The Mercedes-Benz Bionic Car as a Concept Vehicle The boxfish – angular but nonetheless very streamlined This required teamwork: biologists, bionics scientists and automotive researchers from various disciplines embarked on an extraordinary expedition into the animal kingdom which soon led them into the depths of the underwater world – and presented them with a surprise.

 It was not the fast, sleek swimmers such as the shark or dolphin that came closest to the ideals of the research engineers, but a creature that looks anything but streamlined and agile at first sight: the boxfish. It has its home in the coral reefs, lagoons and seaweed of the tropical seas, where it has a great deal in common with cars in many respects. It needs to conserve its strength and move with the least possible consumption of energy, which requires powerful muscles and a streamlined shape. It must withstand high pressures and protect its body during collisions, which requires a rigid outer skin. And it needs to move in confined spaces in its search for food, which requires good manoeuvrability. There is more to the boxfish than meets the eye: despite its angular body, it is an excellent swimmer whose cube-shaped structure is by no means a hindrance. On the contrary, the boxfish possesses unique characteristics and is a prime example of the ingenious inventions developed by nature over millions of years of evolution. The basic principle of this evolution is that nothing is superfluous and each part of the body has a purpose – and sometimes several at once. The outer skin of the boxfish consists of numerous bony, hexagonal plates which are interlinked to form a rigid suit of armour. This bony, armour-plated structure gives the body of the fish great rigidity, protects it from injury and is also the secret of its outstanding manoeuvrability, as tiny vortices form along the edges on the upper and lower parts of the body to stabilise the fish in any position and ensure that it remains safely on course even in areas of great turbulence. It does not need to move its fins in the process, and can therefore conserve its strength. Applied to automotive engineering, the boxfish is therefore an ideal example of rigidity and aerodynamics. Moreover, its rectangular anatomy is practically identical to the cross-section of a car body. And so the boxfish became the model for a so far unique automotive development project. Cd value: boxfish almost as good as the ideal engineering shape The first sub-project tackled by the engineers at the Mercedes-Benz Technology Centre and DaimlerChrysler Research concerned aerodynamics. In wind tunnels and water channels they examined how the attributes of the living model could be transferred to an automobile. The results are impressive. Despite its angular structure, the boxfish has almost as good streamlining qualities as the water drop shape which specialists consider to be the standard for the ideal aerodynamic form. When exposed to an open flow, this streamlined shape has a Cd value of 0.04. Using computer calculations and wind tunnel tests with an accurate model of the boxfish, the Mercedes engineers achieved a value which came very close to this ideal, namely 0.06 – an outstanding result. It explains why the boxfish is such a good swimmer and is so manoeuvrable with minimal effort. To make use of the aerodynamic potential the specialists in Stuttgart first created a 1:4 scale model car whose shape substantially corresponded to the boxfish. The angular outside contours of the living model were adapted in the area of the roof and side skirts, as was the prominent, descending rear end with its heavily scalloped sides and pronounced wedge shape. In doing this they were disobeying important principles in automotive aerodynamics, and were all the more surprised at the results: the Cd value for the car was 0.095. In aerodynamic terms it was just as good as the shape as measured on the ground considered ideal by aerodynamics specialists (Cd 0.09). The research model in the shape of a boxfish betters the drag coefficient of today’s compact cars by more than 65 percent. http://www.daimlerchrysler.com/dccom/0,,0-5-7154-1-503504-1-0-0-503518-0-0-135-7145-20051026-0-0-0-0-0-0,00.html