2015 Spanish GP Tech Highlights

Note: This is essentially my analysis piece for Richland F1, with some added bits and pieces, illustrations and details about the fuel flow monitoring changes that were introduced. Exam season is in full swing so apologies for the not-so-exclusive content this week.

Barcelona is pretty much the best playground for an F1 car. Aerodynamics are severely tested with a variety of long, high and medium speed corners spaced out by a series of straights, whilst the final sector is now a good hunting ground for those with strong mechanical grip after the circuit layout changed in 2008.

With such an emphasis on aero, updates are often developed from around the end of the winter testing period specifically for this race and on into the middle of the season. Teams recognise this as an opportunity to jump ahead of their nearest rival but with almost everyone making gains all of the time, eking out that extra tenth of a second from the overall package is all the more crucial.

Ferrari

Whilst the Scuderia are not quite title contenders just yet, their latest batch of developments suggests that the new-look Ferrari means business. A total of 16 new items made their way onto the SF15-T across the weekend, with Sebastian Vettel electing to run most of the them whilst teammate Kimi Raikkonen reverted to the Bahrain specification parts from Saturday onwards.

© theWPTformula

The most visual updates were the sidepods and the area in front of the radiator intakes.

Ferrari have taken advantage of their unique, angled radiator placement by creating an aggressively shaped sidepod, cutting the outer shoulder downwards and inwards. Such is the extent of the shrink-wrapping, the new bodywork has a small dimple to clear the side impact protection structure.

This creates a stepped surface where the revised vertical turning vane can now bend down and attach to. This is accompanied by a twisted cockpit-mounted vane, flicking up at the end to vorticise flow over the stepped region and achieve better attachment.

As the sidepods reach towards the back of the car, the stepped profile smooths fluidly into a re-shaped outlet which now sits a bit higher, freeing up space around the central section of the diffuser.

Upstream a number of changes have been made to maximise the radical new bodywork. The bargeboards feature a new vertical slot to increase the energy of airflow passing through the sidepod undercut, whilst the front brake ducts have had numerous revisions made to both the vanes hanging inboard of the wheel and also the bodywork that forms the ‘cake tins’ of the front hub assembly.

Towards the rear and there are more complimentary modifications. The floor area ahead of the rear tyre has three additional cuts made in front of the larger L-shaped slot to help disperse rear tyre wake from the outer wall of the diffuser. Even the top of the diffuser itself has a tiny winglet-shaped Gurney tab arrangement added to induce a little extra rear downforce.

The rear wing endplates received a subtle change to the two slots directly beneath the main plane, both increased in size to improve the efficiency of the wing at high speed.

Overall these widespread changes still didn’t move them any closer to Mercedes, as the Silver Arrows also had updates of their own. Clearly the current organisation at Ferrari is working at a higher level than previously, though, as – despite the challenges of making such dramatic changes work in unison – the updates remained on at least one car for the entire weekend.

Mercedes

Having moved forward their Barcelona developments to China two rounds ago, there were only a few minimal changes visible on the W06 in Spain.

However these detail updates will help link the larger parts together. Judging by the fact that Mercedes were still some 0.777s ahead of the next best car, this only justifies their purpose.

Small tweaks were visible on the front brake ducts to further manage front tyre wake. A small twisted vane now branches from above the top of the duct to vorticise flow behind the tyre and offset it from the sidepod shoulder behind.

A neat inlet was made into the very bottom of the sidepod along the side of the car, taking advantage of the high energy flow in this region to cool some internals near the rear end. Of course, tapping some of this flow off could well be beneficial to how they want to control air over the top of the diffuser, rather than just a simple cooling solution.

A total of four curved vortex generators were added ahead of the sidepods, all of which were placed on the side of the chassis around the bargeboards. The two pairs were both above and behind the bargeboard, beneath the sidepod intake.

Vorticising airflow here energises its course around the sidepod undercut, which can also be linked to the new inlet made downstream.

Finally, the small fins on the rear crash structure have been moved upwards onto little ears to stand in freestream air above the sidepod. They appear to be achieving a small upwash effect with these devices despite removing the monkey seat winglet, which has a much greater effect than the fins. I have a few reasons as to why teams are removing the aforementioned winglet, but more on this as the season progresses.

Red Bull

We have heard that the short nose has been coming for some time, I was beginning to wonder if it was even in existence at all! Finally the RB11 received arguably one of the centrepieces of its design.

RB11 short nose

The overall aim of the short nose is to free up more space for air to pass beneath the car and there is now visibly much more volume available for this to occur.

However, because of the length of the nose, there is less space for the crash structure to absorb an impact which ultimately means that more material must be used to pass the tests. Red Bull have had to repeatedly retake the crash tests as they have had trouble keeping the weight down whilst being within the regulations, hence its delayed arrival.

Described by Christian Horner as an “engineering masterpiece”, you can see why it took so long to produce.

It is incredibly short, with the thumb-shaped stub lying as far back within the regulations as possible. The front wing mounting pylons now lean back at a slack angle, with their trailing edges extending both backwards and inwards to form a twisted profile which will aid airflow along the centreline of the car.

Williams

Williams have produced a bit of a turn in performance this weekend, which can be put down to two things: a few upgrades and a better understanding of the tyres. It’s all well and good having a car that produces lots of downforce but if the tyres are not (consistently) in the right operating window that is basically rendered useless. Afterall, the rubber is the only thing that connects the car to the track.

Development-wise a variety of detail adjustments were made across the board but the most note-worthy came in the form of the airflow conditioning devices around the cockpit area.

The number of vortex generators that now align the top of the sidepod have tripled and are now accompanied by a new single horizontal strake along the side of the chassis. These will collectively manage airflow over the sidepod and direct it towards the floor, preventing stagnant flow building up in the process.

The vertical turning vane that stands against the outer shoulder of the sidepod has also been re-profiled slightly. It’s a subtle tweak but the it looks to collect more air from the sidepod’s leading edge and turn it round its circumference. This area is very sensitive to airflow so it is no surprise to see constant work being made to the devices here.

Mechanically, Williams made some alterations to both the suspension components and their setup. A better understanding of the tyres and how to keep them in their operating window helped them establish a small advantage over at least one of the Ferraris, showing that they can still develop alongside the big players in the sport.

Unlocking performance from the rubber’s interaction with the asphalt is a lot harder than producing more downforce, but there is more laptime in doing this. Just look at the way Mercedes climbed the ranks from 2013 to 2014 – this can be put down to a number of things, but by understanding how to stretch the Pirelli tyres out and keep them within a good temperature window was one of the key areas of improvement for them. Williams are looking for the same answers to keep them in the hunt for second place in the Constructors’ championship.

McLaren

It may be described as “dynamic” and “predatory”, but beyond the PR drivel there is a good reason as to why McLaren have opted to switch up their livery.

The new colour scheme has saved the MP4-30 over 1kg of mass over the previous design as the pigments used to produce the predominately chrome look beforehand weighed that a tiny bit extra than those used to make graphite. A small gain but a gain nonetheless.

Honda also brought a number of revisions without having to spend any of their 10 remaining power unit tokens. The beautifully crafted aluminium inlet plenum has now been replaced by a more conventional carbon fibre version to further reduce weight, and a number of seals have been redesigned to improve reliability.

Driveability has also been attended to, with a significant software update allowing better control of the power unit under acceleration and braking events.

These changes, combined with ExxonMobil’s new fuel mixture, have resulted in a solid step forward for McLaren in Spain, as proven by both cars reaching Q2 on Saturday. Both chassis and power unit still aren’t quite there but the signs are promising.

Also, McLaren swapped its aerofoil-shaped lower rear wishbone in favour of a thin, tubular design. This further negates any interaction with the diffuser like they were doing last year, by essentially removing any aerodynamic influence that the suspension member may have had previously. Expect the unique layout to be dropped entirely next year for something more conventional.

Toro Rosso

A detail change was made to the leading edge of the STR10’s splitter, by extending the vertical vane upwards and then splitting it into three. The individual vanes aim to turn high velocity flow along the bargeboard area and through the sidepod undercut. This is beneficial for both feeding the top surface of the diffuser further back and for improving the consistency of the Y250 vortex that runs in parallel with this section of floor.

Fuel flow monitoring clamp-down

Since the introduction of the current power unit regulations, teams have been limited to a fuel flow limit of 100kg per hour. The car can only carry 100kg of fuel from the start of the race so as a result we see fuel saving strategies deployed.

However the development race within the fuel world is just as ferocious as that within the teams, with Shell, Petronas, Petrobras and ExxonMobil constantly formulating new mixtures to eke more power from every drop of fuel.

As a result pretty much every team is able to start the race with under 100kg of fuel, which improves laptime during the early stages.

Given these circumstances you would wonder how anyone could exploit anything beyond 100kg/h without running out of fuel, yet this is precisely what the FIA believe some teams are doing at some periods in the race to increase power output.

The fuel flow sensor is currently positioned between the tank and the fuel collector. It is then pumped up to the fuel rail, through the injectors and into the cylinders. The FIA suspects that some teams are feeding the injectors fuel at a faster rate once it passes the sensor, which can quite easily be done by pumping the fuel from the collector at a higher pressure.

In the FIA’s technical directive sent to the teams it also stated that the flow rate must “remain constant above a flow rate of 90kg/hr”, suggesting that some teams are also able to slow the flow rate within the low pressure systems and save fuel as a result.

It’s an intriguing battleground and one that we should watch more closely in the coming races.

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