http://autos.msn.com/as/minishow/article.aspx?contentID=4024039&s=bibendum2006
The bionic car
Despite its clumsy-looking features, the boxfish is a near-perfect
paradigm of aerodynamcis and rigidity. by Larry E. Hall
DaimlerChrysler turns to the boxfish as the model to create an aerodynamic and
fuel-efficient car. To cut down on aerodynamic drag, the
boxfish-like car has rear wheels which are almost completely shrouded with
sheets of plastic, flush-fitted door handles and the use of rearview cameras
rather than exterior mirrors. The bionic car is powered by a
138-horsepower 2.0-liter four-cylinder turbocharged diesel with a common-rail
direction injection system that can go 0 to 60 mph in 7.9 seconds.
advertisement dap('&PG=CP49EJ&AP=1087',180,150); The bionic
car's diesel engine incorporates a state-of-the-art particulate filter to
minimize soot exhaust and a Selective Catalytic Reduction system to get rid of
excess NOx.
Box and aerodynamic seem to be contradictory. So too, do diesel and clean. But
when DaimlerChrysler engineers from the Advance Concept Studio at the Mercedes
Technology Center in Sindelfingen, Germany, collaborated with scientists from
the company's Research and Body unit, these terms became harmonious in the form
of the Mercedes-Benz bionic car, a concept vehicle that was designed
consistently in accordance with the principles of nature. The term bionics
was coined in 1958 by an American Air Force major when he combined the words
biology and mechanics. But the world's first student of bionics was the Italian
Leonardo da Vinci. No less than 500 years ago, this ingenious all-rounder
designed a flying machine and derived the principle of the helicopter from what
he observed in nature. The Bionic Car Is the Real Thing
The word bionic became part of American pop culture in the 1970s via the TV
series, "The Six Million Dollar Man." This bionic wonder could perform
incredible feats of strength and speed and was later joined by a bionic woman
(which became a separate series), a bionic boy and
ahem
a bionic dog.
While the TV show was just make-believe, the bionic car is the real thing. And
in this case, the word bionic is condensed from a quite recent field of
scientific discipline called "biomimetics," which is derived from the words
biology and mimesis (imitation). Biomimetics is an interdisciplinary subject
which combines engineering science, architecture and mathematics. The basic
principle is to make nature's problem solutions usable for man. The reason is
simple: Nature, through billions of years of trial and error, has produced
effective solutions to innumerable complex real-world problems. The challenge
for the assembled biologists, bionics scientists and automotive
researchers from various disciplines was to design an aerodynamic and
fuel-efficient car using the bionics principle. The car also had to transport
four people comfortably and meet Mercedes' high standards of safety. From
Clumsy-Looking Fish to Sleek Vehicle
When the project team embarked on their expedition into nature's domain, it led
them into the depths of the underwater world where they encountered an
unexpected role modelthe yellow boxfish, or Ostracion cubicus.
Broadband Video The bionic car and F-Cell at Challenge Bibendum
At first sight, the boxfish lives up to its name. It is almost laughable to
think that this plump, polka-dotted, pug-nosed, aquatic creature could serve as
a scientific model. "Quite frankly, we were surprised when this
clumsy-looking fish, of all things, became our model for designing an
aerodynamic and fuel-efficient car," said Dr. Thomas Weber, DaimlerChrysler's
research and development chief. The Boxfish Is An Aerodynamic Marvel
Appearances are deceptive: despite its bulky appearance, the boxfish is a very
skillful swimmer. Its boxlike shape does not prove to be a hindrance at all. In
fact, on the contrary, the fish has unique characteristics and is an ideal
example of the ingenious discoveries of evolution. Applied to automotive
engineering, the boxfish is a near-perfect paradigm of aerodynamics and
rigidity. In addition, its rectangular anatomy is practically identical to the
cross-section of a car body. It therefore comes close to meeting the
requirements of a car that is suitable for everyday use, and has ample place
for its passengers. The first bionic car sub-project tackled by engineers was
aerodynamics. Automakers place a high priority on the aerodynamic efficiency of
a vehicle's body because of its affects on fuel economy. Using wind-tunnel
tests, engineers can measure an automobile's coefficient of aerodynamic drag
(Cd), essentially, how easily it moves through the air. About 60
percent of the power required to cruise at highway speeds is used to overcome
air drag, and this increases rapidly at high speed. Therefore, a vehicle with
significantly better aerodynamics (lower Cd value) will be much more fuel
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'Make:', 'Model:', 'true'); Streamlining specialists consider the
water drop shape to be the standard for the ideal aerodynamic form, with a Cd
value of 0.04. And the
boxfish? Using computer calculations and wind-tunnel tests with an accurately
constructed model of the boxfish, Mercedes engineers achieved a value which was
very close to the ideal0.06 Cd. That helps explain why the boxfish is such a
good swimmer and is so maneuverable with minimal effort. Next came a 1:4 clay
model of the 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. Engineers were elated and
surprised when wind-tunnel tests of the model revealed a Cd of just 0.09, a
value 65 percent better than the best of today's compact cars. Wow, a Cd
Value of Just 0.19
The final task was to develop the full-size bionic car concept vehicle
incorporating the basis of the boxfish contours. Using the Mercedes-Benz
European A-Class car underpinnings, the result of the project is a compact
two-door car with four comfortable seats, a panoramic windshield, a glass roof
and large tailgate167.3 inches long, 71.7 inches wide and 63.0 inches high.
Utilizing the findings from the research in designing the concept, the bionic
car offers a Cd ratio of just 0.19among the most aerodynamically efficient
cars ever produced. In comparison, the 2005 Corvette's 0.28 Cd makes it the
most wind-cheating 'Vette ever, and the lowest Cd of any production car
currently available is Honda's somewhat awkward looking Insight hybrid with a
value of 0.25. In addition to the boxfish-like basic shape, the
slicing-through-the-wind result is made possible by a number of other
aerodynamic features: rear wheels which are almost completely shrouded with
sheets of plastic,
flush-fitted door handles and the use of rearview cameras rather than exterior
mirrors. From Fish Skeleton to Car Body
But there's more, much more about the boxfish that was applied to the bionic
car than just its slippery shape. The boxfish is also a structural
achievement. It has a bony external skeleton consisting of numerous bony, thin
hexagonal plates, which are interlinked to form a rigid suit of armor. This
helps support the fish's basic shape and protects it against injury.
Engineers applied this structure while developing the car's body, whose interim
depiction on a computer screen looked surprisingly like the boxfish's skeleton.
Consulting with outside bionics experts, DaimlerChrysler researchers developed
a computer-assisted process for transferring the growth principle of nature to
automobile engineering. "The boxfish's bone structure, like other animals,
obeys nature's principle of maximum strength for the least weight," said
Mercedes engineer Dieter Gurtler. "The rate of bone growth is always in line
with the forces that are brought to bear on a body." Based on the SKO
(soft kill option) method, computer simulation was used to configure body and
suspension components in a manner that the material in areas subject to lower
loads were made thinner, and perhaps eliminated ("killed"), while highly
stressed areas are specifically reinforced. Gurtler said developing the
computer algorithms for the project was very time consuming, sometimes
frustrating, but in the end, extremely rewarding. The SKO method reduced the
bionic car's body structure by about one third, yet retained exemplary crash
safety, stability and handling dynamics. A Spacious, Uncluttered and Airy
Interior
Belying its awkward exterior styling, the shape offers up generous interior
space with tons of headroom and more than adequate leg, hip and shoulder room
for both front and rear occupants. Likewise, the cargo bay capacity can handle
packing of a decent sized load. The interior is uncluttered and airy, thanks
to the X-shaped cross member that gives the roof its rigidity while yielding
lots of space for glass panels. There is one distractionthe two-tone lime and
pistachio suede seats and trim. With 70 mpg, Who Needs A Hybrid?
With nature being the emphasis of the bionic car you might think, as I did,
that behind the short, stubby nose would be an example of the latest fuel cell
technology, or at the very least, a next-generation hybrid system. Instead,
propelling the boxfish-looking car is a 2.0-liter four-cylinder turbocharged
diesel with a common-rail direct injection system. Mercedes-Benz was the
first to implement Rudolf Diesel's combustion engine principle in a passenger
car some 70 years ago. That legacy will continue into the future, according to
Dr. Weber, who said that DaimlerChrysler is "committed to the diesel engine,
not only in Europe, but also in the United States." Producing 138 horsepower
at 4200 rpm and 221 lb-ft of torque at 1600 rpm, the bionic car accelerated
briskly (0 to 60 mph in just 7.9 seconds) during my short drive in an immense
parking lot at Washington, D.C.'s RFK Stadium. The continuously variable
automatic transmission directed power to the wheels in a seamless
manner and there was absolutely no telltale diesel clatter from the engine.
The diesel engine, combined with the attributes of the superb aerodynamics and
SKO construction, deliver an average of 70 miles per gallon fuel efficiency,
topping out at 84 mpg on a straight highway run. No Stinky Diesel Odor
After a half dozen laps around the mile-long parking-lot course, I stopped the
car, engaged the parking brake, left the engine running, stepped out of the
car, kneeled down and sniffed the exhaust to detect how much diesel odor was
spewing out. There goes the NOx emissions. Earlier, Professor Herbert Kohler,
DaimlerChrysler vice president, body and powertrain research had explained why.
The bionic car's diesel engine incorporates a state-of-the-art particulate
filter to minimize soot exhaust and a Selective Catalytic Reduction system to
get rid of excess oxides of nitrogen (NOx). The SCR system sprays a precisely
measured urea compound (determined by driving conditions) into the exhaust
system. This processes the NOx emissions into benign nitrogen and oxygen. The
urea solution, called AdBlue, is stored in the spare wheel recess. At this
point, the fluid must be replenished at a typical service interval, or about
every 15,000 miles. SCR technology use has already
proven successful in Mercedes-Benz's European commercial trucks. "With the
bionic car, we are showing the potential that SCR has when used in passenger
cars," Kohler said. He says that SCR can reduce NOx emissions by up to 80
percent under road conditions in the U.S. When testing is complete and the
Environmental Protection Agency gives it the nod, the SCR technology will be
offered in the U.S. for light vehicles, Kohler stated. Bionics to Meet
Production Cars
Like nearly all concept vehicles, the bionic car will probably never see a
production schedule. However, the benefits of the research are already paying
off. The SKO method has become an integral part of DaimlerChrysler's vehicle
development engineering, noted Research and Development Head, Dr. Weber. The
first examples will be a variety of small components on several vehicles
beginning next year, followed by the A-pillar for the next Mercedes-Benz
roadster, scheduled for production in 2008. The boxfish may not be the most
alluring sea creature hanging around coral reefs, but it's a keeper. Larry E.
Hall is editor of Northwest Auto News Service and a freelance automotive
journalist based in Olympia, Wash. He has an intense interest in future
automotive technology.
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