The tech details that decided Mercedes vs Ferrari

After three years of dominance, the big question was whether Mercedes could stay on top in 2017 through the major aerodynamic rule changes. As for Ferrari, was this a chance to recover from a poor previous season and get back into the game?

The answer to both questions was yes, with both teams fighting for the championship until Ferrari and Sebastian Vettel lost momentum, thanks to the start crash in Singapore and then failures in Malaysia and Japan.

In pre-season testing, we could see differences in approaches between the cars. Both teams tried to maximise the distance from the front wheels to the leading edge of the sidepods to allow the maximum time to control the airflow, but in very different ways.

Mercedes moved the front wheels forward, hence the longer wheelbase, while Ferrari cut back the sidepods, incorporated some of the crash structures into the bargeboards and then had a complex bargeboard concept to work the airflow. We also saw that Ferrari ran with a reasonable amount of rake, although not as much as Red Bull, while Mercedes had a flatter platform for the car.

Over the course of the season, the Mercedes was the faster car over a single lap. There were only five weekends where the Ferrari set a faster overall lap time - Russia, Monaco, Hungary, Singapore and Mexico - so it was often stronger at the slower and high-downforce-configuration tracks.

The famous comment from Toto Wolff was that the Mercedes was a "diva". And it's clear that in the first half of the season in particular it was harder to get the best out of the W08.

If you have a car that has peaky aero performance, you have a battle to keep it in its optimum working window. A change of half a millimetre in front rideheight is night and day, and particularly in slower corners the cars bounce around all over the place. Mercedes had to work to make it more benign and less rideheight-critical, which it did do.

In many ways, while Mercedes didn't have the pace dominance it had from 2014-16, the team became stronger because it had to get on top of these problems. That's a worry for the competition next year. I'd expect Mercedes to move in the direction of running higher rake, but it's not just a question of jacking up the rear rideheight - it has an impact on the whole aerodynamic concept of the car.

Ferrari had the more consistent car and, in the first part of the season, looked after its tyres better. That made it stronger on race days. And Ferrari did seem to make the complex bargeboard concept work.

The question here is if there is more to come in 2018, or if Ferrari has to choose a different direction. I suspect that there is still more to exploit there. And at the end of the year, Ferrari tried diffuser modifications, so there's a clear direction there. It might also be able to take another step, with the rake being closer to how Red Bull runs its car.

If you have a car that has peaky aero performance, you have a battle to keep it in its optimum working window. A change of half a millimetre in front rideheight is night and day

The main concern for Ferrari is that it appeared to lose that tyre-management advantage over the season, and unfortunately that didn't come with a gain in performance relative to Mercedes.

But overall, I'd liken the Mercedes to a jigsaw with more pieces. If you have 10,000 pieces, each optimised, that will be stronger than a jigsaw that has 1000 pieces. Ferrari needs to take a step with its aero in areas beyond the bargeboards to have the chance to jump ahead.

The positive thing is that Ferrari and Mercedes took two different approaches and were able to have a good battle. This bodes well for next season, if Ferrari can avoid the mistakes and reliability problems that put Vettel out of contention.

Front wing comparison

The front wing of a Formula 1 car is probably the most important aerodynamic component. All the other aero components downstream have to work in its wake, so if you change the front-wing airflow characteristics everything else needs to be optimised for it.

Comparing the Mercedes to the Ferrari front wing, you can see that the general principles are the same but the detail is quite different. The outer end and endplates are designed to move as much of the airflow as possible around the outside of the tyre so as not to direct too much of the turbulent airflow between the chassis and tyre. But inboard of this, there are quite a few subtle differences.

The front-wing main plane on the Ferrari is a much longer chord than that of the Mercedes, and this can cause bigger problems. In general, all of the front-wing flap chord lengths are there to optimise the aerodynamic stall characteristics; the longer the chord, the bigger the stall.

The objective is to get as much front-wing downforce as possible in slow and medium-speed corners, where the cars normally suffer from understeer, and to allow it to taper off for the high-speed corners where the driver wants confidence in the rear of the car.

By having a controlled aerodynamic stall of the front wing you can achieve this. But some teams do this better than others.

Bargeboard comparison

One of the elements opened up in the 2017 regulations was the bargeboard area. This is basically anything between the trailing edge of the front tyre and the leading edge of the sidepod/radiator-inlet area.

This is also the area that differs most between the Mercedes and the Ferrari. The bargeboard area is a very powerful package of components and, optimised, it is responsible for well in excess of 10% of the car's overall downforce.

It doesn't really produce any downforce in its own right - it's about how it manipulates the airflow to improve the performance of the front wing and underfloor. It also improves the sealing of the sides of the floor, making the diffuser more effective.

To give itself more opportunity to manage the turbulent airflow coming off the wider front tyre, Mercedes increased its wheelbase by moving the front wheels forward and away from the sidepod leading edge. This allowed it to introduce extra components that would pick up that turbulent wake and realign it to best work with the front wing and underfloor.

Ferrari went the other way and found a solution that allowed it to move the leading edge of the sidepods rearward, while keeping a similar wheelbase to the 2016 car. Parts of the independent bargeboard mountings were used to house the side-impact structures and that, together with a higher and more horizontal radiator inlet, meant the undercut sidepod was much more pronounced than on any other car.

Which team was right? The jury is still out, but it will be interesting to keep a watchful eye on which direction these two teams take in this area in 2018.

Diffuser

For 2017, the diffuser size was increased to make it 50mm higher, 50mm wider and 175mm longer. This makes the diffuser more powerful and means you can create more underfloor downforce.

But as a standalone component you can only work the airflow so hard before it suffers from airflow separation. When that happens, you get a very quick loss in overall downforce, mainly at the rear.

Which team was right? The jury is still out

This loss in downforce will be more pronounced at the end of a straight. Most teams play with the height relative to the ground that the diffuser will stall at, as this gives a drag reduction and leads to higher straightline speeds. But when you hit the brake pedal, you need the airflow to reattach in nanoseconds, otherwise the rear of the car will be unstable and ring alarm bells for the driver.

By getting the outside area of the diffuser to work in conjunction with the low-pressure area behind the rear tyres, the complete rear of the car works to pull the airflow through the underfloor. In general, it gives more underbody downforce, but more importantly it will improve the airflow reattachment.

Mercedes started the season with the better package in this area, with outer vertical turning vanes helping the diffuser connect to the low-pressure area behind the rear tyre. This not only helps overall downforce, it also helps with consistency of overall downforce.

Ferrari had a more sympathetic design, which allowed airflow coming around on top of the floor's outer foot area inside the rear tyre to fill the void created by the rear tyre.

This was probably more efficient (so less drag), but there are areas on the car for efficiency and there are areas where out-and-out downforce consistency has to be the primary focus. The diffuser is one of the latter.

In Abu Dhabi, Ferrari trialled a version more like the ones Mercedes and Red Bull also use. So watch this space when the 2018 Ferrari first appears.