Braking is the process which brings about deceleration in the car. The technology incorporated in Formula 1 cars is very close to the technology that powers the brakes in modern road cars that we drive; except for the materials involved. All the cars on the grid now use carbon fibre composite brake discs which save weight and are able to operate at higher temperatures than steel discs. A typical Formula One brake disc weighs about 1.5 kg (versus 3.0 kg for the similar sized steel discs used in the American CART series). These are gripped by special compound brake pads and are capable of running at vast temperatures - anything up to 750 degrees Celsius. Previously different sized discs would be used for qualifying and racing, but the 2003 changes to the rules means that all cars enter parc ferme after qualifying - and so therefore set their one-lap time on their race brakes.
Formula 1 car has incredibly powerful brakes and can slow down from 125mph to a standstill in just 55 meters. This process takes 1.9 seconds and generates deceleration forces of up to 5g, making the driver feel five times his normal weight which is enough to force teardrops from driver's eyes. During normal street driving, cars tend to brake early to be safe but this is exactly opposite of what is followed in racing. Braking is very late so as to gain maximum advantage in terms of time. Hence the braking system needs to be very effective and precise. In physical terms we can state that energy is the power to do work. When a Formula 1 car comes down a straight line at 300 km/h or more, that car has lots of kinetic (movement) energy. Due to the fact that energy does not get lost, but can only be transformed one kind into another, at braking most of the kinetic energy is transformed into potential energy, more specifically heat and light. During braking, the carbon brake disks, which are used in Formula 1, heats up to 1000 degrees centigrade in one second and glow red hot. Formula 1 cars have carbon disc brakes with rotating discs (attached to the wheels) being squeezed between two brake pads by the action of a hydraulic calliper. Too much braking through a wheel will cause it to lock as the brakes overpower the available levels of grip from the tyre. Formula 1 previously allowed anti-skid braking systems, which works by applying and releasing pressure on brake discs very rapidly to stop wheels locking up and to allow the driver to maintain steering control, but these were banned in the 1990s. Braking therefore remains one of the sternest tests of a Formula 1 driver's skill.
FIA regulations for Formula 1 brakes
Formula One cars must have one brake system operated through a single brake pedal. However, the system must comprise two hydraulic circuits - one for the front wheels and one for the rear. Should one circuit fail the other must remain operational. Power brakes and anti-lock braking systems (ABS) are not allowed.
Each wheel must have no more than one brake disc of 278mm maximum diameter and 28mm maximum thickness. Each disc must have only one aluminium caliper, with a maximum of six circular pistons, and no more than two brake pads.
The size of the air ducts used to cool the brakes is strictly controlled and they must not protrude beyond the wheels. The use of liquid to cool the brakes is forbidden
Formula 1 tyres don't have air in them like normal car tyres. Most racing tyres have nitrogen in the tyres because nitrogen has a more consistent pressure compared to normal air. Air typically contains varying amounts of water vapour in it, which affects its expansion and contraction as a function of temperature, making the tyre pressure unpredictable. To avoid this, the tyres used in Formula 1 cars are free of water vapour, as a 20% Tyre pressure drop reduces tyre life by 15%. During the race the tyres lose weight! Each tyre loses about 0.5 kg in weight due to wear.
Formula One tyre for dry surfaces measures 660 mm in external diameter and 350 mm wide, containing four longitudinal grooves of at least 2.5 mm imposed by the Depth Regulations. These grooves are symmetrically placed from the centre of the tyre tread and spaced 50 mm apart.The dry surface tyre is a completely new concept, introduced to Formula 1 with the sole aim of reducing the size of the ground contact area, i.e. the surface which ensures grip, resulting from the contact of the rubber compound and track. The aim of the regulations is to reduce the speed of the cars on corners. Their life varies between 80km to 200km depending on the type of the compound used and temperature.
Intermediate tyres are used under fine to moderate rain to ensure maximum grip, when the use of Wet Tyres is not deemed necessary.They have a special role on a drying track, they must evacuate the film of water but also remain competitive on the dry without deteriorating too much. The life of a Intermediate Tyre is extremely variable depending on the track temperature.
Wet tyres must evacuate the water that infiltrates between the tyre contact area and the track. If the film is great, then the tyre loses grip and this results in aquaplaning. These tyres can be used for the entire length of the race and from temperatures between 30 degree Centigrade and 50 degree centigrade.
The Formula 1 car utilises the Bernoulli principle to realise the massive downforce, which keeps the car on the tracks despite the mindboggling speeds which Formula 1 cars achieve. The Bernoulli principle describes the relationship between the velocity of a moving fluid and the pressure exerted by it.The principle states that:
"For an ideal fluid, with no work performed on the fluid, an increase in velocity results in a simultaneous decrease in pressure, or a change in the fluid's gravitational potential energy."
The equation is given by:
v^2 + gh + P/p = constant.
where v is the fluid velocity along the streamline.
g is the acceleration due to gravity.
P is the pressure
p is the fluid density
Figure 1 relates the speed of a fluid moving through a pipe to the cross sectional area of the pipe. It says that as a radius of the pipe decreases the speed of fluid flow must increase. This leads to a resultant decrese in pressure.
Aerodynamics plays a very important role in Formula 1. The high speeds lead to a drag, which increases with rising speeds. The drag encountered by the formula 1 car is proportional to the square of the velocity of the car.More the speed, greater is the drag encountered. Therefore the car is streamlined, so as to minimise the drag. Most drag is caused by eddies in the fluid behind the moving object, and the objective should be to allow the fluid to slow down after passing around the object, and regain pressure,without forming eddies.
The high speeds achieved by the formula 1 cars render it difficult to keep the car on track, especially while negotiating turns.It works in the same way as on an aeroplane, but in reverse. The surfaces of the wings have a different shape on the underside, so the air flows faster underneath, where it has a greater distance to travel. Thus, the air pressure on the underside is lesser than the air pressure on the opposite side. This results in the necessary downforce. Thus, the required grip and high cornering speeds are achieved and the Formula 1 car stays perfectly on line even under centrifugal forces of 4G, whereas a passenger car begins to slide at just 1G, even if it has a sport-type running gear. So the great art of aerodynamics is not only to allow excellent performance, but also to improve safety. Windtunnels form an integral part of Formula 1 engineering.
