Have you ever stopped and wondered what gives a Turn its character?
What makes one turn different than another?
Why are some notorious and others just… “muh!”?
Let’s take a close look at the humble turn – the one simple trick that keeps F1 tracks
from being straights that go on forever!
Corners and turns may seem simple but there are several qualities that each contribute
to its personality.
In this video we’ll build up the nature of a turn, bit by bit.
It may seem like the main contributing property of a turn is its angle.
A smaller internal angle makes for a tighter turn, right?
Well… it’s not quite that simple.
Let’s have a look at a 90 deg corner.
A street circuit might feature a right angled bend like this.
Or maybe like this . Whereas an more open racetrack might have a long 90 deg turn like
this.
Now, in all three corners, points A and B are in the same places but the turns are very
different.
What matters here is the radius.
Let’s have a look at this turn for example.
These two bits are straight, so we can isolate the turn here and show that it’s just part
of a circle.
The radius of a circle is the distance from the centre to the circumference and the larger
the circle, the longer and faster the turn is.
Now, as the track has width, each turn has an outer radius and an inner radius, with
the inner radius being smaller.
But there’s a third, more important radius.
The radius of the racing line through the corner.
We’ll cover racing lines properly in another video but, just to make sure we’re all on
the same page – the racing line is the preferred, fastest line through a corner.
There is no one racing line, but essentially, the car will turn in from the outside of the
track, clip the inside of the track some way through the turn and exit the turn on the
outside of the track again.
You’ll see the racing line forms its own curve with a radius much bigger than any curve
following the actual curve of the turn.
This is much faster, as a larger radius curve can be taken at much higher speeds.
But wait – we’re not done with radiuses (or radii) yet!
See, this turn we’ve been looking at is an example of a constant radius turn.
This means the radius is the same from start to finish – I can shove just once circle
in here to define the corner.
The infamous 130R used to be a single radius turn until it was modified.
130R means it had a radius of 130 metres (and as best as I could calculate, this measurement
referred to the outer radius.
But things get more interesting in variable radius turn.
For example, you might have an increasing radius turn – this means the entry to the
corner follows a small circle but the exit traces a much larger circle arc.
A good example of this is turn 12/13 at Shanghai – it starts as a pretty tight turn but opens
out into a long right hander.
On the other hand, a decreasing radius turn tightens as you travel through it.
Turns 13/14 at Sepang are an infamous example of this type of corner.
If we deconstruct it, you can see the increasingly large circle arcs that make up the corner.
This makes for a very challenging type of corner as you will enter it at a fast pace
but have to break and turn harder midway through, always trying to chase the apex that’s getting
away from you.
A variable radius corner is more interesting as drivers don’t have a “simple brake,
turn, hoof it” tactic.
They have to adjust their inputs right through the turn and it’s much trickier to approach
perfection.
OK, so let’s talk camber.
Camber refers to the tilt of the surface of the track across its width.
The track may be flat or tilted one way or the other, or even be bent across its width.
Don’t confuse this with tyre camber which describes the angle of the wheel relative
to the car.
Again, that’s for another video!
A turn can be flat of course, but if there’s a tilt across the track this can be on-camber
or off-camber.
An on-camber corner is sloped towards the inside of the track.
So if you put a ball at the outside of an on-camber turn, the ball would roll to the
inside.
Classically, the huge banked turns on oval racing tracks are on-camber.
On-camber makes it easier to steer through the turn.
It encourages your car to turn in the direction of the corner.
Why?
Well, let’s imagine a car on a banked turn.
The weight of the car is still acting straight down, not directly at 90 deg to the track.
A quick tilt shows that this force is acting a little bit towards the direction of the
bend.
Conversely off-camber turns slope towards the outside of the turn and encourage the
car to steer away from the turning direction.
This makes it harder to steer properly, producing bag loads of understeer (i.e. the car doesn’t
quite turn enough).
You’ll have to slow down more to force the car around the turn.
Turn 10, at Spa is notoriously off-camber and loaded with understeer – something Codemasters
made sure to put in their F1 games to many players’ delighted frustration.
Let’s not forget changes in elevation though (i.e. the track going up and down).
An uphill entrance to a turn will shorten the braking zone, meaning you can brake even
later than normal whereas a downhill approach will force you to brake surprisingly early
as the slope encourages the car to continue forwards.
Longer braking zones make for better racing as it’s easier to make mistakes and there
is a greater margin for a chasing car to try braking slightly later to nip past.
A corner with a dip or a crest has a massive effect on grip levels through the turn.
Through a dip, the car experienced increased downforce as it accelerates downwards relative
to the track (think about the heavy feeling you get when a lift reaches the ground floor).
It is essentially heavier through a dip and more downforce = more grip.
On a crest, however, the opposite is true.
The car is pulled away from the track and is effectively lighter, with much less downforce.
The car “goes light” and can become very twitchy.
Eau Rouge at Spa has a dip and a crest meaning the car can travel incredibly fast through
the double-turn and becomes very light on exit, ready to fly off the road with the slightest
error.
The most interesting and challenging turns are those with elements of the unexpected.
Turns with changing radiuses, elevations, and widths.
Turns designed to be not-quite-flat-out.
Corners that imbalance the car before throwing you into the next turn.
You’ll notice that Tilke’s worst tracks have far fewer of these elements in them.
Abu Dhabi is a prime example of a very flat track with lots of single-radius corners that
leave no room for flare or interpretation.