5 The Technic
German high technology and design aesthetics in perfection
From the limousine to the coupé - metamorphosis in technology and design
Following the many model phases, whether it be the 1:1 study, the exterior design model as a reference for the form release, the interior reference model, the innumerable wind tunnel tests, the bodywork for the chassis in working order with s 23423w2216x ubframe - eventually these phases of searching and coordination are concluded. Now it is time for the technicians and engineers.
Fulda's arguments were very clear right from the start:
the reference vehicle for the new broad tire generation Exelero must withstand a constant load in use on the road, on the freeway, at trade shows, exhibitions and other events.
The technically impressive values of the Fulda Gemballa show vehicle should serve as a guideline for the Exelero sports coupé.
The standard type 12 Maybach engine with Biturbo turbocharger produces 550 hp. Even this imposing engine cannot accelerate a vehicle weighing around 2.6 tons to a speed of around 350 km/h.
A matter of honor for DaimlerChrysler's engine specialists in Untertürkheim.
The designers dipped into their technical box of tricks and increased the cubic capacity from 5.6 to 5.9 liters. They further optimized the turbocharger and, lo and behold, the 700 hp and torque of at least 1,000 newton meters calculated for the desired speed was achieved. After around 100 hours of non-stop testing on the engine test bed, corresponding to a road test of about 15,000 kilometers, the unit was ready for use.
Leon Hustinx, the Director of Sales and Marketing at Maybach, was so impressed by the Exelero project that he quickly and unbureaucratically provided Fulda with the platform of a Maybach 57 limousine.
How to conjuring up a sports coupé from it? For Jürgen Weissinger, head of development at Maybach, this was not the first tricky question. He is more familiar with the engineering of the Maybach than anyone else and, as project manager in pre-development, he has produced numerous feasibility studies for the make.
When comparing the dimension concepts of the Fulda streamlined car of 1938 with the 57 platform, an astonishing correlation of measurements already emerged. Although today's Maybach is about 290 mm longer, e.g. in the wheelbase, the breadth and height of the veteran car strongly resembled the 57's dimensions.
That simplified construction considerably. Nevertheless, a great number of details had to be changed, among others:
the driver's position including A-column and door had to be shifted back towards the rear axle;
correspondingly the steering column and the pedals as well as the gear shift;
a second front wall had to be integrated;
the position of the tank remained unchanged, the refuelling nozzle had to be shifted etc..
All in all, however, the necessary changes were made in the short time available.
The development work connected with the rim and the wheel proved equally tricky. Rolf Dieter Stohrer, Senior Manager Car Tires and responsible for wheel and tire technology in the Fulda project team contacted several rim manufacturers and realized the rim called for in the design with Ronal. The corresponding design was milled by Ronal from a complete piece of metal, i.e. from a solid block weighing 257 kilograms a rim measuring 11.0 x 23 inches was produced with a weight of just 23 kg. All four rims were individually produced and because they are turbine wheels, the direction of movement had to be taken into account. Thus, two were produced for the left side and two for the right. However, these Ronal rims are only needed for the "See true" vehicle model. This is the exact copy of the Exelero sports coupé which, however, is not used in the road but merely at show events.
The real rims for the high speed tests come from ATP-Excentric in Bremen. The reason: the ATP rims have a cross spoke design which can be simply fully-panelled for the speed tests. This procedure means an additional 3-4 km/h for such gigantic 23-inch wheels. The air pressure of the tires will amount to 3.6 bar for the high speed tests. As a rim can bear a load of 1,050 kilograms, for example, the load on the rear axle of 1,400 kilograms is no problem, i.e. there is a sufficient reserve.
After all technical requirements included in the engineers' specifications had been checked, the tests began.
An idea conquers the road.
May 2005
Technical data of the Maybach Exelero:
Engine:
Construction: V-engine, 60° bank angle
Number of cylinders: 12
Cubic capacity (cm ³): 5908 cm ³
Bore x stroke (mm) 83.0 x 91.0
Compression: 9.1
Valves per cylinder: 3
Valve control: Roll-rocker arm over 1 camshaft per bank
Camshaft drive: Chain
Mixture preparation: Injection
Type of fuel: Super 100 octane
Performance (kW) 515
(Hp) 700
at revs/min 5000
Max. torque: (Nm) 1020
at revs/min 2500
Exhaust gas detoxification: CAT
Engine lubrication: Oil circulating lubrication
Dimensions and weights:
Dimensions:
Wheelbase: (mm) 3390
Length: (mm) 5890
Breadth: (mm) 2140
Height: (mm) 1390
Fuel tank of capacities: (ltr) 110
Weights:
Unladen weight: (kg) 2660
Permitted total weight: (kg) 2960
Maximum load: (kg) 300
Performance:
Maximum speed 351.45
Acceleration from 0 to 100 km/h (s) 4.4
Chassis:
Wheel mounting:
front: Double wishbone axle
rear: multi link rear axle
Tires: Fulda Carat Exelero
front: 315/25 ZR 23
rear: 315/25 ZR 23
Brakes: Internally ventilated disc brakes
Type front: 4x4 piston fixed caliper (2 calipers)
Diameter: (mm) 376
Type rear: 2 x4 piston fixed caliper
Diameter: (mm) 355
ABS: yes
ESP: yes
May 2005
www.fulda.com / www.das-projekt.com
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