Analysis: What Pirelli's mid-season changes will mean
The sudden announcement by Pirelli that they are to change the tyre specifications from the seventh round of the world championship onwards will in...
The sudden announcement by Pirelli that they are to change the tyre specifications from the seventh round of the world championship onwards will inevitably raise many questions: who will it favour, what are the implications for the racing?
With no testing available - a significant part of the reason why Pirelli has struggled to get the tyres right this year - they will have to use a construction solution that has been proven to work in the past, rather than try something new.
JA on F1 technical adviser Mark Gillan was chief operations engineer at Williams until the end of 2012 and has a deep understanding of how the tyres work and what is involved in this change.
Here, with his input, is our analysis of today's decision.
When Pirelli says the tyres from Canada will be more like 2012 tyres what does that mean?
The 2012 tyres were more durable than this year's tyres, which suffer from high degradation. Pirelli has indicated that it will change the construction of the tyres to be more like the 2012 products.
The 2013 tyres have a different construction from the 2012 products, with a steel belt inside the tyre in place of last year's kevlar belt. It is likely that this decision will be reversed with the revised tyres, as Pirelli moves back to a proven solution.
The weakness of the 2012 tyres was wear; typically the inside shoulder of the tyres would wear out and teams would run the tyre until there was no rubber left on the shoulder and then make a pit stop. However the teams understood how to manage them quite well by the end of the season.
For 2013 Pirelli tried to fix the wear problem by getting the contact patch of the tyre more reasonably positioned, but it seems that in changing the construction to achieve this they have gone too far.
Although the reason given for the change is that four stops is considered too many for a race and they would like to reduce that to two or three stops, there is also the safety aspect in light of the tyre failures in Bahrain and Spain. In changing the construction, they have obviously done something to affect the tyre's integrity.
Which teams will be most affected by these changes?
Thermal management of the tyre is the key this year and teams like Ferrari, Lotus and Force India have prioritised this in their 2013 designs. All three have good aerodynamics, but they have engineered in a way to keep the tyre in its ideal operating window by a combination of a stable aero map, a mechanical package which is in sympathy with the tyre and a good set-up.
Red Bull has very good aerodynamic package, as it has for many years now, but inferior mechanical package and thermal management of the tyres.
These weaknesses assume less importance with the changes Pirelli is making, they are likely to increase the operating window of the tyres and increase the durability and that reduces the importance of the thermal management.
What challenges does a change of tyres seven races into the season present to the teams?
The knock-on effects of a change of tyre construction are considerable and this is a major headache for teams, especially as they are about to commit more wind tunnel time and resources to their 2014 designs.
It is unlikely that a change of construction can be made without this affecting the shape of the tyre and how the contact patch with the ground forms. When part of the tyre leaves the ground this changes the shape of the airflow to the floor of the car.
The teams have spent many months modelling this in the wind tunnel and in CFD and if the shape changes even by a few millimetres, this will have an effect on the way the front wing interacts with the tyres, and with the flow down the side of the car and underneath the floor. It will impact the aerodynamic balance of the car and teams that have pushed to get on top of that will suffer.
We are getting close to the time when the teams were hoping to move the 2013 model out of the wind tunnel and start devoting more time to the 2014 model. This change of tyres will complicate this for everyone. particularly for teams with limited resources, it will make for a real headache as they try to stay competitive in 2013 and not lose ground in 2014.
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Pirelli will provide a new range of tyres from the Canadian GP onwards