As presented a few days ago, NASA (United States National Aeronautical and Space Administration) had shown that it carried out acoustic studies in partnership with Joby Aviation (a company based in California that develops all-electric aircraft for commercial passenger service), to assess the noise profile of your full-size pre-production aircraft.
After analyzing data obtained over two weeks of testing as part of NASA’s National Advanced Air Mobility Campaign, Joby’s aircraft was shown to have hit the revolutionary low-noise targets the company set for itself.
The aircraft recorded the equivalent of 45.2 dBA (decibel weighted as per the perception of human hearing) from an altitude of 1,640 feet (500 meters) at 100 knots of speed, a sound level that Joby believes will hardly be perceptible against the environment. of cities.
NASA engineers also measured the aircraft’s acoustic profile during the planned takeoff and landing profiles, recording below 65 dBA, a noise level comparable to normal conversation, at a distance of 330 feet (100 meters) from the flight path. .
“We are excited to show the world just how quiet our aircraft is by working with NASA to make these measurements ,” said JoeBen Bevirt, Founder and CEO of Joby.
“With such a quiet aircraft, we have the opportunity to completely rethink how we live and travel today, helping to make flying an everyday reality in and around cities. It is a game changer” , added the CEO.
All measurements were performed using NASA’s Mobile Acoustic Facility, with more than 50 pressure plate microphones on the ground placed in a grid array at the Joby Electric Flight Base near Big Sur, California.
To measure the acoustic footprint of the Joby aircraft during testing, the aircraft flew over the grid array six times at a speed of 100 knots and at a low altitude to measure as much of the aircraft noise as possible above the ambient background noise. The field data recorded from omnidirectional microphones was then processed by NASA into an “acoustic hemisphere”, representing the sound emission in all directions below the aircraft within a 100-foot radius.
Joby then applied standard processing techniques for spherical scattering and atmospheric attenuation, resulting in an average free-field flight acoustic reading of 45.2 dBA at 1,640 feet (500 meters).
The company also performed more than 20 take-off and landing tests above the grid array, using a variety of acceleration rates and climb angles to allow NASA to capture representative acoustics of likely operational procedures. This data will be used to fine-tune flight software and take-off and landing procedures to further optimize low noise.
From day one, the Joby aircraft was designed with acoustics in mind, with the number of propellers and blades, propeller shape and radius, top speeds and aircraft disk loading, all selected to minimize its acoustic footprint and improve performance. character of the sound produced.
Each of the six propellers can also individually adjust their pitch, rotation speed and blade pitch to avoid blade-vortex interactions that contribute to the acoustic footprint of traditional helicopters.
More details on procedures and measurements will be released by Joby and NASA in technical documents to be presented at industry conferences this summer.
Joby’s five-seat piloted eVTOL aircraft can carry four passengers at speeds of up to 200 mph (322 km/h), with a maximum range of 150 miles (240 km) on a single battery charge and zero operating emissions. With over 10 years of development and over 1,000 flight tests completed, Joby is targeting the launch of its service in 2024.
Joby Aviation information