There must have been times when they thought it would never happen, but James Morton and the folks at G Force Precision Engineering at Fontwell have now completed their part of the ThrustSSC build programme. At times it has almost taken over the lives of those working on it, and has quite literally taken over an increasing area of the G Force workshops. So that's it as far as G Force are concerned with the major build program. The biggest car they have ever built leaves the premises where it was constructed for the short journey north towards London and its new home. As a company already highly experienced in the race car industry, they have plans to step up their involvement still further and recently announced their intention of making good use of the composites workshop set up to build the nose and engine cowlings for ThrustSSC by building a chassis for the newly formed Indy Racing League (IRL). So in future years when you watch the cars screaming around the banked turns of the Indy 500 on TV, look out for the G Force name, the company that built the world's biggest and most powerful car. But it doesn't end there, for while this has been going on, Jeremy Bliss has been leading the work to design and install the systems that will breath life in this 8 ton giant. Here's some of the work that has been going on.
The principal philosophy behind ThrustSSC is a safe car which goes fast and not a fast car which is safe. In order to achieve this goal ThrustSSC has been fitted with a broad range of systems which, while interlinked, are not interdependent. The systems also overlap one another in function, thus one system (or in critical cases, more) can fail without compromising the safety of the car. This layered system approach combined with the lack of interdependency makes ThrustSSC the safest vehicle ever designed for attempting a land speed record.
ThrustSSC has two on-board computers designed by Lotus Engineering which are linked to all the vehicle sensors, the engines, the fire system, the instrument panel, the active suspension, elements of the passive suspension, the abort system and finally the parachute system. The computers also monitor, via the sensors, the brakes, the structure the aerodynamics, the engine condition, the wheel bearings and finally each other. If the computers should fail then there are mechanical and independent electrical systems which can initiate the function of safety critical parts of the system. Loss of the computers does not mean loss of safety. ThrustSSC can survive even after a full electrical and hydraulic failure.
The fire system, designed and constructed by Kidde International's Les Garden and Andrew Hills comes in two parts, a vehicle protection system and a driver protection system. These systems while separate have the same basic components, extinguishers and a control unit. However, while the vehicle system uses fire wire for detection, the driver system uses an optical infra red device.
The diagram above shows the arrangement of the basic components. The core of the system is the controller designed by Andrew Hills. On start-up, the fire system initiates a self test where the pressure sensors are checked to ensure the extinguishers are charged, the fire wire loops are checked to ensure they are complete, and the cartridges on the extinguishers are checked to ensure they have not been fired. The cockpit lights are also illuminated for a short while to ensure the bulbs are working. If any fault is detected then the cockpit fire lights are flashed continuously for 30 seconds. In the event of fire during the run, the fire wire loops will be heated by the flames. This will cause the wire's electrical properties to change. It is this change which is detected by the control system. The system then illuminates the appropriate fire caption in the cockpit. Andy Green can now fire the appropriate extinguisher by pressing the lit caption. If the fire is successfully extinguished then the fire wire will cool and the cockpit caption will go out.
The placement of the fire wire has been left in the experienced hands of Kidde International's Les Garden who has ensured that the fire wire is in the optimum position for detection. Finally in the event of a crash an omni directional inertia switch will fire all the extinguishers. The vehicle protection system is intended to deal with the fire at source, the sources being the engines and the front Hydraulics and Electronics bay and the rear Hydraulic bay. This part of the system consists of four extinguishers, one for each bay and one for each engine. The extinguishing medium is a non-toxic, environmentally friendly halon substitute. The fire detection is achieved by using fire wire run around critical components in the engines and bays. The driver protection system in principle is similar to the vehicle protection system but is only concerned with the cockpit area of the vehicle. This system requires a different detection method, as it is generally accepted that drivers tend to be more sensitive to heat than mechanical systems. Hence, optical infra red detectors are used to sense cockpit fires. As with the vehicle system once a fire is detected then the cockpit fire indicator light comes on. At this point the driver has a choice of extinguishers. The first is a halon type system as found on the rest of the vehicle. This will deal with any flash fires making the cockpit immediately safe from fire. The second system introduces a water mist into the cockpit area for a minimum duration of 15 minutes. This system maintains the survivability of the cockpit crash cell should for any reason the driver find himself trapped for a time. Finally, the same omni directional inertia switch, which will set off the vehicle extinguishers during a crash, will also set off the two cockpit extinguishers. In fact it is safe to say that the omni directional inertia switch can be likened to a medical student, in as much as its sole purpose in life seems to be to set off fire extinguishers. However the inertia switch doesn't drink as much and is considerably cleverer.
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