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The skies are on the cusp of getting busier — and louder — as drone delivery and electric vertical take-off and landing passenger aircraft startups move from moonshot to commercialization. One former NASA engineer and ex-director of Uber’s air taxi division is developing tech to ensure that more air traffic doesn’t equal more noise.

Mark Moore, who was most recently director of engineering at Uber Elevate until its acquisition by Joby Aviation, has a launched his own company called Whisper Aero. The startup, which came out of stealth this week, is aiming to designing an electric thruster it says will blend noise emitted from delivery drones and eVTOLs alike into background levels, making them nearly imperceptible to the human ear.

It’s a formidable challenge. Solving the noise problem comes down to more than simply cranking down the volume. Noise profiles are also characterized by other variables, like frequency. For example, helicopters have a main rotor and tail rotor that generate two separate frequencies, which makes them much more irritating to the human ear than if they were at a single frequency, Moore told TC in a recent interview.

Complicating the picture even further is that eVTOL companies are designing entirely new types of aircraft, ones that may generate different acoustic profiles than other rotorcraft (like helicopters). The U.S. Army recently undertook a research study confirming that eVTOL rotors generate more of a type of noise referred to as broadband, rather than tonal noise which is generated by helicopters. And as each eVTOL company is developing its own design, not all of the electric aircraft will generate the same level or kind of noise.

Whisper is designing its scalable product to be adoptable across the board.

Moore said the idea for the company had been fomenting for years. He and Whisper COO Ian Villa, who headed strategy and simulation at Elevate, realized years ago that noise (that is, less of it) was key to air taxis taking off.

“The thing that was abundantly clear was, noise matters most,” Villa said. “It is the hardest barrier to break through. And not enough of these developers were spending the time, the resources, the mindshare to really unlock that.”

Whisper CEO Mark Moore. Image Credits: Whisper Aero (opens in a new window)

Helicopters have mostly been able to get away with their terrible noise profile because they are used so infrequently. But eVTOL companies like Joby Aviation are envisioning far higher ride volumes. Moore is quick to point out that companies like Joby (which purchased Elevate at the end of 2020) are already developing aircraft that are many times quieter than helicopter, and are “a step in the right direction.”

“The question is, ‘is it enough of a step to get to significant adoption?’ And that’s what we’re focused on.”

Whisper is staying mum on the details of its thruster design. It has managed to attract around $7.5 million investment from firms like Lux Capital, Menlo Ventures, Kindred Ventures and Robert Downey Jr.’s FootPrint Coalition Ventures. It’s also aiming to convert its provisional patents with the United States Patent and Trademark Office sometime next year.

From there, the startup envisions launching in the small drone market around 2023, before scaling progressively up to air taxis. Moore said the goal is to get the thrusters manufactured and in vehicles by the end of the decade. Should the first generation of eVTOL go to market in 2024 (as Archer Aviation and Joby have proposed), Whisper’s product could potentially appear in second generation eVTOL.

In the meantime, Whisper will continue testing and working out remaining technical challenges – least among which is how to manufacture the end product at a reasonable cost. Whisper is also preparing to conduct dynamic testing in a wind tunnel, in addition to the static tests it has undertaken at its Tennessee headquarters, some in partnership with the U.S. Air Force.

“It’s got to be quiet enough to blend into the background noise,” Moore said. “We know this and that’s the technology we’re developing.”