Cornering

From Trackpedia

Jump to: navigation, search

Driving in a straight line is easy, regardless of speed and conditions. However, cornering is where it gets harder, and that's why the concept of cornering, is 90% of racing. This article will touch subjects of cornering strategy, effective steering response, reduction of forces working on the car and increased cornering speed and corner exit speeds.

Contents

Road handling, road holding and cornering

The car's tire grip is what generates the forces that push the car around the turn. The car's handling characteristics describe just how easily and fully can the driver utilize this grip level to the maximum. Every novice can push the car to it's limits of grip. Fewer are the drivers that can push the car to the limits of it's performance envelope. If the driver takes a tight line, jerks the car around the corner, rides the brakes around it and does all other kinds of mistakes - he will be on the limit of grip in no time. However, if the driver takes the wide line, steers smoothly and positivelly and with just the right weight transfer -- he could drive even faster than the other driver, without even being on the limit. The idea is to learn a concept known as maximum exploitation of grip, so we can excert the maximum of amount of performance from the smallest possible slip angle. This way, when we are at the biggest ("optimum") slip angle - we achieve full performance.


Sliding in corners

Sliding is driving beyond the car's grip limits. However, as we stated above, this can be done without driving outside of the car's performance envelope. How? If we drive at a pace below 100% (or "ten tenths") and than make a single provocative action that will momentarily bring the car to the limit and beyond it, we will cause a slide which will not be aggressive enough to cause a lost of control. On the other hand, if we intentionally drive the car to the limit, at the ten tenths, any little unwanted move will cause a completly uncontrolled slide.

Sliding in corners is done when driving at a competitive pace in a driving enviornment which is too slippery or not as well known to the driver as the track. A rally driver is not as well acquainted with the corners as the track driver is. If he will try to drive on the absolute limit, it would be like walking on eggshels. Any little mistake in the assesment of the bend or any slight change of radius or road grip will cause the car to crash at once. Rally drivers slide the car to increase their safety, not the other way around! It's easier to slide than not to. This way it's the rear wheels that tuck the car into the corner, and already down the straight before it, you know you have your front pointed at the desired direction in advance.

The main technique is simply to enter the corner under braking and turn the wheel late and rapidly. The car will momentarily understeer before responding to the steering input, and any additions to the steering input by this stage wil delay the slide and intensify it beyond intention. The driver has to be disciplined to wait and allow the car to kick it's rear around and than quickly reduce the braking and, at the right point, pitching the car on throttle.

Other techniques are generally used when the car is not as co-operative as to slide effectivelly around the corner in the method mentioned earlier. They include rocking the car against the turn before turning in (an "Appel Contre-Appel") used on extremlly slippery surfaces, and likewise utilizing the handbrake (normally on tight hairpins) or even simply lifting off of the throttle and left foot braking just after turning the wheel into the corner. A powerfull rear-wheel drive car can also use power to kick it's tail around the corner. The key in all cases is to choose the smoothest possible input that will still result in sliding the car. Sliding completly sideways is going to be fun and spectacular, but not very fast. For speed, all you need is a slight movement of the back of the car in the right direction.

The racing line

'A method of improving cornering is to make it as close to driving straight a head as possible. It's a common tendency to turn sharply (sticking to the inside of the corner) to make a shorter way through the turn, or to turn wide (sticking to the outside of the corner), to apply less steering input. The best approach is, therefore, a hybrid of the two: you reach the corner from the far end, steer into the inside of it, and exit again from the outside -- outside plus inside plus outside equalls: The racing line. The idea is to utilize the whole width of the track, not only it's length, and therefore turn the car at a wider radius that that of the corner, ideally "cutting" the corner in a straight line.

When you reach the turn, you start turning the wheel into the corner at the turn-in point, progressivelly applying steering into the corner untill the point of maximum amplitude is achieved and the front wheels are turned in line with the corner. This point will exhibit the highest cornering demands on the car. The car will now be driving around the corner up to a "peak" where the radius will be tightest and the speed - lowest. This point is the peak of the corner or, as it is professionally known, the Apex. Any corner, when taken in any way, has an apex. It is the point that ends the corner: Just after the apex, you should start to reduce the steering input back to straight. For the cornering radius to be largest, the apex should be placed on the inside of the corner, and percisely at it's middle, at a 45 degrees angle for a 90-degrees turn. You turn-in from the far end of the corner (left side of a right-hand corner), turn it and "touch" it's inside (right side) and straighten out back to the outside while accelerating. This is the geometric apex line.

The question is whether or not this line is categorily faster? Surprisngly enough, it isn't. The faster line is the late apex line, where the driver turns-in later and clips the inside of the corner at a later apex, in an angle of 50 to even 60 degrees. This will make the car take a tighter line coming into the corner, thus being slower coming into it. But, it has several advantages:

  • It pospones the braking so you can brake later and keep the acceleration down the straight going a bit longer
  • It allows good vision around the bend
  • It allows to complete the steering input more quickly.
  • Most importantly, it allows to pitch the car earlier to accelerate down the road, so you can commence acceleration even before the apex. The corner will continue into the straight, making it longer, so you can overall gain more accelerating out of the corner and down the long straight, than you ever could coming into the tight corner.

The late apex is the basic approach, but not the only one. Some corners and some cars might require turning at the geometric apex, or at an even later apex, called the "last apex" (60 to 70 degrees). Other corners might require an "early apex" position, at a 25-30 degrees angle.

As we are approaching the bend down the straight, we wish to stay on full throttle for the longest duration of time possible. For this sake, we minimize our braking to the smallest possible space and time before the corner, as to stay on the throttle untill the last possible moment. At that point, you perform Threshold Braking by applying the brakes very rapidly (but not instantly, at a "stab") and quite forcifully. You are likely to be moving at a high speed at this point, so this kind of strong braking will be far from natural. But remember, the faster the car is moving, the harder are the brakes working to slow it down. So, you need to compensate by braking harder and more rapidly. You should brake just hard enough to bring the front wheels to the brisk of locking up.

From this point, the speed will reduce, and you will need to reduce the pressure on the pedal very progressively to match it with the speed that is being reduced and keep it just on that limit of lock-up. As you approach the corner, reduce the braking even further. If you use all of the available grip to brake, you could not steer, even though the wheels are now unlocked. Start turning into the corner and share the forces of braking and steering by turning the wheel into the corner progressively while still progressively easing off of the brakes. More steering, less brakes. This is sometimes called "brake turning" and it allows to brake into the corner, and thus brake later down the straight. A secondary advantage of it is that it allows to achieve effective steering by leaning the car unto it's front suspension. You will find that you have more overall grip and a faster cornering speed at this way, even though the initial reaction of the car to the steering input will be slightly delayed.

Once the steering has been turned to the full amplitude required, you need to seemlessly transition from brakes to throttle. The smooth transition is important, because the car experiences the largest side force just after you finish turning the wheel. Imagine the graph that describes the side forces: The more you turn the wheel, the more side force there is. But, in the real world, the line is not smooth but is rather something more like a heart pace monitor, so after you finish turning the wheel there is a small, momentary "peak" and only than does the side force stabilize. Also, by this point the car would be cornering steadily and could possibly oversteer when you go off of the brakes. Professional drivers might choose to apply a technique called "trail braking" where they will continue to brake through this point and maintain the grip deeper into the corner.

The choice of other drivers is to transition to throttle and apply it just positivelly enough as to keep the car at a constant speed, not slowing down or speeding up. Rather, it should be in it's natural balance and be only occupied with cornering. This is called "balanced throttle" and it achieves stability and readiness to accelerate out of the corner. At the right point, shortly before the apex, you should start to increase the throttle input to accelerate the car. Once past the apex itself, you need to start to straighten the wheel, simultanous to furthe acceleration: More power, less steering. This is the key of the late apex, it gives you the extra reserve of grip that allows to accelerate faster out of the corner, but also allows to keep inside and NOT to straighten the wheel and/or apply the throttle, if the outside of the corner is blocked.

In very sharp corners, or successive turns in opposite directions, we might need to take an ever later apex. For this purpose, we will have to slightly compromise the smoothness of turning the car into the corner with the right line. We remain on the outside and than turn the car in more sharply, and reduce the brake effort more sharply too, and than pitch the car on throttle around the turn.

Our vision determines our line. Because we are moving fast, we need to plan it in advance. On the track, we want to get the line just right, within a range of a foot or two, as to take advantage of as much tarmac as possible. For this, we use pre-determind reference points, for braking, turn-in, throttle, apex and exit. There are several kinds of reference points: They can be fixed objects alongside the track (rigid or permanent reference points), or they can be an imaginary reference point, it can be the steering wheel, the engine or the feedback of the car, or even plain out rhythm. A rigid reference point, preferably on both sides of the track, is required for turn-in, apex and exit. An imaginary reference point is used in the street, or in rallying, as well as to determind our braking point and point of throttle application on the track. The steering wheel is used as a reference point in turns where you don't use the whole width of the road, especially tight dual-apex turns, where you look for a point where you get the wheel back straight to know where your exit point is.

An actual driving line differs from the theoretical racing line as it's a more general concpet that gives you one or more of the following advantages:

  • Maximum comfort during a change of direction at a given speed, which includes the reduction of steering input nessecary to the driver and the amount of body roll.
  • Minimum time through the corner and maximum speed within it, which is usually achieved by making the corner longer in metres but shorter in time due to increased speed.
  • Minimum wear on car parts like steering, tires, chassis and suspension, along with a reduction of fuel milleage.
  • Maximal margin of safety through the turn, including a broader field of vision through the turn.
  • A better position to accelerate on the following straight or to turn-in into the next corner.

On the track, following the trail set by tire marks could easily indicate the correct line. However, they cannot replace reference points for braking, turning-in, apexing and turning-out. Additionally, mobilized objects on the side of the road (rocks, etc...), or ones that are too far away from the side of the road will not suffice either.

* Further reading:
*# Slow in, fast out!
*# going faster
*# racing line 
*# racing line B
*# Racing line C
*# Racing line D
*# Racing line D
*# Visual Field 
*# apexing
*# Reference points
*# Visual field
*# Trailbraking 
*# going faster B

Common Mistakes

  • Early Turn-in: You are driving in a tri-digit speed and you see the road up ahead curving to the side. Out of fear and lack of patience, you might try to make the turning motion smoother and faster by starting to turn earlier and down the straight. The problem turns out when you reach the APEX, you find that you start running out of road and you have to start wipe off speed in the straight. "Fast-in, wipe-out"! Instead, wait to when you see the turn-in point slightly to the side and not straight ahead. If you found out you have turned-in too early, straighten the steering, brake and use the steering to move the car back on the right line.
  • Late braking: If you found out you braked too late, keep on braking amd delay your turn-in point, even in the cost of not clipping the corner at all. Be smooth but keep covering the brakes into the corner.
  • Fast corner entry: The late-APEX obligates that the corner exit speeds (which translates into a gain in speed along the whole length of the straight, and not for a few feet inside the corner) is prioritised over corner entry speed, which must be sacrificed somewhat. If you do find yourself going into the corner fast, try and delay your turn-in and rather keep braking in a straight line. When turning, be as smooth as possible and try to cover the brakes into the corner somewhat.
  • Early acceleration: Very often, races are won by the driver who is last on throttle rather the one that is early on it. Get on the gas too early and you will have to come off of it and come off of the right line. The solution is to look up and apply the gas once you see straight through the corner and once you clipped the APEX (both conditions must exist for beginners, professionals rely on the second rule alone). Keep the eyes up through the APEX as if it is a crosshair and look a bit beyond your track out point, and this will allow you to notice whether your thorttle appplication was too early. Once you identify such a situation, do not force the car in by steering, gently ease your acceleration instead. Do not be ubrupt, as this will only decrease your stability. If this happens, straighten the steering and get back on the gas. If you have the nessecary sensitivity with the left foot, dab the brakes without lifting the gas, if you pressed the gas too early.
  • Skidding: If you are not sure whether the car is going to skid and how, take a bit of steering lock out.


Road angle vs. Turning angle

Sometimes, a corner is being made going slightly uphill or downhill, effecting the grip and handling of the car. If uphill, the force of gravity will work to pull the car back and against the lateral force that will push the car out. The car will be effectivelly pressed against the surface, and have increased grip. However, the car is going to have reduced dynamic capabilities, it will take longer to change directions and could develope a pesky understeer due to the weight transfer to the back. The acceleration will also be reduced. Going downhill, the car will take on forces and increase speed that would attempt to throw it out of the corner. Also, the weight shift to the front will make the car more prone to oversteer. The solution is a smoother, more geometric line, less speed and push through the corner.

A corner can also have a side slope or banking. It effectivelly works like camber in wheel alignment. A corner that is "cambered" so that it is higher on the outside than on the inside, will again make the force of gravity work against the car's moment of inertia and allow to corner faster. Corners that are "off-camber" will tend to tip the car and throw it out of the corner, again requiring reduced speed and earlier apeces. Some corners have changing camber, where the corner begins leveled or with a certain incline, and than turns "off-camber" in this case you need to readjust your line to a late apex, so most of the cornering is done in the first, grippy section of the corner and the dangerous one is done in a more straightish line.

Wet tracks are another problem. Cars tend to drop dirt and oils onto the racing line. Further oil and dust are drained to the edges of the track. The idea is to look for a line that goes around the slippery areas. The driver does not take as wide a line at turn-in, apex and exit. You will have also have to stay out and take the "last apex", if at all. Watch out for areas of deep water, concentrated oil or mud, as well as smooth road surface (areas of worn tarmac or concrete patches and berms), as well as presence of dry leaves. Don't forget to find a way to get your tires into working temperature and to weave sideways to avoid being in other driver's spray, as well as to use puddles to cool off hot tires. Once a dry line starts to form, use it.

* Further reading:
*# Camber-corners
*# Visualizing the line
*# wet lines

The road driving line

The only way to sink in racing habits is to apply them in our everyday driving. Furthermore, so-called "performance driving" can be applied on some public roads, and have a special enjoyment to it, something different from the track. Many European countries, like Italy or Germany, abundant with famous race tracks, are also host to a whole culture of applying "performance driving" down the mountain roads that are so typical to their landscape, even though they also have race-tracks.

For general road driving purpose, we recommend taking a very late apex, to give you a good glimpse around the corners. Remember, this is a public road. If you can't see beyond the corner, assume the worst be waiting for you beyond it. Be smooth, drive quickly by nowhere near the limit and only do such driving in times and areas where the road is empty, and where there are wide, paved shoulders as a certain run-off area, and relativelly good visual field and grip levels. Slow down to normal pace around oncoming traffic and never overdrive the limits of vision.


Corner classification

It's best to classify the different aspects of cornering, according to the different sorts of corners you can encounter. These aspects include: braking and access speed, turn-in (smooth vs. decisive), cornering (neutral throttle vs. trail braking), apexing (geometrical APEX vs. late APEX), understeer and oversteer corrections (pedalling vs. steering), visual field and etc. Each type of corner has typical beginner's mistakes and stresses.

Not all of these corners appear as frequently as others. Most corners are a medium-speed moderate bends, while a smaller amount of corners can be considered sharp. Almost every track has one or two fast curves, typically also an esses, and a hairpin or two, and several chikanes. Long, closing corners are less likely to appear.

The less severe is the corner, the higher is the access speed, the earlier is the APEX, the smoother is the steering, and the less trail braking is nessecary (if at all). The sharper the corner, the slower the acess speed, the later the APEX, the faster is the steering and more trail braking is nessecary. Sometimes, a driver can turn in early (a geometric APEX) and keep the throttle on (Power maintanance). In rare instances (really sharp corners) the driver has to take the latest possible APEX, turn the wheel almost sharply while trailing off of the brake.

When skill builds up, you will need to consider yet another factor in your cornering strategy, which depends not only on the type of corner, but also on the larger picture, of what is coming before and after the corner. The far most important type of corner in that regard is a medium-speed or fast, open corner, in between two long straights. Drivers with skill would attempt to maintain as much speed as possible from the first straight and into the second. Many of the most famous and notorious corners on F-1 race tracks belong to this category.

Open corners followed by short straights rely on mid-corner speeds, and can often very hard as well, however being of lesser importance in practice sessions. A third type is a corner opening or being a part of a corner set.

For visual illustrations of multiple racing lines, look in these articles:

*Racing lines  
* Kart lines.

A fast curve

This is a small and flat curve or a fast esses or fast sweeper. It's the simplest form of a corner, yet also the most tracherous. The point of this curve being that, you approach it without significant braking' (and therefore not necessarily threshold braking with a marked starting point), often approach it from mid-track rather than fully outside, and go through it with light or moderate acceleration. If there is no need to downshift while braking before this sort of curve, you may consider braking with the left foot to reduce pedal transition time and return more quickly to the throttle, hence keeping the revs up.

After the speed and gears have been matched, and the accelerator is threaded lightly or moderatly and the left foot applying pressure against the footrest. Few fast curves are negotiated flat-out, and some are negotiated by easing off of the throttle just as you turn-in.steer slowely and gently. The approach through such a curve is simply the most straight foward line you recognise with your eyes, typically an geometrical APEX (clip the curve at the percise, geometrical, center), without hitting the rumble line on the edge of the roadway if it means shocking the car, all while looking far out through the curve and past it. It's better in this case to turn too less rather than too much, and early rather than late, since you want to keep the car stable, because the direction of travel does not change. If you turn too early inside, you can straighten up and brake to put the car roughly back on the right line.

After the initial steering input, the arch through the curve, is better controlled by "breathing the throttle" application. Keep in mind that, in such a curve, slight and controlled understeer is better than any sort of oversteer. More throttle equals more understeer (a wider arch), less throttle is less understeer (a tighter arch). Going off of the throttle equals oversteer (a "too tight" arch), while going full on the throttle equals a lot of understeer, but no slip. If you need to decelerate significantly, use slightly left foot braking.

Therefore, if the back-end does feel as if it's not gripping, do not hesitate and don't countersteer but simply thread the throttle quickly, to allow the back axle to re-grip due to a rear-ward weight transfer. This works for all sorts of drives, as the engine cannot spin the wheel in such speeds (remember, a lot of understeer, but not slip). The same applies for post APEX acceleration. As you are about to reach the APEX, increase throttle. As you are at it, you may put the power down quite quickly, since you are not likely to spin any of the driving wheels.

A common mistake is to slow down and/or apply too much inputs of either steering, power or braking. Also, do not fight with the car. If it really "wants" to go off-line, don't force it. A jerky corrective input will be more costly in lap time than a slight error in lines. It's better to drive smoothly off-line than drive jerky on line, make last second saves, or "fight with the car". Don't force the car (althoguh it might feel fast), ease it in.

A fast curve is successful if taken smoothly, through the geometric APEX, with constant power-understeer all throughout. This is also indicated by the wheel being turned-in smoothly and accurately, and turned-out just as it is turned in. In complex corner sets, a fast curve will normally appear in the beginning, before a sharp or moderate corner, possibly requiring braking through the corner.

Alternatively, it will appear at the end of the corner set. In this case, the fast curve is usually not considered part of the set as far as the line is concerned, because it is driven with the accelerator and in the geometric line. Meaning that your priority will be an early and fast exit from the turn leading to the fast curve. That is, a late APEX on the preceding corner.

An esses (Or S's) is a chain of small fast curves, through which the driver takes the most straightforward line. Notice that there might be a chance that a driver would have to brake through a fast curve or esses in order to negotiate a following sharp corner. This requires having the skill necessary to brake mid-corner.

A moderate bend

This is a normal 90 degrees bend, typical of race tracks, taken in a moderate speed and steering inputs. Because of the speed involved (more than other benefactors of grip or weight transfer), the car must be made to turn smoothly through this sort of corner, with very little roll or weight transfer, which is achieved by driving smoothness and accuracy. It's important not to be slow with applications such as steering and/or power, but the stress here is on being smooth.

Because of this, a lot of people tend to slide during this kind of corner. It is also a great place for passing another car. Note that the approach speed in this sort of bend can is moderate, not slow neither fast, and can be improved if you turn on the brakes. Than, turn the wheel as necessary, smoothly and in one fluid motion, but not too quickly, to avoid needlessly shocking the car. If you drive a rear-wheel-drive with a high tendency of oversteer, be even more gentle and smooth with your steering.

You should get the car to turn in (ideally with a late turn-in) with light braking pressure (brake-turning, in some cars and corner setup maybe trailing-throttle: gently ease completely off of the brakes just as you turn the wheel) and than apply neutral throttle and apply acceleration as you reach the APEX, progressively accelerating and retracting the steering towards the exit. If your car and personal skills allow you to use trail braking and maybe Left foot braking, it might be advantageous if you brake before the corner with the right foot, and trailbrake through the corner with the left foot. Turn in as you can see at least most of the bend. Don't be afraid of slightly cutting the corner at the APEX, since the inside wheels will be unladen, and would easily take the hit.

If the car oversteers, use one of two methods:

    1. In a rear or all-wheel drive: Pick up the throttle and countersteer while applying constant throttle.
    2. In a front-wheel drive: Get back on the power to a state of light acceleration while taking off a nice bit of lock, trying not to straighten out the wheel or turn it the other way. If done correctly, you wil not have to countersteer, even in a weak car.

If the car is understeering, you need to ease off of the power smoothly, reduce the steering lock and maybe even brake slightly to get the front to grip again, and than positivelly steer back into the corner.

Note: In moderate speed turns, car configuration details like softness, grip to-power ratio and weight take a greater consideration: A weaker car just might be better off driving through a geometric APEX, giving it more cornering speed, rather than a "fast" exit.

These types of corners are often more important than slower corners, since they are typically longer and therefore a greater sum of time is spent through them. Additionally, in such fast corners, there is a great requirement of percision, often leading to a potential risk of spinning or being overtaken, or simply losing speed and time, far more drastically than you would in a slower corner.

Common mistakes: a fast or early turn-in, turning in with too much braking or without braking. Early apexing.

A sign of success through this sort of corner is the feeling of a smooth ride.

 Furher reading material.

A sharp corner

Mostly, this sort of corner will not be present at race tracks, although most hairpins can be considered as sharp corners. If in doubt, treat like a slow moderate bend. Such a corner is turned into with the car somewhat oversteering, reaches neutral handling around the APEX and understeers out of the corner.

Here, the car must be forced to change direction completely and quickly. Therefore, you should begin with braking to slow down, typically more than what might feel right. It's better in this case to brake a bit early rather than late. According to the "slow in -- fast out" discipline, this corner entry speed should be down right slow, quite slower than what feels right. In sharp corners, almost all drivers, professionals and trainees alike, would have a quite similar access speed, since an any faster access is simply not possible, regardless of skill, or simply won't be beneficial.

You need to keep your outside line and wait for an APEX later than usual, and once you see through most of the corner, Turn into the corner decisively and quite quickly, while still staying just lightly on the brakes, introducing the lateral force rapidly rather than progressively. Be accurate with the steering input; on the wet the car might respond with a slight "delay", but wait for it to turn without turning the wheel more. Generally, in a sharp corner, if in doubt, it's better to turn the wheel slightly more than slightly less.

This corner is best approached with a very-late APEX. (The "Last Apex" Don't be afraid of hitting the rumble line and cutting the corner slightly!). In an very loose rear-wheel drive, you need to be a bit more smooth. Anyway, let the car turn very tightly to line it up to the APEX and for acceleration. As you are about to reach the APEX (but before on it) start to accelerate and maybe begin unwinding the wheel. In this type of corner, trail braking from the turn-in to the APEX is recommended. The turn-in point is going to be alot further down the road than what is going to feel appropriate.

If carried out in maximal efficiency, the back-end might feel "loose" as you turn-in. At that fraction of a second, you can take off most of the lock while going off of the brakes and onto the throttle, you could make the car slide in a neutral state all throughout the corner, and control the arc of the turn with the throttle. This is the fastest way around this sort of corner. However, if the car does suddenly tends to oversteer, react in one of two ways:

1. In a Front-wheel drive: Get back on the gas and accelerate strongly for a moment while taking out a nice bit of steering, and than ease back to light acceleration and keep steering the car through the corner. The acceleration will transfer weight backwards and simultaneously spin the front tires for a moment, to allow the centripetal force to push the front away, and back into the direction of intended travel.
2. In a rear or all-wheel driven car: Take the lock off while keeping the car slightly accelerating. Countersteer as nessecary while peeling off of the gas somewhat to a state of neutral throttle. Pause and straighten and than accelerate forwards slightly.

If understeer occurs, use the Apel contra Apel method and be decisive and quick, rather than smooth, as in a more moderate bend. In severe cases, where the corner is very tight and sharp (and slick) you might want to consider to combine this method with a moment's worth pull of the handbrake. Take off a bit of lock while braking hard than ease off the brakes while reapplying steering ubruptly into the corner, than take off most of the lock and than nip the E-Brake for a moment. You need to keep the ratchet button on the E-brake depressed and the gearbox declutched. Than, set a gear, re-engage clutch and power out.

Note: Understeer in the first half of a sharp corner is typically caused either directly by excessive speed (to late a braking) or more typically by excessive braking into the turn-in, putting too much load on the dampers and too much adhesion demands on the tires. This, however, is also caused by excessive speed.

The solution is, should this occur, to prefer braking that is a bit too early than too late (for sharp corners). Novice drivers make this mistake, but are inclined to believe they were running smoothly as they should. Alternatively, they might mistaken the phenomenon for a problem of car setup, which is far less likely. One sign is when the car is pushing in one or two particular corners, which can further suggest faulty driving technique rather than setup problems. If the issue does appear to be in the setup, start with the tires, and only if you are sure it's the car's alignment or dampeners which are to blame, begin readjustments. Don't swap a whole setup for one or two corners.

A common mistake is to be too slow (or, alternatively, more sharp) with the steering. Additionally, drivers tend to believe that they are smooth, while actually being too tight or smooth, especially if adopting the early APEX, or one that is not late enough.

The sign of success through this sort of corner is that the car is not shaken, and that a very late APEX is being clipped.

You can read more about this in here.

A hairpin

A hairpin, switchback or "U-Turn", is a tight 180 corner. In order to adopt the racing line into this corner, you need to brake it down into two corners, a bend and a sharp corner. Begin with a generally slow access speed, and run wide along the outside of the hairpin up to the center of the corner, trail braking into the corner, slightly tightening the line into the center of the corner as you go, but generally maintaining a wide line.

The speed you carry into this phase of the corner should not be too fast, as you should tighten up the arc by 90 degrees soon enough. Now, you treat the second part of the corner as a seperate corners. Having said that it is the final exit speed that matters, get through this second corner by the racing line, preferably with a last-APEX. You should see the whole hairpin before you engage it.

As you reach the hairpin, look for the geometrical center of the hairpin. At that point you should be almost on the centerline, and should see clearly through the rest of the corner or so, and than tighten up the steering while trailing off of the brake. Once the desired line is obtained, begin power application, from neutral throttle to light acceleration before the APEX and full power after the APEX.

If Oversteer occurs, you will have to ease off of the brakes and even accelerate moderatly to recover. In a RWD, you might need to countersteer and let the car slide a bit around the corner. If understeer occurs in the first half of the hairpin, it should be solved smoothly. In the second half, you can be far more decisive with your flick.

A common mistake is to turn-in too early, at the first half of the corner, or at the early APEX mid-corner (like a parabolic turn). Another mistake is to again believe you are going smooth, actually driving in a relatively jerky radious that constantly tightens-up, reaching the middle of the track half-corner, again leading to a too early turn-in.

The sign of success is again a relatively smooth ride and the clipping of the very late APEX.

Changing-Radius corners

This sort of long and progressive bends were found in old and big race circuits, and are thought to be the most challenging.

  • Increasing radius: This is a corner that is tight leading to the APEX, but winds-off as you exit. The idea is to approach the geometric APEX and accelerate as the road unwinds.
  • Decreasing radius: You should wait for a late APEX and use your eyes to see most of the corner as you turn-in towards the APEX.

Signs of success: A smooth ride and early acceleration.

For illustrations, see  the HPDE Manual, pages 9-18

Long bend

Long bends are considered the most challenging to drive in speed (due to G-forces) and in traffic. Oval tracks are basically a combination of straights and long bends (they are not completly circular, they are oval). Many American tracks include "NASCAR" corners simulating part of an oval track or actually being part of such a track, encorprated with a road course.

The driver keeps the car turning around the outside, and than begin to dive in towards the center of the track and the geometric APEX, from wherehence he might keep the car inside slightly before tracking back out.

A common mistake is to tighten up the steering too much.

Dual APEX

Approach in moderate speed. This is a long but progressive and smooth bend. While a tightening bend or hairpin are a combination of a bend and a sharp corner, this corner can be considered a combination of two bends. The driver should aim for a geometrical APEX, and exit to the outside centerline of the track, take the lock off while applying the footbrake sensitively, and than turn-in to clip a second, late APEX, running wide at the exit. It's a common mistake to think some dual-APEX corners for a single APEX corner. Indication of success are simply a smooth ride.

You can read about dual-APEX corners here.

Successive turns

A real problem occurs when the driver needs to go through a complex of successive turns. The general idea here is usually to prefer a fast exit from the last corner, rather than a quick access to the first. This is called "corner prioritizing". You are not "sacrificing" corners, you are prioritizing!

To begin with, most of the braking should be done before the first corner, allowing to committ most of the braking in one time, rather than splitting it, even if it means going through one of the corners normally the first or middle one, slower than what you believe is possible, or in a slower line. This might also require braking through corners. Here, the driver has to be both decisive quick and almost "sharp", but still maintain the critical amount of smoothness.

In order to recognise the situation, the driver must see as much of the winding track to begin with, and than start dealing with each corner.

First off, if the turns are closely gathered, you might not always have the privilege of running wide exiting each corner, or of going through each corner using the racing line with the late-APEX. The main thing is that the last corner be taken in maximal efficiency, smoothness and be passed with as early full throttle as possible (late APEX). For this end, the first corners are taken either with an early APEX or a very, very late one, both giving the driver to option to stick to the inside of the track, allowing him to enter a following, opposite corner, from the far end of the track.

The steering should be made smoothly, but as quickly as nessecary. The tighter the corner, the quicker the steering. However, you need to minimize lateral weight transfer, so do not be as sharp as you would in a normal sharp corner. Note that if a situation occurs where the steering has to be rotated from one direction to the other quickly, you will need to pull it excessively in order to overlap the original steering input. In order to steer 90 degrees left and than 180 degrees right, you will need to place the left hand on 12O'Clock, pull 90 degrees, than place the right hand on the bottom of the wheel, with the palm and fingers pointing up, and pull it 270 degrees, to reach a 180 degrees left-hander.

Acceleration should be progressive.

If oversteer occurs, it must be resolved quickly and percisely. If you exit the left-hander (from the above example) with oversteer, do not turn right before making a full recovery. You may feel capable of doing it, but that thought may mislead you, as the second oversteer is due to be much harsher than the original slide (The pendulum effect). To correct oversteer, avoid counter-steering if it means pointing the wheel towards the edge of the roadway (with two successive corners in the same direction):

1) In a front-wheel drive: Try to spin the front wheels while straightening the wheel, or countersteer while applying neutral throttle. 2) In a rear or all-wheel drive: Countersteer while applying neutral throttle.

If understeer occurs, you need to deal with it fast, with the Apel contra Apel method. Use it quickly, not as smoothly as you would in a more moderare bend, but not as sharply as you would in a sharp corner.

It's a common mistake to misjudge entry speeds and the lines, attempting to make it quickly through the first corner or set of corners on the expense of the later corner. It's also a common mistake to use steering techniques which require much hand-work, causing a much less accurate and less smooth handwork in this case, especially if you have acquired the habit of shuffling the hands. Also, pushing the wheel or relocating both hands over it, will force you to go through the center point when steering from side to-side and will also cause a lost of smoothness and awareness the angle of the front wheels.

The indication of success is a smooth ride and fast exit speed. Many driver are believe that they ran the corner set smoothly and quickly, while what they actually did was to carry speed into the first corner or two corners on the expense of a fast exit.

Here are a few examples:
* prioritizing corners
* Corner set A
* Corner set B

Chikane

Chikanes are little twists on the track, sometimes also used in rally stages. They force the driver to make a successive left and right turn, thus forcing him to slow down. This is actually a safety tool, usually placed carefully before sharp corners or hairpins located just after a long straight road section. This fact is important to drivers too, since they should refer to the chikane according to what lays ahead and beyond it, and not just by the tightness of the chikane. To recognize this, you will need to take an initial view through the entire chiakne and past it. Than, you will need to recognize the turn-in and the two APEX points. The tighter the chikane, the shorter the gap between both APEX points. You will need to increase this gap, normaly by an early first APEX and a later second one.

A slow-in fast-out chikane

The driver prioritizes the second, faster part of the chicane by turning in very late on the tight portion of the chicane, lining up to take a normal, late APEX at the second turn. As you enter the chikane, you should look to the late second APEX and than the exit.

"A Slow-out chicane"

However, according to the location of the chicane in respect to other corners and straight before and after it, it might begin with a fast curve and than tighten up, allowing to carry a bit more speed into it and exit it at a slow speed with almost no regard to the entry speed. You should not go flat into it, so it's not a "fast in, slow out" chicane, it's just "slow out".

Brake as late as possible, and continue trail braking into the first portion of the chikane, which is negotiated at a straight, geometric line. Mid-way you can take off the steering lock and apply the brakes quite harder, and than turn into the second, and than turn late into the second part of the chicane and exit. You must keep as close possible to the left hand bend, possible riding on the second bend apex. However on the exit you have to wait for the car to straighten up before you can start to accelerate again.

If oversteer occurs in the chikane, you will need to release the footbrake and even apply light acceleration to stick the car to the road. If understeer occurs, you will need to do to opposite, and decrease acceleration/increase braking pressure, without turning the wheel even more.

The common mistake is to misjudge entry of the chikane, by speed and approach, making for a slower exit than possible, or to try running flat through the tighter chikanes.

Indication of success is that the car is not shaken through the chikane and exits it quickly.

Turn by-turn guides

See Also: Track Turn by-Turn guides

A race driving practice carried out in the Pisti track near Izmir, Turkey, and a BMW HPDE lap

Here follows guide that will take you corner by corner through different tracks. Thier instructions might not be synchronized with the suggest approaches, but they are very good still. It's advised that you read at least one of these guides fully and comprehend them, for the sake of better understanding of the racing line through complex cornering sets.

You will find tons of guides under the "turn by-turn" guides article, but these are some of the most informative and important:


Summary

Not all corners are made alike, thus the driving habits in driving through them, are changing. The protoype of a cornering line begins by turning from the far-end and diving into the inside of the turn roughly at the center of it, from wherehence the driver begins to accelerate while progressively undoing the steering and letting the car track back to the outside edge of the road. You pay for the whole track so, where it is advantagous, use the whole track.

Your natural instinct as you see the corner coming is to turn early, making the turn more gradual and fast, but having to tighten it up at the APEX, losing whatever advantage you earned by turning in early. Instead, wait and turn-in later, later than the geometric line. Yes, this would be slower into the corner, but you could accelerate faster going out. A few milleseconds into a turn is nothing compared to a several seconds over the hounderds of feet covered over the following straight. Since corner entry speed and corner exit speed are often contradicting, go "Slow in, fast out".

This whole dogma, of course, depands on the exact type of corner involved. Fast curves are usually negotiated by the geometrical APEX, rather than the later one, while very tight corners are negotiated by an even later APEX and without turning-in as progressivelly, but rather by turning-in at once from the outside of the turn.

Trails:

  • "I will enter my corners slowely and late enough to make an effective exit"
  • "I will work with weight transfers to make cornering more effective"
  • "I will be smooth and accurate to avoid unnessecary forces being loaded on the car"
  • "I will experiment with lines over winding mountain roads and practice effective driving lines"

External links