F1 teams and drivers use telemetry extensively to hone in their lap times and car setups. A couple
of decades back you’d hear legendary tales of how nerdboffin Michael Schumacher would study pages
and pages of data and telemetry overnight to work out exactly how to optimise his lap and the car.
Nowadays that kind of work is fairly par for the course, though will vary between drivers.
Telemetry essentially maps out data traces from the car across a lap
and at first glance can appear a confusing mess of lines and be a little impenetrable.
Now there’s a million things we could go into here but I’m going to give this something of a light
touch and also focus on some points of interest. I’ll link to some deeper
articles on this in the description if you’re interested in exploring more.
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So, this the main kind of data you’ll often see on a telemetry. Here we’re looking at Albert Park,
home of the Australian Grand Prix. I’ve mashed a bunch of data together from various sources and
years so, again, this is all more of a guideline. Ok, first things first. The width of the chart
maps to the length of the circuit. So we start at zero metres over here and
go all the way to 5303 metres over here. And from there we can map in things like
sectors and turn numbers to make following the graph lines even easier.
So, roll call then. We’ve got speed here in red. RPM here in orange.
The gear we’re in is here in a kind of aqua colour
The throttle or accelerator position sits here in brown
The brake pedal pressure is marked in purple And the steering wheel angle is
this dark blue line here. I’ll go into these and more in
a sec. On the telemetry each graph line has its own colour-matching scale down
the side so you can always know the absolute values for what’s going on.
So let’s have a look at the run from turn 2 to turn 3, which is essentially
a straight - a long acceleration zone out of a slowish corner into a hard braking zone.
A curve like this on the speed trace is the shape of an accelerating car.
The steeper the line the harder the acceleration, so coming out of a corner like turn 2, you put
your foot down (as seen by the throttle pedal hitting the maximum) and the car accelerates,
quickly at first then the speed rises more slowly, which we see as the line shallowing out.
We can see the driver flicking through the gears, coming out of the corner in 5th,
then 6th, 7th, 8th - each journey through a gear accompanied by the engine revs rising and then
dropping at each new gear engagement. Then, when we reach the braking zone,
obviously the speed plummets to meet the 100k turn 3 corner speed.
If we look at what the driver’s feet are doing, we see in this case their
right foot come off the accelerator pedal and the left foot immediately slam on the brakes.
There’s basically no overlap and no coasting here. That’s not necessarily always the case.
While the driver is off the throttle, they blip down the gears, which barely register as engaged
until they are just about ready to get back on the throttle and accelerate out of the corner.
The steering angle line is centred around a zero axis - this is just when the
steering wheel is perfectly straight. Readouts may vary, but in this case:
if the wheel is to the right of centre, the line rises above the centre line and vice versa.
If the steering trace is climbing, the driver is turning the car more to the right, and if the line
is falling the driver is rotating the wheel left. So essentially if we follow the wheel through turn
3 here. It starts off basically neutral, in the dead straight position.
Then as we turn right, the line rises as the wheel turns and turns to a
maximum of about 95 degrees and then we ease the steering wheel back towards neutral again.
This maximum steering point should roughly be where the apex of the corner is.
OK so now we’ve got an idea for how the shape of these charts translate
to what the car is doing, how is this useful? Well the easiest way to extract some useful
information is to compare your chart to another chart as a baseline. Your team mate, for example.
So what we can do first is trace a new line across the whole lap that shows how your lap time
compares to your team mate’s lap - a time delta. So if this line is at zero, you’re on an identical
lap time at this point. If the line is below zero, you’re ahead; above zero, you’re behind.
So we can see that over the course of the whole lap, our lap is about
six tenths faster than our team mate. That’s good, but there might still be work to do.
If this line is dropping, we’re gaining time on our benchmark. But if it’s rising, we’re losing
time. So that might be worth investigating. And if we look, we’re losing time
through roughly turn 6 to 8 so let’s zoom in closer and find out why.
OK, so a couple of things. We’re braking a smidge earlier into 6 than our team mate as you can see
both on the speed and braking trace. We also coast slightly instead of getting straight onto
the brake pedal once getting off the throttle. Our team mate carries more speed through turn
6 and can carry than extra speed all the way through the acceleration zone towards turn 8
as we can see by their speed line being higher through this part of the track.
Another thing you can see here is that we’ve probably realised we were a bit
slow into turn 6 so try and make up for it on exit. We slam our foot onto the accelerator a
little too hard and a little too early, which induces snap oversteer in the car.
We can see that first on the steering trace - this is us fighting the wheel to turn into the slide
and get the car under control. We also have to back out of the accelerator a bit while we do so.
All of this contributes to the slow exit through 7 and down to turn 8. Clearly we get it back though.
Something else to look for is when we’re changing through the gears. Are we changing up too early?
Too late? Mapping these changes against our team mate or against multiple runs and seeing
how that translates to acceleration curves and lap time deltas will help you hone that in.
Now, as a team, you’re also keeping an eye on what’s going on to try and hone the car
itself in or spot problems as they happen. So, as an example, you might track the wheel
speed of all four wheels. That’s just, how quickly they’re rotating.
And you may think - well, that’s obviously just going to match the car speed isn’t it? The
faster the car, the faster the wheels turn? But actually, not really. When the driver
changes up a gear, you’ll often get a bit of wheelspin in the rear wheels. Just a touch,
nothing normally to worry about but something you don’t want getting too out of control if
you want good traction out of the slow corners. Obviously locking up the front wheels becomes
immediately obvious by a flattening of the wheel speed trace AND you might be able to spot an
inside front wheel under rotating through a corner if its lifting off the ground as the car rolls.
If that’s undesired then you might want to fiddle with the suspension.
And speaking of suspension, you can track the forces acting on the suspension dampers as the
car rolls and pitches under various forces. So if we mapped all four wheels independently,
if the car is at rest, we can say the suspension dampers are at neutral loads.
As the car accelerates, it pitches backwards, putting load onto its
rear suspension and relieving the front. Similarly as it brakes, the centre of
mass moves forwards and the front of the car takes more of the load than the back.
Going through a corner, the car will roll, moving the forces to the outside of the car.
So through a left turn, the right side of the car will lift and go light,
while the left side of the car takes the brunt of the rolling forces through the suspension.
All of which we see traced through the telemetry and, when matched with other
data like acceleration and time deltas, we might want to check the suspension setting as
appropriate for the desired performance. And we could go on and on and on. There’s
lot of graphs and charts available through a google search, so have a look
through them and see if you can decipher what’s happening through these simple lines on a chart.