Chassis construction

Since the early eighties F1 cars have been produced in carbon fibre and honeycomb composite. The processes and constructions have altered over the years.

First pioneered by McLaren and Lotus two paths were adopted. Lotus created a large flat sheet of carbon fibre and laid over the alloy honeycomb topped with another layer of carbon fibre, this large sheet was then cut, routed and scored, to enable the entire piece be folded up around the bulkheads to form the enclosed chassis shape. This format allowed a low tech approach to gaining the benefits of a carbon fibre chassis.
McLaren using a US aerospace partner (Hercules) created the tub with a mould. Laying up the plies around a male mould, before alloy honeycomb and a second carbon skin were applied to the outside of the sandwich. Two moulds formed the top and bottom half and were bonded together around the bulkheads to form the final chassis. As the hard points for the suspension mountings needed to be accurate and as they were to be attached to the inner skin\bulkhead, the chassis was moulded inside out, as explained earlier the male mould was used to lay up the inner skin directly against the mould, so removing any variance sin sandwich thickness form the final suspension geometry. This resulted in the outer skin being laid up against the honeycomb and not a mould face, hence the outer finish of these chassis were relatively poor.
Other teams soon followed the carbon fibre chassis route almost entirely adopting the McLaren moulded route. Then for the 1983 ATS D4 under the technical direction of Gustav Brunner, made a female moulded chassis taking advantage of the neater external surface of the moulded chassis, by also making the monocoques outer skin the primary bodywork for the car and discarding separate bodywork for the large part of the front of the car. Ferrari adopted this design soon after for their first full carbon chassis, the 126C3. Meanwhile other teams adopted female moulded chassis but still using separate bodywork.
For the large part of the following seasons two part moulds forming upper and lower halves of the chassis were used. Towards the end of the nineties the changing shape of the chassis and the stress placed along the centre line of the car forced the designers into splitting the chassis into a main tub moulding and capping it with a smaller floor moulding. During this time metallic bulkheads were discarded and replaced wit either a carbon\Honeycomb bulkhead or the requirement for the bulkhead deleted completely through the adoption of Finite Element Analysis (FEA) techniques substituting the bulkhead for thicker plies of carbon fibre on the chassis skins.
Finally moving into the millennium teams required to make much more complex chassis shapes broke the tub up into several sections, as described with BAR004 (2002) chassis in the following pictures (apologies for the quality as they were taken through the window..!)









The chassis comprised:
Top front section
Fuel tank\roll over section
Full length lower section
Seat back
Rear bulkhead
(N.B. No other bulkheads were used in the BAR004)

Renault explained their forthcoming R24 (2004) chassis design and explained they have formed the tub from a deep lower section topped with shallower left and right moulding for the top of the chassis.