Fish-Inspired Vehicles?

Happy Monday! Here's an excerpt from How to Catch a Robot Rat by Agnès Guillot and Jean-Arcady Meyer to kick off the week.

Forms

Forms present in nature have mathematical properties that have inspired inventors.

In 1420, appearing before the eminent committee that questioned his competence to construct the cupola of Santa Maria del Fiore in Florence, Filippo Brunelleschi rapped an egg on the table and crushed the shell lightly at the base. Everyone could see that the egg remained vertical and immobile, whereas if the architect had tried to explain in words the planned construction, to do it would have seemed impossible. This egg presented in Florentine style (later used by Christopher Columbus) must have been convincing because Brunelleschi obtained carte blanche, and the gigantic dome that he built is still in place. He conceived it (by coincidence?) according to a principle that recalls the eggshell, so that bricks laid fishbone style mutually block each other and thus totally bypass the need for classic supports such as wooden arches. An ingenious encasing of two cupolas likewise ensures a good distribution of pressure.

An egg obviously does not contain arches, which would obstruct the embryo in development, yet its structure is capable of resisting considerable force: the shell of a hen's egg is 0.3 millimeters thick and can withstand up to 3.0 kilograms of pressure, and that of an ostrich egg is ten times thicker and can withstand a pressure twenty times stronger! The shells expoloit a "trick": the crystals of the mineral salts that constitute them are oriented toward the center of the egg and are self-blocking, like the bricks in the dome of Florence. Various architects--including the Germans Frei Otto, Carl Zeiss, and Heinz Isler--have recently adopted these characteristics to calculate the exact thickness needed to cover various domes or to establish force lines for immense stretched structures.

The oblong form is known to move rapidly in the air and in water without too much effort. Bizarrely, marine animals are also the best models for terrestrial or aerial mobiles! For example, the engineers of Daimler AG are currently trying out the form of the tropical boxfish to save precious liters of fuel in future automobiles. This research has resulted in a prototype presented in Washington in 2005. Although the animal presents an almost cubic belly, this characteristic makes it paradoxically very hydrodynamic and even, according to measurements undertaken by engineers, more aerodynamic than current cars, with a coefficient of air penetration of 0.06 instead of 0.30!  The "Mercedes-Benz bionic car" would boast a coefficient of 0.19 and could save 20 percent in fuel and 80 percent in nitrous oxide emissions. Its body, like the rigid carapace of the fish, is conceived as if it were composed of numerous hexagonal panels supported by a metallic vertebral column. Such a car would thus be very competitive in both lightness and robustness, the two great principles of both nature and the automobile industry.

Even an airplane of the future might be shaped like a fish, too. The Smartfish, being developed by several international companies and research laboratories at the initiative of Swiss engineer Koni Schafroth, is inspired by the form of several fish, especially the tuna, the fastest and most agile animal in the sea. A meterwide miniprototype has already successfully achieved first flight, in April 2007...