Understanding F1 chassis

The chassis is the central structure of the car, the part that the engine and suspension are bolted on to and the part that the driver sits inside. It’s usually referred to as the tub because that’s what it looks like before you bolt all the stuff onto it.
Formed from carbon fibre, the chassis has to be strong to withstand repeated downforce loadings (the weight pressing down on the car as a result of the airflow over it) of over 2,000kg, yet it weighs only around 30kg. If the chassis were insufficiently stiff, the car wouldn’t be able to translate the aerodynamic loadings to the tyres. Stiffness combined with low weight – two conflicting requirements – are the keys to a good chassis. The chassis is manufactured by laying up sheets of carbon fibre with a bonding agent in the shape required via a mould. This is then “cooked” in an autoclave (think of it as a big oven). You may think that a Formula One driver would rather not trust his life to something that sounded like it had been put together more like a cake than a car. An understandable concern, but you’d be wrong. The material provides much more protection in a big impact than the aluminium from which a Formula One chassis used to be made. Stress analysis tells the structural engineers precisely where the strength needs to be in the chassis, and so extra layers are incorporated at key points, such as suspension mounts. Getting the necessary stiffness is extremely difficult when the structure has to include one great big hole for the driver to sit in and another one for the fuel tank. But the engineers manage it; that’s what they’re paid the big bucks for.
Technical regulations require the chassis to have a flat floor (so limiting the amount of aerodynamically-induced grip). Regulations also specify minimum cockpit dimensions and minimum space requirement for fuel tank size (which is driven by how many laps the car needs to do on those tracks that induce the heaviest fuel consumption). Within those constraints, the chassis has to be as compact as possible to keep its frontal area, and therefore its air resistance, down.