Oct. 15, 2018
In the not-too-distant future, remotely piloted vertical takeoff and landing (VTOL) aircraft are expected to change the face of on-demand air transportation in cities.
Once exclusively the realm of science fiction, a variety of vertical takeoff and landing (VTOL) aircraft transporting people and cargo may be plying urban skies in the relatively near future. Several companies are working to develop this new class of aircraft, which holds tremendous potential for numerous business aviation uses.
Development of these VTOL urban mobility aircraft has been underway for several years, but recent industry initiatives have driven renewed interest in the concept.
For example, one of those efforts that garnered widespread attention last year was the announce-ment of uberAIR, a program to establish commercial “flying taxi” service in cities, including Dallas, TX; Los Angeles, CA; and Dubai, United Arab Emirates.
The value proposition put forth by uberAIR, as well as other urban mobility solutions providers, is that on-demand aviation using VTOL aircraft has the ability to provide greater productivity, fuel savings and time savings for companies, while also improving the speed and quality of daily commutes for passengers.
Baseline design guidelines from Uber include accommodations for up to four passengers (including a pilot) in an aircraft capable of reaching up to 150 miles per hour with a maximum range of 60 miles. These uberAIR vehicles may utilize hybrid-electric or full electric propulsion (eVTOL), with the eventual potential for pilotless operation.
The rideshare service has partnered with five aero-space companies to bring such vehicles to market as soon as 2023. Proposals include supersized versions of existing quadrotor unmanned aircraft systems (UAS) fitted with passenger cabins, winged aircraft equipped with one or more rotors to enable VTOL operations, and reconfigurable multi-rotor vehicles able to seamlessly transition from vertical to horizontal flight.
APPROACHES TO URBAN MOBILITY
Aurora Flight Sciences, a Virginia-based subsidiary of Boeing, has developed several UAS and autonomous aircraft technology demonstrators, including an optionally piloted Diamond DA42 twin-engine light aircraft. In 2016, the company partnered with Honeywell and Rolls-Royce to develop the XV-24 LightningStrike VTOL aircraft under a Defense Advanced Research Projects Agency program.
While that program was later cancelled, the company is drawing on that experience to develop an eVTOL capable of operating a variety of missions in congested urban areas.
“There are some pretty significant commercial markets there,” said Aurora Chair and CEO John Langford in a recent presentation for the Go Fly competition to spur development of personal-use VTOL transportation. “It’s the business angle driving so much of this enthusiasm for on-demand mobility, and Aurora sees autonomy as the differentiator by building certifiable autonomous systems that will enable all of tomorrow’s intelligent aircraft of any shape.”
Initially founded in 2006 to bring its Transition road-able airplane to market, Boston, MA-based Terrafugia has extended its focus in recent years to include VTOL urban mobility.
“We’ve done extensive feasibility studies in this space and dug into the economic models,” said Carl Dietrich, company cofounder and chief technology officer. “We came to a similar conclusion as Uber regarding the vehicle size and capacity that makes the most sense from an economic perspective, and for practical roll out over densely populated urban areas and Class B airspace.”
Terrafugia’s proposed TF-2 design utilizes a detach-able compartment for passengers or cargo, enabling quick transfer between a flight vehicle and ground vehicle without the need for those onboard to disembark. Initial plans call for the TF-2 to be introduced in 2023 as a piloted, hybrid-electric aircraft, but Terrafugia intends to adopt all-electric and autonomous systems as those technologies mature.
The potential for widespread VTOL and urban mobility applications has also spurred interest from traditional aircraft manufacturers such as Embraer. In 2017, the company formed its EmbraerX division to lead development of future air transportation systems.
“We share Uber’s vision that on-demand aviation has the potential to radically improve urban mobility, improving the quality of life for people who live in congested urban communities,” said EmbraerX President and CEO Antonio Campello. “However, the development of eVTOL is not just an opportunity to change urban mobility for the better, but also to find new technologies with the potential to improve the performance and efficiency in a variety of aerospace applications.”
At the Uber Elevate Summit in May 2018, EmbraerX unveiled an eVTOL conceptual design featuring eight vertically oriented rotors mounted on twin, wing-mounted overhead parallel booms, with a rear-mounted horizontal fan to provide forward propulsion. The company’s website also features an online portal that enables enthusiasts to configure their own urban VTOL design.
Campello concluded, “We are continuously listening to end users and members of the community, capturing their feedback and input about their needs, expectations and use cases for this vehicle on topics such as entry and egress accessibility – even for people with special needs – as well as safety perception, privacy, aural and visual comfort.”
ELECTRIC PROPULSION AND AUTONOMOUS OPERATION
One key design consideration for any urban mobility concept is electric propulsion, which, in addition to having zero emissions, would also significantly lower noise levels and maintenance costs, compared to existing light helicopters.
While availability of full-electric propulsion for cross-country aircraft remains constrained by current battery technology, it’s a viable option for shorter-range trips. It also provides numerous design advantages.
“Electric propulsion makes sense in a distributed fashion with multiple thrusters,” Aurora’s Langford said. “The mechanical complexities with doing that with a standard gearbox or mechanical drive would be so expensive from a weight point-of-view.”
Last year, Aurora demonstrated its autonomous aerial cargo/utility system, which enables an operator to use a mobile device to summon a Bell UH-1 helicopter outfitted with sensors and mechanical systems that enable pilotless operation.
While adapting such systems for safe operation in congested urban airspace requires further development, Langford believes practical commercial urban mobility applications hinge upon regulatory approval.
“I don’t think any of us know what the successful design will really shake out to be. But whatever the vehicle looks like, certifiable autonomy will be absolutely essential for that to be a successful commercial product,” he said. “If you have two or four seats on an aircraft, you can’t afford to devote one or two of those seats to an operator – and you don’t need to. We’re standing on the cusp of a revolution in mobility.”
Dietrich believes the factors that will determine widespread acceptance and use of VTOL urban mobility vehicles are more economic than technological. “The ability to provide people or companies with this level of transportation, for a ticket price in the range of $20-$40 – comparable to taxi rates or Uber – is staggering to the point that it’s not the biggest concern,” he continued. “Overcome these barriers and the market will be there.”
There’s also the matter of public perception – the willingness of passengers to fly onboard a completely new aerial vehicle design, likely without a pilot onboard.
This could be a challenge, but it will be very exciting to see how the industry evolves over the next decade,” Dietrich said.