|
Price |
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-- |
Production |
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Engine |
6.3
liter V8 |
Weight |
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Aspiration |
natural |
Torque |
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HP |
563
hp @ 6800 rpm |
HP/Weight |
-- |
|
HP/Liter |
89.4
hp per liter |
1/4 mile |
-- |
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0-62 mph |
-- |
Top Speed |
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(from Mercedes-Benz
Press Release) Development of the new Mercedes-Benz SLS AMG
Roadster - Revelation: stable even without gullwings
Affalterbach – After the gullwing version, the open-top variant is
the second car to be independently developed by AMG. The Coupé and
Roadster concepts were created in parallel – which brought decisive
advantages during the development process. During this approx.
3-year period for the SLS AMG Roadster, the engineers devoted
particular attention to the aspects of bodyshell rigidity, driving
dynamics, the soft top and NVH.
Greater Stuttgart area,
spring 2011: the new SLS AMG Roadsters are slightly disguised as
they cover their test routes. Easily identified by those in the
know, others only see these two-seaters with a fabric soft top as
some prototype or other: there are no Mercedes stars or model
designations to be seen, just black adhesive foil at the front, rear
and along the sides. The proportions speak for themselves, however:
a long bonnet, large wheels and a short rear end indicate that this
is a sports car of breathtaking design.
There are still several
months to go before the world premiere at the International
Automobile Show in Frankfurt/Main in September 2011. Enough time to
verify the maturity of the new SLS AMG Roadster. The personnel
responsible at AMG have already completed most of the work involved,
as the Coupé and Roadster were created in parallel. The development
and testing of a new AMG high-performance car is based on the
digital prototype (DPT). Extensive investigations help to achieve
specific objectives. Whether these concern the bodyshell design,
weight distribution, engine position, centre of gravity or axle
design, or of course the handling dynamics, aerodynamics,
ergonomics, crash behaviour and production process – the very latest
simulation programmes allow the very realistic representation of a
vehicle and all its characteristics. The digital prototype is
therefore a complete, virtual automobile.
In the process AMG also
uses the extensive know-how of colleagues at Mercedes-Benz: as in
the case of the Coupé, networked development with selected
Mercedes-Benz development departments at the Mercedes Technology
Center (MTC) in Sindelfingen was intensified.
The latest simulation
software and extensive test drives on all continents make the 420 kW
(571 hp) Roadster fit for its market launch in autumn 2011. The
focus of the specialists in Affalterbach was particularly on
bodyshell rigidity, handling dynamics, the soft top and NVH (Noise,
Vibration and Harshness).
Synthesis: rigidity, performance
and a close-fitting soft top
Naturally all these
development aspects are closely linked, as Tobias Moers (44), head
of overall development and member of the Executive Board at
Mercedes-AMG, explains: "Without bodyshell rigidity there are no
handling dynamics, and neither can the close fit of the soft top be
guaranteed." As the Roadster variant was already taken into
consideration during the conceptual phase for the SLS AMG, the
lightweight and extremely rigid aluminium spaceframe was specified
at a correspondingly early stage. Owing to the omission of a fixed
roof and gullwing doors, it was necessary to design the side sills
more robustly. But not primarily to meet the legal requirements in
the event of a crash – in principle the Roadster would also manage
this with the side sills of the Coupé. Studies and test drives
showed that the driving dynamics could be improved even further with
this measure, therefore side sills with greater wall thicknesses and
chambers were developed for the open-top SLS AMG. Tobias Moers: "The
SLS AMG Roadster is a super-sportscar – just like the Coupé. It goes
without saying that AMG is also determined to achieve superior
driving dynamics with this open-top variant."
In order to achieve
handling dynamics identical to those of the Coupé, despite the lack
of a fixed roof, the Roadster has two features designed to increase
the rigidity of the bodyshell: the cross-member carrying the
dashboard has additional supporting struts at the windscreen frame
and at the centre tunnel, and a strut mounting stay between the soft
top and the fuel tank makes the rear axle even more rigid. These
features prevent unwanted vibrations from the start, and make the
use of additional, weight-increasing vibration dampers such as those
often employed by competitors unnecessary. As another important
aspect, it is only if the bodyshell has the requisite rigidity that
the soft top can be safely and reliably opened and closed
electrohydraulically while on the move at up to 50 km/h. The side
members of the front and rear modules in both SLS AMG models are
identical. The bodyshell of the Roadster tips the scales at only 243
kilograms – which is comparable to the low, 241-kilogram weight of
the SLS AMG Coupé's bodyshell.
A few specific modifications to
the aluminium spaceframe
Owing to the omission of
the coupé roof and gullwing doors, the open-top SLS AMG has a
reinforcing cross-member behind the seats which supports the fixed
rollover protection system. Not forgetting the 250-watt subwoofer of
the Bang&Olufsen BeoSound AMG high-end sound system: This is
accommodated in the cross-member, as the Coupé-specific location on
the parcel shelf is not available owing to the Roadster's soft top.
One particular challenge was acoustic insulation of the
cross-member, which acts as a subwoofer housing for the two
165-millimetre speakers connected in series. Numerous improvements
became necessary before the required listening pleasure was
achieved. It was only with the help of a special bulkhead within the
aluminium cross-member that all audiophile standards could be
satisfied.
The three-layered fabric
soft top of the SLS AMG Roadster, which is deposited behind the
seats in a Z-formation to save space, is also an aspect relevant to
handling dynamics. This weight-optimised, combined magnesium/steel/
aluminium construction ensures a low centre of gravity and is
designed for speeds up to the maximum of 317 km/h (electronically
limited). Whether open or closed, even at top speed there must be no
intrusive flapping, booming, hissing, clattering, whistling or
howling. Likewise the push-on glass draught-stop and the panelling
in the interior, on the soft top and along the beltline must be
vibration-free. Nothing must be allowed to compromise the open-air
enjoyment. The basis for verified, customer-compatible results in
extreme conditions is provided by precisely defined test drives on
the high-speed tracks in Papenburg, Nardo (Italy) and Idiada
(Spain).
The excellent acoustics
– which AMG engineers have naturally also verified with
sophisticated measuring technology – also benefit from another
special feature, namely the seamless, bonded-in rear window of
single-layer safety glass. A special production process not only
ensures a smooth transition between the outer skin of the soft top
and the glass, as the sum of these design measures also leads to low
wind noise when the roof is closed – at any speed.
125 years of experience with
innovations in open-top vehicles
Ensuring that the soft
top is wind and waterproof is a complex undertaking, and AMG and
Mercedes-Benz have used the enormous experience gained during 125
years of innovation. There have always been open-top vehicles in the
history of Mercedes-Benz – and unlike in the case of many
competitors, in an uninterrupted sequence.
Every soft top is
different, however, and even objectives already defined become more
ambitious over time. The five challenges to which the AMG developers
of the SLS AMG Roadster gave great attention and commitment were
water, sand, dust, heat and cold. One special feature of the compact
soft top is the continuous water pocket: this is attached below the
soft top to catch rainwater and direct it down to the underbody via
two apertures on each side.
All the development
aspects of a vehicle which involve flexible deformation are always
very complex. Simulations can sometimes lead to false conclusions,
and do not always provide the most cost-effective solution. Classic
test procedures often help to achieve rapid results. Development
project manager Holger Strahl (34): "In this field it is not
possible to simulate everything with CAD, and it becomes a matter of
trying out, driving, testing and improving. The solution finally
approved must also be suitable for series production, of course. Our
specialist departments and the overall development team work
together very closely in their common search for the perfect
solution." He also adds: "There is no such thing as the second-best
alternative for AMG."
Endurance test with 16 criteria:
the "Sindelfingen rain test"
The rain test at the
Mercedes Technology Center (MTC) in Sindelfingen is particularly
demanding, and every new vehicle bearing the Mercedes star is
required to pass it - whether it has a fixed roof, a soft top or a
vario-roof. Extreme quantities of water are used to ensure that the
result of the development work is watertight – which is a particular
challenge in the case of roadsters or cabriolets. 16 tests must be
successfully absolved before approval is granted.
Whether during the hose
test, when all soft top, door and flap seals are sprayed with a
water-hose, the continuous, overnight rain test, the fording test,
the icing, swirl and high-pressure tests, or the final session in an
automatic car wash – the rain test simulates every conceivable
situation that can occur on any continent.
Bench testing and practical trials
in all climatic zones
In addition to various
test facilities such as the water chamber and the climate/ wind
tunnel, the AMG specialists have recourse to test drives in all
climatic regions of the world, where problems can be identified and
solutions sought. In Laredo, Texas, for example, there is a
particularly fine dust which finds its way into practically any gap
– and tests the seals to the absolute limit.
The compact fabric soft
top, which can be conveniently opened and closed in just 11 seconds
at the touch of a button, even at speeds up to 50 km/h, must also
submit to various tortures. One of these is the standardised soft
top endurance test used for all new Mercedes roadsters or Mercedes
cabriolets: 20,000 closing cycles on a stationary test rig must
present no problem for the hydraulic cylinders, electric motors and
joints. There are also 2500 closing cycles while on the move,
whether in great heat, icy cold, high humidity or dry desert winds.
In this area too, nothing is left to chance – and for excellent
reasons: the aim of this enormous effort is to give the customer
limitless driving pleasure in their SLS AMG Roadster.
Endurance trial as a final quality
check
All the optimisation
stages have been absolved, and the production tests at the
Mercedes-Benz plant in Sindelfingen have been successful, but the
developers have still not reached their goal. The quality of the
overall vehicle is now the focus of the accompanying endurance
trials. These simulate an entire vehicle life under the toughest
conditions in accelerated test cycles. The aim is to verify the
level of maturity before production of customer vehicles commences.
The endurance testing at
a glance:
Long-term
testing on a variety of different roads:
All the components
and systems are tested together in everyday operation. Loaded up
to their permitted gross vehicle weight, the test cars are put
through a precisely defined test programme on country roads, on
motorways and in city traffic.
Endurance testing on heathland:
In this case, the developers focus on the durability of the
chassis and suspension components, the entire bodyshell and the
integral subframe on which the front axle, steering and engine
are mounted. The test cars are loaded up to their permitted
gross vehicle weight.
"Accelerated" endurance testing:
Testing of the entire vehicle, focussing on the powertrain,
chassis and suspension. Special features of the AMG programme
include 10,000 kilometres on the Nürburgring's North Loop and
10,000 kilometres in city traffic.
Full-load endurance testing:
Extreme acceleration and braking manoeuvres with a high
proportion of full-load operation, making extreme demands on the
cooling, fuel-delivery and braking systems.
Long-term corrosion testing:
Corrosion testing of the entire vehicle simulates the toughest
dynamic and climatic environmental influences.
Final board approval:
All-inclusive verification of the degree of development and
production maturity.
World premiere on 13
September 2011, at the International Motor Show (IAA) in
Frankfurt/Main
This is an extensive and tightly scheduled programme, and for many
an AMG engineer it will only begin to lose its immediacy at the
world premiere on 13 September 2011, when the new SLS AMG Roadster
is presented to a barrage of media attention at the International
Motor Show in Frankfurt/Main.
