86 fibre and the company’s own proprietary resin materials. “Traditional pressure vessels are Type 3 or 4 systems, made using either a metal or plastic liner respectively, and completely overwrapped with carbon fibre in order to have the strength to contain the pressure inside the tank,” explained Michael Tate. “However, other fibres can work too, such as fibreglass, aramid materials or even basalt fibres, technically speaking. “What we’ve done is eliminate the need for that liner by having just a carbon fibre structure and an integrated resinrich layer, which gives the systems integrator more internal storage volume and a lighter tank for the same external footprint, as well as faster lead times and typically lower costs than other aerospace pressure vessels.” In most Type 3 tanks, the metal liner accounts for up to 10% of the mechanical loading, while in Type 4 vessels the plastic accounts for 0%,” Tate said. “These materials generally serve primarily as a mandrel for forming the carbon composite tank shape around them, and as a barrier to prevent fluids leaking into or out of the vessel.” Infinite Composites has instead used a proprietary tooling system to form the tank structure and geometry. The tooling is then removed to leave the carbon fibre structure and a resin-rich layer, the latter serving as the permeation barrier without taking up the internal physical volume of the metal or plastic. “We get the same or better permeation rates as a Type 4 tank, and very similar rates as a Type 3, while also passing all the industrial standards in terms of the performance and capability requirements from the DoT and other governing bodies,” Tate added. Advanced materials company Venture Aerospace attended the exhibition to show and discuss two new proprietary composite solutions. “The first is called Melanyte, a carbon fibre alternative,” McKenzie Davis said. “It’s lighter, stronger and about twothirds the price of traditional carbon composite, while also being more ductile. “That means it won’t disintegrate or delaminate, like many carbons do when they hit their mechanical failure point. It’s also isotropic – strong in all directions – whereas carbon fibre is weak under compression, such that when you apply force in any direction other than the length of it, it will fail. “It can also be shaped into various geometries and reshaped, such that a tubular rotor arm could be re-moulded into something else if needed.” Davis attributes Melanyte’s original invention to Sasha Mela (formerly of Venture Aerospace), the inspiration having come from an ornithologist associate of Venture’s CEO who had cited toucan beaks as having one of the highest strength-toweight ratios of any organic material. “Melanyte therefore has essentially an expanding foam on the inside, and is cured with an unshrinkable skin on the outside, thereby mimicking the material in a toucan’s beak,” Davis said. “Our second material, Lennoxite, follows a very different idea. It’s meant for protecting sensitive electronics against thermal and mechanical stresses. It has high conductivity and wicks heat away like a heat sink, but it’s non-metallic, so it won’t interfere with magnetics. “So as well as using it to protect PCBs, you could use it in an e-motor. We’re working on a way to extrude it to envelope copper windings.” August/September 2023 | Uncrewed Systems Technology Infinite Composites’ new pressure vessel for hydrogen fuel storage and similar applications
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