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31 Jul 2013
Mercedes Rear Wheel temperature control Trick?

Mercedes were of course venturing a little into the unknown in Hungary having been excluded from the Young Drivers test where other teams had, had the luxury of testing the new tyres. They could however take solace in the fact that the construction is the same as Pirelli provided in 2012, meanwhile the Italian tyre manufacturer were also able to share the data collated by their engineers at YDT. Tyres have been the bane of Mercedes existence since their rebirth in 2010 but no more so than this year with the Brackley squad seemingly being able to hold a candle to their rivals Red Bull through qualifying. Up until Hungary the team have performed well on a Saturday but gone backwards throughout the race as their tyres thermally degraded quicker than everyone around them. The return to a 2012 construction therefore should have been music to Mercedes ears with the team able to take a fresh approach to tyre management. 

In light of the change in tyre construction Mercedes have obviously been working closely with their wheel manufacturer Advanti. Advanti started working with Mercedes this year but have plenty of F1 experience having supplied wheels to Toro Rosso since 2008 (until the end of 2012). The reason I bring this is up is a possible development made to the rear wheels. Up until now the team have played with painting the inner face of the wheel black, this has more to do with heat absorption/dissipation than aesthetics (See image below). Along with the dotted sections inbound you also note in the image below that a strip on the face has been definitively marked with a 2 silver bands set around an inch apart.

Now although the above image was taken during the Hungarian GP weekend the following image also surfaced (Thanks to @F1Talks for the heads up)


This image shows the team have reverted to a normal finish on the inner face of the wheel but what does remain is the roughly 1 inch strip toward the inner shoulder of the wheel. 


As we can see in the image above a much larger bead/lip defines the edge of this strip on these wheels, now both @F1Talks and many of the folks over on F1Technical.net's forum are concluding that this is indeed an aperture in the surface of the wheel (as indeed did I at first glance, until I looked deeper at the past design of the Mercedes wheel).  Now going from what the eye see's (or perhaps wants to see) that could be one explanation with an inner structure of the wheel allowing airflow to permeate the inner structure of the wheel thus cooling the wheel and in turn the tyre. It's a fanciful notion perhaps but could a double skin within the wheel not only be strong enough to cope with the forces at hand but also allow air to transfer from one chamber to the other dissipating the heat?

Personally I don't think so I simply believe they have learnt from their experiences so far this season by coating the inner face of the wheel black and adapted it for use with the 2012 construction.  Afterall we know that Mercedes decided to drop their 'Coanda' exhaust after Austin last year as they were over heating the shoulders of the tyres.  Of course they have developed their 'Coanda' exhaust hugely for use on the W04 but it could still be a concern with a change back to 2012 specification tyres.


Another lesson in perception perhaps with the black strip simply being a coating to the wheel but it is still something that Mercedes are trying in order to reduce the temperatures and therefore degradation this season.
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27 Jul 2013
25 Jul 2013
18 Jul 2013
Technical Roundup - 2013 Young Drivers Test - Silverstone

The teams (with the obvious exception of Mercedes) have descended once more on the old airfield in Northamptonshire, Silverstone.  The Young Drivers Test (YDT) has obviously been changed by the option of race drivers being able to join the youngsters on track to assess the new Pirelli tyres.  Each team is allowed to use 1 day of testing with their race drivers (Either one driver for a whole day or a day split between 2 drivers)
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17 Jul 2013
How much difference can changing the tyres make?

Tyres have been a hot topic of conversation over the last couple of seasons with teams unable to 'switch' on the 2012 tyres and keep them in the operating window early in the season.  Meanwhile this season has seen the teams draw a line in the sand as some clearly got it right early on whilst others struggled.

2012's construction featured a sidewall that didn't deform dramatically under load, the downside of this is the tread platform wasn't rigid enough to provide a significant contact patch.  (The contact patch is the area of the tread platform that is exposed to the track)  With a stiff(er) sidewall and narrow contact patch the tyre becomes more difficult to 'excite', creating difficulties for the teams in extracting 1 lap performance (Qualifying).  Moreover the management of the tyre over a race distance exacerbated this challenge as the delta between 1 lap qualifying pace and creating a race strategy led to the tyres 'falling off the cliff' toward the end of a stint.  The 2012 construction also led to further frustration as the contact patch of the tyre was more or less a tram-line with the shoulders of the tyre wearing more heavily than the central portion of the tyre.  This meant that as the tyres came off the car they'd often look beaten on the outer edges but have plenty of life left in the centre of the tyre.

Of course as the season progressed the teams used setup changes (Camber, pressure, temperatures, etc) in order to relieve some of these issues.  Their challenge was also eased as Pirelli reduced the severity of their compound choices making it much easier to make the appropriate stint lengths work.

Enter a new tyre construction for 2013, with Pirelli looking to bring a more performance orientated design to once again challenge the teams.  The 'Mark 1' Pirelli 2013 Tyre (Used from Melbourne to Silverstone) featured a much more forgiving sidewall mated to a tread platform that was significantly beefed up.  The aim of this was to bring an emphasis onto thermal degradation. (the movement of the sidewall increases the temperature within the tyre)

This mechanical advantage (the tyres get upto temperature and stay within that window more easily) came with an aerodynamic downside.  The deformation of the sidewall leads to increased airflow instability which can cause issues in crucial area's of the car, none more so than the Diffuser.  'Tyre Squirt' is always an issue for the teams as it impinges on the natural flow of the Diffuser, disrupting it's ability to produce downforce.

Over time the teams found a way to increase the performance of the Diffuser by reducing the impact of Tyre Squirt, this was initially done via EBD (Exhaust Blown Diffuser's 2010/11) where the exhaust plume was directed in the gap between the tyre and the car's floor.  This is what many corner's of the media refer to as 'Sealing the diffuser' as it creates an airflow skirt, allowing the diffuser to work more efficiently.  When the FIA made adjustments to the regulations in 2012, the teams once again outsmarted them by using the 'Coanda' effect to target the exhaust plume in a similar region to the previous EBD solutions.  Of course the effect is reduced when compared to EBD but it is a far better solution than not having it. 
The image above is a basic explanation of how tyre squirt can influence the diffusers performance with Yellow representing the airflow moving over the cars floor to the rear tyre, blue represents the airflow moving under the car and through the Diffuser, whilst red indicates the intended target of the exhaust plume.

The use of the 'Coanda' style bodywork by the teams has also led to an increase in the use of both tyre squirt slots and vertical floor strakes ahead of the rear wheels.  The quantity and intricacy of these have increased throughout 2012/13 as the teams try to further manage the effects of tyre squirt on the diffusers performance.

Above: As an example Red Bull have this season run with 2 Strakes rather than 1 and added an intricate selection of tyre squirt slots. These slots and strakes further manipulate the airflow, increasing the exhausts effect of sealing the diffuser.

This season has also seen a rise in teams adopting leading edge holes in their Rear Wing Endplates, a design decision implemented by Williams, Force India, Toro Rosso and Marussia in 2012 we now find similar solutions being used by Red Bull, McLaren and briefly (Silverstone) Ferrari.  These holes allow airflow that would normally be encumbered by the Endplate to bleed through to the other side, reducing the pressure in that region.  On top of this, throughout 2012 most teams ran brake ducts that featured a vertical section on the end of the fins, for 2013 these have disappeared from most teams designs.

Above: In this image of the VJM06 we can see the hole placed at the leading edge of the Rear Wing (Just in front of the blue O)

The issues created by the deformation of the tyre are not isolated to the rear of the car either, the Front Wing is the first element to guide airflow, whilst generating vortices that set up flow structures further down the car.  The front tyres deformation therefore means that the teams have re-designed elements of the front wing in order to cater for this, rectifying any issues being caused downstream.

The tyres being tested currently at the Young Drivers Test at Silverstone and to be used for the rest of the season feature the same construction as the 2012 tyres but the more aggressive compounds from 2013 will be allied with them.  These Mark 2 tyres therefore offer both a different mechanical and aerodynamic set of principles to those seen so far this season.

Essentially what I'm getting at is that the teams have adapted their cars to meet with the challenges of the Mark 1 2013 tyres.  What we saw at Nurburgring (Pirelli's Mark 1.5 interim tyres) was a change in fortune with Force India struggling whilst teams like McLaren and Sauber took advantage.  This change was subtle one and most likely had more to do with the FIA banning Tyre Swapping and putting restrictions in place for the camber and pressures used by the teams.

It's a curve I expect will continue to become apparent with the teams responding best to the change in construction (Mark 2) taking advantage early on.  Teams like McLaren, Williams and Sauber have already been vocal about their situation being born from a misjudgement of the 2013 tyres during the birth of their cars and so a switch to the Mark 2 Tyres will only aid these teams in their pursuit of performance.  Furthermore the advantage gained by some teams who utilised tyre swapping will be nullified with the Mark 2 tyre being symmetrical whereas the Mark 1 tyres were asymmetric.

I suspect over the next few races we will see teams taking retrospective steps in order to better extract aerodynamic performance from the 2013 Mark 2 tyres.  The likely result will be changes around the Front Wing, in front of the Sidepod, on top of the Sidepod (Vortex Generators / Fins), the floor around the rear wheel, rear Brake Ducts and the Rear Wing Endplates


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11 Jul 2013
10 Jul 2013
Why did Mark Webber's rear wheel bounce off down the pitlane and what can be done to prevent it in the future

Some would say the FIA have taken swift and decisive action in order to avoid a repeat of the incident that befell FOM cameraman Paul Allen during the German GP.  However the problem still remains, all that has changed is the likelyhood of someone that's not part of the pit crew (ie wearing protective clothing) being struck by an erant wheel.

So what went wrong?

Well the nut didn't go on... But do you know why?

Since 2010 (Post refueling era) the teams have looked for ways in which to speed up the process of changing wheels during Pit Stops.  This wasn't such a problem during the refueling era as the car would be stationary for many more seconds getting fuel than was needed to change the 4 wheels/tyres.

All the teams have similar retaining devices now but as it was a failure on Webber's car, lets look at Red Bulls



As we can see I have added arrows to show the retainers that push in and out of the axle in order to retain the wheel.  When removing a wheel, the gun is pushed over the retainers and they fall into the axle, the wheel gun is spun to release the nut from the threads, releasing the wheel.  The new wheel/tyre is then placed on the axle and forced over the retainers with the gun as the gun spins it threads the wheel onto the axle.

In Webber's pit stop it would appear that the wheel was placed on the rear right of the car but the gun failed to thread the wheel to the axle.   However more importantly as the retainer's weren't in their locked in position as the gun came off the axle, the wheel spun off the axle and careered down the pitlane.

So what's changed to make these Pit Stops quicker than pre 2009?

Pre 2010 the retainers used on the axle were different to the ones we see in use today, with a clip in the end of the axle required to be operated by hand after the wheel was attached.  As can be seen in this video below (Scroll  through to 3.24)


This adds a further element to the process of the pitstop and so to generate quicker stops the teams abandoned it for what we see now.  But is it time to mandate how quick a stop can be?  Reverting to this style of wheel retainer is one way of adding an element of safety back into pitstops as it's additional procedure for the pit team to undertake.  However by virtue of that exact same statement it's another element of the stop that must be completed to get their driver out of the box as quick as possible and could be missed or fail.

So what else can be changed to prevent this kind of Safety issue re-occuring?

You could argue that with around 18 team members crowded around a car it is too many, but with fewer personnel the pressure to complete the tasks at hand only increases. I was fortunate enough recently to try out a pit stop scenario when I went to Red Bull's Openhouse.
Armed with the wheel gun my task was simple enough, remove the nut with the gun so another member of my team could take it off, another mounted a fresh wheel and I use the gun to put the wheel back on.  Sounds simple doesn't it.  Our first attempt was around 11 seconds, some distance from the 2 second world record we've seen Red Bull achieve and yes of course we were not using current equipment or the correct gun pressures etc but it becomes apparent very quickly where the time gets eaten.  Our best stop was just over 7 seconds (best of the day was around 6.5) and felt extremely quick but I'd still say we had the ability to go quicker.  We hovered around the 7 second marker for 2-3 attempts before I had an issue with the nut coming out the end of the gun.  Having watched in slow motion as it fell to the ground I scooped it up, placed it back in the gun and completed the stop in 13 seconds, not bad having had an issue.  However it brings to light how things can and will go wrong, we didn't have the pressure of a race driver sat waiting for us to do the job, the intense heat emanating from the car or perhaps most importantly the car coming to a stop from the pitlane speed limit.

The FIA did make some efforts to slow teams pit stops down when in 2012 they banned the use of Helium for driving the wheel guns.  Helium was being used as it is of a lower density than air and so spun the gun quicker giving rise to the opportunity of a quicker pitstop.  Since then teams have continued to make strides in this area by virtue of the guns design and the thickness/diameter of the piping used to transmit the air to them.

As Pit Stops represent both a human challenge and an engineering one, the latter could be removed with Wheel Guns and associated equipment spec'd by the FIA.  All of the teams currently use Dino Paoli manufactured guns anyway (along with the GP2, DTM, WSR etc field) but their spec varies dependent on the team.  Dino Paoli do have a Torque sensing gun with built in Torque sensors that illuminate when the correct torque loading is seen and could or plausibly already have been integrated into the teams traffic light system pit release boards.  These illuminated pit release boards have been controversial since their inception with different levels of success as the technology has improved, for me though they offer no difference to a lollipop as the human element is still involved at the end of the process giving the signal to proceed.

The last and perhaps only real way of reducing incidents is introducing a time component into the stops, with stops averaging 3 seconds but errors/failures increasing this time exponentially it could be argued that the pressure of generating the quickest stop ever would reduce some of the error factor.  A mandatory time stationary would enable the pit crew to complete their stop without the pressure they currently face leaving the driver to leave the pits in a more controlled manner.  The teams could continue to complete their stops as quickly as they desire but a stop/go system controlled by the FIA would signal whether they were free to leave in the mandated time.  It's difficult to quantify but with the stops we are currently seeing, even double (6 seconds) should be enough to control the pit crews pace and reduce errors.  I'd however be inclined to see a 10 second stop and go, to cover other eventualities.

I'd enjoy your comments on how you feel Formula One could reduce the risks involved in Pit Stops and as always will do my best to answer any questions you may have.
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5 Jul 2013
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In light of the events at Silverstone the FIA have finally seen sense and made stipulations on the teams in regard to the operation of the Tyres. Pirelli have long sought the help of the governing body in terms of regulating the way their tyres are used and so in a document issued to the teams the FIA made the following statement:

Tyre Operating Procedures

For safety reasons, we have been asked by Pirelli to ensure that the tyres on all cars are run under the
conditions listed below. It will be the responsibility of each team to satisfy the FIA technical delegate that
their cars comply with the following requirements at all times :


1) Minimum starting pressure front and rear : 16psi.
2) Minimum stabilised running pressure front : 20psi.
3) Minimum stabilised running pressure rear : 19psi.
4) Maximum negative EOS camber front : 4.0°.
5) Maximum negative EOS camber rear : 2.5°.
6) Front and rear tyres must be used on the side of the car for which they were originally
designated (no swapping from side-to-side).
7) The blankets strategies set out in 13R09NUR Preview V3 must be observed.


Performance can be leveraged from all of these parameters and so it will once again mean that some teams (who perhaps do not operate on the fringes) will benefit.  Teams operating on or below Pirelli's recommendations will find their advantage however small, marginalized.
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4 Jul 2013

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