The hot-water rocket
Accelerating a test vehicle with a towing unit was not an ideal method. Dr. Ernst Fiala created a solution in 1962 – for the crash experiments performed by Karl Wilfert's team, he designed a hot-water rocket which propelled the vehicles without a tow rope.
The device was mounted on a single-axle trailer positioned behind the test vehicle and consisting of a pressure tank, a quick-opening valve and a discharge nozzle. The tank was filled with water to roughly 75 percent of its capacity, and in order to produce thrust, the tank was heated until the temperature of the water had reached approx. 260°C (500°F). The resulting excess pressure propelled automobile and rocket forward after the valve was opened, accelerating the unit to over 100 km/h. However, the hot-water rocket sometimes propelled the automobile in such a manner that it missed the barrier or ramp altogether.
Crash tests without such incidents became possible from 1973 onwards at the new test centre in Sindelfingen. On the 65-meter acceleration track, a linear motor producing a thrust force of 53,000 Newton accurately pulled the automobiles into a 1000-ton barrier, which rested on a very sensitive force measuring platform.
The crash test facility was then thoroughly renovated in 1998 with the creation of the Mercedes-Benz Technology Center (MTC). At an expense of 2.3 million euros, the facility was refurbished with state-of-the-art technology. The length of the acceleration track was increased to 95 meters; as a result, all types of crash test variants were now possible at the facility. In particular, this included offset crashes, in which only part of the frontal width of the vehicle impacts the obstacle or other party and which in reality occur much more frequently than head-on vehicle collisions. The test sequences are no longer recorded by a high-speed film camera, but by video technology. The very high frame rate has been maintained so that the crash tests can be evaluated in extremely slow motion. The facility was also equipped with a roof during the renovation so that passenger car and commercial vehicle testing can now be performed regardless of the weather.