Some residents from Logan, Brisbane have had enough of Wing’s delivery drones flying over their homes, on occasions close to eighty times a day, reports Australian Channel 9 program, ‘A Current Affair’. “They are very very noisy,” says one resident. “It’s gone too far!”

For example, Dan Ling has to put up with Wing’s drones flying over his house, often eight times an hour, each day and every day. He describes the noise like that of “a swarm of mosquitoes.” Another resident says, “They sound like a fly stuck in your bedroom when trying to sleep”; a third describes them sounding “like a dentist’s drill.”

Watch Video:

Apart from being attacked by birds (!) the Wing’s drones vulnerability has always been its noise. The company is acutely sensitive to the issue and why few if any of the company’s videos marketing the delivery service has the flying sound incorporated. Instead, it is washed over by a music background.

Just over a year ago, Wing was able to reduce the noise of its drones, but this is still not enough, it seems, for some residents living under a flight path.

Ling tells the current affairs reporter, “I feel annoyed as it actually stresses me sometimes. You’re sort of chilling out after working all day and you hear the buzzing noise like a very very loud mosquito and it gets louder and louder.” He adds, “We feel like we’re prisoners to this noise. We have to close the front door because you can hear it coming.”

Dan Ling

Drone delivery services have been introduced in suburbs across Australia. In Logan alone, Wing has made over 75,000 deliveries this year from transporting fast food and drinks to small grocery items. 

However, another resident, Dale Carter, who lives close by from Ling says he uses the service every day and loves it. “I don’t see much of a problem. If you’ve got a busy road close by, you hear cars and trucks. It’s no different.” Carter says he often places six or more orders a day, thereby being partly responsible for Ling’s torment.

In a statement to ‘A Current Affair’, a Wing spokesperson said it has only received a handful of complaints throughout several years of operation. It reads, “While the number of complaints is low, we take any community feedback about noise extremely seriously.”

It goes on, “Last year we introduced a quieter drone model in the Logan community, that almost halved the sound level experienced during overflight, making it much quieter than other typical noises in a neighbourhood such as a delivery car or truck on the street, or a leaf blower or lawnmower in a neighbour’s yard.”

Drone noise in Australia is regulated by the federal government’s Infrastructure and Transport Department. At present, Wing must operate during specified hours. “Many drone operators, including Wing, require a noise approval under the regulations to fly,” a statement by the department said. It goes on, ”As drones become more popular for commercial and recreational use, the government recognises the issue of noise is becoming more important.”

Noise has always been a major issue for both the drone and eVTOL industries. Like electric cars, very low levels must become the gold standard. A carbon-free green environment should not attract noise pollution. The two do not equate.

“Joby As Quiet as a Conversation” (image: Joby)

JoeBen Bevirt, founder and CEO of Joby Aviation, takes great pride that his eVTOL is “as quiet as a conversation” and sounds like “the gentle swishing of trees in a mild breeze” given its less than 65 decibels (dBA) at a distance of 330 ft. Guy Norris, editor of Aviation Week wrote, “The aircraft makes only a partially perceptible sound that would almost certainly be undetectable against everyday noise background of an urban environment.”

Yet, delivery drones have a problem when flying low over suburbs. Given the close proximity and need to interact with the residents, they should be even quieter than eVTOLs where silence is almost golden.

During Wing’s American trials over Christiansburg, Virginia, starting in late 2019, a peer-reviewed study from Virginia Tech showed that while 89 percent of respondents had used the service or planned to soon, major concerns included noise and privacy. Even so, three-quarters of those who said they were bothered by the noise still liked the idea of the service.

One of the best known researchers into “noise-free” is former NASA engineer, Mark Moore, and now co-founder of Tennessee-based startup Whisper Aero. At this year’s HAI Heli-Expo in Dallas, Texas, the company disclosed that its drone propulsion is inaudible from just 200’ away. A huge help for people like Dan Ling.

A panel discussion on eVTOL acoustics at Heli-Expo 2022, organized by the Vertical Flight Society (VFS), featured Juliet Page of Blue Ridge Research and Consulting, Ben Goldman of Archer Aviation, Mark Moore of Whisper Aero (centre), and Rex Alexander of Five-Alpha LLC. (image: VFS)

During an Heli-Expo panel forum on eVTOL acoustics, organised by the Vertical Flight Society where Moore contributed, the importance of how such craft would sound within its environment including the time of day it operates was discussed. For example, during rush hour a louder vehicle may blend more into the background.

Ben Goldman, acoustics manager at Archer, shared, as like Joby, that the noise emissions of its eVTOL craft has been a focal point for the company since the start. He commented, “This is a critical aspect of the vehicle design, in terms of integrating it into the market. We’re slowly learning how to quantify public acceptance and annoyance, but the question becomes how much is a percent, a dB, worth to its design? That’s been a challenge in driving the noise down as low as it can go while still being able to close the business case.”

He continued, “Much consideration is put into mixing the noise sources in such a way that there are no dominant tones.” Adding, “We’re really focused on trying to make this vehicle blend into the background.” To become one with the environment is certainly a noble goal.

Moore then stated, Whisper Aero’s mission is “propelling quiet electric technologies from fans to flight,” and that its electric aircraft design was always intended “to be a community-friendly solution.”

He observed the world is becoming increasingly urbanised and people are living and working closer and closer together. Moore pointed out, “For any existing heliport and small airport where operators are trying to fundamentally change the nature of the operations and go to scale, it requires a new level of buy-in from the community.” Adding, “We live in a future – especially in Europe – where noise will be budgeted.”

So, an almost silent drone means a silent drone hub.

Ion Propulsion (image: NASA)

One power system could be ion propulsion. Florida-based startup, Undefined Technologies, recently announced its Silent Ventus ion propulsion eVTOL drone has cleared an essential test flight.

With noise levels around 75 dBA, this is still no better than some eVTOLs, although the company claims that by next year, this should be reduced to being on par with Joby’s 65 dBA.

The pressure is on the drone industry to resolve its noise issue, especially when companies like Manna Drone Delivery is expecting full commercial and BVLOS certification next year leading to a major expansion in to Europe. Those living close to drone hubs or under busy flight paths are the ones who may complain. It is unlikely noise can be completely erased, but the lowest possible level is required. Around 35 dBAs or less is feasible? Either that or find a way to create a sound that is pleasing and acceptable to the human ear. Mosquitoes, a swarm of bees or a dentist drill are certainly not.

Fascinating Article on Drone Noise (a must read)

(Top Pic: Wing)