Some Brief Descriptions

DRIFTING

Drifting is a driving technique where the driver intentionally oversteers, with loss of traction in the rear wheels or all tyres, while maintaining control and driving the car through the entirety of a corner. Car drifting is caused when the rear slip angle is greater than the front slip angle, to such an extent that often the front wheels are pointing in the opposite direction to the turn (e.g. car is turning left, wheels are pointed right or vice versa. This is also known as opposite lock or counter steering). Good and responsible drivers do it on closed tracks, whilst irresponsible and criminal drivers feel free to do it on quiet roads with lots of excessive bends. Please click on the link below to see a sample of drifting taken by me at Nutts Corner Track. Note that the track has been deliberately soaked to increase slipperiness (or reduce friction) . It is also done to help preserve tyre wear  because drifting seriously damages tyres and seriously shortens tyre life. My research shows that drifters often have two sets of tyres, one set for everyday use and another solely for drifting. It is also worth noticing at this stage that the front wheels of the drifting cars are pointing in the opposite direction to the direction of travel.

http://streamable.com/nu9sh

 

As part of my investigation, I employed an experienced drifting instructor from England who visited the scene, studied all the evidence and wrote a detailed Report which I will refer to later in more detail. Suffice to say that, although the corner in question was insufficient to carry out a full drifting manoeuvre,he concluded that the Subaru collided with the Nova in a serious oversteer  configuration. He will also say that drifters often fit uni-directional tyres backwards, not to make drifting easier, but to preserve tyre wear. He does so at his own drifting school because of the cost savings.

Later again, I will detail Reports from Bridgestone Tyre Company Canada, a full Report from a senior tyre researcher from Goodyear, another Report from an engineer from Europe’s leading tyre trader along with other expert views.

Neither the PSNI nor Forensics ever properly researched the use of reversed uni- directional tyres in the wet let alone the tyres fitted to the Subaru. Either they couldn’t be bothered or they didn’t want to know the truth lest it would reflect badly on themselves or on Carson.

Uni-directional Tyres

These are tyres that should only be fitted in one direction onto a car. The direction is indicated by an arrow and the word Rotation as demonstrated in this photograph.

Unlike the multi-directional tyre used on most family cars, if this tyre is fitted against the direction of rotation there is a serious loss of adhesion between the tyre and the road surface. This applies only if the road is wet and not if the road is dry. The degree of deterioration of grip is varied  depending on the amount of surface water, the depth of tread remaining and the speed of the vehicle. It is recommended that these special tyres should be fitted only by an experienced fitter.

The uni-directional tyre was brought into use to overcome a problem with modern sporty cars such as the Subaru Impretza driven by Carson. It was found that the new wheel width and flatter profile fitted to such cars could not disperse the water on the road surface fast enough to ensure that the rubber of the tyre was in contact with the road surface. Research found that these tyres needed a special tread pattern.  A channel which pointed rearwards to the direction of travel was the most successful way to disperse the surface water. This in turn meant that the tyre itself could only be fitted in one direction, otherwise the channels would tend to fill up with water instead of dispersing it. This in turn would decrease the speed where aquaplaning could take place, or the speed at which the car would skid and control could be lost.

The water channels are facing rearwards to clear the channels. If the tyres are reversed then the road water will tend to be forced into the channels and turn the tyres into a slick surface. It is less simplistic than I have  described but, in my defence, there are hundreds of scientists around the world working to fine tune these tyre patterns to achieve maximum grip with many possible combinations. To see the effect of slick tyres on wet tracks just watch the next F1 race when a sudden downfall hits a dry track. The race cars slow down and gingerly make their way back to the pits to change to wet weather tyres. Some might even crash on the way back to the tyre change.

Uni- directional tyres are fitted on most motor bikes and scooters and the simplest pattern can be seen on the rear wheels of a Tractor! You might ask a farmer what happens if he has to reverse a tractor  across a muddy field. The channels will soon fill up with mud and the wheels will proportionally lose their grip. These are just two examples of uni-directional tyres. I might ask Forensics and the Police, who insist the tyres are irrelevant if they think they know more than a vast team of dedicated scientists. I’m sure they don’t.

Aquaplaning

This term is used when a layer of water forms between the surface of the car tyres and the road surface, breaking the contact between the car tyres and the road. When the car begins to aquaplane, its tyres lose contact with the road and the car stops responding to control inputs such as braking, steering and acceleration.

Tyres also fulfil the duty of helping the car grip onto the road through corners. The grooves in them are designed to dissipate water that is on the road. If the volume of water on the road is greater than the volume of tread on your tyres, there will be a surplus of water which cannot be dissipated and the car can start aquaplaning. If  the tyres are reversed against the direction required by the design of the tread, then the risk of aquaplaning is increased as the tread depth is decreased as the channels fill with water which is noncompressable. My tyre expert in Canada estimated in his Report that the loss of traction of the reversed tyres in the Subaru could be up to 48%.

In the next post, I will deal in greater detail with Carson’s second verbal and second written statement. I will also detail the  extent of the PSNI response to my well founded concerns about the falsehoods in their initial investigation.

 

 

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