Perhaps my thoughts are better organized today. Let's see...
(Holy ---, even by my standards this is long. No filler, though.)
Phil wrote:... [Mercedes] have by far the most powerful PU so can run the car with more downforce which is key in getting the most from these tires.
There's the fundamental misconception, and it's based upon pre-Pirelli era logic. There was a time when having the most downforce was ideal, but that's not necessarily the case anymore.
Tires have always been the ultimate arbiter of performance, because they constitute the sole link between the car and the track. In the days of the tire war, it was the job of tire manufacturers to produce rubber that could withstand anything the cars dished-out for as long as they needed to dish it out. If a tire company did its job correctly, the tires would seem to be a non-factor, as their performance would be invisibly integrated into that of the total package.
Grossly simplified, picture a graph with axes that represent "grip" and longevity. The ideal tire will have performance characteristics that fall directly upon the diagonal line that evenly splits the two. Because the scale of each axis is wholly dependent upon both the car and the track, the tire war compelled manufacturers to bring different tires to each circuit in order to ensure their performance always fell upon the ideal line.
In the Bridgestone era, the tires became
heavily biased toward longevity, which meant you could throw anything at them and they could withstand it. That gave rise to the two-compound rule, because it was the only way to challenge teams with control tires.
Ever since Pirelli arrived on the scene, tires have been
ridiculously biased toward "grip," and that means they don't last very long. Longevity has improved over the years as a result of increased understanding and the slight shift toward harder compounds, but it's still nothing like it was throughout the tire war/Bridgestone era.
On the nature of hysteresis...
Wikipedia wrote:A characteristic of a deformable material such that the energy of deformation is greater than the energy of recovery. The rubber compound in a tire exhibits hysteresis. As the tire rotates under the weight of the vehicle, it experiences repeated cycles of deformation and recovery, and it dissipates the hysteresis energy loss as heat.
Though I'm leery of this being an (irresponsible) oversimplification, consider all tires to have a sort of "hysteresis budget," and that they're worthless after it's been depleted. Broadly speaking, this occurs along a spectrum of performance on a per-stint basis such that you can put energy into the tires at a high rate over a relatively short period of time or you can put energy into them at a lower rate over a longer period of time. The former is limited by the number of tires available to each driver throughout a race weekend, and the latter is limited by the need to run two compounds during a race. Anything that works the tires harder increases the rate of "hysteresis budget" depletion: rapid acceleration, deceleration, and cornering, i.e. "pushing"; adding downforce; increasing slip due to running in "dirty air," etc.
As counterintuitive as it may seem, Red Bull's mistake in 2013 was to design a car that placed an undue emphasis on peak downforce. It indicates they failed to fully appreciate the importance of tire use in the Pirelli era. (To be fair, though, I don't know that anyone truly understood them at this point.)
As if to underscore the oversight, Newey made the following comments...
f1fanatic.co.uk, November 5, 2013 wrote:“We had a big change over the winter, an unexpected change,” said Newey. “Pirelli introduced a new tyre which was much more sensitive, it was very easy to overload it and because our car, a lot of its lap time is under braking and in the high speed corners, where you’re putting a lot of load into the tyres, we couldn’t really exploit that without the tyres going off very quickly.”
“So that tyre change hurt us and helped some other people, such as Lotus, Ferrari perhaps. For me that was purely luck.
“I think Lotus and Ferrari are making making big noises about how clever they were over the winter to read that far. But to be perfectly honest they were just plain lucky, we were a little bit unlucky, and of course the the politics take over. So it’s been a challenging year but a very rewarding one.”
The change was
not unexpected...
crash.net, November 19, 2012 wrote:“We'll be bringing some of our 2013 prototype tyres to Brazil in order for the teams to get a taste of them during free practice,” Pirelli motorsport boss Paul Hembery said. ”With no testing until February otherwise, this will be an extremely valuable opportunity for them to see what our new tyres are like as they finalise their 2013 cars – so let's hope that it doesn't rain on Friday!
“Both the compounds and construction will be different, which means that the characteristics of the new tyres will be altered, with a wider working range and some compounds that are slightly more aggressive. We've yet to finalise where exactly all the compounds will sit in relation to each other, which is why we are calling the tyre to be used in Brazil a 'prototype' rather than giving it a specific nomination, but it will be very representative of our general design philosophy next year."
Please don't take this to mean that I think briefly testing two prototype compounds results in an ability to know precisely how everything is going to turn out months later. That's not at all what I'm saying. But, I do believe you can somewhat narrow down the possibilities, or establish a broad trend, by comparing prototype data to that which was collected throughout the season, and Red Bull should have designed the 2013 car around the resultant estimations. It's not an uncommon practice...
Racecar Engineering (print) wrote:"When we work with a customer chassis manufacturer like Lola or Courage, they don't ask us to make a special tire for their cars," explains Michelin's competition manager for four-wheel activities, Matthieu Bonnardel, "instead they try to design the car to suit the tires. So they look at what tire sizes we have and get some physical data, then they get data from us on the characteristics of our tires, which will help them optimize the aerodynamic design and the suspension. Then when the car is complete they can bring it to our test track in France where we can gain real understanding of the car's behavior - the downforce for example. We have a few devices that allow us to take a closer look at what happens on the car, as well as on the tires, and the teams like that."
(This is why Mercedes readily volunteered for that
"secret" tire test after the 2013 Spanish GP.)
So, whatever caused this...
"If we use our full potential, we cannot even last a full lap of qualifying. To tell your drivers that they are not allowed to drive some corners properly is not easy," claimed Marko.
...was a mistake, and there was no guarantee it could have been fixed with "routine" in-season development, because certain chassis characteristics are locked-in.
Sky Sports wrote:“We’ve improved things throughout the whole year,” Allison, Ferrari’s Chassis Technical Director, said. “The car is much more to his liking now than it was then, but there are certain fundamental characteristics that are sort of ‘baked in’ to a car when you lay down its architecture."
“That architecture is not really modifiable in a given year. You can make it better, and we have made it better, and we continue to make it better. But there are limitations.”
Hence, Horner/Marko Bitchfest '13. Without a move to more robust tires, Red Bull could not develop the car according to plan, because downforce squares with speed, which means adding downforce exponentially increases wear/degradation.
I won't even pretend to understand the details beyond that, because such knowledge is
waaaaaaaaaaaay above my pay grade. But, I do know that an increase of just 5-10kph through a corner can have exaggerated consequences in terms of tire wear/degradation, because...
Racecar Engineering (print) wrote:One thing that is sometimes overlooked by chassis designers is that the tires are a critical part of the machine, not just something to bolt on and go racing with. Some acknowledge that the sidewall of a tire has an effect on that corner's spring rate and damping, but Bonnardel reveals that the situation is far more complicated than that.
"There are a lot of complex things going on in a tire when it's running on a track. For example, the tire spring rate does not just depend on the sidewall - that would be too easy - the sidewall construction is a factor, but so are many other things. It can vary with tire type, size, temperature, load and pressure. It will even change depending on how much camber a car is running. The more you run, the more it leans on the shoulder and that puts more load into the sidewall. A tire that is overloaded has less spring rate than a tire that is not loaded, for example. And finally, spring rate changes with speed, so one tire does not have one spring rate, it has billions of spring rates in the same tire. We know a basic rate and communicate that to our partners, of course, but we also have to communicate the range of different rates and how it changes through the various usage of the tire."
The tire failures at the British GP, in which the practice of
running the tires backwards reached its inevitable conclusion, enabled RB9's late-season dominance.
I think the secret to Mercedes' chassis success is that, after years of struggling with tire use, they figured out that the Pirellis effectively put a cap on useful downforce. So, rather than develop toward increasing downforce, as has been standard practice since wings were introduced in the '60s, the ideal strategy now is to find the downforce limit and then develop toward maintaining it as consistently as possible.
What gave it away to me is when they deliberately sacrificed downforce with this development...
The wider end plate reduces wingspan, i.e. reduces peak downforce, but it helps the wing maintain efficiency over a wider range of conditions. It seems Red Bull figured it out, too...
There's no telling how long it will take them to catch up aerodynamically, and that's why it's not a given that a better PU would immediately vault them to the front of the field.
For reasons I mentioned in
a previous post, they have to transition from an aerodynamic philosophy analogous to this...
...to one that more closely resembles this...
...and they have to do it with arguably the most finicky tires ever produced, all while successfully integrating ERS concepts for which they're the least-experienced team.
I can see why Newey would rather work on boats and supercars.