Page 30 - Flight International (January 2020)

BELL NEXUS 4EX

focused on moving passengers as efficiently
as possible from point to point.
The Nexus 4EX is to have a maximum gross
take-off weight of about 3,200kg (7,050lb) and a
cruise speed of 130kt (241km/h).
Based on conversations and surveys of po-
tential customers and stakeholders, such as
ride-share companies, as well as city, state
and national governments, the company esti-
mates flights on average would be 13-22nm
in length.
Each aircraft is likely to operate for 2,000h
per year, the company says.
Bell believes hundreds to thousands of
eVTOL aircraft would be needed within a
city to significantly change traffic patterns on
the roads.
The company declines to say how many
aircraft would be required to reach profitabil-
ity, noting its analysis is ongoing, but it
expects that eVTOL aircraft would be pri-
marily used for faster ride-share, public
transportation and cost-sensitive traditional
helicopter applications.
At least in the beginning, Bell does not ex-
pect eVTOL aircraft to stimulate travel demand
– in other words, trips people would not take if
they did not have access to the speed and range
of the aircraft. Rather, early users will likely fly
out of curiosity or as an experiment. Gradually, Shutterstock
the company expects the aircraft to become a
more established feature of business and Helicopters provide some urban transport, but volume operations will require automation
personal travel, says Drennan.
manager” on board as a back-up. arrangements of digital flight controls.
PREDICTING UPTAKE Indeed, because eVTOL aircraft are so For cost and safety reasons, Bell is aiming
Bell says it is forecasting demand using traffic, novel Bell is taking the opportunity to rethink to ultimately make its eVTOL aircraft fully au-
mobility and mobile phone databases, many aspects of the aircraft’s flight controls, tonomous. This would save operators the cost
examining how different factors such as including removing the helicopter’s tradition- of a pilot, one of the most expensive parts of
passenger load, weather, digital infrastructure al collective and cyclic sticks and foot pedals. flying a helicopter. Also, there are simply not
and eVTOL airport loading patterns might enough pilots currently, or capacity to train
affect usage. “It is imperative to smartly more of them, to fly the hundreds or thou-
Predicting aircraft usage will be key to man- sands of eVTOL aircraft within the cities of
aging the battery charge levels and life-cycles manage fleet operations and the future that Bell envisions.
of a fleet of eVTOL aircraft, says Drennan. Moreover, Bell believes fully automated
“State of charge at any given moment in the battery system operations by flight controls would allow it to operate at a
life – and really the operating day – affects the mixing flight distances” higher flight frequency, avoiding human error
next flight available because of time of re- and fatigue problems.
charge required and the life of the battery,” he Scott Drennan In the light of two recent Boeing 737 Max
says. “Therefore, it is imperative to smartly Vice-president of innovation, Bell crashes caused by that airliner’s automated
manage fleet operations and battery system flight controls – the Maneuvering Character-
operations by mixing flight distances to opti- “When you’re talking about fly-by-wire it istics Augmentation System (MCAS) – Bell
mise operational cadence and battery life for just doesn’t make sense anymore to make peo- is quick to explain its belief that designing an
our customers.” ple move their feet, move their hands and wig- automated eVTOL from scratch is safer than
The Nexus 4EX’s batteries are to be sup- gle their ears all in unison to make this thing bolting automation on to a manned aircraft.
plied by Electric Power Systems. Algorithms fly,” says Drennan. “A fly-by-wire aircraft can “By starting with the understanding that
within that company’s battery management have control laws that can take into account in- it’s going to be fully autonomous from the
system will be used to monitor battery tem- tention [and] mission. And, if we integrate that beginning you have a different mental
perature, current, voltage, discharge and in the right way we will take a great step right starting point than when you iterate to
charge rates. through the piloted piece to the autonomous.” something over time,” says Michael Thacker,
Bell is aiming to build an eVTOL aircraft Using its Future Flight Controls simulator, Bell’s executive vice-president for technolo-
that has fully autonomous flight controls. the airframer says it has studied how more gy and innovation.
However, to initially gain public trust and than 6,000 participants, including profes- While investigations into the two 737 Max
US Federal Aviation Administration (FAA) sional helicopter pilots, but also a wide crashes remain ongoing, flightcrews’ efforts
certification, will have a pilot or “mission variety of amateurs, interact with different to understand and correct the behaviour ❯❯

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