By Simon Smythe
We’re used to seeing flow fields represented in colour in computational fluid dynamics (CFD), but wheel brand Swiss Side has developed a new aero measurement system that enables real-world aerodynamic drag to also be viewed in full colour, allowing engineers to see where drag is coming from and with what intensity in the wind tunnel as well as on the computer screen. According to the company’s CEO Jean-Paul Ballard, “it literally doubles our measurement capability in the wind tunnel.”
The Swiss Side pressure measurement rake measures the energy lost in the airflow behind an object, aka its aerodynamic drag. It does this, according to Swiss Side, by using an array of 128 kiel probes which are illuminated by 288 individually controlled LEDs, which change colour depending on the measured air pressure.
Swiss Side explains that this traverses across the airflow field capturing a complete live colour picture of the aerodynamic drag and its intensity across the area measured.
Because such a device has never existed before, according to Swiss Side, the company’s engineering team developed everything in house, from scratch, to their specific requirements. This included the design and assembly of every component from the rake hardware itself, the pressure measurement system electronics and data logger, all the way through to the software systems.
Swiss Side says it also uses an ‘internet of things’ system approach, where the extensive array of sensors used by the rake system are connected wirelessly over a local internet network, making it “truly state of the art.”
This isn’t Swiss Side’s first foray into pressure measurement rake technology, which is used in F1. In 2019 it developed two rake systems - one for the wind tunnel (but without the LEDs) and one that directly mounted to the bike and was positioned behind the rider for real-world testing.
According to Swiss Side the pressure measurement rake provides a hugely valuable development tool for any application. It also provides extremely useful data for correlation back to CFD simulation models, to improve and refine the development process.
The ‘Swiss Side Aerodynamics’ activities now reach well beyond cycling, with its involvement in aerodynamic development projects across a wide range of industries from sports to automotive.
One of the biggest enemies for any object moving through the air is aerodynamic drag and therefore minimising that drag saves energy and/or enables higher speeds. In cycling, at above 15kph aerodynamic drag is the largest resistance force and is proportional to the square of speed - meaning it becomes increasingly higher the faster you go. Therefore, says Swiss Side, understanding what causes aerodynamic drag and how to minimise it is the number-one consideration for the aerodynamic development of any system.
Read our review of the Swiss Side Hadron Classic 485 wheels and check out our guide to the best road bike wheels.
Simon Smythe is Cycling Weekly's senior tech writer and has been in various roles at CW since 2003. His first job was as a sub editor on the magazine following an MA in online journalism (yes, it was just after the dot-com bubble burst).
In his cycling career Simon has mostly focused on time trialling with a national medal, a few open wins and his club's 30-mile record in his palmares. These days he spends a bit more time testing road bikes, or on a tandem doing the school run with his younger son.
What's in the stable? There's a Colnago Master Olympic, a Hotta TT700, an ex-Castorama lo-pro that was ridden in the 1993 Tour de France, a Pinarello Montello, an Independent Fabrication Club Racer, a Shorter fixed winter bike and a renovated Roberts with a modern Campag groupset.
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