California-based Joby Aviation claims its eVTOL aircraft is quiet enough to “barely be perceptible against the ambient environment of cities.”
The company announced on Tuesday that initial results from acoustic testing that Joby completed with NASA in September 2021 using its full-sized pre-production aircraft are now ready.
The tests were conducted over two weeks at Joby’s Electric Flight Base near Big Sur, California, as part of NASA’s Advanced Air Mobility (AAM) National Campaign. Using the agency’s Mobile Acoustics Facility to conduct the tests, Joby said the results demonstrate that the aircraft has met the low noise targets the company set for itself.
Joby said the company registered the equivalent of 45.2 A-weighted decibels (dBA) from an altitude of 1,640 feet (500 meters) at 100 knots airspeed.
To collect the data, the eVTOL developer conducted six flights over more than 50 pressure ground-plate microphones. NASA processed the data into an “acoustic hemisphere,” which represented the sound emission in all directions below the aircraft out to a 100-foot (30-meter) radius.
Joby then used standard processing techniques for spherical spreading and atmospheric attenuation to determine the overhead flight acoustic reading of 45.2 dBA.
The eVTOL developer also conducted more than 20 take-off and landing tests above the microphones, using a variety of acceleration rates and climb angles. Its acoustic levels during take-off and landing were below 65 dBA, measured at a distance of 330 feet (100 meters) from the flight path — a level “comparable to normal conversation,” the company said.
“We’re thrilled to show the world just how quiet our aircraft is by working with NASA to take these measurements,” said JoeBen Bevirt, founder and CEO of Joby, in a press release. “With an aircraft this quiet, we have the opportunity to completely rethink how we live and travel today, helping to make flight an everyday reality in and out of cities. It’s a game changer.”
Joby said it has designed its five-seat aircraft with acoustics in mind — one of the elements many industry experts believe will play a crucial role in public acceptance for eVTOL aircraft.
Both Joby and NASA plan to present the data in technical papers presented at industry conferences this summer.
“We will use this data to help us understand the vehicle’s performance characteristics, the acoustics profiles, as well as information that will help us develop modeling scenarios,” said Shivanjli Sharma, acting lead for the AAM National Campaign, in a statement. “Not just one or two flights per day, but at the scale that we predict these vehicles will begin flying when used by the public.”
NASA said it also plans to conduct similar acoustic testing with Wisk Aero, and the data will be used to help define and optimize AAM routes and low-noise flight paths, as well as government regulations for eVTOL operations and airspace integration.