Materials

Biomimicry: how the most innovative of Shinkansen designs was inspired by a small bird’s hunting practices

Have you ever been lured off track by something beautiful? It happened to me five times over on the weekend – what was a trip to Nezu Museum to see the Sometsuke exhibition soon became a hunt for a fleeting bird. Its bright plumage and streamlined beak was too entrancing; I had no choice but to stalk it from one side of the pond to the other in attempt to capture a shot.

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Image showing how the beak of a Common Kingfisher penetrates water; image sourced from Bio Based Press 

I got my shot and identifying it wasn’t difficult either. It was a Common Kingfisher (Alcedo atthis), prized for its beauty and hunting skills. Its smooth dive into water was impressive – the  lack of splashes and shockwaves spelled doom for its prey. A quick look at its dietary requirements and habitat reveal why evolution favoured such pointy beaks: an adult Common Kingfisher (Alcedo atthis) requires 60% of its body weight in food a day and prime hunting grounds, segments of a river with clear water and perches, are limited. Most passerbys would merely gasp in awe upon witnessing a Common Kingfisher (Alcedo atthis) hunt, but a Japanese engineer applied his observations to Shinkansen designs.

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Image of the JR500 Shinkansen; sourced from Wikipedia

Shinkansens first appeared in Japan in the 1960s, but it wasn’t until the 1990s that models with the signature pointy nose were made. Design and testing of the JR 500, the first model with the pointy nose, started in 1989 and completion was slated for 1994. The JR500 was intended for the Sanyo Shinkansen Line that ran from Shin-Osaka to Hakata, a route that had more tunnels than other routes. The Shinkansens of that era weren’t equipped to deal with the issues that travelling through a tunnel at high speed would entail: “when a train rushes into a narrow tunnel at high speed, this generates atmospheric pressure waves that gradually grow into waves like tidal waves. These reach the tunnel exit at the speed of sound, generating low-frequency waves that produce a large boom and aerodynamic vibration so intense that residents 400 meters away have registered complaints“. Eji Nakatsu, the former Director of Technical Development and Test Operation Department of JR-West, was an avid birdwatcher who drew inspiration from the Common Kingfisher’s (Alcedo atthis) hunting practices. He noticed that  few splashes were created when the Common Kingfisher (Alcedo atthis) dived beak-first into water, despite the large difference in air resistance between air and water. Further, its prey seldom escaped – possibly because the dive created minimal shockwaves, thereby minimising warning and time for the fish to react. Eji Nakatsu hypothesised that the shape of the Common Kingfisher’s streamlined beak had something to do with it. The company tested the idea and the results were promising – “this shape has enabled the new 500-series to reduce air pressure by 30% and electricity use by 15%, even though speeds have increased by 10% over the former series”. The JR500’s pantograph and pantograph supporting shaft were also modelled after birds: the Owl (Strigiformes) and Adélie penguin (Pygoscelis adeliae).

There has been a biomimicry boom of late – evidenced by countless inventions that have been modelled from living organisms. Everything in nature survived millennia of ruthless trials, so it makes sense for us to learn from their lessons.

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