McLaren harnesses natural composite fibers

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Swiss company Bcomp’s natural fiber based composite materials have been on the market for several years, but as with so much in racing, many race car constructors have been reticent to depart from tried-and-tested carbon-based materials. However, McLaren has now taken the leap of deploying the company’s materials in its F1 car, specifically, for construction of the seat.

“For decades, F1 has been an innovation lab for technology that has transformed not just motorsport, but the automotive industry and beyond,” noted McLaren F1 technical director James Key. “The sport must continue down the road of getting to an increasingly environmentally friendly set of conditions, and our development and application of natural fiber composites is an example of how we’re accelerating this journey, as well as the ongoing evolution toward cleaner mobility.”

The Bcomp materials are based on flax fibers, and engineers at the company have also developed a 3D weave, dubbed powerRibs, to maximize stiffness. These ribs consist of thick yarns of flax fibers, which are then used to reinforce the company’s standard reinforcement fabric, ampliTex. In the case of the McLaren seat, these ribs are used to increase stiffness on the sides of the seat.

McLaren spotted an opportunity to use the new materials in the seat because of a regulation change in 2019 that specified a minimum driver weight of 80kg (176 lb). If the driver weighs less than this, ballast has to be added to the seat area.

“With the introduction of the new regulation in 2019, the seat now forms part of the driver’s weight budget, so it’s overengineered as a result,” explained McLaren F1 principal composites engineer Steve Foster. “And with Carlos [Sainz] and Lando [Norris] weighing in at 72kg and 68kg (159 lb and 150 lb) respectively, there’s plenty of scope to do that. It meant that, if we needed to, there was margin to use additional biocomposite material to ensure sufficient strength and stiffness in this safety-critical component.

“The original carbon-fiber seat design was reverse-engineered by Bcomp,” he continued, “and then we optimized and manufactured the new design. The seat was run in pre-season testing without any problems and we hope to be racing with Bcomp flax seats in the near future.”

Notably, according to McLaren the flax-based composites have greater vibration absorption characteristics than traditional carbon, by a factor of five; an important benefit in the context of a driver’s seat. If vibrations can be reduced, driver fatigue will be lessened and theoretically, performance increased.

The material is also less brittle than carbon, and this can be harnessed to improve energy dissipation in an impact. “It is not as fragile, and while it still breaks, the softer debris remains attached to the main structure with the help of the powerRibs, which help dissipate the energy,” explained Bcomp CEO Christian Fischer. He noted that these characteristics could make it suitable for future use in delicate aero components that are prone to in-race damage.

With an eye on the cost cap regulations arriving in 2021, it is significant that the natural composites are around 30% cheaper than carbon, which could bring benefits both on and off the car. “Where we see significant potential is in the non-critical, semi-structural areas of the car, such as the driver’s seat, as well as off the car,” said Fischer. It’s the latter application, reveals Foster, where the immediate scope for further adoption of natural-fiber composites really lies. “When used intelligently, the flax fibers reduce weight and cost, while maintaining and, in some cases, even improving performance. There is a range of possible applications beyond the car itself, including pit gear, truck panels, packing cases, timing stands and mold tools.”

Taking the final example of mold tools, Fischer notes that currently, most of the molds used to make parts of the car are made of carbon-fiber composite, due to low thermal expansion reducing dimensional changes when autoclaved. Flax fibers also possess this property, potentially making them a suitable tooling material for molding performance parts that are made from standard composites. Therefore, even if the part being produced isn’t made from natural-fiber materials, the tool to manufacture it can be – allowing the team to reduce the cost of mold tools and their environmental impact.

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