Today’s aircraft manufacturing industry moves at what could easily be described as a snail’s pace. No company makes more than 700 samples per year, across its entire lineup. Meanwhile, even the fussiest ultra-premium carmaker on earth still manages to crank out 50 or 60 a day.
The challenge of manufacturing looms large over the eVTOL industry, especially given the fact that the aircraft will need to be mass-produced from composite materials, which are exceptionally time-consuming and tricky to make. One company, however, is developing a solution that could massively speed up the process: 3D printing of carbon-composite structures.
At the moment, Silicon Valley-based startup Arevo is using bicycle-frame manufacturing to develop its techniques — and also generate revenue as it ramps up — but chairman and co-founder Hemant Bheda said the ultimate goal is to use the process to manufacture aircraft structures quickly, reliably, and on demand. “Composite manufacturing is still in the Stone Age, and we see a huge opportunity to transform the process,” Bheda said. “First and foremost, it’s a software challenge. Second, there’s the potential to introduce new techniques to layer the material itself. Third, we need to introduce automation in what has traditionally been a very labor-intensive process.”
Bheda started out manufacturing extruded plastic components for machined parts, but quickly saw the potential for additive manufacturing in that space. A customer’s challenge to create continuous carbon fiber laid down in specific patterns and shapes led him to 3D printing, and the challenge of using composite materials with that technique. He and his team of 35, including 25 engineers, have developed a system for embedding continuous carbon fiber strands in thermoplastic polymers, with the latter transferring loads to the former. This process eliminates the need for time-consuming curing of the material, as is currently required with the thermoset composites used in aviation.
The big challenge, he said, was developing the software to control the robotic arm that aims the heated material. “That’s the reason we’re using a robot, which gives us the multi-axis motion to lay down what is essentially a spider web of material,” he said. “When we look at something like an aircraft or air taxi, we know that the pattern that works best is what nature has already told us via the spider’s web. That’s the ultimate construction, and eventually, we’ll have an army of spider-bots that can weave this structure together.”
There have been many challenges along the way, from developing the proper heating element that won’t damage the carbon fiber material — laser-based direct energy deposition, rather than a conductive heating element — to ensuring the software can properly manage the curves and twists of the physical mold, the 3D surface, in which the material is laid down. Other challenges still remain, including testing and analysis of the parts to ensure they meet aerospace standards for strength and durability, while at the same time using minimal material and weight. Arevo is using predictive modeling software to analyze the performance of the printed material, which is partly where the bicycle strategy is proving extremely beneficial, Bheda said. Those frames have to be extremely rigid and strong yet perform in nuanced ways that pro riders can benefit from, so their development is a precision process.
In that realm, the Arevo team has been surprised by the speed with which their innovation has made an impact. The company worked with bicycle design firm Studiowest on a prototype, which was completed in just a few days. “We printed the frame, took it to a bike shop to assemble it, and took a ride. It rode like a bike, and didn’t seem like a big deal,” Bheda said. “But when we called the designers over, they were surprised by how well it performed. We were puzzled by this, pointing out that it did exactly what they wanted it to do. Their response was that it usually takes 18 months to make this happen, including several rounds of revision.”
Arevo is working to hone the bicycle manufacturing strategy — its business plan is not to sell the printers, but the service of printing itself — and it expects its processes to be able to produce custom single-piece bicycle frames in a single day versus the 14 it currently takes, given the assembly and fusing together of dozens of individual components. Of course, the software that Arevo is using to develop the frame printing strategy can also be a design tool to hone the product, customize it, and quickly prototype actual final products, all of which will further appeal to clients.
Arevo has secured $7 million in funding from venture capital firm Khosla Ventures, which has support from Bill Gates; and additional backing from Airbus Ventures, AGC, and Sumitomo, to the tune of $34 million. It will take another three to five years before it begins producing aircraft structures, and until then the bicycle manufacturing will help refine and scale the process, while also generating cash flow. Along the way, Bheda also expects to lure in industrial and automotive manufacturers with the new technology, further paving the way to the flying-car future.
“There are many companies pursuing air taxis,” Bheda noted. “It’s real, and it’s good, and I believe we can help make the manufacturing fast enough to really support it.”