Preparations to launch air taxi services in the Paris area during the 2024 Olympic Games moved up a gear this week when Volocopter and local partners conducted noise emission flight trials at Pontoise Airport in France. The tests are part of work to understand how the two-seat, all-electric vehicle can be flown with the lowest possible noise profile to clear the way for public acceptance of flights in and around the French capital.
During an event at the airport on March 21, Volocopter conducted two public flight demonstrations attended by local officials and stakeholders with its 2X technology demonstrator aircraft. The company is using 2X for very specific aspects of development work in tandem with the full-scale pre-production VoloCity prototype, which started flight testing in December.
“We have been measuring acoustic data from the VoloCity and can already confirm our assumptions about the noise signature are as predicted,” senior aerodynamics engineer Ulrich Schäferlein told reporters. The smaller 2X sounds different but using it as a testbed for work conducted with EASA and aircraft noise specialists Anotec has helped the Volocopter team to fully understand the noise characteristics resulting from the disc-loading of the 18 sets of rotors and the architecture of the rotor blades.
Schäferlein explained that he and his colleagues are looking for ways to reduce the number of revolutions per minute (RPMs) for the rotors to optimize the aircraft’s noise profile. So in planning operations, such as those envisioned for the Paris Olympic Games, they are considering specific takeoff and descent paths and the possibility of adding a couple of seconds to the time taken to hover on takeoff to cruise altitude to avoid disruptive noise.
The noise measurement campaign works to the standards set by ICAO’s Annex 16 Chapter 8 document. However, Volocopter aims to exceed those requirements with a view to achieving a high degree of public acceptance for eVTOL aircraft, especially in urban areas.
Predicting acoustic noise for new aircraft configurations has required eVTOL aircraft developers like Volocopter to establish absolute baseline values in very specific conditions using carefully calibrated recording devices. The flights conducted at Pontoise Airport, 22 miles northwest of Paris, have been the first involving a pilot on board the 2X, with the aircraft being controlled by Volocopter’s test pilot Paul Stone.
Some of the flight tests compared the noise from a 2X to that of the Robinson R22 helicopter, which is of a similar size. Volocopter reported that the eVTOL vehicle was 10 dB quieter while climbing and 15 dB quieter while hovering at 75 meters (246 feet). At that altitude, the 2X had the same noise profile as the R22 at 500 meters (1,640 feet).
According to Schäferlein, as it continues to refine the VoloCity and also the larger, longer-range VoloConnect aircraft and the autonomous VoloDrone freighter, the company is considering further refinements to the rotors and altering RPM speeds and other propulsion system settings to minimize noise output. Volocopter is mindful that, above certification requirements, individual locations considering whether or not to permit urban air mobility flights could set their own exacting noise requirements.
Paris ground transportation group RATP is one of the local stakeholders working with Volocopter as part of the Re.Invent Air Mobility project, which has established the so-called sandbox project in which multiple companies are working on the plans for the 2024 Olympics in Paris. Joran Le Nabat, an acoustical engineer working on acoustic and vibratory studies for the company, explained that his team is preparing noise maps around specific potential routes across the city and possible sites for vertiports.
One of these sites is the Gare d’Austerlitz railway station on the east side of the city, and RATP is exploring the potential for eVTOL flights to shuttle passengers to other transport hubs from there. RATP is already using autonomous cars to carry passengers to the Gare de Lyon station, which is just over 600 yards away.
Le Nabat told reporters that the challenge is not simply a case of achieving a specific “magic number” of decibels from the eVTOL aircraft. Instead, public acceptance for the new mode of transportation involves a complex matrix of considerations that also includes factors such as operational safety, economic impact, and contribution to the good of the wider society.
The Re.Invent Mobility partnership’s plans for introducing advanced air mobility services to Paris envision flights connecting the city’s main Charles de Gaulle Airport with Le Bourget Airport (which will host the Olympic media village) with the main Olympic village and also with at least three vertiports around the metropolitan area. Other key partners in the project include airports group Aeroports de Paris, Skyports, and Pipistrel.
"We have demonstrated our pioneering power once again here in Paris," said Volocopter's chief commercial officer Christian Bauer. "By flying our aircraft in a crewed configuration at a Paris airport, we are proving to one of our launch cities firsthand that our aircraft will offer a practical addition for potential airport to city routes."