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Rollercoaster ride

Continental’s main European test facility is benefiting from some of the biggest upgrades in its 36-year history. We visited the Contidrom to see them for ourselves

by Graham Heeps

 

The Contidrom is one of the best known of all tire proving grounds. First opened in 1967, its revered wet handling track is the cornerstone of its reputation as a must-use facility for vehicle manufacturers such as Porsche, Mercedes-Benz and Audi, in addition to its primary function as a proving ground for the development of Continental tires.

The 365-acre site in the Lüneburg Heath, north of Hanover, retains a compact, familiar feel that’s said to be popular with employees and OE customers alike. Given that the surrounding land is in the hands of many different private owners, that’s not likely to change anytime soon because a large-scale expansion of the test area would undoubtedly prove difficult and costly.

New investments

That’s not to say that the testing options at the Contidrom are limited – far from it. Two recent investments underline Conti’s commitment to the facility. The first is a new office block, opened in June this year, to accommodate a workforce that has swelled from around 60, five years ago, to more than 90 today. The company’s head of objective outdoor tire testing, Stefan Heine, is delighted with the improved working conditions the building will offer and hopes to add more staff in the coming year as the new automated indoor braking analyzer (AIBA), for which he’s also responsible – despite his job title – ramps up to three-shift operation.

AIBA was first revealed last year (see Tire Technology International, November 2012) and is housed in a brand-new building within the high-speed oval, alongside one of the straights. Up close it’s impressive indeed, perhaps most of all because it relies almost exclusively on existing technology, but joined together to form a unique whole.

When a test is to be performed, the tires are first mounted and the test equipment installed in a preparation area. The vehicle gets a Continental-standard Digitalker III unit for data recording, plus an AIBA-specific ‘brain’, likewise developed with Hentschel, which receives input from the measuring system, communicates braking distances back to the control center, and triggers the braking robot at the correct time. On a rack in the trunk are the electronics for the Anthony Best Dynamics braking robot and AEB system, of which more shortly. The regular GPS-type outdoor measurement systems (Conti uses Racelogic VBOX) are not suitable for use inside AIBA, so a Kistler optical system measures the vehicle speed, from which the stopping distance is derived. Information about the test can be viewed on a rugged Panasonic PC screen inside the vehicle.

Top and above: Measurement equipment and tow hitch of a test car in the preparation area at AIBA. Trunk contains a Digitalker III recording device as well as control electronics for the emergency braking system and the AB Dynamics braking robot

Rollercoaster technology

Once it’s fully kitted out, the test vehicle is attached to the rail – which comes from rollercoaster technology – via a sledge that has a bar mounted on the chassis at the front and a standard caravan-style tow ball and hook at the side. From this point no human intervention is required, as the controls and measurement equipment operate via wireless LAN.

Now inside the test hall, a caddy pushes the car, SUV or van to the far end of the 300m-long, 30m-wide facility, where a turntable swivels the test vehicle 180° before it reaches the launch position.

If the pre-launch checks to the vehicle and test equipment are satisfactory, it is automatically accelerated – using standard monorail technology – to just above the test speed. The accelerator draws its power from supercapacitors (AIBA has its own power supply) and operates via magnetic induction for precise speed control. The acceleration distance is fixed at 100m. By way of example, the VW Golf Mk5 test vehicle that we observed during our visit was accelerated from zero to 100km/h in under four seconds, a procedure that requires only 400 of the system’s 1,200 available horsepower. It is powerful enough to push a 3.5 metric ton van or SUV to 120km/h in 100m.

On reaching the braking zone, the accelerator stops within 2-3m, leaving the test vehicle to run on by itself and be automatically brought to a standstill by the onboard braking robot. A backup emergency braking system, developed from series production AEB technology by Conti’s Chassis and Safety division, provides redundancy in the event of a failure in the robotized braking procedure. With the vehicle at a halt, the caddy collects it and takes it forward to the end of the track and another turntable, from where it can be returned to the launch area for the next test. Two test vehicles can be operated at one time in a shuttle system.

Top: Test car on the turntable. Note the yellow caddy that shuttles the car to the start area
Above: After acceleration to the required test speed, the vehicle enters the braking area

Cassette player
The test surfaces themselves are mounted on steel cassettes, on rollers that allow them to be slotted into and out of the braking area as required. Conti currently has three surfaces to test tire performance on different grades of asphalt; a maximum of five cassettes will be accommodated in the future, one of which will have a concrete surface. A separate indoor conditioning area brings test surfaces to the desired temperature; new surfaces are laid out of doors, where they are also conditioned to bring them to within the specifications dictated by label regulations. Future plans envisage an automated burnishing vehicle that will run up and down new cassettes outside, 24 hours a day, to prepare them for use, thereby freeing up resources for test work.

The test-surface temperature and air temperature within the test hall can both be precisely controlled – perfect for label testing – but the former can take up to two days to change, so efficiency dictates that major temperature changes are implemented week to week rather than day to day. In addition the water used to flood the test surface to around 1mm for wet testing, can be heated from its natural temperature of 10°C to a maximum of around 25°C.

If one includes pre-tests, evaluation of the system and testing tires under different conditions, more than 6,000 accelerator ‘shots’ have already been fired at AIBA, with one ‘brake test’ comprising around 7-12 test runs per tire set. The current record for a single shift stands at around 130 runs. Dr Mariano Doporto, who is department leader for test method development for objective outdoor tire testing, says that the test procedures will be optimized as operations ramp up to full capacity over the coming year (the theoretical maximum of 100,000 does not account for maintenance time, surface changes, tire changes, etc).

Room for improvement
One of the optimization possibilities is to speed up the way the caddy collects the vehicle post-test. Another is to reduce the interval between tests; currently a test doesn’t start until the preceding vehicle has been locked into the other side of the rail by the turntable, even though it is well beyond the braking area. A final improvement could remove the need for the test vehicle’s engine to be running, which is currently required to maintain battery charge. Doporto says that with 400V available in the rail, his engineers are working on a system to recharge the battery direct from the rail, on the way to the launch point.

Above: The wet-handling track with the high-speed oval in the background

Next door to AIBA, running parallel to it within the same structure, is the new ice braking hall. This facility is not fully automated and still requires a driver to conduct the test, which is directed and recorded by a Digitalker III. But with full control over ice and ambient temperatures, and still air, it should certainly provide more consistent test conditions, and more repeatable test results, than a frozen lake in northern Sweden.

“This hall enables us to greatly improve our test position on ice for traction and braking,” confirms Doporto.

Ultimately pre-testing compounds in the Contidrom’s ice hall will reduce the number of alternatives sent north to Conti’s proving ground at Arvidsjaur for winter testing by more than half. But first the results from the ice hall need to be correlated with those from Arvidsjaur due to the different characteristics of the ice in each location – a project that is currently underway. The hall’s artificial ice has a friction coefficient of around 0.1µ, whereas for the rougher natural ice the figure is approximately 0.2-0.3µ.

AIBA and the associated ice hall represent an imaginative, innovative move by Continental that should pay dividends at a time when the steps forward in reducing braking distances are becoming ever smaller, demanding more accurate and repeatable test methods. The facility is thought to be unique in the tire industry, although competitors are doubtless already considering how they too might develop something similar.

Use the force
Two years into its life, the ContiForceContact, a semi-slick trackday tire, is to get its first OE fitment. From this autumn, the design that was originally developed with aftermarket tuners AC Schnitzer and TechArt, will be available as an option on the Jaguar F-type in the size 255/35 ZR20 front, 295/30 ZR20 rear. Other OE approvals are also in the works for Conti’s flagship UHP tire, which boasts a unique patented Black Chilli compound with special high-grip resins and a hybrid third-layer belt of Aramid and nylon. The design is claimed to offer better performance in the wet than its rivals in the trackday niche, with the 265/30 ZR19 size boasting a B label rating for wet grip.

 

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