MBUSA
Dynamic rollover stability estimates
| Mercedes | height | track ft/rr | side force | slide speed | rollover | ESP | |
| model | [inches] | [inches] | [ g ] | [ MPH ] | [degrees] | ||
| SL500 R129 | 50.4 | 60.3/59.9 | 1.19 | 5.93 | 50 | available | |
| SLK230 | 50.7 | 58.6/58.5 | 1.15 | 5.7 | 49 | n. a. | |
| 500SL R107 | 51.2 | 57.2/56.7 | 1.11 | 5.6 | 48 | n. a. | |
| S430 W220 | 56.9 | 62.0/62.0 | 1.09 | 5.8 | 47 | standard | |
| 500SEL W126 | 56.7 | 60.8/59.7 | 1.07 | 5.7 | 47 | n. a. | |
| 450SE W116 | 56.1 | 60.0/59.3 | 1.063 | 5.73 | 47 | n. a. | |
| '00 E320 | 56.7 | 60.2/59.9 | 1.059 | 5.7 | 47 | standard | |
| CLK320 | 56.1 | 59.5/57.8 | 1.045 | 5.6 | 46 | standard | |
| C230K | 56.1 | 59.3/58.0 | 1.045 | 5.6 | 46 | standard | |
| 300E | 56.9 | 58.9/58.6 | 1.033 | 5.6 | 46 | n. a. | |
| 190D | 54.4 | 56.2/55.7 | 1.028 | 5.4 | 46 | n. a. | |
| 240D | 56.6 | 58.6/56.9 | 1.02 | 5.5 | 46 | n. a. | |
| 220SE conv | 60.2 | 56.2/57.9 | 0.95 | 5.34 | 43 | n. a. | |
| A140 | 62.0 | 59.2/57.2 | 0.94 | 5.38 | 43 | standard | |
| ML55 AMG | 69.3 | 61.2/61.2 | 0.883 | 5.39 | 41.4 | standard | |
| Euro ML320 | 69.9 | 61.6/61.6 | 0.881 | 5.38 | 41.3 | standard | |
| '00 ML430 | 69.9 | 61.2/61.2 | 0.876 | 5.37 | 41.2 | standard | |
| '99 ML430 | 69.9 | 60.4/60.4 | 0.864 | 5.31 | 40.8 | standard | |
| '99 ML320 | 69.9 | 60.4/60.4 | 0.864 | 5.31 | 40.8 | standard | |
| G320 Long | 76.2 | 58.1/58.1 | 0.76 | 5.0 | 37 | n. a. |
The side force estimates the lateral acceleration the car experiences in a curve. The faster and sharper the curve the higher this force becomes until the limit value listed above is reached. At the limit the total weight rests on the two outside tires while the inside tires are close to lifting off the ground. Further increases lift the inside up until it reaches the listed critical rollover angle and then falls over. This is an untripped rollover and some claim it's the most insidious type since it happens on clean road surfaces; but infrequently.
The car can also continue to slide sideways. Whether it keeps sliding or rollsover depends on the tire-to-road adhesion. With low adhesion the car slides easily. When the speed with which the car slides sideways exceeds the critical slide speed listed above, the car has enough energy to roll over when hitting an obstacle, like a curb, a rough patch etc. This is a tripped rollover, which is more frequent, and depends on the limited space available before a tripping object is encountered, and the inability of the driver to regain control during the sideways slide into it.
ESP can help in both cases, within the laws of physics.
Several reasonable assumptions were made to derive the above estimates. Among them that tire deflection and suspensions can be neglected. So use the numbers with care. It's further assumed that the front and rear axle have the same rollover characteristics. It's also assumed that the automobile rolls over from a constant velocity and constant radius curve and that it slides into the curb with a constant lateral velocity. Transient response and moments of inertia are thus neglected and may alter the above estimates.
GDV Study
"Two years ago, the Institute for Vehicle Safety in the Association of
German Insurance Businesses e.V. (GDV) analyzed the causes of accidents
with serious or fatal injuries. From a total number of 15,000 reports,
the experts evaluated 831 accidents in depth. The analysis revealed that
60 percent of all accidents with fatalities were caused by side-impact
crashes.
In 30 to 40 percent of all fatal accidents, the vehicle began to skid due
to excessive speed, exaggerated steering reaction or driving error.
Based on this result, the Institute issued a clear recommendation in
favor of safety systems, such as the electronic stability program (ESP),
which enhances vehicle stability. ESP can prevent skidding or at least
better control the vehicle. According to experts, introducing ESP as
standard equipment could reduce the number of serious accidents."
- Günther Plapp, Vice President, Engineering, ABS and Brakes, Bosch
written in 1998 and updated from time to time
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Hollywood has stuntmen. Mercedes has ESP. |