Inside the Exacting Process of Bringing the AS2 to (Model) Life

The completion of wind tunnel testing was one of many milestones achieved last year by Aerion Supersonic. Rigorous validation helped bring the AS2 supersonic business jet (SBJ) to fruition as the first privately-designed supersonic jet for the civilian market. Aerion’s assessments at state-of-the-art facilities in France and the U.S. yielded a major step forward for the company. We undertook more than 1,000 individual trials with models of the AS2 flying more than 72,000 nautical miles and amassing an astounding 200,000 in-flight data points to put the finishing touches on the AS2’s final design.

Wind tunnel testing of the AS2 proved to be an efficient process thanks to Aerion’s all-digital design process, powered by its proprietary Digital Carbon platform. This allowed Aerion to power a “digital twin” process to evolve the AS2’s design into the supersonic aircraft that will roll off the assembly line in the coming years. As Forbes explains, “Think of a digital twin as a bridge between the physical and digital world.” Instead of wind tunnel testing being a time of trial and error — as it often is in traditional non-digital design scenarios —  Aerion’s assessment was much more specific. This is because we designed thousands of variations of the AS2 that digitally flew millions of miles in a perfect simulation of real-world conditions.

Given the power of the Digital Carbon platform and the real-world fidelity of digital twinning, it may seem like preparing for the wind tunnel was a snap. Simply a matter of exporting a final design file, firing up a digital printer, and heading over to the lab, right? Not so much. No matter how advanced digital design technology becomes, this is wishful thinking. In fact, the process to create effective physical models of the AS2 SBJ took many months. It also required the expertise of some of the world’s top modelers at NLR – Netherlands Aerospace Centre.

Royal NLR, based in the Netherlands, has been improving and advancing the technology of flight for more than 100 years. This unique organization, employing more than 600, specializes in solving difficult problems in the aerospace world. From advancing environmentally friendly engine technology to solving the challenge of airplanes hydroplaning on wet runways, NLR disentangles thorny issues facing both private industry and governments alike, explains Jan Bos, Manager Aerospace Industry. As Aerion approached the point in the design process requiring wind tunnel data on the AS2, we knew NLR was the right partner to take on the job.

Even so, complicating an already challenging assignment, the project was just getting underway when the coronavirus pandemic spread around the world. NLR project manager Justin Dorneanu (since succeeded by Jelmer van Vilsteren) reflected on its impact, saying: “This is the first project where we never met face-to-face to shake hands. But we made it work with weekly meetings via the internet, and both teams really came together to support the mission.”

The first step in the process was to design the model, a collaborative effort between Aerion and NLR. Still, crafting something durable enough to withstand the rigors of a supersonic wind tunnel is no simple matter of scaling down the AS2’s design. That’s why Dorneanu is so proud of the way the teams collaborated. “The communication between Aerion and NLR was the highlight of the project for me,” he said. “We worked closely together to tackle many problems, which resulted in the best model possible.”

One of the challenges of supersonic wind tunnel testing involves choosing the right material to build the model. Plastic is out of the question. Even aircraft aluminum won’t stand up to such high stresses at a small scale. Accordingly, the Aerion model was crafted out of special steel-alloy beyond even that which NLR typically uses in wind tunnel models. As each model piece was milled to exacting standards, experienced craftsman polished the parts, carefully connecting them to body, thereby ensuring the necessary degree of movement for components, like the tail assembly.

The model AS2 was also packed full of electronics, including sensors on all key sections of the aircraft. Aerion was particularly interested in testing supersonic stresses on the flaps, so this was an area of focus for NLR’s electronics team. Composed of experts, they worked through microscopes to connect wires the size of human hairs to the tiny sensors that would generate data from the wind tunnel.

From the initial session between Aerion and NLR, it took almost six months to construct the model AS2. Due to travel restrictions, the acceptance meeting took place via internet, as did all others throughout the project. Finally, the completed model was shipped to Paris for supersonic wind tunnel testing, resulting in an incredible success. Aerion Supersonic is no stranger to breaking down barriers. Even so, our partnership with NLR to produce our supersonic wind tunnel model was a major step in achieving the goal of bringing the world closer together through the power of supersonic flight.

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03 16 2021