17/04/2013
FEATURE BY MATT SOMERFIELD
Round Three of the Formula One World Championship took the teams to China, with three weeks between this and the Malaysian race the teams would have been busy trying to further understand their 2013 challengers and Pirelli's latest offering.
Pirelli and its tyres has been a topic of conversation up and down the paddock over the first few races with seemingly everyone having their own take on whether the tyres application are good for the sport or not.
I thought I'd weigh in on the topic from my own and a more technical perspective:
Pirelli has altered the construction of its tyres for this season and although perhaps unintentionally it has not only changed the way the teams have to approach setup to harness downforce vs mechanical grip but also the feedback the driver gets from the car.
The 2013 tyres feature a less rigid sidewall and reinforced tread pattern, this works to maximise the contact patch available, increasing the amount of mechanical grip the tyre is willing to give up.
This makes selecting tyre pressures, ride height and suspension stiffness a balancing act in 2013 as the teams try to extract performance from the tyre whilst being mindful of the effects on aero.
If we were to assume that the teams ran X suspension stiffness for 2012 with Y ride height coupled with Z tyre pressure in order to balance the larger contact patch available they must re-proportion X,Y & Z in order to manage the tyres characteristics in 2013.
Below I have quickly sketched a comparison showing the difference between the 2013 and 2012 tyres:
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As we can see with the new construction, as force is applied to the tyre a much larger area of the tyre is subjected to the track, whereas with the more rigid sidewall of the 2012 construction it was the shoulders of the tyre that would wear. This is what Pirelli mean when it refers to the tyre increasing thermal degradation, as by virtue of the larger contact patch the tyre will create more heat thus wearing the tyre more quickly.
So as teams spent most of 2012 looking to generate more heat to get the tyres into their performance window, it seems this year will be about who can best manage the heat generated.
This is where I find the comments made by Red Bull interesting, with the team alluding to the fact that with more downforce the tyres are much more difficult to work with. This simply translates to more force placed on the tyres (downforce) = the more heat is being generated at the contact patch increasing thermal degradation. So this is where tyre pressure comes into play; we all know the more heat generated within the tyre, the more this increases the tyre pressures which will once again raise degradation levels. So if we assume X,Y & Z have not been altered from 2012 the degradation will be much higher, by altering X or Z to a less stiff or lower pressure respectively it is therefore viable to increase tyre life by virtue of the downforce loss as the aero platform is less consistent.
It is a trend that I'm sure we will see throughout 2013 as the teams naturally adjust their approach to extract performance. Lotus, Red Bull and Mercedes have already started to make these alterations with the latter two teams seeing the type of setup Lotus ran in Australia. Of course the designers will then work outward from there making alterations to the way in which the car is designed to further enhance this.
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Above: We can see from this image of the Mercedes W04 that as the car is straightened to exit the corner the tyre deforms under load creating a bulge in the Sidewall. This bulge will push the airflow laterally into the Diffuser's path disrupting its natural flow and reducing the downforce it generates (Tyre Squirt). This is why the teams endeavour to target the exhaust plume in the gap between the tyre and the Diffuser's outer wall, creating an air skirt (Sealing the Diffuser). Of course, not only the targeting of the plume but also the consistency of the plume is important and so the transition of on and off throttle moments need to be carefully managed whilst also thinking about the tyres' dynamics.
The other area of debate amongst fans and the media alike is the longevity of the tyres. It's a difficult topic, as we saw last season it took around 7-8 races before the teams really got on top of the Tyres. From there onwards though I felt Pirelli could have moved the goalposts in order to spice things up further taking more aggressive compound choices to each GP. It seems they started 2013 with the intention of doing just this, forcing the teams to really think about strategy, increasing overtaking both out on the circuit by virtue of driver tyre management and in the pitlane as mixed strategies are employed. The problem with this however is that it not only reduces the amount of time the teams spend out on track during Free Practice sessions as they look to save tyres but it creates a strategy dilemma for qualifying.
This came to a head in China with Button, Vettel and Hulkenberg all failing to set representative times in Q3 in favour of saving tyres or maximising their strategy. It's a call I made back in Australia as I couldn't understand why Button, with a much slower car in Q3, hadn't simply qualified on the Medium tyre maximising his race potential.
The pundits and fans however don't seem to like this deliberate strategic attempt at maximising the drivers' race potential and feel they have been robbed of an element of qualifying. Being within the rules then and with some teams clearly behind the curve at the start of the season this is a positive step by those teams in my opinion to maximise their race chances, after all there are no points for where you qualify...
Perhaps then in order to rectify this situation for the fans a regulation change might be made that will stop this situation occurring during Q3. There are several ways this could be implemented and here are a few of my thoughts:
Qualifying Tyres: Q3 runners are given a set of additional qualifying tyres specifically for Q3 which they hand back at the end of the session. This levels the playing field for Q3 and ensures the quickest drivers are ranked in position. The problem with this is what tyre do you then allow the driver to start the race on? His Q2 fastest time tyre or a free choice?
102% Rule: Everyone in Q3 must run within 102% of the pole time, thereby forcing everyone to run in the session and putting pressure on the teams to run the fastest tyre. Failure to reach 102% of the pole lap results in a grid penalty.
No Sitting Out: Simply amend the regulations to stipulate that no driver can sit out of a session unless extenuating circumstances prevail. Failure to comply results in a grid penalty.
Points: Give out points to the quickest qualifiers, there is nothing like an incentive to further increase the capacity to race.
An interesting development may come out of China in terms of Pirelli's supply however with the tyre manufacturer reportedly working on a deal to supply additional tyres for Free Practice 1 that can only be used by a young/development driver. This would not only be a step forward in helping the teams develop their cars at a given race weekend but help in the promotion and development of younger drivers.
The three week break from racing was an opportunity for the teams to get development parts shipped out East in order to improve performance. As we know the largest development packages will be available to the teams when they arrive back in Barcelona for the European leg of the season. However with teams eager to make strides early on, knowing that development for the highly complex 2014 cars needs to be started early whilst also wanting to challenge early in 2013 there were plenty of upgrades flying around the F1 paddock.
Ferrari took many new Front Wing developments to Grand Prix throughout 2012 but seemingly failed to implement them for qualifying/race. Having realised its correlation issues throughout the tail end of 2012 and now solely working from the Toyota Wind Tunnel facility in Cologne it appears that when the Italian team brings its upgrades to circuit they are fruitful. For China the team took another new Front Wing:
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The team removed the section of Endplate that allowed airflow to move inside to the Wing flaps (Blue arrow) but added an additional hole in the footplate (Red arrow) changing slightly the way in which the wing operates and attachment occurs on the outer portion of the Front Wings flaps.
Further to the Endplate changes a small change was made to the Cascade element with the central strake now joining with the rear of the cascade rather than stopping short as it previously did.
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The Front Wing update was also accompanied by a change of under nose Turning Vanes which now feature a triple element for increased efficiency:
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Ferrari also had some mild revisions at the rear of the car as shown in the image below with a new more vertical cooling exit (Blue) Whilst the team revised the rear brake drum fin arrangement removing the Endplate it usually uses (Yellow).
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Mercedes made a small alteration to its Front Wing in China removing a vertical section of the Cascade. (Upper).
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Lotus has added a new element on the Sidepod Airflow Conditioner, the upswept element is used in combination with its usual horizontal cockpit wing in order to aid in the movement of airflow as it downwashes towards the exhaust channel.
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It is also worth noting at this stage that the upgrades introduced on Raikkonen's car in Malaysia were also made available to Grosjean.
Red Bull introduced a new floor in China, featuring twin Vertical Floor Strakes aft of the Exhaust Ramp. It's unclear at present (with the images available) but it appears that the floor may well be cut out in between these two Strakes. This will form an interesting area of development for all the teams from here onwards as the use of the twin Strakes helps to target the Exhaust Plume between the Tyre's Sidewall and the Diffuser. As I discussed earlier in the article this is a critical area in terms of managing the difference between this and last year's Exhaust effect on Sealing the Diffuser and Tyre Squirt affecting downforce levels. The floor being cut away between the Strakes will push the teams much further toward the sort of solutions we saw them use when they used their floor mounted exhaust blown diffusers in 2011. The cut away will allow vortices to be generated which will further aid in both the 'Sealing effect' and Diffuser extraction.
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McLaren as we know has struggled with the MP4-28 so far this season, the team has alluded to a sensitivity to ride height and so made amendments to the aerodynamics to rectify some of these issues. It would also seem that McLaren seem to have been caught out the most by the tyre dynamic vs Diffuser impingement I mention earlier in the article having cut away sections of the Diffuser's outer wall to compensate.
A much larger signal that the team is suffering for aerodynamic balance and rear downforce issues was its ethos change in China taking a new portion of Sidepod bodywork.
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The new bodywork sees the Sidepod shortened altering the position the exhaust plume will fall onto the floor. This also allows the airflow coming around the Sidepod to migrate under the exhaust plume into the coke bottle region differently. Also worth noting is the hump in the bodywork above the exhaust channel which will alter the way in which the downwash coming over the top of the Sidepod will affect the exhaust plume.
Sauber has also struggled in the initial races to realise the potential of the C32, having clearly keyed the initial design of the car to use DRD (Drag Reduction Device) they have yet to use this in race conditions. Taking a backwards step in order to rectify some of its other issues the team tried a new Rear Wing during Free Practice in China but reverted to the normal wing in Qualifying/Race.
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The Rear Wing trialled during Free Practice can be seen above on the right and is much more akin to the type of Wing we see in F1.
Williams has alluded to the issues it faces with the FW35. Mike Coughlan, the team's Technical Director, has said the team is still struggling to maximise the Semi-Coanda exhaust citing problems simulating the effects of the exhaust plume in the Wind Tunnel as just one of the issues. The team once again however took a new Front Wing to China that saw the Mini Cascade detached from the Main Cascade. It would be interesting to see what kind of movement this Cascade sees under load with its attitude changing dependant on speed.
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Summary:
In a race that served up plenty of action (although I expected more) there are a few things worth considering that may have changed the face of the race:
Raikkonen's collision with Perez left the Finn with a damaged Nosecone and Front Wing, the team has since alluded to the fact that the damage was sufficient enough to cost around 0.25 seconds per lap. We all know however, that changing the Front Wing would have resulted in a longer pit stop (around 12 stationary seconds, rather than the 3-4 he was stationary) which would have put him out of sync with the lead pack and most likely in traffic. The damage sustained to the Front Wing was to the conditioning elements of the Wing, with the front section of the Endplate damaged, the Cascade and the inner turning vane gone. These elements don't produce a huge proportion of downforce and instead condition the airflow received by the Tyre. Had these elements been removed on the other side of the Front Wing then I think the team would have had no alternative but to make a Front Wing change as that Tyre takes more load.
Webber's collision with Ricciardo saw the Australian out of sync in terms of pit strategy having to take a new nose / wing and ultimately that stop brought his race to a conclusion with the rear wheel detaching later in the out-lap. I must however question Red Bull's strategy at the start of the race with the team electing to pit their driver after just one lap even though he had made good progress through the field (I believe he had gained around 5 places). I wonder why the team didn't chose to run the full length of that stint (5/6 laps) with him negotiating the traffic on the quicker tyre but heavy fuel load. The other option would have been for him to use the same strategy as his team mate running into the race on the Prime tyre and recovering as many positions as he could with a race trimmed car (the only one in the field) before making the switch to the Option tyre late on during the race.
Vettel's late charge on the Option tyre saw him reel in the Mercedes of Hamilton with the pair finishing within a car length of one another. Had the German taken the Option tyre a lap earlier would the tyre have fallen away? From the performance he was seeing toward the end of the GP I'm not so sure and it could have led to a podium placing for the Red Bull driver.
With only one week between China and the Bahrain GP I don't expect we will see too many more upgrades lavished on the cars by the teams but perhaps those that did chose to test/run parts in China will have a better understanding of their package come race day.
Note: All pictures can be found in higher resolution here.