Pirelli Tyres in F1

Pirelli Tyres in F1

I listen with amusement to the gleeful pronouncements made by the F1 presenters, that the new Pirelli tyres have revitalised the sport. All this while watching the world’s best drivers and race engineers struggle to make the things work.
My opinion was that the tyres are rubbish, but that was based on a technical perspective, so I took it upon myself to find out what I could about these mysterious black doughnuts.

First thing I found was that the F1 teams are forbidden, under pain of exclusion from the championship, to run the tyres on a tyre testing rig like that at Calspan. It would be normal, given the budgets in F1, that the tyres would be tested in order to better understand them. Instead, Pirelli have every tyre bar-coded in order to keep track of it and gather them all up after each race or test session and return them to the factory in Turkey, where they are destroyed!

That’s right, Turkey! The Pirelli’s are not Italian tyres, but instead are built in Turkey by mostly migrant workers from Iran and Iraq. Why Turkey? Well, it seems that the tyre compounds include some ingredients like polycyclic aromatic oils that are banned in the European Union!

What Pirelli has done is run a very thin layer of a super-soft compound on top of a thicker layer of very hard compound; hence they fall off the ‘cliff’ when they wear into the hard stuff. Other tyre companies have done similar things, but with less extreme differences between the layers.

This is often the best way of balancing cornering stiffness and grip. That is, you get good drip from mechanical interlocking with the soft ‘cap’ compound, and the stiff ‘base’ compound gives you low slip angles. Of course you can get higher cornering stiffness by just running a thin layer of soft compound and reducing the overall thickness of the tread, but this can make warming the tyre more difficult and you can risk wearing the tread out completely, or have a catastrophic tyre failure during a brake lockup.

The tyres have a very narrow band of working temperatures, so the teams struggle to get temperature into the front tyres and out of the rears. This has led to them spending hundreds of thousands of Euros on developing trick brake ducts to achieve their aim. One F1 supplier told me new brake duct designs come in on an almost weekly basis; sometimes these very expensive components are consigned to the bin before they have even been fitted to the car!

In the event the tyres are fitted, their performance can be assessed on track in only five laps! Given the huge amount of money spent pursuing tiny amounts of downforce, I find it interesting that Red Bull are now running carbon fibre shrouds over their drive shafts. This counters the ‘Magnus effect’, which generates a small amount of downforce as the shaft rotes and moves through the air. Perhaps it was interfering with the airflow to the rear diffuser?

On the topic of aerodynamics, the ‘DDR’ (Double Drag Reduction) system introduced by Mercedes, and which put the other makers into a spin, causing such systems to be outlawed by the FIA from 2013, seems to have been something of a flop. The system works by opening a valve when the rear wing drag reduction system is operated. This permits air to be ducted back to the front of the car where it is used to stall the front wing, thereby reducing drag (and downforce) at the front of the car.

The problem there is that, due to the hysteresis in the system, a delay exists between closing the valve at the rear wing and the airflow reattaching itself at the front wing. This upsets the braking balance and turn into the next corner, so understeer has already set in, slowing the car through the entire corner and the entrance speed to the following straight. It also means the reduced grip means the Mercedes eats tyres. Some might say that Mercedes Benz were too clever by half and been caught out.

Meanwhile, other teams have been spending up big in an attempt to emulate them! The amount of money being spent by the F1 teams on aerodynamic tweaks giving infinitesimal improvements is obscene and one wonders how long it can be permitted to continue.

Meanwhile, back to the Pirellis. It seems the real problem with the tyres is inconsistency from one tyre to the next. The car works well on one set yet another supposedly identical set transforms it into an ill-handling mess. It seems my first opinion – that the tyres are rubbish – might be correct, even if it does make for a ‘good show’. Everyone is in awe of the ability of Fernando Alonso to handle the inconsistencies. If he can win the World Championship, it will be a deserved victory.

One has to ask though, if the intent of Pirelli is to sell tyres to the public based on the publicity generated in F1, could the inconsistent performance actually leave a negative impression with the potential customers? It has does with me!

‘Til next time

Pat

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