|BMW Sauber F1.06|
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Although the most important change to the regulations for the 2006 season concerns the engines - down from ten cylinders to eight and 3-litre displacement to 2.4 litres - there are also far-reaching onsequences for the chassis construction. The V8 power units are shorter, use less petrol and require a smaller radiator surface, which has a significant effect on the car's design. The minimum chassis dimensions stipulated by the FIA ensure that the cars' overall dimensions will remain almost unchanged. The reduced tank capacity of the BMW Sauber F1.06 influenced both the design of the monocoque and the position of the engine. Added to which, the shorter engine allowed the engineers to extend the length of the 7-speed transmission's titanium casing. This, in turn, encouraged the construction of a particularly svelte rear end.
Although knowledge gained from the development of the Sauber C24 has not surprisingly found its way into the new car, the BMW Sauber F1.06 is every inch a new design. The engineers focused in particular on aerodynamics, widening their objectives beyond just optimum downforce to enhancing efficiency as well. The construction, arrangement and design of all the car's sub-assemblies and components were based around these criteria. The front section of the new car has been given some striking new features. The chassis has been lowered considerably at the front, with the effect that the lower wishbones are no longer attached below the monocoque but to the side of the chassis. The nose of the car has also been lowered further to the ground, with its underside curving upwards slightly. Naturally, the front wing has been modified in line with the other changes through a host of optimisation measures. All of these measures help to optimise the air flow around the aerodynamically critical underbody.
The reduced cooling requirement of the V8 engine allows not only the use of more compact radiators, but also smaller apertures in the sidepods. This also benefits the car's aerodynamics. The same applies to the rollover bar with integral air intake, which has been reduced in size due to the engine's lower air throughput. Plus, complex finite-element calculations made it possible to significantly reduce the weight of the rollover bar, while at the same time meeting the stringent safety stipulations. The shorter engine has allowed the rear end of the BMW Sauber F1.06 to become even leaner and more harmonious, ensuring optimum air flow over the rear wing. The exhaust tailpipes have been moved further back from their location on the C24. The engineers used computational fluid dynamics (CFD) to position them in such a way that the hot exhaust gases are channelled around structural components such as the rear suspension and rear wing in the most efficient way possible.
Revolution, not evolution: the Formula One World Championship will not just be welcoming new engines to the fray in 2006, but a whole new generation of engines. Thanks to a change on the regulations, the new V8 units with 2.4-litre displacement replace the 3.0-litre V10 powerplants which ruled the roost last year. Although the V8 with the now compulsory cylinder angle of 90 degrees may look like a sawn-off V10, technically it is an entirely separate concept with its own specific characteristics. The V8 has a distinct firing sequence and requires a fundamentally different crankshaft design. Whereas a 72-degree offset crankshaft was used in BMW's V10 Formula One engine, V8 powerplants can feature crankshafts with either four throws spaced at 90 degrees or four throws spaced at 180 degrees. Standard production cars are fitted with 90-degree crankshaft variants due to their better dynamic attributes, but a 180-degree crankshaft is favoured in racing-car engine design. The improved performance this allows offsets the disadvantages in terms of dynamics.
In addition to the inherent differences in the design of a V8 engine, numerous other specification details contained in the new regulations have sent the engineers back to the drawing board. Lightweight construction principles have taken centre stage. The new V8 has to be heavier than its predecessor, even through the 2005 engine had two extra cylinders. This season's powerplants must tip the scales at no less than 95 kilograms. This should include the intake system up to and including the air filter, fuel rail and injectors, ignition coils, sensors and wiring, alternator, coolant pumps and oil pumps. It does not include liquids, exhaust manifolds, heat protection shields, oil tanks, accumulators, heat exchangers and hydraulic pump.
Mechanical dynamics and vibrations represent a particularly critical area of development for the new generation of Formula One engines. The V8 units have different firing sequences and intervals from their V10 predecessors, which leads to a totally different situation in terms of vibrations. The V10 entered a critical area between 12,000 rpm and 14,000 rpm. However, this was not an issue as the engine did not spend much time in this rev band and smoothed itself out again once the driver stepped up the revs. And, since the upper rev band was where it spent the majority of its time, vibrations were not a worry. A V8, on the other hand, is not so well off. Its vibration curve enters critical territory later than the V10 - from approximately 16,000 rpm - and continues to climb from there. It's therefore no longer possible to think in terms of getting through a difficult patch and everything will be all right. Now, the problem of constantly increasing vibrations has to be confronted head on.
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