Hello everyone. Let’s go for something a little less controversial
this week. Race Strategy. During an F1 race weekend, you’ll hear things
like “we’re expecting one stop strategies at this track” or “two stop strategies
are the norm, but some teams might try and go for the one-stop”. What factors determine
what makes for the best strategy at a given track and how do teams go about calculating
this? In this video I’m going to go over the basic
variables that build towards an effective race strategy. Let’s simplify this right down to make it
easier to see how everything works. Let’s imagine a ten lap race. I’m going to draw
a bar chart, with the length of each bar representing a laptime. Let’s start by looking at different pit
strategies with different compound tyres. Let’s say you’ve got the Soft tyre that
lasts for 5-6 laps and gives lap times of 80 seconds and the SuperSoft tyre which lasts
for 3-4 laps and gives lap times of 75 seconds. A pitstop will cost you 25 seconds. For the moment we’re ignoring all other
variables and rules. For now, we keep it simple. One strategy could be running the soft tyres
for 5 laps, pitting and then running the soft tyres for another 5 laps.
Another strategy could be running the SuperSofts for 4 laps, pitting, running them for another
3 laps, pitting, then running a third set of SuperSofts until the end.
Which is the best strategy? Well, we can work this out by adding up all
the laptimes, plus the pitstops. The one-stop, soft tyre strategy is 80 second
x 10 laps, plus 25 seconds for the pitstop. That’s equal to 825 seconds.
The two-stop, SuperSoft strategy is 75 seconds x 10 laps, plus 2 x 25 second pit stops. That’s
equal to 800 seconds. In this very simplified model, the two stop
strategy is fastest. Now, we build on this. One thing we need to add into our model is
the Tyre Wear Profile. This describes how the grip level of the tyre drops off with
every lap. I’ll go into more detail on how and why tyre performance degrades in another
video but in basic terms, the tyre will be at its fastest when fresh and get slower and
slower with every lap. The way in which the tyre wears will depend on things such as the
compound, the track and the temperature but we can essentially draw a curve like this
to describe how the tyre wear affects the lap times over time. Faster lap times up front,
lengthening over time. We can see the ‘cliff’, here – when
the laptimes start to plummet rapidly. Drivers will want to pit before this point – in
our little model there, the cliff hits around 5/6 laps in and the tyre starts to lose all
grip before degrading completely. When we say the tyre ‘lasts’ around 5 laps, we’re
talking about how many laps it can continue to deliver reasonable lap times.
Here’s how the one-stop strategy changes if we factor in the tyre wear profile
It’s easy to see how much time can be lost due to tyre wear over the course of a race
and dealing with this is vitally important. Now, this model strategy isn’t allowed in
real F1. As we know – in modern F1, each driver has to use two different compounds
of tyre (out of a choice of three) during a race. How you use the available compounds
by assembling a race out of a number of ‘stints’ can make all the difference to your result.
Let’s extend the model to give them twenty laps now. This will make the stints easier
to see. Now, an example of a ‘conservative’ strategy
might be: start on the supersoft tyre (it’s almost always best to use the grippiest tyre
for the start to get off the line well and get in the fight for early positions). Let’s
say the SuperSoft has 6 good laps in it. After 6 laps you might then take a pit stop and
run the medium tyres all the way to the end of the race. The mediums aren’t amazingly
fast but they are consistent and will take you to the end, meaning you don’t have to
take another pitstop. Alternatively, you might take an ‘aggressive’
alternative strategy: start with the SuperSofts for 6 laps as before, but then switch to the
soft tyre. The soft is faster than the medium but won’t make it to the end of the race.
You plan to take a second pitstop and switch back to the SuperSofts for a final sprint
to the finish. You will be on a faster compound of tyre than the conservative strategy for
14 laps (that’s 70% of the race!) BUT you have to take an extra 25 second hit for that
2nd pitstop. We might find that the aggressive strategy
is actually SLOWER than the BUT you might still use it IF
a) You think your driver and car are much better at managing the tyres than the competition
b) You expect some disruption to the race, like a Safety Car. More on this in a bit. Now we’ve added a simple model for tyre
wear, let’s consider fuel. There’s no refuelling. The cars are filled
up at the start and over the race the fuel drops, which makes the car get lighter over
the race which improves overall laptime (the car has to expend less energy pulling its
own weight around) and makes the cars easier on tyre wear (we didn’t factor this in before
but this could mean that SuperSofts last only 10 laps in the first stint, but could last
13 laps in the final stint). For simplicity’s sake in our model, let’s just say the car
gets faster as it uses up fuel in a fairly predictable way.
BUT, because there is a maximum amount of fuel the car can use over the course of the
race, the car may not be able to actually run at full pelt for every lap of the race.
The car is allowed to use 105 kg of fuel but running at maximum performance for the whole
race may require closer to 200 kg! Not only that, but fuel weight is SO detrimental to
racing speed that strategists might not even want to fill the car to the brim. This means
some fuel management is needed through the race.
The SuperSoft may do those 75 second laps at full beans but can maybe only do 78 – 80
second laps when conserving fuel and energy. Managing when to use which engine mode will
often depend on what’s happening in the race, but race strategist will arrive with
certain expectations: middle parts of each stint will probably be fuel conservation times,
whereas the start of the race and the laps around the pit stop phases will be the prime
time to go maximum on the power. See the UNDERCUT video for how this may work to a driver’s
advantage. And then there might be a Safety Car or two,
just to throw a spanner into the works. Safety Car and VSC periods are run slow: the
engine will use much less fuel and the tyres will take much less wear and tear.
This means that the more laps that are run behind the safety car, the harder the cars
can run in the remaining laps of the race. They can take the softer tyres longer. They
can run in higher engine modes for longer. If the SC period occurs here this neutralises
these laps which – and bear in mind, I’m over-simplifying this – effectively chops
these laps out of the race. We should almost ALMOST ignore these laps altogether, meaning
we subtract these missing laps off the END of the race.
So in this example, the SC comes out on lap 12 for three laps. At the time, teams were
expecting 8 more laps of racing, but now they only have 5 more laps of racing. The car on
the conservative strategy can switch things up, take a free pitstop and match the pace
of the aggressive SuperSoft strategy. Now, you can’t predict a Safety Car or a
VSC but you can make an educated guess. Some tracks have a high change of a SC (Monaco
and Singapore for example) so you might create some strategies that allow you the flexibility
to change things up and switch strategy given the opportunity, or you might go aggressive
with the fuel if you believe you’ll be able to save some while under the SC. We’ve covered some of the basic variables
that go into building some race strategies but there are other factors that will need
considering along the way. WEATHER – The weather: variations in temperature
and the probability of rain might affect your compound choices.
TOUGH TRACKS – If the track is difficult to overtake on, you might choose not to go aggressive
as aggressive strategies normally require some overtaking (you take an extra pit stop,
which puts you behind other cars. You’ll need to overtake these cars to exploit your
lap time potential) ROAD BLOCKS – You may even get stuck behind
an unexpectedly slower car through no fault of your own. Jarno Trulli used to be know
for qualifying well and not being able to maintain a good pace during the race, resulting
in the infamous “Trulli train” where a queue of faster cars would get stuck behind
him. In cases where traffic comes into play, you might choose a strategy that puts your
car out of sync with drivers that might end up as potential literal road blocks to your
success. TEAM STRATEGY – Also, a team will often concoct
strategies that take into account BOTH of their drivers: to make sure they are both
fairly treated, to keep them out of the way of each other or to allow the number 2 driver
to assist the number one driver in their quest for title glory.
I hope this has provided some insight into the way that strategies are put together.
As the very essence of a race strategy is always modelling how lap times will unfold,
adding those laps together and finding the shortest way to the end of the race. Simple,
really, right? Right?