"Daniil Kvyat did some runs with aero rakes fitted behind the front wheels of the Red Bull. These units that look like sections of a fence are fitted with tubes that measure what the airflow does after it leaves the car's surfaces and wings."

Image source, Knutson

Andrew Benson
Chief F1 writer

"Fernando Alonso's health and the accident suffered by him at the end of the second test continue to dominate discussion in Formula 1. McLaren boss Ron Dennis did little to clear up the confusion over what happened and what is Alonso's condition despite a half-hour news conference on Thursday.

"Meanwhile, Alonso's accident has raised fresh safety concerns about F1, as such incidents always do. Lotus's Romain Grosjean pointed out that drivers are still relatively vulnerable in lateral impacts and that there were questions about the wisdom of using Astroturf around the outside of corners.

"'I hate the astroturf because it makes it very slippy,' Grosjean said. 'We can be happy he's OK and left the hospital and the second thing we can learn is to get the drivers safety up in a lateral impact.

"'If you hit sideways, the (suspension) wishbones are not done to be breaking that way. So they either bend or stay in one piece and if they stay in one piece the energy will go one way and that's into the driver. The FIA is looking into it and I'm quite glad they are."

Ok, McLaren are truly out of the traps now. That's 14 laps done, the quickest so far a 1:28.868, putting Jenson Button sixth.

It's not going to have Mercedes and Williams quaking in their boots yet but it's heading in the right direction at least.

Image source, Getty Images

We're 90 minutes into today's action. As it stands, the Mercedes of Nico Rosberg is leading the way, with the team looking to make up for lost time after the frustration of losing a whole afternoon to a hybrid problem yesterday.

The German's time of 1:25.730 from 18 laps is a little over a second faster than the Williams of Valtteri Bottas, who, as we have seen, has done a lot of running with the added weight of an aero rake.

Sauber's Felipe Nasr is third quickest after 21 laps, ahead of Lotus' Pastor Maldonado (22), Toro Rosso's Max Verstappen (17), McLaren's Jenson Button (10), Ferrari's Sebastian Vettel (23) and Daniil Kvyat's Red Bull (14).

The new Force India will make its belated track debut this afternoon.

After missing the year's opening test and running a modified 2014 car last time out, the Silverstone-based team are finally ready to start the campaign in earnest. Nico Hulkenberg will be at the wheel this afternoon.

The team have been teasing us on Twitter:, external "This bright garage door hides our new VJM08, which is here at the track and currently being worked on! #FeelTheForce."

Image source, Force India

Good news for McLaren and Honda.

After managing just seven laps in the whole of yesterday, Jenson Button has just ranked up his eighth today. And we've only been going for just over an hour.

Fingers crossed this is just the start of a better day for the McLaren team.

As usual we want your thoughts on the day's action, or indeed any matters F1.

Send them in using #bbcf1.

Andrew Benson
Chief F1 writer

"Most of the teams have major upgrades a this test as they bring their cars close to Melbourne specification. The most obvious on Thursday was a new nose on the Toro Rosso. Carlos Sainz said he felt an immediate improvement. 'It felt different, it felt really good to be honest,' the Spaniard said. 'That's why I want to congratulate all the guys back at the factory for the great job they have done because out of the box I already felt it is a step forward, a more complete package. I always say the first impression for a driver is very important, and my first impression when I started pushing was really good. It's pure downforce, pure overall grip and better car balance. Having consistent car balance through corners helps.'"

We mentioned the aero devices being run by Red Bull and Williams earlier, and here's one in all its glory.

The device being used on the Williams of Valtteri Bottas below is aero rake, which is dotted with probes that measure the aerodynamic wake of the specific parts of a car.

In this case, the wake over the front tyre is being analysed.

Image source, Getty Images

Andrew Benson
Chief F1 writer

"That noise you can hear over the sound of the engines is the clock ticking ever louder in the McLaren-Honda garage.

"Thursday was another dreadful day for the team in a dreadful winter. Jenson Button managed just seven laps before a hydraulic leak stopped his running for the day, and with only three days of testing remaining time is rapidly running out for McLaren to be anything like prepared for the new season.

"The car has not even run anywhere close to full speed yet; that's how bad it is. The team really badly need a full day's running. But we've been saying that pretty much every day for a month now. If there's any light at the end of the tunnel, not many can see it yet."

McLaren tweets: , external"And we're away. JB heads out for his install lap. #F1Testing."

Image source, McLaren

The McLaren managed just seven laps on Thursday due to hydraulic issues.

Sauber led the way in terms of mileage yesterday with Marcus Ericsson rattling off 122 laps, and at a brisk pace too - the C34 ending the day second fastest after a late soft-tyre run.

It seems the Swiss team has similar intentions today. With Felipe Nasr at the wheel, they are already up to nine laps completed and comfortably lead the way with a best time of 1:27.965.

A new story from our Andrew Benson has gone up this morning, concerning the identity of the main investor behind the revival of the Manor Marussia.

Stephen Fitzpatrick, boss of energy firm Ovo, has rescued the team that went into administration in October and missed the final three races of last season.

He secured the deal with his personal finance. It is separate from Ovo, where he is founder and chief executive.

Read more of this story here.

Image source, Getty Images

Here's a reminder of yesterday's times. Felipe Massa's time of 1:23.500 is the fastest of the Barcelona tests so far.

1. Felipe Massa (Williams) 1:23.500 (103 laps)

2. Marcus Ericsson (Sauber) 1:24.276 (122)

3. Lewis Hamilton (Mercedes) 1:24.881 (48)

4. Daniil Kvyat (Red Bull) 1:25.947 (75)

5. Romain Grosjean (Lotus) 1:26.177 (75)

6. Kimi Raikkonen (Ferrari) 1:26.327 (80)

7. Carlos Sainz (Toro Rosso) 1:26.962 (86)

8. Jenson Button (McLaren) 1:31.479 (7)

All eight of the drivers in action this morning have already posted installation laps.

The Mercedes of Nico Rosberg has already done five laps so it seems yesterday's hybrid problems are sorted, while Jenson Button's McLaren is already up to two laps, having managed just seven all day yesterday.

The Sauber of Felipe Nasr is circling with flow-vis paint (below), while prominent aero sensors are seen on the Red Bull and Williams cars. Still so much number-crunching for these teams to do.

Image source, Sauber F1 Team

Andrew Benson
Chief F1 writer

"Lewis Hamilton, who hands over the Mercedes to team-mate Nico Rosberg today, has only one day's testing on Saturday left before he takes the car out for first practice in Melbourne, but he was upbeat yesterday despite only doing 48 laps because of a failure in the car's hybrid system.

"Hamilton said he was already feeling 'ready to go'. And the team look that way too.

"Felipe Massa might have set the fastest time of the winter in his Williams but even he admits Mercedes are 'quick'. There is increasingly little doubt about last year's champions' status as favourites this."

Lotus F1 Team ‏on Twitter:, external "Buenos dias - it's a lovely day here at @Circuitcat_eng - everyone ready for some test action? Grab a seat, kick back."

Image source, LotusF1

Day two of this final pre-season test in Barcelona gets under way.

It's a lovely morning too.

The air temperature is 7.9 degrees centigrade and the track temperature is 11.7 degrees centigrade.

In no particular order, your drivers today are:

Pastor Maldonado (Lotus), Nico Rosberg (Mercedes GP), Daniil Kvyat (Red Bull), Jenson Button (McLaren), Sebastian Vettel (Ferrari), Felipe Nasr (Sauber), Valtteri Bottas (Williams), Nico Hulkenberg (Force India), Max Verstappen (Toro Rosso).

Image source, EPA

Welcome to day 10 of pre-season testing for 2015.

Williams showed their hand a little more yestrday with some impressive pace. Will Valtteri Bottas pick up where Felipe Massa left off and keep the FW37 at the top of the pile?

Mercedes will surely have something to say about that, assuming they have overcome yesterday's hybrid problems. Nico Rosberg is in action for them today.

McLaren will hope to improve on yesterday's seven-lap showing and again run with Jenson Button, with reserve Kevin Magnussen - scheduled to replace the convalescing Fernando Alonso - missing out.

We'll also see the new Force India this afternoon.

Let's do this.