Bell has finally revealed details of the design for its urban air mobility vehicle, and has named the programme Nexus, after 12 months in which the airframer regularly dropped hints about the aircraft's possible configuration.
With its six tilting ducted fans driven by a hybrid-electric powertrain, all-electric control system and potentially a pilotless cockpit, the aircraft is a radical departure from anything previously produced by the helicopter stalwart.
In addition, rather than unveiling Nexus at an aerospace event, Bell has instead debuted the design at the technology industry's annual International Consumer Electronics Show in Las Vegas.
While suppliers to the programme – which include Garmin, Moog, Thales and Safran – represent the traditional aerospace industry, Bell views the "early adopters" of the tech business as vital to the Nexus's initial service entry, which it expects in the mid-2020s.
"We believe the future is real, possible and coming to a city near you," says Scott Drennan, head of innovation at Bell.
He says the development of new technologies enable the "safe, quiet and efficient and – perhaps most importantly – affordable urban air mobility operations at scale".
That goal will be met by "small heavily automated electric and hybrid-electric aircraft", he says.
Nexus will use a Safran-supplied turbine engine – mounted high on the rear of the fuselage – to drive an electric generator, which will provide the power for the six direct-drive, 96in (2.43m)-diameter ducted fans. These are mounted fore and aft, with a third pair on stubby 2.4m-long wings midway along the fuselage.
Any excess power generated will be stored in a battery pack from Electrical Power Systems. As well as providing a boost for the propulsion system as required, this will also give the aircraft an element of redundancy in case of an engine failure.
"You'll see some of our competitors out there using parachutes and so forth, but Bell will not be doing that in the urban environment that we are talking about being in," says Drennan.
"We believe in controlled descent to the ground under power which would be provided by the battery system."
Kyle Heironimus, propulsion lead for Nexus, says that the selection of a hybrid-electric architecture was driven by Bell's targets for speed, range and payload – in the latter case, four passengers and one pilot, with a gross weight of around 2,720kg (6,000lb) – plus consideration of the technologies available in the short term.
However, that "doesn't mean we are shutting the door to an all-electric solution in the future", says Heironimus.
He also points out that with the relative simplicity of the individual components "comes reliability, reduced maintenance cost, [and] lower purchase prices".
While the majority of Nexus's design and supply chain is settled – with the exception of the composite fans and fuselage, which Bell is still determining whether to build in-house – the cockpit configuration remains under discussion.
Although the initial full-scale technology demonstrator, which is due to fly at the beginning of next decade, will be fully autonomous, Bell has yet to decide whether this will apply to the eventual production aircraft.
"We may find out that as we go into service, people want to look left and see somebody with them for the initial flights, depending on who you are or how comfortable you feel with autonomy," says Drennan.
"But there might be a lot of folks or even certain markets that adopt it more quickly from just an autonomous state off the bat."
However, economic considerations may drive the advance of autonomy: Drennan points out that if an operator can increase payload by 25% through removing a pilot, then it "becomes significant to take them out of there and stop them being a cost on the system".
In the short term, Bell is researching what control interfaces and aircraft responses will be required for Nexus by current and future pilots.
The study's aim, as company test pilot Jim Gibson puts it, is eventually to design a flight-control system that "allows individuals with limited training to safely and efficiently operate urban air vehicles".
A lower standard of entry for prospective pilots – or "safety officers" as Drennan refers to them – will be key to ensure there are – initially, at least – sufficient crew for the thousands of urban air taxis envisaged by Bell and others.
And Gibson believes that aviation regulators are aligned with that view. "I think they understand that something has to change," he says.
"They understand the economics of what it takes to become a pilot today. That's not going to work in a situation where you need 2,000, 3,000 or 4,000 more pilots."
Source: FlightGlobal.com
