Ferrari and McLaren's new cars go in search of downforce after 2014 woes

The new cars of arguably 2014’s two biggest under-achieving teams – Ferrari and McLaren – were revealed at Jerez, each of them very significantly different to their predecessors, both teams imbued with a sense of optimism that big performance gains have been made.

The respective weaknesses of each team’s car last year were very clear. The McLaren could never generate enough front downforce – the performance loss from this exacerbated by the tiny set up window it forced upon the car. Despite being powered by the standard-setting Mercedes power unit, it qualified around 1.4s per lap slower than the works Mercedes W05. Averaging 1.1s off the Mercedes, the Ferrari’s biggest shortfall – around 60% according to the team’s techical director James Allison - came from a power unit which lacked horsepower, had poor energy recovery efficiency and difficult driveability. The remaining 40% of the shortfall was reckoned to be aerodynamic, in particular a lack of rear downforce. Allison’s figures suggest that the Ferrari’s aerodynamics were responsible for around 0.45s of its deficit to the Mercedes.  Therefore, the Ferrari’s aerodynamics, whilst not good enough, were much better than the McLaren’s. 

A lack of downforce at one end of the car or the other invariably impacts at both ends. For example, Ferrari was constantly forced to run its car with less front downforce than it was capable of generating in order to have a car balance that the drivers could live with. This in turn meant that it would often not heat up its front tyres quickly enough (especially if the tyre compound was on the conservative side) decreasing the front grip even further. In this way the underlying shortage of rear downforce was giving problems at the front. Similarly, the McLaren was unable to take advantage of what may potentially have been the highest rear downforce of all (if the camber and departure angle of the rear wing was any guide) simply because the front proved stubbornly immune to generating good levels of downforce.

Although the problems manifested differently, both teams failed in 2014 to meet the big challenges of the new aero regs – getting enough front and rear downforce and then balancing the two. At the front the big obstacle was that the narrower span front wing (which stopped halfway across the tyre’s width rather than flush, as previously) made it exceptionally difficult to generate the airflow vortices (circular currents of air) just ahead of the sidepods that had previously sped up the flow over the front wing by sucking it back harder. Generating rear downforce had been made more difficult mainly by the abolition of blowing exhausts and the lower beam wing.

Only two teams –Mercedes and Red Bull - successfully resolved both those challenges with their 2014 cars. They each did it in different ways and in the new McLaren MP4-30 we see an almost straight copy of the Red Bull philosophy. Visually, in the way that its body surfaces flow, the MP4-30 has more in common with the Red Bull RB10 and 11 than it does with the MP4-29. In a way, this is unsurprising, given the recruitment to McLaren of Red Bull’s former aero chief Peter Prodromou. Essentially, he seems to have designed McLaren a Honda-powered Red Bull.

Just like the Red Bull, the stand-out feature is how tightly the car’s bodywork is waisted between the cockpit and rear wing. This ‘coke bottle’ profile is extreme, as the sidepods cut in very aggressively in plan view. Ron Dennis calls it ‘size zero’ and points out that it has been facilitated by how aggressively compact Honda has made the power unit. Gone are last year’s ‘mushroom’ blockers along the rear suspension that linked up the airflow of the diffuser and rear wing and which did so much to boost rear downforce (but at the expense of drag). The new car generates its rear downforce instead from that tightly-waisted rear bodywork. That has been made more easily achievable by Honda’s placement of the compressor at the front, just as on the Mercedes motor. Compared to the conventional rear compressors used by Renault and Ferrari this reduces the plumbing requirement for the intercooler, gives the compressed air a more straightforward route to the engine and allows the compressor itself to be bigger without damaging the airflow around the aero-sensitive exhaust area.

But what of McLaren’s problematical front end? Last year’s car had a considerable gap between the underside of the nose and the upper surface of the front wing beneath. Whilst this increased the flow to the floor and thereafter the diffuser (increasing rear downforce further) it militated against front downforce. On cars such as the Red Bull, the much smaller gap between the nose and wing created a diffuser effect as the air was forced through a narrow opening that widened behind, creating a negative pressure there. Although the new-for-2015 dimension regulations have forced everyone to change the noses of their cars, the general philosophy still applies: you can have either a narrow gap there (good for front downforce) or a big one (good for rear downforce). With the MP4-30, the McLaren has moved from the latter to the former. New front brake ducts, a blown front axle (guiding the airflow through the wheel to exit at the side) and sidepods which begin further back than on last year’s car, should make the optimum placement of those vital vortices ahead of the sidepods easier, boosting front downforce further.

But there is another way of achieving front downforce under this formula – as Mercedes demonstrated last year. Like McLaren, it opted for a big gap between the nose and wing to help with rear downforce. But it clawed back the loss of front downforce by an innovation in the front suspension layout. Instead of the conventional ‘A arm’ or wishbone arrangement, it instead had what in effect was just a single arm but with a forked end into the chassis. To get the equivalent strength of a conventional wishbone, this had to be much heavier but in eliminating the second arm it removed a key aerodynamic blockage in the creation of the vortices ahead of the sidepod. The Mercedes W05 therefore got to have its aerodynamic cake and eat it, with good front and rear downforce.

This suspension innovation has been copied by Ferrari on the new SF15-T. Although the car retains – uniquely among the 2015 field – pull-rod front suspension, it has Mercedes-like single lower arms with forked ends. The pull-rod layout already gives a clearer airflow passage (because the lower arms are higher, further out of the way of the airflow coming off the front wing) but with the single lower arms, it’s now clearer still. Ferrari’s aerodynamicists should have plenty of scope to place the vortices in just the right place to accelerate the overall front airflow. This should be vital in clawing back front downforce almost certainly lost to the very different nose layout.

Last year Ferrari had quite a narrow gap between the nose and wing. This restricted flow to the rear but helped the front. Although the siting of the oil tank within the gearbox casing (on all other cars the oil tank is in the gap between the cockpit and engine) allowed Ferrari to bring the engine further forwards to create a bigger diffuser area at the back, the nose layout was probably unable to feed that with sufficient airflow to maximise its potential. On the new SF15-T, when viewed from head-on the long nose being used for initial testing disguises the gap between nose underside and wing, making it look smaller than before. But when looked at in profile it can be seen that the gap is actually bigger than previously – feeding more flow to the rear of the car. This flow will be increased further when Ferrari makes its planned switch to a shorter nose (just as soon as it can pass the crash test). This is exactly what Mercedes did last year, when it introduced the shorter nose at the third race.

Ferrari’s rear downforce should be enhanced further with a tighter coke bottle section (though still nowhere near as tight as Red Bull’s or McLaren’s), a new rear wing family that James Allison reckons has been designed not for more peak downforce but more robust downforce that will stay attached better as the car turns or in windy conditions.  

In essence Ferrari has surrendered some easy front downforce for more rear and McLaren has done the opposite. In terms of engine Ferrari is very bullish about significant power increase and better energy recovery. There is informed talk of an extra 80bhp. Last year’s motor was reckoned to be around 50bhp down on the Mercedes (though this year’s Merc is reckoned to have an additional 60bhp). If those figures are accurate, the Ferrari will begin the year 30bhp down on the Merc rather than 50 – and not be as limited as before on energy recovery from the ERS-H. In its initial form the 2015 Ferrari motor still has a rear-mounted compressor (and no longer split with the turbine to fit in the ERS-H) but it’s possible that the revised rules allowing engine development tokens to be used through the season will see Ferrari introduce the Mercedes and Honda layout of a front-mounted compressor later in the year.

Both the McLaren MP4-30 and the Ferrari SF15T, in the direction they have been developed from their predecessors, underline that the Mercedes W05 of last year was a year ahead of the game in both its aero and power unit. The Red Bull, in a different way, achieved similar aerodynamic excellence but remained under-powered. Whilst accepting that Mercedes will likely have made further gains, it would be surprising indeed if McLaren and Ferrari have not significantly reduced their deficit. Their first attempts proved to be false starts and they each now look on the road to the optimum paths suggested by Mercedes and Red Bull last year. Respectability – and maybe even competitiveness – beckons. 

MH

The Sky Sports F1 Online team will be providing live commentary from all four days of testing in Jerez –  from dawn on Sunday to dusk on Wednesday. Sky Sports News HQ will also have live updates from trackside.