Previously when discussing corners, we covered how the racing line through a corner has a much larger radius than any path which follows the curve of the corner itself. Let’s now look more closely at racing lines themselves and how they work. Something you may find intuitively obvious, is that you can drive faster through a curve of larger radius, than a tight curve with a very small radius. This is related to how much lateral grip a car has, something which is tied up in more factors than just tire rubber. Downforce, suspension and traction are among the many elements that help give a car its turning grip. This car is going around in a circle as fast as it can, let’s say, 40 miles an hour. It’s able to keep to the circular path, because the lateral friction from the grip of the car is pulling it inwards towards the center of the circle, while the drive of the car and it’s continued momentum coaxes it to continue in the direction it’s pointing. These two forces together lead to circular motion, and, as we discussed last time corners are just bits of circles. This circle’s radius, its size, is defined by the grip of the car at this speed. Now if the car were to speed up a bit, to 50 miles an hour, it wouldn’t be able to hold this tight loop. It would start to slide and drift outwards towards a larger circular path. And, as it continues to get faster, the car drifts to wider and wider arcs. Now all of this was just to reinforce the idea that a bigger arc, a curve with a bigger radius, a longer corner, will allow you to drive faster through it. So, looking back at our corner: a simple, single radius corner, with no complicated tightening parts or whatever, that we discussed in the last video. If we want to find the fastest line through this corner, we just have to find the circle that takes us from the outside of the track, clips the inside in the middle, and then launches us back to the outside of the track on the other side, right? Well not quite, as it happens. While you can, given all the measurements of a corner, calculate and plot the mathematical racing line we just discussed, things aren’t all that simple. Let’s talk about the apex for a second. Now, the apex, when mentioned by drivers and commentators, is the inside most point of a corner that cars brush past on their line through. Our mathematical line will find the true apex, or Geometric Apex, the point at the absolute middle of the corner, and actually produce a symmetrical line through the turn. Hopefully we’re all good so far. Now, while this racing line will absolutely give you the fastest way through the corner, it’s often not the best line to take. Remember, you’re not trying to maximize your speed through one corner, you’re trying to maximize your speed over the whole track. Taking the corner as fast as possible between point A and point B might actually be detrimental in getting to point C down the next straight. So how do we maximize our speed from A to C? So this part here is a straight, and what are straights but acceleration zones. A moment wasted not accelerating will hurt you getting to higher speeds at the back end of the straight, which can add up to some pretty massive deficits. So, a driver will actually brake a bit later, and harder, turning into the corner later, but straightening up much earlier. They’ll brush the inside of the turn later through the corner, which is known as taking a late apex, all in service of creating a much straighter line out of the bend. So now we’re all good to go with hoofing out of the corner from this point, so we should be much faster by point C at the end of the straight. In our normal line, we’re still straightening the car up all the way through here, so, we’re exiting the corner slower, than when we took a later apex. Taking a late apex is increasingly effective, the slower the corner. This is because you have a much bigger acceleration potential when starting from a slower speed, and from a higher speed. This is why hairpins in particular are taken with such a maximally late apex approach, distorting the racing line much more than the faster gentle corners. Exit speed isn’t everything though, you can flip what we just said on its head and go for an early apex, if you want to maximize entry speed, throw the car into the corner and sacrifice the exit speed trying to sort the car out. Now why would we ever do this? Well, what if our corner was followed, not by a straight, but by another corner, or sequence of corners? In this case, we don’t care about exit speed from the first corner that much, as we’re not trying to maximize acceleration here. Instead we care about position and stability so we can take the next corner as fast as possible. In fact, in a sequence of turns, be it chicane or any kind of complex, you’re really looking to maximize your final exit acceleration, while taking the fastest possible line through the middle of all the corners. In which case you’ll probably take an early apex here, our entry to the complex, take the more mathematical path of least resistance through the middle, and, if possible, get yourself a nice, late apex at the exit. Through a sequence, you might not want to exit an early corner as wide as possible, instead you may need to keep the pace steady and stay tucked in, ready for the next corner. All sequences are different, and working out which turns are the most important to carry speed through is part of a driver’s skill. Now you may have heard commentators talking about the karting line, so, what is this? Well, for reasons I don’t need to go into in this video, it’s often faster for karts not to hit the apex through some corners, but instead take a wider line. See, carts travel faster when keeping momentum, instead of hard braking, turning and accelerating, as they are naturally very slidy and unstable. Now why would an f1 car ever take this line? One reason is if its tires are absolutely knackered. Another might be if it rains. When the track is wet, there are two good reasons to take a wider line One is for a very similar reason to the karts: it’s better and faster to keep momentum through the corner than trying to brake hard, turn fast and accelerate from low speeds on a slippy surface. The car is much more likely to get away from you when you’re being a bit dramatic with it, using techniques designed for the grip of a dry track. Secondly, if there’s been dry running, the dry racing line will be covered in a layer of rubber. This rubber becomes super slippery when wet, much more so than the track itself, which has grain and texture to displace and absorb the water. Taking a wider, karting line, avoids the rubber through the slipperiest parts of the corner, and this is especially important in slow corners, which rely heavily on good traction. So these are the basics of racing lines, but believe me, it’s all very well on paper, but things get much more complicated out on track. Bumps on the entry, exit and inside of the corner will affect your choice of path through. Changes in track surface, camber and elevation will come into play. What are the curbs like? Does the exit of the corner have a tarmac runoff, gravel trap, grass or a big hefty barrier ahead? In the end, the lines through the corners will bear out from the many qualities of the nature of the whole track. You could pick up the Variante Ascari chicane from Monza and stick it into Monaco, and people would take it very differently. Watch cars through corners and try and work out the decisions being made by the drivers as they take their lines. And I haven’t even mentioned how lines change again if you’re not on your own, but in a battle with another driver. But that’s for another time. Thanks for watching this video. That wraps up our short series on corners and racing lines and such. If you want to know anything more that I haven’t covered yet, let me know in the comments, because next week we’re moving on to how Pirelli pick their tire choices. Thanks very much to my subscribers on Patreon, you’ll see their names flashing in front of you now, and if you want to join me on Patreon, there’s a link at the top, and I’ll see you next week for our journey back to tires, before we start looking at aero.