By Elan Head

An award-winning journalist, Elan is also a commercial helicopter pilot and an FAA Gold Seal flight instructor with helicopter and instrument ratings. Follow her on Twitter @elanhead

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Airbus explains design philosophy behind its CityAirbus NextGen

When Airbus unveiled its CityAirbus NextGen eVTOL last week, the most striking thing about the aircraft was its lack of ambition. The piloted, fully electric air taxi has just three passenger seats, an expected range of 80 kilometers (50 miles) and cruise speed of 120 km/h (75 mph) — targets well below those set by rival eVTOL developers including Joby Aviation, Beta Technologies, and Lilium.

CityAirbus NextGen
CityAirbus NextGen’s performance targets are below those of most winged eVTOLs, but Airbus believes its simplified design will offer sufficient performance for 95% of UAM missions. Airbus Image

Nevertheless, the airframer is confident in its decision to prioritize simplicity over performance, Airbus Urban Air Mobility (UAM) head Joerg Mueller told eVTOL.com. When it comes to moving people within (as opposed to between) cities, he said, 80 kilometers of range is generally more than enough. 

“If you over-design your vehicle, then the battery gets heavier, the vehicle gets heavier to operate, more expensive to operate, etc.,” he explained. “Simplicity with a certain level of performance is able to create a real value for our passenger in the city.” 

That rationale is one of several competing theses that will be tested in coming years as legacy aviation players and aggressive startups race to define the UAM market. While eVTOL leaders like Joby expect to commercialize their air taxis a year or two ahead of Airbus — which is targeting certification with the European Union Aviation Safety Agency (EASA) around 2025 — even a moderate delay in their complex certification programs could erase their first-mover advantage

Airbus is betting that its simplified design will speed the technical development and certification of CityAirbus NextGen, in addition to offering advantages in reliability and operating costs. Although eVTOL.com initially described the aircraft as lift-plus-cruise, Mueller explained that the design is actually a winged multicopter. 

Unlike lift-plus-cruise aircraft that have dedicated thrusters for vertical take-offs and landings and separate thrusters for forward flight, all of NextGen’s propellers are operational throughout the entire flight regime, including the two fixed-tilt propellers on the aircraft’s tail. Those propellers, which are also used for yaw control, provide an additional forward thrust vector in cruise flight, which is counteracted by the remaining propellers through a slight nose-up attitude in the hover.

Although NextGen has a wing, it never transitions to full wing-borne flight — which is how most winged eVTOL designs gain their superior cruise efficiency and performance. 

CityAirbus eVTOL demonstrator
Although the NextGen is different in appearance than the original CityAirbus demonstrator, the aircraft share similar design principles. Airbus Photo

Like the lumbering technology demonstrator that was the first to carry the CityAirbus name, control of NextGen will be achieved by varying the RPM of its eight propellers. Mueller said that Airbus’s experience with that 2.3-tonne (around 5,000-pound) demonstrator “makes us confident that we can live without tilting parts and moving surfaces.” That’s in contrast to the company’s other full-scale eVTOL demonstrator, Vahana, a tilt-wing aircraft that logged just over 13 hours of flight time across 138 test flights before the program was wrapped up in 2019. 

Airbus plans to fly a NextGen prototype in 2023 using existing lithium-ion battery technology. Mueller said it’s too soon to say what type of cell chemistry will make it into the production aircraft, although Balkiz Sarihan, head of UAM strategy execution and partnerships, noted that Airbus is developing batteries as one of its core in-house technologies for applications across its product portfolio, including hybridized helicopters and satellites. 

NextGen, which is being developed to meet the standards of EASA’s Special Condition (SC) VTOL enhanced category, currently has no provisions for safe emergency landing in the event of total power loss — meaning no gliding ability or ballistic parachute. Instead, Airbus will be required to demonstrate that the probability of such a catastrophic failure is vanishingly remote, on the order of one event in a billion flight hours. Mueller said he expects that the U.S. Federal Aviation Administration will accept this approach as well, although “as a European manufacturer, we’re starting with the European regulation,” he told eVTOL.com. 

Defining the passenger experience 

In arriving at its NextGen design, Airbus drew on its experience not only with the CityAirbus and Vahana technology demonstrators, but also with Voom, the helicopter seat booking service that operated in São Paulo, Brazil; Mexico City; and the San Francisco Bay area before shutting down in March 2020

According to Mueller, the Voom experience demonstrated that “there are very strong dense passenger streams in and around cities . . . for example, from airports to certain points of interest or certain business districts.” He confirmed that the “sweet spot” for such missions seems to be around 25 miles (40 km), which is around what Joby is predicting for its average UAM mission length. 

CityAirbus NextGen eVTOL
CityAirbus NextGen will have fixed rather than wheeled landing gear for weight savings and operational flexibility. However, exactly what those fixed skids or legs will look like is still being determined. Airbus Image

The 150-mile (240-km) range of Joby’s aircraft should allow it to do more of these missions at times of peak demand than CityAirbus NextGen, because it won’t need to recharge fully between flights. Even with a recharging requirement, however, Mueller said it should be possible to optimize the fleet and route network to sustain a viable business. 

Although Airbus expects that NextGen will eventually be autonomous — and is actively developing the necessary technologies for that transition — the company is counting on conventionally piloted operations at the outset. The aircraft has a single pilot seat up front and a bank of three passenger seats, “each designed to have their own experience,” according to Sarihan. “We actually just had the opportunity to sit through the VR rendering of that last week and it’s really quite impressive,” she added. 

Sarihan noted that Airbus’s designers are also paying close attention to accessibility, not only from a safety perspective, but also in terms of “the ease with which different people will be able to climb in and out of the vehicle” — which, along with affordability, will be key to offering a UAM service to the general public. 

Rather than operate that service itself, Airbus expects to work with various operator partners to deploy CityAirbus around the world, drawing on its existing strong customer relationships. Sarihan suggested that Airbus’s established reputation will help set it apart from competitors in the space, as it comes with an “implicit degree of trust.” 

“Our responsibility is that we are going to design vehicles to the highest operating levels, highest safety levels, and we will always be in a position where we are iterating with our operators,” she said. “That’s exactly how we develop any of our product portfolio — from the smallest helicopters to the largest jet.” 

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2 Comments

  1. The current iteration of AAM vehicles are “Model-T ford” vehicles.
    They miss the mark on creating a new form of Transportation!
    The current AAM Vehicles…
    * use a primitive form of propulsion
    * not autonomous, using “swarm” drone flight control
    * don’t have VHD 10x battery systems
    * too large of a Form-Factor
    * too noisy and dangerous
    * too electrically inefficient
    * too limited in performance
    * too limited in passenger capacity
    * can not fully recharge in less than 1 minute

  2. e/hSTOL solutions, for a variety or reasons, are the pathway to rapid AAM maturation.

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