Ferrari SF15-T

SF15T

At first glance, you may be fooled into thinking that this year’s Ferrari F1 challenger is no more extraordinary than the (rather ordinary) F14 T of last year. When I first saw the launch photos I was, at first, amazed by the apparent lack of change. Look closer, however, and – especially when comparing it with the 2014 car – the SF15-T becomes more logical and sophisticated.

Ferrari were winless for the first time in two decades in 2014. Ultimately, heads rolled and total restructuring across all departments was made during the early winter. Perhaps the fruits of the upheaval won’t be apparent until 2016 or even 2017, but I get the feeling that the SF15-T is the first Ferrari to really have James Allison’s influence stamped all over it entirely.

sf15t nose

 

Like McLaren, Ferrari have opted for a longer nose to control airflow over the rest of the car. The longer nose will have an effect on the production and quality of the Y250 vortex that runs in parallel with the car centreline from the main plane of the front wing to just beyond the sidepods. This is lighter than a shorter nose and easier to pass the crash tests with but at a loss of total air volume that passes underneath and onto the leading edge of the floor.

The required cross sectional areas are met by implementing a small keel beneath the tip to keep the main profile as thing as possible. The keel slowly forms into the underside further up the car to create a smooth surface before airflow heads onto the rest of the chassis.

Ferrari seem to be a bit behind the curve when it comes to using the nose pylons as a way of manipulating airflow and the current ones in use are quite chunky. These could well be slimmed down and/or reprofiled as the season goes on to help flow management ahead of the splitter like other teams are doing.

sf15t nose cameras

For the launch of the car Ferrari stuck on some basic dummy camera pods. These were replaced in Jerez for the above solution, taking the Mercedes ‘horn’ design one step further and creating a ‘handlebar’ shape by dog-legging the pod’s mounting pylon. This will aid the control of airflow along the side and top of the chassis, particularly around the suspension as they fall more in line with the wishbone arms than other similar designs on the grid.

However there is rumour that Ferrari (along with Mercedes, Toro Rosso and even McLaren) will have to relocate the camera pods despite them seemingly being within the regulations. Whilst there is a rule that states that no bodywork (aside from Pitot tubes) must penetrate a diagonal line made from the top of front bulkhead to the nose tip, teams have interpreted the handlebar mounts as part of the camera pod regulations which are excluded from this line. Recent news from the Barcelona tests suggests that Charlie Whiting has said enough is enough and that they must be removed before Melbourne for a conventional placement elsewhere on the nose cone.

Ferrari tend to use the back of the nose to place the first of a series of cascading vanes that occupy the underside of the chassis. This year is no different as the SF15-T features a long protruding vane just ahead of the pickup point for the nose box on the front bulkhead.

The front wing is new but little different to what the team ended 2014, as is generally the case for all teams heading into winter testing. A small amount of work has been done to the cascade winglets and two smaller vanes have appeared near the IR cameras that face back towards the front tyres, but the main change has been made to the endplates. The single fence with a slot is now gone and in its place a twisted vane – that replicates last year’s Mercedes – to shift air around the front tyre.

As of 2012, Ferrari have stuck with a pullrod front suspension layout. In terms of mechanical performance, there is little to choose between a conventional pushrod system versus the pullrod. They operate in virtually the same way except that the pullrod system is effectively upside down. The reason why pushrod is more popular is because it is much easier to work on. All of the suspension components are packed into the tight front bulkhead area so accessing this area from above makes it a little less tricky to swap out small bits and pieces. Getting to all these parts in a pullrod system involves coming in from underneath the car, which is a pain if you’re a mechanic trying to make a quick torsion bar change during Free Practice.

However, for all the hassle there is a significant aerodynamic advantage to be gained from using a pullrod system should you choose to design the rest of the car around it. On the SF15-T, the pullrod lies at a nice shallow angle which makes air pass more easily over it and onto the sidepods. Looking at the car head on and you can see it is much cleaner than those with a pushrod. This is made more apparent by the lower front bulkhead height introduced last year.

The pullrod is passed through a new lower wishbone, its design replicating the Mercedes uni-body concept from last year. This is again another aerodynamic benefit and generally the Ferrari’s suspension package is a pretty efficient setup. The wishbones themselves lie much flatter than recent Ferraris, lowering the roll centre of the car for better tyre management.

Having dabbled with the concept for a while, 2015 sees a return of the blown front axle. It seems as if multiple teams have stumbled across an advantage with using this design after a year’s worth of knowledge of the front aero workings on the current generation of cars. It works by enlarging the front brake ducts and creating a separate channel for air to pass straight through the hub assembly and out of a hollow front axle. This pushes air coming around the front tyre from the front wing further out, helping decrease front tyre wake and redirecting flow towards the rear of the car for better use.

According to former Head of Race Engineering for Ferrari, Steve Clark – live on Sky Sports F1 last week – the blown axle can be worth up to a few tenths per lap – a lot of laptime in F1 terms. The downside of using the blown design is actually the flat faced stub that forms the end of the axle. When Williams first started experimenting with the idea they found pitstop performance was reduced significantly as the blunt end impacted the wheel-gunman’s ability to attach the gun to the nut. This is why teams make the axle endings sharp tips as this reduces time in the pitstop.

Moving further back and Ferrari have done extensive bodywork modifications. Comparing the sidepods of the F14 T to the SF15-T and the whole aerodynamic philosophy has changed. Gone are the Red Bull-esque inward slopes and sharp tapering – the new sidepods are more undercut across their entirety and pinch smoothly into the gearbox at the back. This will ease the transition of airflow into the Coke-bottle region and over the top of the central section of the diffuser. It’s less aggressive, but it’s the back-to-basics stuff that could allow the Scuderia to leapfrog others.

These sidepods are fed by reprofiled bargeboards. Again they have copied a few ideas from Mercedes, connecting the vertical turning vane that flanks the sidepod to the bargeboard at 90 degrees and forming a tunnel for air to pass through away from the front tyre wake that so often impinges this area. Like the 2014 car the aforementioned turning vanes bend over the shoulder of the ‘pod to form a horizontal vane, attaching to the cockpit side. The vane pushes air down the sidepod’s gradient which decreases drag by dispersing stagnant air and helps provide rear downforce by sending the air towards the floor.

SF15T rear

The rear of the SF15-T is an evolution of last year: the rear suspension and brake ducts have been refined and the packaging of these has generally been touched up. There’s nothing radical but it makes complete sense for a team trying to rebuild.

Ferrari are another team to gravitate towards the large outswept diffuser design and utilising the central boat-tail section by discarding a few turning vanes and adding small pairs of vortex generators where the plank meets the upsweeping underside of the floor. Voriticising this flow will aid attachment to the upper wall of the diffuser to generate a greater upwash effect. Overall the volume of the diffuser is slightly lower than that of the Mercedes and Red Bull as the outer edges have been curved slightly. A pair of Gurney tabs line the top edge to create a greater pressure delta between the upper and lower surfaces, pulling more air out from beneath to suck the car down further.

During testing the team have been interchanging between the above design and a slightly modified version of last year’s, although it would seem as if they favour the new design after spending the last two days of Barcelona with it on.

The exhaust exits between a large central outlet for the rear bodywork, with a small Monkey Seat winglet attach to the rear wing’s central pylon just above. This will help pull air towards the bottom of the wing and allow a higher angle of attack without risk of stalling.

SF15T

The rear wing remains unchanged but the endplates have seen some revisions. They are basically the same ‘plates that Ferrari used at the end of last season but introduced at the bottom are a series of horizontal slots, similar to ones seen above the wing planes at the top. It’s difficult to tell if they are drawing air in from the outside of the endplate that is coming off the rear tyre or whether its being projected upwards from the inside face.

They are placed ahead of the vertical twisted vanes that hang off the back of the endplate, so my guess is that, regardless of which side the air is coming through them, the horizontal slots must interact with this region and the outer extremities of the diffuser to generate more up/outwash.

The SF15-T is tidy enough and pre-season testing has so far gone well for Ferrari. Along with vast improvements to the power unit – particularly in how they manage the use of the MGU-H during a race situation – this could well be the car that can start the climb back to the top of Formula 1. Then again, we’ve said this in the past but I have a feeling this could move them onto better things soon…

All other images courtesy of Scuderia Ferrari

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