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Australian Grand Prix Tech Review

With the 2018 Formula 1 technical regulations still being relatively immature, it is likely that the rapid rate of development seen during 2017 will be maintained this year as well.

It was, therefore, no surprise that a number of new parts were brought to some of the cars although the top team, Mercedes, remained quiet in this regard, seemingly sticking to its philosophy of iterative development packages every five races or so.

Renault

Despite finishing with both cars in the points in Melbourne Renault had a disappointing weekend, finishing almost two seconds from the pole time when it had hoped to gain significant ground over the winter. Albert Park does tend to exaggerate the gaps to the front runners, yet their performance still did not meet expectations.

A minor upgrade package was brought to the race, with modifications being made to the new front wing concept tried at the end of testing (compare v2 to v1 below). The update concerned the use of a triangular shaped cut-out from the upper flap, something also present on last year’s wing.

Note that in the wet FP3 session, Renault returned to its 2017-spec design, which it also ran for much of pre-season testing, but with truncated flap tips (v4). This was most likely aimed at simulating the new wing, but not risking damaging it in the tricky conditions, given the lack of spares at this time of year.

Also new were the bargeboards on the R.S.18, with the team deciding to combine the original version with that tried on the last day of testing.

The v1 and v2 designs differ in philosophy – the initial design featured a greater number of slots, which ran deeper into the main bargeboard element than the height of the steps of the second design.

Using the slotted approach may reduce the strength of the vortices shed, as each mini-element must act more in isolation, with a pressure difference set-up either side of each curved element, whereas, the step approach uses more of the bargeboard’s overall pressure difference to produce these rotating flows.

However, the slotted approach allows a greater height over which elements can be shaped as desired, whereas, the step method is constrained more by the overall bargeboard curvature.

Ultimately, there is not a vast difference in performance, evident by the fact that Renault has chosen to combine the v1 front part with the v2 rear part, in order to best control the front tyre wake and optimise flow to the rear of the car.

Renault had scheduled to run a T-wing on the final day of testing, but poor reliability prevented this – instead, the new part was added to the R.S.18s for final practice, although only Sainz opted to continue with it for competitive sessions.

Renault’s t-wing certainly does not look to be a downforce generator in its own right, with virtually no camber for the most part and a relatively flat profile – the inboard section actually slopes downwards.

It appears as though there is a little camber on the inboard section, which, together with the downward orientation, makes the device seem to work the oncoming flow by moving it slightly downwards vertically, as opposed to changing its angle. This could be important under yaw, perhaps influencing the position of the shark fin vortex, or shifting the front tyre wake beneath the rear wing.

As in testing, two rear wing designs were employed, both with a much greater angle of attack than the design used in Melbourne for the 2017 race. The v1 design features a little more camber, except at the tips and centre, together with a shorter chord upper flap and larger central vee cut-out. This was the standard 2017 wing, used at the majority of tracks from Russia onwards.

The v2 design, however, was favoured at higher downforce circuits. It is a measure of how much progress has been made on reducing the drag of the Renault over the winter (a major weakness in 2017) that the most aggressive rear wing is now an option at an ‘average’ circuit, and indeed, this design was chosen for the race.

Despite running a larger rear wing than Red Bull, the works team’s straight-line speed was comparable with that of its long-term engine customer. Finally, the cooling outlets at the rear of the car were an area of major focus for Renault last weekend.

The iteration used in testing (v1) was not considered for the race in Australia, given the much higher ambient temperatures relative to Barcelona. Instead, the team arrived with two much larger engine covers, perhaps unsure of which design would be best since the unusually cold pre-season testing conditions prohibited significant relevant data collection on the cooling of the car.

Ultimately, the v2 design was chosen, but expect the third concept to return for Bahrain daytime sessions at least. Cooling is still an area of weakness for Renault – despite running the same power unit as both Red Bull and McLaren, it has much larger air intakes (both behind the driver’s head and for the sidepods), while the rear of the car has had to be opened up considerably more. Development in this area will be ongoing, not only for 2018, but also beyond.

Force India

Force India introduced a significant upgrade package for the opening race of the 2018 season, having run with largely 2017-spec Aero surfaces during pre-season testing. Publicly, the team claimed that the late introduction of a plethora of new parts was to give designers more time to develop and although this may have been the case, the lack of an advance in FOM payments over the winter was probably a greater factor in this decision.

This put a great deal of pressure on the team to maximise the package’s potential in only two practice sessions (the team did not run in the wet FP3 session to avoid damaging the two sets of new parts). In the end, there certainly seemed to be some unrealised potential, with the new rear wing and monkey seat not being raced, while the team was disappointed at its uncompetitive performance.

However, there is some cause for optimism in the team. Whenever Force India has added major updates in the last couple of years (Spain 2016, Bahrain and Singapore 2017), it has always taken them a race to fully understand the package before returning with a much better performance at the next round. Additionally, a new front wing is scheduled for Bahrain, and given the importance of this device on the rest of the car, this could solve some of the problems encountered.

The most visual change to the VJM11 for Melbourne concerned the vertical airflow conditioner area beside the sidepod. Previously, a relatively simple set-up was employed, with one device hugging the sidepod and the other one sitting at the end of the bargeboard.

The former has now been split into two, with the pink part being widened, but located in a similar position, and the black part being larger and further outboard, with a step-change in height along its length. Also note the addition of another element between the two previous ones, which transitions from a vertical to a horizontal element at its base, taking some inspiration from Mercedes.

This horizontal extension of the middle element could use the vortices shed by the bargeboards, diverting them into the desired position while also producing a further rotating flow at its tip, all to guide the front tyre wake outboard and improve rearward Aerodynamic performance.

Finally, note the extension of the floor fin, which now meets the end of the bargeboard.

Looking from the front of the car, these vertical elements are directed outboard, but not so much that it is clear that they are attacking the front tyre wake, attempting to minimise its impact on the rear of the car by moving it significantly outwards.

They will produce vortices along their top edge, due to the vertical cross-sections resembling those of cambered aerofoils, and these will either bring some order to the turbulent tyre wake or shift it outboard.

Looking at the rear of the car, the rear wing was modified, with a flatter central vee in the flap, and a more aggressive design in terms of mainplane camber – however, this was also not used in competitive sessions. The most aggressive camber was previously in the central section before it decreased quite quickly as one moved outboard.

This level of camber is now maintained for a greater span either side of the wing’s centre section, which will produce more downforce with the proviso that flow must remain attached to the part’s underside.

If it does not, there is a major loss in Aerodynamic efficiency, with a rise in pressure drag and loss in downforce. Note also that this higher camber design will set-up a greater pressure differential either side of the wing, thereby increasing the strength of the wingtip vortices.

It is possible that the wing was unused in the race due to separation problems in practice – perhaps the team will introduce a revised monkey seat/t-wing in the next couple of races and return to this rear wing configuration.

After overhauling its diffuser design in Singapore last year and seeing the good results that followed, Force India was never likely to make major changes in this area for the start of 2018. The update in this area for Melbourne was very much one of evolution, with a change to the top edge of the diffuser taking place.

Previously, this area was almost flat, whereas it now curves downwards as one heads outboard, before moving upwards as it evolves into a mini-winglet which also extends further outboard than before.

In this way, the expansion of the outer part of the diffuser, necessary to smoothly transition the low-pressure region under the floor to the ambient conditions around the car, is lower than previously. This may have been made with the efficiency of the diffuser in mind, given the sideways and vertical expansions in this area.

They create adverse pressure gradients, bringing into focus the possibility of separation which would decrease downforce and increase drag, although in special cases it can improve straight-line speed (probably more focused around the lower ride height central section). The extension of the outboard winglet will also have been made with expansion in mind, as the team attempts to achieve the best compromise between outright performance and consistency.

Toro Rosso

Toro Rosso introduced a surprisingly large update package for the first race of the season, with developments being made from the front to the back of the STR13. Firstly, a new front wing flap configuration was tested and raced, with an additional element being preferred.

The new design should have improved separation characteristics, with a decrease in the chord of curved surfaces and the greater ability of cleaner flow on the top surface of the wing to pass through the slot gaps and energise the boundary layer on the underside.

Note the addition of a large gurney tab to the upper flap’s trailing edge, which should help gain back some of the downforce lost by transitioning to a greater number of flaps.

Moreover, the vortices shed along the inboard section of the wing will have been altered in terms of their strength, with three weaker rotating flows replacing the two from before. This will change their interaction with the Y250 vortex, and hence performance downstream.

Having started testing with a medium downforce, spoon-shaped rear wing, Toro Rosso moved to a higher downforce configuration, together with heavily revised endplates, for the second test. This wing was broadly the one used in Australia, including in the race, although tests were conducted without the gurney tab along the flap’s trailing edge in order to trade-off the drag of the configuration against its downforce, for optimal performance around Albert Park.

A new design was also tested during practice, also with a spoon-shape, but different to that run during testing. It included a vee in the centre of the flap, but most interestingly, a revised general mainplane and flap shape.

The top of the mainplane does not dip down but actually rises as one moves inboard, while its bottom surfaces decrease sharply in height. The result is a great deal of camber in the central three-quarters of the wing, while maintaining the lower angle of attack configuration towards the endplates.

Note that the flap is itself spoon-shaped, with the lower chord near the endplate working best with the different angle of attack there – the old design had this, but to a lesser degree. This design keeps the benefits of the spoon wing in terms of lower induced drag, since the sections contributing most to this form of drag have the lowest pressure differential either side of them, while significant downforce is still produced from the central section. This suggests that the team is taking a realistic approach to its power deficit, knowing that it will likely be a season-long issue despite planned improvements from Honda.

See further analysis by Iman Hansra here>>>