Breaking down the design of Supernal’s new eVTOL

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Four years ago this week, Hyundai Motor Group unveiled its first electric vertical take-off and landing concept, the S-A1, at CES 2020 in Las Vegas. This year, Hyundai’s rebranded advanced air mobility division, Supernal, is back at the consumer electronics show with a substantially modified concept, the S-A2, that reflects what the company has learned about eVTOL aircraft in the interim.

“In 2020, it was a vision concept where we’re calling this a product concept,” explained Supernal Chief Technology Officer Ben Diachun, who provided The Air Current with a deep dive into the fully electric S-A2’s design and underlying philosophy. “The significant difference is the maturity level of where we’re at, what we’ve put into the design, the level of rigor and work that we’ve done.”

Related: Special Report: Surveying the eVTOL competitive landscape

The S-A1 had four tilting propellers for vertical and forward flight, plus four sets of stacked co-rotating propellers for vertical flight only. Multiple eVTOL developers including Archer Aviation, Wisk and Vertical Aerospace are similarly using a combination of tilting propellers and lifting props that are not powered in cruise flight. 

By contrast, the S-A2 takes a novel approach with eight tilting props on booms attached to the wing — four that tilt upward in the front, and four that tilt downward in the rear, all of which are powered during all phases of flight.

“We’ve learned a lot about the dynamics of fixed rotors in forward flight and there are a lot of, we believe, unfavorable characteristics when you have to stop lift rotors or try to stow lift rotors,” Diachun said. “You get large asymmetries on the blades; you can have large moments on the hub assembly that’s holding those blades. So, one of the key differences you see is that we’ve gone to an all-tilting configuration.”

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