The chassis is one of, if not THE most important part of an F1 car. The design process generally starts in July of the previous season, and is crash tested at the beginning of the next year (generally mid-late January, early February). The chassis must conform to bodywork, strength, flexibility regulations. Everything bolts to the chassis. The front suspension is placed in a little compartment about 4 inches in front of the drivers’ feet, the brakes, the fuel tank and the engine are all attached to the chassis.
The chassis forms 2 functions. The first and arguably most important is the drivers’ survival cell. This is the ‘crash-proof’ structure that is safety critical. It must be impact resistant, in a frontal impact it must remain undamaged. The crash structures that are mounted onto the survival cell are the front and side crash structures, the front and rear roll over structures and the rear impact structure is mounted on the gearbox. It must also have FIA specified intrusion panels that stop debris and car parts from puncturing through the chassis and seriously injuring the driver. The material that the intrusion panels are made of is Zylon. These intrusion panels have to pass strength tests which the Haynes Owners Manual on the RedBullRacing RB6 was 1mm/s intrusion for 150seconds. The force that is required to meet this intrusion level is calculated and must meet a minimum requirement. In 2012 the Zylon has to be in multiple layers for extra strength.
The second function is to provide a mounting point for all the mechanical components, and provide good feedback through the suspension to let the driver know what is happening. A bad chassis will inherently flex a little too much and provide poor feedback from the suspension. It will also handle slightly worse, making it inherently slower. If your chassis is bad, then no matter how many mechanical or aerodynamic updates you bring, you will have a slow car. I think this is probably the problem with the HRT. The car seems to have a complete lack of balance, and the drivers seem to have no confidence in the car. It looks completely unpredictable. Narain Karthikeyan said that the car feels as though it has more downforce, and it probably does, but mechanically the car is terrible. It seems to be a very hard car to set up correctly, and they need to have a complete rethink in the way they design their cars.
The fuel tank is situated directly behind the driver, in the chassis tucked between the engine and the back of the cockpit.
The structure of the chassis is very complicated. It’s essentially solid carbon fibre, but rather than being a one piece moulding, it’s actually cast in two halves, which are then bonded together. Each half is made from several hundred plies of carbon fibre, each of which is cut to a different shape, layered in the female chassis mould, and checked against a construction manual before the next ply is positioned on top. The plies are layered in a way that gives the chassis overall strength, but more strength in critical places, such as the suspension mounts and the engine mounts.
Once all plies are positioned correctly the whole assembly is placed in a bag, which the air is then sucked out of to create a near vacuum and then placed in an autoclave where it undergoes a thermal curing, at a set pressure and temperature. The completed halves are bonded together after the curing process is complete. The two surfaces to be bonded together are meticulously cleaned as no fasteners like screws or dowels are used to supplement the bonding.