Brazil and Abu Dhabi technical review

Right up until the very last race of the 2010 season, there were three teams still principally involved in a tight battle for a world championship title. Unsurprisingly then, Red Bull Racing, Ferrari and McLaren all continued bolting updates to their cars in an attempt to stay the fight until it was either won, or finally lost. An opportunistic Renault squad kept pushing development right to the end too.

AUTOSPORT's technical consultant Gary Anderson takes a look at some of the more critical developments by those teams over the last two races of the season in Brazil and Abu Dhabi.

Maximising the McLaren F-duct

As we know, McLaren invented the F-duct system which feeds airflow to the rear wing flap, this changed the characteristics of the wing and reduced the drag therefore increasing straight line speed. But doing that only really reduced the flow to a certain percentage of the wing, because the main plane airflow remained attached.

Then Renault came out with a system which affected a much greater part of the wing, so it enjoyed a larger straight-line speed advantage, as we saw in Abu Dhabi.

McLaren has now copied that with its own updated version and we saw Lewis Hamilton running it on the Friday at Yas Marina.

McLaren's F-duct now feeds onto the main plane of the wing. The intent is to create a bigger drag reduction. But the team has had problems getting it to work consistently. Obviously the last thing you want is a driver lacking confidence in the wing's ability to create downforce when he takes his hand off the duct mechanism at the end of a straight.

But by Abu Dhabi, McLaren seemed to have got it working well, and in the end, both drivers used that wing assembly for the race.

And the Renault one...

You can see that Renault still has an upper hand in this area. The R30 definitely wasn't the quickest car in a straight line before the team introduced its F-duct. But in Abu Dhabi, Vitaly Petrov held off Fernando Alonso, assisted by a good F-duct system that works very well.

Renault's refined F-duct

Renault is the team that went the 'whole hog' with the F-duct, to try and make it work better. There is no point in simply copying someone else's idea because at best you are only going to achieve the same result - so at Renault the design team has tried to do it differently, and succeeded.

The duct leads from the engine the cover and connects on to the rear wing main plane. It feeds the air inside the volume of the main plane and flows through a slot in the under-surface. You can see between the N and the A of the Renault name on the rear wing that it has also got a small upper third element, just to make that area of the wing work a little bit harder.

It's a combination of a lot of parts, it's not just one thing that makes it all function well. As well as the advantages of stalling air on the main plane you also get a bigger downforce loss. So you need to ensure that the airflow reattaches in time to give the driver confidence when braking.

We saw in Korea that people couldn't really use their F-ducts because the track was so slippery. Drivers needed both their hands on the steering wheel and they needed the grip at high speed anyway to make sure they didn't get aquaplaning or wheel spin. At 250 km/h the rear wing assembly can generate upwards of 600 kilos of downforce. The F-duct can reduce this by as much as 50 per cent so in wet and difficult conditions that is a lot of grip to throw away for a little bit of extra straight-line speed.

The secondary tube you can see that points under the main plane also features on the Red Bull F-duct assembly. It could be to avert the flow that goes into the rear-wing chamber, when it is not required to go into the main plane.

You are not allowed to change the aerodynamic characteristics of the car, so you are not allowed a mechanical system that would alter the airflow. So what you have to do is devise a system that is operated by different air pressures. By changing air pressures within a certain area, via ducting, you can change what the flow is doing and where it is going to. It's pretty tricky and that's why some teams have had problems getting it to work. It's also why these systems didn't work too well in Brazil, because the altitude is quite high at Interlagos and you therefore work with different air pressures.

I think this tube is something that allows that airflow to go one way or the other whenever the driver covers a hole in the cockpit. You have to put the airflow somewhere after all, it can't just stay where it is.

Red Bull F-duct

The team has the same engine as the Renault, so you have to imagine that the secondary tube could be a result of a collaboration between the two teams because obviously they will be working together closely in this area.

Red Bull's final version of the F-duct

Red Bull is ducting into the rear wing main plane, you can see a duct section going down on to the top profile of the main plane. The one thing this team has on its wing is a very long-cord main plane and short-cord rear flap. I'm going to stick my neck out here because I believe Red Bull is using the rear wing as a slightly different tool. I think it is using it for downforce.

If you have a one-piece rear wing you can only camber it a certain amount before the airflow stalls and won't follow that curve around anymore. What you do to stop that is insert a slot gap and a flap so that you allow high-speed air to be injected through that slot. This keeps the flow attached so you can make it work harder for longer.

If you look at the curvature of the Red Bull rear wing main plane it looks like it has far too much curvature for airflow to stay attached all the time.

So I believe it feeds airflow into that wing chamber, and the team has effectively made it into a three-piece wing. There is a slot gap in the under surface of the main plane of the rear wing which is allowing airflow to go in there through this gap. You don't have to have a slot gap running from front-to-back, you just have to have an air supply to that slot, to allow airflow through it.

As with most things in life there are many ways of achieving the end result.

Option one is to have airflow going through another slot in the under surface of the wing, which would effectively turn the under-surface into a three-piece wing - which you can get away with now because of the way the regulations have been interpreted. Then to stop the rear wing working so well you would shut that airflow off to that slot gap. You stall the rear wing by shutting the airflow off, as opposed to what everyone seems to think which is that you feed air on to the wing to stall it.

Option two is if the wing stays attached and works properly, with no airflow coming through another slot; once you feed airflow into that slot you reduce the performance of the wing because you are feeding high pressure air into a low pressure area. That way you reduce the performance of the wing fairly consistently.

So there are two ways of going about achieving this change of performance from the rear wing, and I think Red Bull and Renault use their systems to create more downforce initially then stall this assembly to reduce drag.

Ferrari's extra gills

Ferrari was using two of these before and now it has increased to three.

Ferrari added an extra gill to its floor for the final races

What happens with the airflow on the top of the floor and on the bottom of the floor is fairly critical because you are trying to create a sort of skirt effect. You'll notice the way the floor tapers down to the outer edge, it goes from about 12mm thick to something like 3mm, but the difference between having this thin knife edge and a flat edge can be a huge amount of downforce.

Under braking, the height of the bodywork in front of the rear tyre will probably be 120mm from the ground, so a huge amount of airflow can go underneath there. That means that the diffuser just can't speed up the volume of that airflow because there is too much of it. It simply can't suck anymore air.

So you need to make the edge of the floor work as a skirt, for the same reason as skirted cars did in the late 70s and early 80s - to prevent unwanted airflow from getting underneath the car.

Putting these gills in front of the rear tyre, which are angled towards the inside of the lower corner of the wheel connects with the displaced airflow around the tyre contact patch - this air is actually quite high energy.

Connecting that airflow through these gills means that they will suck the air down through the top of the floor and basically help seal this area, acting as a skirt. You then create a low pressure area which more air then wants to rush into it, so the net sum of the airflow going underneath the car is actually reduced. This means the diffuser can do a better job of utilising the airflow that is under the car. This in turn creates more downforce.

Understanding McLaren's diffuser

The lower diffuser area is what you would classify as a normal diffuser (as opposed to a double diffuser). Going from the centre line outwards, the first two strakes are turning vanes. They go right down to reference plane height, in other words they are at the lowest part of the car other than the plank.

This whole chamber is working on the reference plane. Also, because it is at the lowest part of the car it is actually quite critical to airflow separation when it gets close to the ground.

Those vertical splitters are to reduce different airflow pressuresfrom mixing with other pressures in the outer sections. So you have different little sections of diffuser doing specific jobs and you try and contain and maximise them without allowing each to influence the other too much.

Beyond that you want to obviously then use the maximum height allowed, because the airflow required is then getting closer to the outside world. Again the splitters compartmentalise the air because it's not one whole area of consistent pressure, it is different in separate sections. When a certain part of a diffuser does stall or separate, you want to try and contain it into one of these little boxes, because if you didn't it would affect the performance of the whole diffuser. You are trying to contain the problem whenever this happens.

Above all that is a turning vane that stretches across under the rear light. That is helping the airflow and the lower beam wing 'talk' to each other. McLaren is trying to get the beam wing involved in the airflow management on the underside of the car. By turning the airflow there, it is getting the two airflows to go in the same direction and eventually connect up with each other, working them twice as hard.

The beam wing and the whole back of the car is really a double diffuser section. All of that is sucking on the bits of floor, and the ground, that you can see in the image. The double diffuser system works as a huge duct. It's a four-sided device - a box section - and it works a bit like a radiator duct. It's sucking air through from underneath the car. The combination of all these components add up together to give you the downforce.

The very outer vertical splitters, the ones that turn around towards the tyre, are trying to turn the airflow out as wide as possible and yet keep the flow attached to the inner surface of the component. This is where the exhaust-blown diffuser helps, because if you can connect the low pressure area from in behind the contact patch of the rear tyre, it will have a similar effect to the beam wing working with the diffuser. It makes the diffuser a much stronger device.

It's about getting all the bits of the back of the car working and talking to each other. If you can get it all working in unison then the sum of all those parts working together is greater than the sum of them all working separately.

Why Ferrari loves its diffuser

Ferrari's diffuser is much less intricate than McLaren's, but it is doing the same thing. There are less turning vanes and the curvature of the splitters is not as severe around the rear tyre.

Ferrari's heart-shaped double diffuser

The team's double diffuser section, which is the part that starts at the bottom of the light and ends at the top of it, is a much smaller exit area than that of the McLaren's. It's very different, considering this part of the car performs in more or less the same manner. The centre section, for example, has a higher trailing edge so this area will work a bit harder than the McLaren's because there is more clearance to the ground.

The fact that these diffusers are so different adds weight to the argument that you need big, big differences before you can see small changes in lap time. There is a lot to the Red Bull, for example, that nobody else understands yet - and it is faster than both the Ferrari and the McLaren.

Whenever you have a lot less trickery in a component it points to more consistency, but potentially less peaks in downforce. So often it comes down to team philosophy.

Some teams want consistency out of the downforce they generate as opposed to ultimate total force. You can see that Ferrari has gone for consistency, which allows the driver to drive the car, while McLaren is going for peaky downforce which in turn means the driver has a white-knuckle ride. That's great for someone like Lewis Hamilton, but Jenson Button perhaps needs less peaks in downforce because he drives with his fingertips.

About two races ago Ferrari started playing with the diffuser a bit and increased the centre section so that the bottom part was a bit lower and the turning vane part higher. The final version was more shapely. I think they are in love with it because it is heart-shaped!

One interesting thing about this image are the brake-duct-mounted turning vanes. All of those things are designed to turn the air flow upwards and try and get low pressure underneath the car. They certainly have nothing whatsoever to do with cooling the brakes. The lower vane is nigh on a wing, it's got an outer endplate, it has a slot gap... everything you want to create downforce and it's all just to work the diffuser harder.

Complicated but powerful

McLaren has made quite a lot of aerodynamic modifications recently but it has had trouble getting them all to work. Jenson Button has been back-to-back testing a lot of stuff on Fridays.

McLaren's new (top) and old front wing endplates

On this front wing endplate, there are three holes in it. The team has made the rear one with the triangular plate over it bigger, to allow more airflow through it. These holes in the endplate allow airflow through where the flaps attach. The middle hole - you can see how the flap comes through there and bends down - is a three dimensional component. The inner endplate surface curves so much that it is intended to keep the airflow attached to the surface of it. You need something like a slot gap there to allow you to achieve that.

The team has been experimenting with the size of those holes, because obviously it is a very complicated concept. If you look at the small front hole to the very large second one and the medium-sized third one, they have all changed compared to the old one. Small detail changes like this can generate twice as much airflow.

The intricacies of the various components and getting them working together and balanced can be an absolute nightmare. A small change can make a difference to the balance of the entire car.

By adding that gurney flap - the black strip at the trailing edge of the wing flap - you can change the entire characteristic of the wing. Yes it will give you a little bit more front-end but it will also change the airflow to quite a lot of other stuff on the car.

McLaren probably has the most complicated front wing system in the whole paddock now.

Simple but effective

For me the success of the Red Bull RB6 is the sum of everything all working together. It's not any one component, because actually the Red Bull diffuser itself is fairly normal and standard. The rear suspension, being pull rod, is all lower than the other teams' versions, for example, this allows it to get the cooling ducts on to the back of the engine cover to work a bit better, so the engine cools a bit better. All that sort of stuff adds up.

Red Bull's diffuser

The diffuser is a typical example of that. It's nothing too dramatic but it is adequate to do the job. It's not exploiting anything the way that McLaren has done.

The team has made changes to the diffuser in the last few races but it has only tidied up little loose ends.

One interesting thing, if you look at the outer vertical strake, where it turns out behind the tyre, on the top of that there is a tiny piece of carbon fibre on the right hand side. That is there to set up a high-energy vortex flow which can help extract the air from the diffuser.

Little things like this mean you can get good downforce out of the car. Designing F1 cars now is all about vortex management, if you can get them working and helping your airflow, it makes the car much more powerful. Red Bull has been very good at exploiting all these little areas and making them work this year.