Understanding Compound Corners

Let's say we have a single corner that leads into another corner. If the line that we take on the first one is the fastest possible, then you have time to start doing the second corner. These two corners are not compound because you have time in between to prepare the next one and satisfy the ideal line for both corners. You can use all the track and do pretty much the fastest arc for each corner separately.

However, if we were to actually trace the fastest line for the first corner, you can clearly see that it's pretty much impossible to bring the car back. You have to sacrifice the first corner or sacrifice the second corner, or a little bit of both, to find the fastest line. This is a compound corner, and the exit of the second corner depends heavily on what to do not on the exit of the first one, but on the entire first corner.

Key Principle of Compound Corners

The important thing about compound corners is that when you're starting to brake for the first corner, you're already thinking of where you're going to be at the exit of the second corner, how much speed you're going to be carrying there, depending on how long the straight is after.

Rule Number One: Never Be Under the Limit

The rule number one for compound corners is to never ever be under the limit in between them. You don't have time to relax. You have to be on the limit, bringing the car as much as possible, creating as much force as possible in the direction of the first corner. Then, as soon as you change direction, you immediately start creating as much force as possible in the direction of the second corner.

This means never go straight in between these corners. Whenever you have a compound corner, you should never ever trace a straight line in between them:

• If you're going straight, you're too slow

• There is no time to be straight in between compound corners

• You must always be using the available grip

Common Mistakes in Compound Corners

Example: Not Using All Available Track

Here's a very good example of a mistake. A driver uses all the track on the first corner, hits the apex, gets back on power, and uses almost all the track. The next corner is very close, it's already to the left, and it's a fast corner that requires using all the track. The driver thinks they're sacrificing the first corner to benefit from the next one.

But then the driver goes straight. If you're going straight in between the corners, that means you could have probably used a little bit more of the track on the first corner and gained a little more time, then used all the time in between to keep bringing the car to the correct position.

This becomes a double mistake:

• Not using all the track on the first corner exit

• Going straight instead of transitioning

• Turning in with the wrong angle, not pointing toward the outside

• Not using all available track width at turn-in

This type of mistake can cost over a tenth of a second just because you relaxed in between these corners.

The Correct Approach

What you should do instead is bring the car as much as possible and use the white line, being parallel to the white line before you start turning in. If you're braking into the second corner, then trail braking with tiny amounts of brake (like one percent), that means the corner is not easy. If you used more of the track on exit of the first corner, you would gain easy time just by planning in advance to keep bringing the car earlier to the correct position and benefiting from that extra track usage.

It doesn't look like a big difference, but you're using more of the track and not relaxing. You keep bringing the car over continuously, then change direction. By the time you start turning in, you're perfectly using all the track before the second corner. This is what you need to aim for lap after lap. It's just a small change that is worth over a tenth in not even two corners, but in what to do in between them.

Example: Over-Preparing the Second Corner

Here's another very good example where a student does a very good preparation for the next corner, trying to open up as much as possible to set up the best exit because there's a long straight after the second corner. The problem is that the student was actually over-preparing the second corner by not using all the track on the first corner, and then having some time available, some remaining grip that was not used.

In between the first corner and the second corner, the driver was actually under the limit for a few fractions of a second, which probably cost around two tenths in that section only.

The correct approach uses more of the exit of the first corner, then stays on the limit bringing the car as much as possible to the correct position, and then quickly changes direction and starts trail braking into the second corner. You leave absolutely no fraction of a second left over. You use the grip throughout the entire compound sector.

Comparison: Slow vs. Fast Drivers

This is a great example of drivers not using all the grip in between compound corners. A slow driver turns into the corner, and then at some point goes straight. This driver is not using the grip and is losing time both on the exit of the first corner and on the second corner as well. It's a double problem.

In comparison, at the front of the grid, the fastest drivers don't go straight. They're turning left, left, left, then immediately right. You can see them changing direction right away. Of course, it's difficult to see from external cameras because it's so subtle.

The Line of Consequence

Understanding Cause and Effect

Remember that entry is cause, exit is consequence. Whatever you do on entry of the first corner will determine the line through the rest of the compound section. We're going to call this the line of consequence, because whatever you do on the first entry will affect the entry of the second corner.

The second corner entry already depends on what you do on the first corner exit. No matter how hard you try to bring the car over, if you carry too much speed on the first corner, you will go wide. You're just going to be scrubbing speed, losing the car, destroying the tires, and understeering or oversteering. You're not going to be able to bring the car back to the correct position if you go too fast.

Decision Making at the First Corner

Your decision right at the first corner entry determines everything:

• Whether you're doing a late apex, hitting the later part of the curve and accelerating earlier without using all the track

• Or carrying more speed, hitting the inside earlier, then carrying more speed on the exit and bringing the car to the correct position

These different lines are already consequences of your entry decision. It's a very common mistake for drivers to do whatever they want on the first corner, and as soon as they get back on power they realize they want to bring the car to a different position and try their best to do it. It won't happen because the car is too fast, and then you have to lift or do something that will make you lose more time.

This consequence depends on the first entry. You have to make the decision at the first entry thinking about where you want to put the car for the second corner.

Using the MRP (Minimum Radius Point)

A very practical way to think about it is to adjust your MRP. Remember that the MRP has:

• A positioning (lateral placement)

• An angle (direction of the car)

• A longitudinal positioning (how late your MRP is)

If you want to sacrifice the first corner more, just do a later apex. You can even brake in the same place, you just turn in a little bit later, hit the inside a little bit later, get back on power, and then the car is going to be on the perfect line of consequence that takes you to the entry of the next corner.

Adjust your MRP, and then your line of consequence will be adjusted. Think about the first corner area, and then see what happens in the transition and second corner area.

The Snowball Effect

You see, we're talking about two corners, and the second corner already depends on the first, but the first also depends on the entry. That depends on the braking point. So in a way, if you are on the limit of both corners, the first entry determines everything. This entry determines everything. You have to nail the first corner entry in order to be able to nail the transition, and then nail the second corner entry, and then nail the second corner exit.

You have to think ahead. This is the actual vision technique. It's not only visual vision, it's a visualization in your head, in your mind, of what lines you're going to trace. We're talking about two corners, but imagine when we talk about three or four or five. Think about the Suzuka S's—all the corners depend on the previous one in a snowball effect.

Avoiding Common Errors

Think about the line of consequence. This is important because it's very common for drivers to just force the car in between compound corners. There is a stage where you will be forcing the car—you know the car is not capable of doing it, but because you're over-committed on the first entry, you really force the car in the transition area.

You have two types of drivers:

• Type 1: Drivers that over-prepare the second corner. They go a little bit too slow on the first corner, get back on power, and then they have this space of being under the limit. They just go straight, do nothing, and then finally they get back on the limit thinking about the exit and the long straight after.

• Type 2: Drivers that force too much. They want to go fast, so they go all the way on the first corner, but then as soon as they get to the transition they really force the car as much as possible. They end up destroying their tires and being frustrated because the car is not going where they want it to go.

Remember, it's not in the transition that you're going to make the decision—it's at the first corner entry.

Deciding How Much to Sacrifice

The Spectrum of Choices

What about the decision of whether you're going to sacrifice the first corner or the second corner? You have a spectrum. You can either completely sacrifice the second corner, or you can completely sacrifice the first corner. In the end, we actually have a full spectrum of choices that we can make.

The 50/50 Baseline Approach

At what end of the spectrum do we want to be? The best baseline is literally 50/50. You do a 50/50 approach—bring the car more or less to the middle position, then try this line. This 50/50 approach is a good starting baseline to have an idea of how much time you gain or lose, and then you start adjusting from there.

General Rule: Sacrifice the First Corner More

After this baseline of sacrificing half and half, you start moving towards sacrificing more of the first corner. Generally, sacrificing more of the first corner and bringing the car a little bit more towards benefiting the second corner is better, because it's very important to carry more speed on exit since cars are a little bit less efficient in acceleration than deceleration.

But this also depends on how long you're going to benefit. If there is a very long straight after the compound section, then definitely you want to bring the car more to the correct position, bringing the car as much as possible (always on the limit, remember, to not go straight anywhere), and then having the best exit you can possibly have to carry the speed throughout that long straight.

Factors to Consider

This is one of the factors: how long is the straight after that compound corner? Do you have a long distance to continue benefiting from the exit speed? Then sacrifice a little bit more of the first corner.

However, we're considering two kind of identical corners, and you know that's very difficult to happen. Generally, we have compound corners that have different radii. Let's analyze some examples where we go through why we choose to sacrifice sometimes more of the first corner, sometimes only the second corner and not sacrificing the first at all, and so on.

Practical Examples of Compound Corners

Example 1: Short Radius Leading to Long Radius

Let's take a look at a corner combination where we're doing a right-hander that leads into a longer left-hander after. We are approaching the first corner at a particularly high speed. What should be the ideal line here?

Initially, we said that generally we want to sacrifice a little bit more of the first corner to get a better exit on the second one. But there are two factors that will make us actually sacrifice none of the first corner:

• First factor: There isn't a long straight after the second corner

• Second factor: The first corner is a much shorter radius and the second corner is much longer

We have to decelerate a lot to do the first corner already. Because the next corner is long, we can take a double apex approach.

The best way to do this corner combination is to actually not sacrifice at all the first corner. Get back on power early, go all the way to the outside, and then because we are already at a lower speed, just start trail braking and do the second corner more or less hugging the inside. But in the end, you're actually doing a double apex approach—using all the curve, going a little bit wide and off the curve, then back a little bit to the left before running wide all the way to the outside at the exit.

The very reason we don't sacrifice the first corner is because it has such a shorter radius. If you were to actually sacrifice the first corner to benefit from the second one, the amount of time that you lose to sacrifice the smaller one will not be worth it. You will not get that time back on the second corner because the second corner is much longer.

Whenever you have a short corner that leads into a longer corner that can be double apexed after, try to not sacrifice the first one. Try to gain as much time as possible on the first corner, and then do a double apex approach in the second one. You're going to see that it's definitely going to be worth it. If you just sacrifice the first corner, you're going to have to slow down way too much, and by the time you actually turn into the next corner, you're going to be way under the limit. The car is going to be able to turn more than necessary and you're going to bounce off the apex.

Example 2: Interlagos Turns 1, 2, and 3

In this example, we have turns one, two, and three at Interlagos. What you really need to know here is that after turn two, turn three is going to be flat, and there's going to be a long straight after that. The amount of speed that you carry over turn three and onto the straight is going to be invaluable.

You have to make sure that you sacrifice turn one as much as possible to prepare for turn two, because turn two is the corner that can kill your speed if you don't sacrifice turn one correctly. Make sure you bring the car as much as possible to the correct side on turn one, doing a very, very late MRP. By the time you change direction into turn two, you have a very big radius allowing you to carry more speed. Then you can maintain that speed on turn three because that's an easier corner with a much bigger radius, and you can just carry that extra speed for a long time after.

It's a very common mistake to see a lot of drivers bringing the car way too much to the wrong side after turn one because they want to go fast on turn one. Turn one is quite long and has a kind of closing radius, so it makes you want to accelerate earlier and end up having to sacrifice way too much in turn two.

What you want to do instead is be patient, place your MRP pretty late on turn one, and then bring the car to the correct position. Then when you change direction, you can really carry a lot of speed on turn two, and you can benefit from all that speed from turn three all the way to the straight before turn four.

Example 3: Silverstone Brooklands

Next up we have Silverstone Brooklands. Again, we have a compound corner where the second one is much longer, and by the time we get there we are at a lower speed and we can double apex that corner.

The ideal line: you can see everyone pretty much not sacrificing the first corner at all and going all the way to the outside after the first corner. Because right now you are at a lower speed, you can just hit the first apex very early, let the car go wide, and then bring it back to hit the second apex. You can see everyone pretty much doing the same line.

If you were to sacrifice the first corner, you would enter the second corner at a lower speed, and that corner has a big radius. You would not be able to benefit from that lower speed in a wider arc because the car would be under the limit very easily. That would require you to accelerate too early, but then the car would start spiraling out because of the acceleration, and you would have to actually brake again.

The best way is to carry as much speed as possible, so you already carry that speed into the second corner. You will have the time in the second corner to bring that speed down as you do the closing spiral in the first half of that double apex.

Example 4: Three-Corner Combination

Here's something that you should never ever forget: the final exit leads into a very long straight that depends on where we apex in the final corner. But that line depends not on the final corner entry, but on the middle corner. Where you apex on the middle corner depends on where you apex on the first corner.

If we were to do a reverse engineering all the way from the corner that leads into the straight, back to the very first entry, you realize that the moment you apex on the first corner determines the rest. Think like that: a small change at the first corner affects the line on the middle corner, which affects the line on the entry of the final corner. There's a snowball effect here.

What you should do is plan the apex on the first corner more than everything else. Here's a secret: plan the apex on the first corner—plan where your MRP is going to be, when you're going to hit the inside. Then just be on the limit for as long as you can, going all the way to one side, then quickly changing direction all the way to the other side and opening up as much as you can. Then you benefit from the final corner.

Whatever happens, if you want to do any adjustment, just adjust the MRP on the first corner. The other corners will just be consequence. Of course, yes, we want to do a tiny lift when bringing the car to the correct position for the middle corner, to just get a little bit more rotation. But even with that adjustment, you still need to have a very good line. If you carry way too much speed on the first corner and you position yourself incorrectly, you get pushed way too much to the wrong side, and your entry for the third corner is terrible. You cannot carry any speed onto the long straight.

You see, it's a snowball effect. Whatever you do on the first corner is 80% of the outcome.

Two Key Things for Complex Compound Corners

• Adjust the first MRP

• Adjust the first line (whether you late apex or early apex)

• Stay on the limit on all the other corners

That's already going to give you so much information about this set of corners that you're already going to be ahead compared to almost everyone.

Example 5: Circuit of the Americas Complex

Let's talk about Circuit of the Americas. Let's count how many corners are connected by the same line where you have absolutely no time under the limit in between them. We have one corner, two, three, then four, then another right-hander (five) leads into a left-hander (six), then a closing radius right-hander (seven), and then finally eight—a fast, cresty left-hander.

These corners always keep you on the limit. There's absolutely no moment where you're not on the limit. Let's discuss the traps and problems in this section—it's all about the snowball effect.

The First Corner Trap

The first corner looks easy because you can do it flat, right? But the next corner is to the opposite side, so you have to be as much as possible to the correct side on this first one. Even though the corner is flat, you shouldn't relax. You shouldn't just turn in a little bit early and end up putting yourself in the middle of the track after, because then you're going to compromise the entry for the actual corner that will be over the limit and where you have to slow down.

Instead, turn in a bit later on the first corner. I know it's flat, but choose the right line still, and try to be as much as possible to the correct side after this first apex. By the time you change direction, you are using the correct side of the track.

Navigating the Sequence

Now you're on the limit, so you're still going to try to bring the car as much as possible to the next position, and you're going to change direction more or less in the middle of the track for the next corner.

But here's the thing: the next corner is a double apex. It's a long corner and it's a double apex as well. So what you can do—you don't need to sacrifice the previous corner, you don't need to sacrifice the exit of it. What you can do is just go as fast as possible and let the car run wide, because the next corner is long and it's a double apex. You can turn in early, let the car run wide, and the corner is long enough that it will give you space to bring it back to the second apex without having to slow down too much. Then you hit the second apex.

Now, again, still on the limit. You won't have enough time to bring the car all the way to the edge, so you have to bring it as much as possible without relaxing, without going straight. Then right away change direction for the next corner, hit the apex, and then get back on power. Bring the car as much as possible to the correct side, and then again, right away change direction and start braking for the next corner.

This is a closing radius corner—be patient, patient, patient, still on the limit. Then quickly change direction again.

You see, absolutely no time to go straight, absolutely no time to relax. You have to plan your line. All these lines depend on what you do on the first corner, which is the easy one. The easy corner is the trap itself, because if you end up not using all the track there, you're creating a snowball effect that is terrible. You go wide on the second corner, so you go wide on the third corner, and then you go way too wide on the next one. Then you're not being able to carry as much speed as possible in the double apex section.

From this point, you can kind of already recover from the snowball effect and do the remaining corners as fast as possible, but by the time you do recover from it, you already lost way too much time on the S's.

The answer: think ahead. Reverse engineer where you want to be on each corner, and then try to satisfy the line requirements on the corners before so you have the chance of nailing the next corners.

Car-Specific Considerations

Different Cars, Different Lines

You have to also know that the same compound corner can have drastically different lines depending on the car that you are driving. For example, we have a very long left-hander that leads into a very fast right-hander kink. What do you think would be the ideal line? Well, that actually depends on how you can take that kink afterwards, depending on how much grip the car has.

For example, a Formula One car with a lot of downforce is able to take that right-hander flat even if we do not sacrifice the left-hander before. But if you're driving a car with low downforce, a heavy car, that right-hander becomes a bottleneck for your speed. You really need to prepare that right-hander in order to carry as much speed as possible on that corner and on the short straight after.

Examples of Extreme Approaches

The fastest line on a Formula car here involves absolutely no sacrificing, whereas the fastest line on a GT car here involves double apexing aggressively the left-hander and sacrificing its exit so you can have a good positioning and angle for the right-hander after.

Of course, these are the two extremes, so pretty much every other car will be somewhere in between those two extreme lines.

Finding Your Car's Optimal Line

The fastest way to identify this line is by trying to stay on the limit for as long as possible and see how much speed you can carry on the second corner. If you can't carry speed on the second corner and you have to slow down way too much, then you sacrifice a little bit more the exit of the first corner. Always test the limit, always try to never go straight, never relax in between these corners. Try to keep the car loaded and see where it ends up depending on your approach on the first corner.

Remember: always the first corner is adjusted, the second corner is tested.