Press Release
Puristic Roadster soft top with coup??????????????????-like qualities
The carbon-fibre body is crowned by the snug-fitting soft top roof. The lean, sporty soft top nestles close to the passenger compartment, emphasising the Roadster's flowing form. The silhouette appears even more elongated than on the Coup?????????????????? version and gives the vehicle's lines an even more pulsating look ??????????????????????????????????????? especially with the roof down, of course. The design team paid painstaking attention to the tiniest of details in order to achieve harmonious integration of the roof. This included carefully smoothing out the transition between boot lid, roof and rear wall to make it perfectly flush so that even this area of the Roadster seems to have been cast from a single piece, both with the roof open and closed.
The soft top retracts fully in order not to disrupt the flowing forms when driving with the roof down. To open the roof, the driver simply has to release the catches in the roof frame and lift it up slightly; the side windows then open and, once a concealed switch in the centre console has been pressed, the roof folds together in a "Z" and stows itself away behind the seats on a level with the boot lid. The roof can only be operated with the vehicle stationary for safety reasons. Drivers are able to make the very most of every break in the weather as the semi-automated mechanism opens and closes the roof in just over ten seconds flat, thereby harmonising the desire for convenience with the purist nature of this top-class Roadster.
However puristic the roof's design may appear it is in actual fact highly elaborate, with three carefully harmonised layers that ensure excellent insulation and therefore pleasant levels of comfort, even in poor weather. A newly developed roof material featuring different coloured threads for warp and weft creates a striking, yet very elegant-looking finish, whose curious formation ties in fittingly with the car's carbon-fibre structure.
The front section of the roof incorporates a fixed header bow made from aluminium. Not only does this give added stability, it also dispenses with the need for an additional cover when the roof is down, as it lies perfectly flush with the tail's contours. This is once again a reflection of the puristic character of the SLR Roadster.
Furthermore, the hard roof shell, the short spacing between the bows and the optimum attachment of the roof fabric give the soft top on the SLR Roadster very different properties from the majority of cabriolet roofs. There is none of the usual prominent arching outwards at high speeds; even at top speed, its contour alters by just a couple of millimetres at the rear. Drivers of the new high-performance two-seater from Mercedes and McLaren can therefore push it all the way to its top speed far beyond the 300 km/h mark with complete peace of mind, even with the roof up.
Honed for high speeds in the wind tunnel
The Roadster's handling, aeroacoustics and aerodynamics were optimised for high-speed driving in the wind tunnel. It borrows the same aerodynamic concept already familiar from the Coup??????????????????, comprising a front splitter, flat underbody and diffusor, as well as a speed-controlled airbrake incorporated into the boot lid. This unique concept keeps the axle load perfectly balanced whilst maintaining high, uniform downforce at the front and rear axles. There has only been a slight increase in the Cd figure for the Roadster compared to the Coup??????????????????, measuring 0.376 with the roof closed and 0.4078 with it open (airbrake in 10???????????????????? setting for both measurements).
The aerodynamics engineers have also taken great care to make the Roadster a shining example in terms of its aeroacoustics too. Painstakingly meticulous work on the soft top bay, on the roof itself and on the transition point from the soft top to the body have cut wind noise substantially. As an example, the distance between the roof when closed and the boot lid was fine-tuned with such precision that no additional sealing lips are required here. The airstream felt in the passenger compartment when the roof is down is furthermore reduced to great effect by a Plexiglass draught-stop bearing the SLR lettering, that measures little wider than a hand and is inserted between the two rollover bars. Thanks to the sophisticated aerodynamics and the highly effective draught-stop there is very little turbulence even at speeds in excess of 200 km/h, allowing the occupants to converse with ease.
Restraint system with adaptive airbags, sidebags and kneebags
A state-of-the-art restraint system comprising six airbags, belt tensioners and belt force limiters completes the SLR Roadster's elaborate safety concept, ensuring that it meets all Mercedes standards in this regard too.
In the event of a head-on collision, the electronic control unit first triggers the high-performance belt tensioners, which can pull up to 15 centimetres of loose belt strap taut in fractions of a second, reducing the forward displacement of the occupants caused by the impact. The Mercedes-Benz SLR McLaren Roadster is also fitted with kneebags, which - together with the two-stage airbags - provide a large protective cushion for the driver and passenger in a frontal collision, complementing the effect of the seat belts and belt tensioners.
Upfront sensors for rapid airbag deployment
The belt tensioners are also activated if a roll-over situation is detected, triggered by a roll-over sensor which reliably recognises this type of accident and relays its data at lightning speed to the central control unit for the restraint systems. The sensor is located in the centre tunnel.
A sophisticated system of sensors also allows adaptive control of the front airbags, which deploy according to the severity of the accident. If the sensors register a light head-on collision, they each trigger just one chamber of the two-stage gas generators so that the 64-litre driver airbag and 125-litre passenger airbag are deployed with a lower internal pressure. If the sensors register an accident of a higher severity, the electronics also trigger the second chamber of the gas generators and the airbags inflate with a higher pressure.
Two upfront sensors on the radiator cross member fulfil an ancillary function for this adaptive deployment of the restraint systems. Thanks to their forward positioning in the front structure, they detect the severity of the impact even earlier and more precisely. The deployment algorithm uses both this signal and the signal from the central crash sensor on the centre tunnel.
While the occupants sink safely into the airbags, the belt force limiters reduce the force exerted by the belt strap on the upper body, further decreasing the risk of minor chest and shoulder injuries.
Sidebags with additional protection for the head
Protection in the event of an impact from the side is optimised by the integral sidebags in the doors. These cushion both the head and the upper torso which is why they are referred to in specialist circles as "head/thorax bags". In a side-on collision, this specially developed sidebag rips open a seam above the armrest and inflates within milliseconds to form an asymmetrically shaped airbag, the upper edge of which extends higher than that of conventional sidebags. The airbag's design reduces the risk of the head hitting against the side window or any object which may penetrate the interior.
The automatic child seat recognition system, developed by Mercedes-Benz, is also part of the SLR's standard equipment. It deactivates the passenger airbag if one of the special child seats from the Mercedes-Benz accessories range is installed on the passenger seat. These child seats have a transponder system which receives and responds to signals from two antennae in the seat upholstery. As a result of the exchange of data, the airbag electronics recognise that a child seat is fitted and deactivate the airbag on the passenger side since its deployment is not desirable in these circumstances. The belt tensioner and sidebag remain activated, offering the young passenger additional protection in the event of an accident.
