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Automobile R&D Center, Honda R&D Co., Ltd.

Designing for design’s sake—with aerodynamics built in

Ken Sahara, Seniour Designer and exterior design project leader (PL) of the Clarity Fuel Cell

Ken Sahara,
Seniour Designer and exterior design project leader (PL) of the Clarity Fuel Cell

Clarity Fuel Cell design sketches

Clarity Fuel Cell design sketches

Creating that European luxury sedan feeling

  Exterior design was critical to achieving a value and appeal exceeding that of gasoline engine vehicles. Ken Sahara, Seniour Designer at the Automobile R&D Center who oversaw the Clarity Fuel Cell's exterior design, describes aspects of his design approach that were a priority:

"Given the model's large price tag, the goal was to create distinctiveness and feel that measured up to European luxury sedans in the same price range. A low profile, small tires, and cramped look would not be commensurate with its price. It needed a dignified frame with balanced proportions, with wheels and tires of matching size, all working together to convey a sense of stability. In a sense, we aimed for proportions that set it apart from other Japan-made cars."

  Aerodynamics was another crucial element of the new FCV's design. That's because extending its cruising range to the level of gasoline engine vehicles meant minimizing all forms of driving resistance, including air drag. Shugo Kamemoto, Assistant Chief Engineer at the Automobile R&D Center in charge of aerodynamic properties of the Clarity Fuel Cell, explains the importance of aerodynamics for the Clarity Fuel Cell.
"Gasoline engine vehicles see their fuel economy improve when cruising at faster speeds. But for FCVs it's the exact opposite; whether cruising or not, motor efficiency declines when speed increases. For that reason, improving aerodynamic performance and reducing driving resistance has a greater impact for FCVs than it does for gasoline vehicles. That's why I felt that, to achieve the cruising range target set for the new FCV, we also needed to push the boundaries of aerodynamics."

  But aerodynamics is heavily dependent on exterior design. In many cases, unique, free-spirited design and high aerodynamic performance are mutually exclusive, as cars with a low air resistance tend to look the same.
  With Sahara's design priorities on the one hand, and Kamemoto's airflow requirements on the other, the two would need to compromise somewhere—if, that is, they were following a conventional approach. This time, however, they decided to try out of a new development approach to achieve the impossible.

Showing by example the synergies of design and aerodynamics

"Before getting into the design process, we started by having the designers meet with the aerodynamics engineers to talk and develop a shared vision for what kind of car we wanted," says Kamemoto.
  In the conventional approach, the two teams start work separately, converging at a later time. But for this project, the two groups met face-to-face on day one, deciding design and airflow characteristics as a team.

"Designers generally know what kind of designs or forms are more aerodynamically efficient. But in this project the topic never came up. Instead, the two groups talked repeatedly about what kind of design would be suitable for a flagship FCV sedan, what aspects of the design created drag, and how to fix it. That way the designers never added an element they didn't want simply because it improved aerodynamics," says Sahara.

  Instead of aerodynamics, the designers prioritized creating an attractive, distinctive, one-of-a-kind exterior. This resulted in overall proportions for the Clarity Fuel Cell that achieve advanced aerodynamic performance as an inherent function. They also actively incorporated airflow features that were in the spirit of the design concept. Symbolizing this process are the air curtains incorporated into the front and rear wheel wells.

  Although the Clarity Fuel Cell is the first sedan in the world to include rear air curtains, Kamemoto prefers to downplay their significance as an innovation.
"The impact of the air curtains themselves is not particularly large. But they are part of a whole series of improvements that add up to a significant impact on overall driving resistance. The result is an impressive sedan that sets an example for the kind of synthesis that can be achieved between design and aerodynamics."

Shugo Kamemoto, Assistant Chief Engineer and finished vehicle performance project leader (PL) of the Clarify Fuel Cell

Shugo Kamemoto,
Assistant Chief Engineer and finished vehicle performance project leader (PL) of the Clarify Fuel Cell

Front air curtain

Front air curtain

Rear air curtain duct

Rear air curtain duct

With a solid understanding of packaging,
A young engineer makes a confident decision for the team

Kei Kobayashi, Packaging designer of the Clarity Fuel Cell

Kei Kobayashi,
Packaging designer of the Clarity Fuel Cell

Clarity Fuel Cell packaging design

Clarity Fuel Cell packaging design Dividing hydrogen storage into two tanks for more efficient placement contributed to greater riding comfort and a longer cruising range.

Dividing hydrogen storage into two tanks for more efficient placement contributed to greater riding comfort and a longer cruising range.

An FCV that looks like an engine vehicle—but built like an FCV

  Another Honda associate who deserves mentioning when talking about the Clarity Fuel Cell's design is packaging designer Kei Kobayashi.
  As a packaging designer, Kobayashi’s job was to coordinate the work of the designers and engineers and bring their conceptual aspirations to a practical resolution. Though younger and less experienced than his colleagues, Kobayashi feels satisfied with the Clarity Fuel Cell despite the various challenges he faced when designing its packaging.

"People have said the Clarity Fuel Cell has a very natural, car-like design," he says. "We fit the entire powertrain into the front end, so they assume we benefited from our knowledge of engines, but that's far from the truth. FCVs have a load of functional parts—hydrogen tanks, for example—that aren’t used in engine vehicles. The number of parts we had to fit between the four wheels doesn't even compare to an engine vehicle. If we designed the FCV like an engine vehicle, it would look nothing like it."
  At motor shows and other events, Kobayashi has taken a secret pleasure in surprising journalists who examine the Clarity Fuel Cell and find parts in unexpected places. It's part of the joy of being a packaging designer, he says.

  The packaging designer also plays an organizational role among the development staff, gathering requests and suggestions from designers and engineers and coordinating them from a bird’s eye view of the project. The hydrogen tanks are an illustrative example.
  One unique feature of the Clarity Fuel Cell is that it has two hydrogen storage tanks: one behind the rear seats and the other below the floor. There was a time in development when the engineers sought to combine the tanks to reduce weight, but this required sacrificing hydrogen capacity, riding comfort, or cargo space—a decision that could negatively impact the product's value.

"Kobayashi gave a definitive answer: 'One hydrogen tank will be disastrous for the vehicle,'" laughs Shimizu. "So we gave up on the single tank idea and everyone went back to the drawing board to think of how we could add storage somewhere else."
  Despite his age, Kobayashi told Shimizu his opinion directly and without hesitation, and Shimizu accepted without objection. Such a relationship was possible because Kobayashi had a solid understanding of what packaging design was most appropriate for passengers, and because it aligned with Shimizu's vision for the FCV.

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