The world is loud. If delivery drones and air taxis — also known as electric vertical take-off and landing (eVTOL) aircraft — gain the level of market saturation investors are hoping for, cities and neighborhoods are only going to get noisier.

That’s the assumption, anyway. But Whisper Aero does not seem to care much for assumptions.

The premise of the two-year-old startup is that there should not be a trade-off between technological progress and noise: You should be able to quietly rid your lawn of leaves, heat and cool buildings, and even take an air taxi ride. To get to that future, Whisper says it has developed a never-been-done-before electric propulsion device (to get really specific, an electric ducted fan) that’s both quieter and more efficient than ones already on the market.

Whisper is headed by Mark Moore, a former executive at Uber Elevate, the ridesharing giant’s ambitious air taxi initiative that it later sold to eVTOL developer Joby Aviation. Moore told TechCrunch that he came out of Uber with an understanding of “the compelling need” of urban air mobility: a lower noise profile.

“If you want to get to scale with delivery drones or eVTOL air taxis, you better be really quiet,” Moore said. “You’ve got to be quiet enough that you’re not disruptive to those communities.”

Whisper has designed an electric ducted fan that can be scaled up or down for different applications. Over the past two years, the company has designed, built and flown nine generations of this propulsor. They’ve settled on a product that both reduces the amplitude — how loud something is — and that shifts the tonal profile of the noise to something more pleasant. The company says they’ve even been able to move some of the tones into the ultrasonic, beyond what the human ear can detect.

The implications for the tech are significant. Noise reductions have always carried some kind of sacrifice in performance or weight. Instead, Whisper COO Ian Villa said the team has taken a first principles approach to propulsion and noise, starting with the most basic questions about how to turn electricity into thrust.

“Most companies only think about designing for low noise by reducing disk loading and tip speed with a willingness to sacrifice efficiency,” Whisper said in a statement. “We never accepted this premise.”

Going ultrasonic

Since emerging from stealth two years ago with $7.5 million in funding, Whisper has maintained a low profile. It is headquartered not in California or Colorado or Texas, but in  Tennessee — in a small town called Crossville with a population just north of 12,000. The website is still essentially just a landing page. It’s only now, having spent the past two years entrenched in research, design and testing, that the company is ready for its coming out party.

To reflect that, Whisper has recently closed a $32 million Series A led jointly by Menlo Ventures, EVE Atlas, Capricorn Investment Group and Connor Capital. Additional participation came from Kindred Ventures, Abstract Ventures, Moving Capital, AeroX Ventures, Cosmos Ventures, Linse Capital and LaunchTN, a public-private partnership with the state of Tennessee.

Following a well-trod path in aerospace, Whisper will focus its initial commercialization efforts with the U.S. Department of Defense, an agency that they’ve already been working with for testing. Whisper has scored a handful of small government contracts from the DOD, including the Air Force Research Lab, to validate their propulsor.

The relevance of a quiet aircraft to the DOD is likely obvious. Whisper has validated that it can fly a 55-pound drone with its electric ducted fan at an altitude of 200 feet that is completely undetectable, at least by noise, from the ground. To put that in context, Moore said Boeing’s popular military drone, the Insitu ScanEagle, would need to fly at least 3,000 feet above to not be heard.

Whisper Aero’s 55-lb demonstration drone in flight. Image Credits: Whisper Aero

“It’s sort of a breakthrough in terms of what surveillance drones are capable of doing in terms of missions, by being able to get so close and not be detected,” Moore said. “Especially at night, where you won’t be able to see it. It can be flying and loitering right overhead and you would have no idea that’s there.”

Whisper has “very specific platforms” it’s looking to integrate with its product, Moore added, from very small drones all the way up to platforms large enough to carry people.

There are plenty of commercial aviation applications, too. Chief amongst them is eVTOL, a nascent industry that the biggest and most well-funded players, Joby and Archer Aviation, say could reach commercial service as early as 2025. Whisper itself is not building an electric aircraft, but its tech could be used to make them quieter. Moore said it also “fundamentally transforms what the aircraft look like and what they can do.”

The company is quick to point out that the benefits don’t just lie in decreased noise, but also in the efficiency gains — a metric that’s all the more important as more of the world’s technologies switch to electric, and must depend on the limited lifespan of batteries. The company also says that many aircraft have speeds that are limited by open rotors (or open propellors), as opposed to ducted. Instead of operating at 150 miles per hour, an eVTOL could potentially fly as fast as 300-400 miles per hour.

The world’s quietest electric leaf blower?

With this new round of funding, Whisper is looking to double their Tennessee-based team, which currently stands somewhere between 10-50 people (they declined to be more specific). The company is also moving into two new facilities, an 8,000-square-foot facility in Nashville for design, engineering and rapid prototyping and a 40,000-square-foot space in Crossville, for testing and production, that is collocated within a larger Tennessee Tech University facility.

This capital raise marks an inflection point — what Villa called “phase two.” If phase one was all about R&D, this second phase is focused on generating revenue on the defense side of the business.

Phase three is likely a ways off yet, but eventually, Villa said the plan is to enter into non-DOD verticals: commercial aviation, industrial and consumer. The company’s already developed a demonstration electric leaf blower that uses its electric ducted fan. That’s just one of the many possible applications that are clearly already on the company’s mind.

“We are this future Pratt & Whitney mashed up with a Dyson,” Moore said, referring to the giant aircraft engine maker and the consumer tech company best known for its vacuums and hair dryers.

“We’re very anxious to take this technology to people’s everyday life.”