Racing in the Rain.

While driving the fastest in dry weather conditions can be hard to attain, the ability to be competitive in the rain, is one of the signs of a truly gifted racing driver.

Water either on the track, or in the air can dramatically affects visibility, while also can change the approach of racecar set ups and driving techniques. We need to approach each one of these separately to be competitive, while racing in the rain.


Racing In The Rain Components.

Visibility in the Rain: the ability to see the track ahead and changing track conditions, wet weather racing lines and potential hazards are critical. Clear visability will increase dirver confidence and pose a big advantage over misty eyed competitors.

Racing Car Set-Up in the Rain: dry weather racecar set-ups will not be as competitive as tried and tested wet weather configuration.The rain will affect tyre selections, suspension tuning configurations, aerodynamic profiles ect. This is why it is critical to optimise your set up for the rain, if you want to be at the front of the pack.

Driving Technique in the Rain: the traditional racing line will not always be the fastest way round a racetrack in wet weather conditions. Overall traction is reduced and depending on the the race and set up, including tyre selection, you will need to modify how you drive for maximum lap times.

Table of Contents: 

I would go as far as saying that visibility is going to be the most important factor while racing in the rain. It will affect both car control and safety of avoiding potential hazards on the track. Next up is the actual racing car set up for wet weather conditions- this will ultimately affect the overall potential grip levels available on track. Finally comes driving technique, having the ability to use all the potential grip levels and traction available from the set up for racing conditions.

Visibility in the Rain.

As we mentioned in the "Racing in the Rain" section of the website, visibility especially in the rain is one of the most important factors in driving fast in wet weather conditions. Some other the issues with racing in the rain we are stuck with, others we can change.


Visibility issues we are stuck with:

Spray from competitors vehicles is a real issue and comes into the stuck with category. With closed wheel race series this is still an issue but with open wheel race series this becomes a real problem. Open wheel racing cars tend to create a huge spray as they drive through surface water on the track, lifting it off the ground and producing a mist effect with lingers in the air. This is especially bad at the back of the pack following all the other competitors on track, which contribute to the mist effect. The top runners may have less of an issue with visibility from other cars on the track, but as the race develops they are likely to encounter slower moving traffic and will still be subjected to this issue. It is pretty much the same for all competitors and there is very little, if anything we can do about this.


Visibility issues we can change:

things we can do to enhance visibility issues can include keeping our racing helmets visors and windscreens mist free. Full race helmets in wet weather conditions, are an ideal environment for mist and fogging to occur inside the helmet visor or windscreen. A combination of warm and humid  air inside the helmet visor and cockpit, plus the addition of warm air from breathing and body heat, further contribute to the situation. Especially when it comes in contact with colder air situated outside the helmet visor or cockpit, an ideal recipe for low visibility

In regards to minimising the misting and fogging effect, there are a few possible solutions to the problem. In closed wheel racing, retaining some of the ventilation system from stock specifications, can help to defog the windscreen and is a viable option. With regards to the helmet visor, especially in open wheel racing, even just leaving the visor open with a small gap can aid in keep mist and fog levels in check.

Other ways to keep combat poor visibility issues can come in the guise of coating the surface areas prone to mist and fog, in specially formulated chemicals. These coating can help to combat the situation totally and some even have the effect of letting water bead off rather than sitting on surfaces too long. The outside of the visor in open wheel racing, normally does not have this issues of water sitting on the visor as much due to the high velocity airflow hitting the visor at speed- start lines, pit stops and low speeds are still going to have some impact though. 


Tear off strips in wet weather racing might causes a problem, especially in large downpour situations, this is caused by water getting between the layered strips, having a big impact of visibility Also experimentation with different coloured visors could aid in visibility, depending on the racing regulations. Avoiding darker coloured visors, which are more suited to high light levels and will have a negative effect in low light situations, fitting a lighter colour like yellow could have an effect of heightening contract for example. Specialised helmets visors with heating elements incorporated into the design are also another option. These work by passing an electrical charge through the visor element, normally from a battery supply, creating de-misting and anti-fogging functionality.


It does not have to been specialised equipment or engineered chemical compounds, there are a few low-tech solutions which can be just as advantageous. Keeping a towel, sponge or even chamois in the car (where practical), can be useful in closed wheel racing. Even the good old squeegee, maybe with extended handle could be used to good effect, in between gear changes, or on the straights for example. At the end of the day, it does not matter if these low-tech solutions do not scream racing driver, anything which works and increases visibility should be the aim of the game.

 Racing Car Set-Up in the Rain.

In order to maximise traction levels for the tyre´s contact patch, when racing in the rain- dry-weather set-ups are not going to do, as reduced grip and slippery conditions need their own specific configuration.

Tyre sections, suspension tuning configurations, brake bias, engine tune and even aerodynamic down force levels are are critical to be competitive in the rain. This is because overall wet weather conditions reduce acceleration, braking and cornering loads and adjustments are needed to compensate.


Rain Tyres:

One of the first decisions for the racecar set-up in the rain is tyre choice. This will depends on your racing format and regulations, if wet weather tyres are available, or if your have to run street tyres, semi-racing tread patterns. In dry conditions, maximum grip comes from having more rubber on the track, but this is not the case when racing in the rain. Due to standing water on the track, the tyre needs to expel enough water via the tyres contact patch pattern, in order to stop aquaplaning (hydroplaning). Otherwise grip will be dramatically reduced and it will feel like you are driving on ice.


Rain tyres are designed to provide ultimate grip in wet weather conditions, being able to operate in cooler conditions- the construction is normally from softer rubber compounds which operate in these temperatures, than traditional racing slicks. There are also different tread patterns depending on the actual rain tyre, with more aggressive tread patterns for full wet weather conditions (less rubber). Or there is also intermediate rain tyres which will be designed with treat patterns half way between full wet (aggressive tread pattern) and a full slick tyre (maximum rubber for grip). Intermediate rubber compounds will be slightly harder than full wet tyres, but not as hard as a dry weather slick tyre.


Intermediates rain tyres are normally used in conditions of light rain or drying track conditions, where only partial parts of the track will be wet. They are designed to only operate in these conditions, if the track conditions change in any way (drying out or getting wetter), there maybe be a point when a tyre change will yield increased performance. If the track gets too wet, the intermediate tyres could start to aquaplane as the tread patterns are not as aggressive as a full wet tyre. If the track starts to dry out, due to the softer compounds used in both intermediate and full wet weather tyres, designed for colder conditions. The tyre will overheat quickly, with increased wear rates, with greater possibility of construction failure and even the chance of tyre chunks being ripped of from rotational forces of the wheel. In situations where the weather conditions are unpredictable, it might be worth keeping existing tyre selection in place and driving through puddles to keep the tyre temperatures in check. Otherwise the only option will be to make the tyre change and hope your selection will be right for the conditions.

In race series where there is not tyre selection for wet weather racing, the only option will be to use existing tyres which are allowed, with maximum tread depth e.g. ones which have not be scrubbed in or shaved for dry conditions. Also an increase in tyre pressure has been shown in the aeronautical world on air plane take off and landing, to increase tyre traction through heavy standing water. This is because the aquaplaning speed of a tyre increases at the square-root (multiplied by a constant) of tyre inflation pressure.

 

Rain Set-Up.

Due to the fact that in wet weather conditions the race track is constantly evolving or changing, a pure wet weather set may be recommended, in changing weather conditions. Let me explain further, a dry weather race set up will be optimised for the dry, but will perform adequately in the rain. On the other hand, a full wet weather rain set up will be optimised for the wet but will not perform well in the dry.

Unless the weather conditions are constantly wet and not changing throughout the race, a wet weather set up for the rain will be compromised. If the track is drying out in any way, it will not be advantageous for a wet weather rain set-up. Due to the fact that racecar set-ups and designs vary so much, what might work fro one car, may not work for another. Having said that, there are some adjustments to varying degrees, which will improve wet weather racing conditions. Lets explore the different adjustments we can make in more depth.


Brake Bias:

Generally speaking wet weather brake bias can be adjusted universally to many different racecar designs and configurations, with the same effect. Like most things when it comes to racecar set-ups, the exact adjustments levels can only be found by testing and experimentation. As there are reduced grip levels in the rain, it is safe to say that deceleration and braking forces will be reduced. This means that less braking forces and forward weight transfer are present in racing in the rain. Logically the brake bias setting of a racecar in the rain, should be set more to the rear to compensate for this (versus a dry weather set-up). This should be done in small increments, as it is better to be safe than sorry. Locking up while approaching a corner fast, can be daunting in the dry, let alone in the rain with reduced grip levels.


Rain Suspension Settings:

Softer suspension settings of the springs, dampers and anti-roll bars (sway bars) are favourable in wet weather conditions. The reason behind this can be broken down into the following two concepts-


1. Traction is reduced in slippery raining conditions, by being able to find the the limit of grip more slowly and progressively- it is easier to retain and maximise car control on the track. Softer suspension settings enable us to do this, with gradual weight transfer rates. Roll and pitch of the suspension system and chassis, increases with softer suspension settings- enabling tyre loading to be more progressive. Overall it lets the driver find the limits of grip and adhesion, in a tip-toe fashion, rather than quick and full-on responses.


2. Reduced traction in the rain will also mean that there are less forces acting on the vehicle under acceleration, braking and cornering forces. Cornering forces have the biggest loses in the rain, compared to acceleration and braking. By reducing the suspension settings (making it softer), it is possible for the same amount of suspension component travel to happen as in the dry with stiffer suspension, but with reduced forces acting upon them. Camber suspension settings for example, rely on the cornering forces of roll to be present, for the optimum settings. Softer suspension settings while racing in the rain, can achieve these levels with less forces on the suspension components.


Engines and Rain:

The racecar engine can be effected by the rain and wet weather conditions, especially Petrol engines (minimal if any effect for Diesels). The ECU (electronic control unit), ignition and other vital components which rely on electrical or electronics, don´t like water introduced into the system. While most racecar and road cars have been designed with this in mind, it is still important to isolate or protect the engine compartment and associated devices as much as possible from damp and moist conditions.

Induction or Ram-Air systems are also at risk from rain, if water enters the intake air system and manages to get into the engine, there is big trouble ahead. A great dry weather set up for forcing fresh clean air to feed the engine can be a potential weakness for reliability in the wet. It is important not to have direct spray of any kind, affecting these systems and relocation of these components might have to be a consideration, or repositioning during rainy races.

Another point to bear in mind with racing in the rain is throttle response. Depending on the exact available adjust-ability of the current configuration possible, e.g. via the ECU and engine management system (electronically), or with the throttle cable (mechanically)- it is best to have a less aggressive throttle response than you would normally in dry conditions. 

This is especially true for car with big BHP and torque figures, which tend to have the ability of generating huge acceleration forces through the tyres. If there is very little throttle movement requirements to go from idling to full throttle, wheel-spin will be difficult to modulate with throttle response in the rain.


Gear Ratio:

Gear ratio set-ups for racing in the rain is a much debated subject, and there are two schools of thought, depending on driver preference in most cases.


1. It could be said that using a higher gear ratio than normal can aid in reducing wheel-spin This is a recommended driving technique for driving in the snow for example, where grip levels are reduced.


2. The other common idea is contradiction to the first in that you should lower the gear ratio. This provides better throttle response and control, with the other advantage of straight-line acceleration increase.


I feel that it personally depends on a few factors, one the actual weather conditions, light rain and hard rain or in between; the actual driver preference and driving style, also the strength and weaknesses of the racecar. Horses for courses comes to mind, with the driver preference leading the way on this one I believe Ultimately which ever way you look at the options, you will benefit from having a gear ratio with the best RPM´s to provide maximum power with the right level of control for wheel-spin.

Driving Technique in the Rain.

The traditional dry racing line is all about maximising corner speeds, through driving the biggest radius possible, to get the highest top speeds on the straights. While driving in the rain, all that can go out the window and you must drive for maximum traction- the dry line may not yeild the fastest lap times.

This can at times be a combination of the tradition dry line with the largest radius for corners, or even be a line which requires taking the dry part of the track with the most grip- this may mean you drive around the outside of the corner. Add to the equation that the race track conditions can normall be constantly changing, with the the track either getting wetter or drying out. What might of been the fastest lap possible on one lap, could easily change the following lap.


Lets have a closer look at why the traditional dry line may not always be the best path to take while driving in the rain.


Road Camber:

On the track were camber or banking towards the apex of the corner is present, two things tend to happen which affect the rain racing line.


1. Due to the fact that the apex is the lowest part of the track in this layout, water collects at this part of the circuit and tends to create deep puddles. Depending on the tyre selection and the actual puddle depth or standing water levels, driving through the normal apex could result in a total loss of tradition in extreme cases. When this does happen, it does not matter how large a radius you take to negotiate a corner, all cornering forces and traction may be zero. This is caused by aquaplanning, where water builds up under the tyres contact patch, separation the rubber compounds from the track surface- resulting in a total loss of traction and directional control. In this situation you will slide across the water until traction is regained, modifying your driving line will yield better lap times.


2. The outside of the track will be the opposite of the first scenario, with corners with banking and camber towards the apex. Water will tend to run away from the outside of the track and towards the apex, being helped by the camber and banking. This means that the outside of the corner (rim), will most likely yield the best traction potential and fastest line through the corner.


The two points we have just looked at for driving in the rain with cambered and banked apex´s, are not the definitive rules for wet weather conditions, it is used as an illustration how the dry line may not always be the best line all the time. As previously mentioned before, the track conditions will most likely be constantly changing, depending on weather conditions. There maybe times when the fastest lap times possible will be in between the tradition dry line at the apex of the corner (inside of track) and around the outside of the track. Or with a quickly drying out track, with full wet weather tyres fitted, you would want to drive towards wetter parts of the track in order to cool the tyres.


Road Wear Rates:

The traditional dry racing line will have been driven over more than other parts of the race track. This in dry weather conditions can be extremely advantageous for traction, as more and more rubber from traffic is layed done, layer upon layer, you get the effect of the track rubbering in. As the race progresses this "rubbering in" continues to aid traction, with the traffic on the racing line depositing even more rubber on the track surface. This has an effect of filling in the small track irregularities with the rubber deposits, creating an ideal environment for rubber to work in. This is great for the dry but very problematic for racing in the rain.

When it begins to rain, all the "rubbering in"  starts to get washed away, nullifies the advantage seen with dry runs. This leaves a highly polished track surface underneath on the traditional dry racing line, compared to other areas of the track which are subjected to less wear. As there are higher wear rates on parts of the track on the dry racing line, when it rains water tends to just stand there and not drain away, as seen on more porous parts of the track. This combined with all the oil, anti-freeze and other track containments washed off the track, now tends to settle where the water does, creating a big problem for grip levels. Effectively causing the traditional racing to become undrivable.

Generally speaking darker or duller areas of the race track in the rain, tend to reward the driver with more grip. They have been less worn down than other parts of the track and are more porous. Lighter or more polished parts of the track, tend to be more slippery and could retain deeper standing water. The outside of the race track, or off dry line sections, tend to be more porous and water can easily drain off them, also there tends to be less track containments present, when it does start raining.


Rain Corner Driving Technique:

When driving in the dry, we use the tachometer to help us see corner exit speeds, with different line applications. Ultimately which ever racing line we take which yields the best corner exit speeds, is the one to take. This is no different in the rain and due to the nature of constantly changing track conditions, if the corner exit speeds start to change on your chosen racing line- it is now time to modify your driving style. Grip levels on the track will be changing and it is time to start experimenting with the now new track conditions.


Outside Corner Driving Line:

Especially effective on long sweeper corners or hairpins, with lots of cornering forces required or a longer time period. As cornering forces on the dry line are reduced, even if the corner is taken at a bigger radius, the more time spent cornering at higher speed results in reduced lap times. The outside of the track is grippier and lets the tyres work with more grip to generate lateral cornering forces, reducing time spend negotiating the corner. Higher corner exit speeds translate into more top speed on the straights, reducing overall lap times.


Late Corner Turn-In:

With shorter and tighter corners, the advantages of the outside corner line driving technique in the rain, becomes less effective. This is because the amount of time spent cornering is greatly reduced. In this situation it would be better to utilise available grip for braking and acceleration to maximise lap times with the lower and shorter time spent cornering. By braking slightly later and harder, corner turn-in speeds are reduced, meaning we can straighten the car up quicker. This gives the advantage of earlier throttle application, in a more aggressive nature, as all grip can be used for acceleration once the braking and cornering is completed. This technique realises on the driver turing the short and tight corners into a series of braking and acceleration zones, with slow speed turning linking it all altogether.

Both of the two rain driving techniques explored with involve crossing the tradition dry racing line at some point. Smooth progressive steering, braking and throttle application is required to minimise the potential of spinning out in this situation.  It is also critical to take into account racetrack surface materials and overall layout into the equation. You rain driving technique could may well be a combination of "outside line" and "late turn-in", also combined with the traditional dry line. Depending on how the weather conditions continue to have an effect on track conditions, this can change from corner to corner and even be different on each individual lap.


Rain Straights, Driving Technique:

While driving on the straights in the rain, it is possible to get wheelspin, even in low powered cars. The traditional dry line will not do in this situation, as you might of guessed adjustment of your driving style might be in order. It is always best to drive on the driest part of the track, if even if it does put you out of position for the pending corner. This might not seem a logical manner to go raining in the rain, but we will see why this is the case. 

Hitting standing water at speed, has a dramatic braking effect on the car, let alone the possibility of aqua-planning. If one tyre, or side of the car is subjected to this situation (hitting a puddle), a spin is the most likely outcome, especially at greater speeds. If you have no choice and have to hit standing water, it is best to approach it square on if possible. That way you may skim over the surface water and have a chance of pointing in the right direction, having driven through it. 


Rain and the Braking Zone:

Traditional braking zones are most likely to be different when racing in the rain. Again weather conditions, track surface materials and race track layout will determine this. 

It comes down down to the fact that the racing line in the dry will again have the highest wear rates. In the braking zone this shows itself as ruts in the race track, which tend to be filled with standing water in the rain. Much like the dry line apex when it is raining. Ruts filled with water in the braking zone will greatly affect the racecars ability to brake effectively. If you can adjust your driving style to position your tyres on the crown of the braking zone ruts, and not in the troughs as they will further limit braking force potential.


Overtaking in the Rain:

Overtaking in the rain is especially difficult, but is not impossible. Not all drivers are the same and some are less effective at reading ever changing track conditions, especially with a evolving racetrack. You can use this knowledge to your advantage, keep your driving style as cool, smooth and consistent as possible. Patience is definitely a virtue in this situation and can mean the difference from finishing the race or not.

Caution must be taken when even attempting to drive off the driest line, grip will be greatly reduced and this path will pose greater risk. Spinning out in the rain is a real risk, especially of the wet line, putting pressure on the car ahead can be a good tactic to use. The driver ahead could be forced into making a mistake, in the heat of the moment, opening up the opportunity to overtake and gain that much awaited grid place.

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