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Inspired by the birds

The new models inspired by the kingfisher and owl not only reduced noise but also air resistance.   | Photo Credit: Pxfuel.com

On October 1, 1964, just 10 days before the opening ceremony of the Olympic Games, Japan inaugurated its ‘Bullet Train’. Still emerging from the devastating impact of World War II, the country’s slogan for the Olympics was ‘faster, higher, stronger’. The Bullet train speeding past Mount Fuji became the defining image of new Japan.

As the years passed, the speed kept increasing but, by the 1990s, this began to pose a new challenge: that of noises. One was the result of a sort of whirlwind rushing over the pantographs where the train derived its energy from overhead electric wires. A solution was found and inspiration came from owls, or rather their wings. Comb-like serrations on the edge of the bird’s primary wing feathers break down air rushing over the wing. This muffles sound and allows them to fly silently. Japanese scientists began to prototype pantographs using this mode. In 1994, a new pantograph, dubbed the “wing-graph”, which mimicked the owl’s wing structure replaced the traditional design.

The other problem was more complicated. The shape of the train’s face caused a cushion of air to build up as it entered a tunnel. When it exited, a booming sound was produced that disturbed people in the vicinity and the wildlife in the area. Again the solution came from a bird. The head engineer, who was also a keen birdwatcher, and his junior had noticed that kingfishers dived into water at high speed from a great height but created a minimal splash. It struck them that the shape of the bill allowed this seamless transition. The engineers found that the kingfisher’s bill was unique, with the both the upper and lower beak having a triangular cross-section with curved sides.

Testing by the design teams confirmed that the kingfisher’s bill was the most efficient shape and a series of prototypes were built and tested, with a train nose very close to the kingfisher bill being adopted. In 1997, the 500-Series Shinkansen train was able to run at its maximum speed (300km/hour, which was a world record for that time) while also meeting strict noise standards of 70 dB. Thus the new models inspired by the kingfisher and owl not only reduced noise but also air resistance, resulting in twin benefits: of reducing energy consumption and cost savings.


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Printable version | Oct 20, 2021 9:34:55 AM | https://www.thehindu.com/children/how-the-engineers-who-worked-on-japans-bullet-train-found-solutions-in-nature/article36602637.ece

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