as a Y-lon.

This mounts to the gearbox and wraps around the exhaust, before the inverted Y-shape forms a slim, light pillar to support the rear wing. As with most teams adopting this design, the pillar sits just ahead of the rear wing and then curls down to mount on the wing's top surface, in a swan neck shape.

Other details on the Williams for this week included revised sidepod vanes, now following a Red Bull like shape where the vertical vane folds over to mount on the shoulder of the sidepod. A small detail change, but one that will divert airflow over the engine cover towards the rear of the car.

In a bid to catch Mercedes, Williams has also considered potential gains from the power unit. Although it runs the same specification as Mercedes, it uses a different fuel and also cools the turbocharger's air in a different way.

Since mid-2014 Williams has run Petrobras fuel blended specifically for the team. Its technical director Pat Symonds believes there is no reason that it cannot find a more powerful fuel mix than the Mercedes factory team.

Furthermore, power can be released by running the air from the turbo into the engine at lower temperature. Mercedes runs a water-to-air intercooler on the W06, which is a better solution for aero packaging because it requires less sidepod space. But it does not have the same cooling effect as a conventional air-to-air intercooler.

Williams still uses an air-to-air cooler and has managed to package it into very small sidepods.

Red Bull

It's clear the RB11 is a car with good potential, but few updates have been added through testing. This week a revised rear wing endplate has been the main visual update, albeit heavily disguised by the camouflage livery.

Nearly every F1 rear wing endplate has a series of louvres above the wing and a further vertical slot on the leading edge of the endplate. Red Bull has joined up these slots, with the vertical slot rising up to meet the top louvre above the wing.

It's hard to fully understand the effect of this - it's most likely adding downforce rather than trying to improve drag. The slot makes the otherwise large flat endplate appear more three-dimensional to the airflow, allowing more mass flow through the wing for more downforce.

It's an odd idea, but one that's likely to attract the attention of its rivals' aero departments.

McLaren

With so much attention focused on getting the Honda engine running, little development has been directed at the chassis. This week the team ran a Y100 monkey seat for the first time. It's not a particularly massive performance part, but it's a sign that attention is being diverted back to the chassis.

Detail changes to the front wing have been tested, with the fences under the wing being multiplied to have four vanes under each side of the wing.

Evidence of reliability and pace is currently hard to detect, but the potential in the 'size zero' package is still huge.

Force India

Although the VJM08 is necessarily an evolution of the 2014 car, the team has a new aero programme ongoing in Toyota's windtunnel in Cologne, Germany. While Force India was designed at its Silverstone base and in its Brackley windtunnel, the new car's bodywork is a stop gap, before the Cologne programme bears fruit at the Spanish Grand Prix. These restrictions notwithstanding, the car is neat and has several interesting details.

At the front the nose is a thumb tip design, longer than the Williams but far shorter than the McLaren/Ferrari length. It's believed a shorter nose is in development, but not yet ready for crash testing.

In the same area, the car sports an 'S' duct: a letterbox inlet under the nose feeds a duct that exits through the large protruding exit over the top of the chassis. Red Bull is the only other team using an S-duct, which was initially a Sauber idea, this year.

More inspiration from other cars is evident with the front lower wishbone, with the two legs of the suspension arm being narrowed and joined into one aerodynamic profile as seen on the Mercedes last year.

Towards the rear the VJM08 has a notably neat cooling package, the heat being managed by coolers in the sidepods as well as one fed by the inlets around the rollhoop. Cooling air and the exhaust both exit through a Y-lon rear wing mount, again using the common format of a swan neck top mount that also connects the DRS actuator pod.

Just aft of this a Y100 monkey seat is formed both above and below the exhaust exit. This double-decker arrangement is designed to collect the exhaust flow to create a greater aerodynamic upwash between the diffuser and top rear wing.

Toro Rosso

Toro Rosso arrived at the final test with a huge update - the STR10 getting nearly a complete overhaul on its aerodynamics from nose to tail.

Most obvious is the new nose, following Williams with the ultra-short thumb-tipped design, but unexpectedly without an S-duct, which was a feature of its 2014 car. Allied to the nose are front wing and turning vane revisions, but one other front end aero feature is something of a novelty in current F1, with strakes being fitted along the edge of the monocoque.

There are tight regulations of the cross section and width of the car from the cockpit forwards, but the rules do allow some freedom around the edges of the monocoque. Toro Rosso has filled this area with a strake, which acts much like the little vanes we often see near the wing mirrors. A wake will be shed from the strake that continues over the sidepods to keep the air attached to the tight curvature of the bodywork. It's a neat trick other teams are likely to investigate.

With the revised sidepods, the secondary inlets around the rollhoop have been removed, however the rollhoop inlet is still split to feed the engine's airbox and the oil coolers mounted either side of the engine.

The neat rear-end features a new Y100 winglet, and from the triangular two-element wing there is a now far larger triple-decker set-up, mounted just above the exhaust to drive the exhaust plume further upwards.

Lotus

Lotus has been working hard to catch up on the small delay to its testing schedule, with the car now sporting its full launch package. Only the small addition of a Y100 winglet was seen in testing this week.

Oddly, despite testing a new steering wheel in 2014 updated with the larger LCD dash display, the team continues to run the older, simpler LED display on this year's car.

The E23 is clearly a better package than the difficult 2014 car, so Lotus is likely to be in the thick of the midfield scrap this year.

Sauber

After attention grabbing runs in previous tests, Sauber has been placed in more realistic positions this week. Clearly the chassis is improved from 2014 and that combines with an improved power unit from Ferrari. Sauber can head into the season knowing it can be near the pace and run reliably to the flag.