The aviation industry is racing towards the development of electric vertical take-off and landing (eVTOL) aircraft as recent technology advancements have made their goals closer than ever. However, they are not all going to make it there at the same time or through the same path.
Industry leaders in this field provided updates during recent webinars at the Vertical Flight Society’s 2021 Autonomous VTOL Technical Meeting and Electric VTOL Symposium on how their companies were advancing towards the deployment of eVTOL aircraft in the coming years.
Joby Aviation may be the closest company to eVTOL certification after agreeing to G1 certification conditions with the Federal Aviation Administration (FAA) earlier this month. Joby’s aircraft will be certified using Part 23 requirements with special conditions to account for the unique nature of the aircraft.
While moving closer to certification, Joby is also working on building a production system, Eric Allison, chief of product at Joby Aviation, said. They are working on this project in a partnership with Toyota.
While certification of eVTOL aircraft is a big hurdle, it is not the only one. Allison said Joby is looking at their product in a holistic way.
“Fundamentally the product is not the airplane itself, the product is the service,” Allison said. “The product is providing people the mobility that they want on an everyday basis. The freedom to move in a way that's not stopped and clogged and slowed down by the congestion that they regularly face.”
To enable the eVTOL technology they are developing, Joby is using data and analytics to decide where optimal spots for skyports.
“What we can do is take these demand insights and allow us to build sequential networks,” Allison said. “...The question is how do you use the data insights that come from really understanding this movement in a very granular way across the region to ask where's the next best skyport to put in.”
However, while completing this analysis Joby realized that one big constraint is that most people do not fly every day right now.
“A few lessons learned that we took out of this experience of actually doing this truly multimodal service is that there is a behavior change that's necessary,” Allison said. “So as we build this out over the next few years at Joby, we're thinking closely about these lessons learned that people don't fly every day right now, and in order to build these systems and to develop the routines that are going to be necessary for people to actually save time on a regular basis by using this type of technology to change behavior.”
Boeing is collaborating with Wisk on an autonomous two-passenger eVTOL powered by 12 independent lift fans and one cruise prop, Brian Yutko, chief engineer of sustainability and future mobility at Boeing, said.
“One of the things that we've been interested in for some time now is the applications of battery-electric architectures at smaller scales, where the physics determines that there's some potential there right now in terms of delivering products and services in emerging markets,” Yutko said. “And so within the future mobility space, these are really sort of proving grounds for some of those sustainability enabling technologies. But ultimately, within Boeing, what we're going to be doing is sort of looking across the total spectrum of markets and products to really hang together, how to apply these technologies at various scales.”
Yutko said Boeing is very focused on safety and testing when it comes to its eVTOL partnership. Cora, Wisk’s fifth-generation aircraft, has undergone 1,400 test flights.
“The design philosophy behind the aircraft is that there's no single point of failure,” Yutko said.
One area that has seen major testing is the use of autonomous systems. Yutko said the idea behind autonomous systems is lowering the ratio of pilots to aircraft, however, this is a challenge because it involves more tasks being completed by machines.
Yutko points to CFR Part 91.3 as being important to the autonomous flight challenge because it gives pilots the ability to deviate from any rule in an emergency situation.
“The pilot in command of an aircraft is directly responsible for and is the final authority as to the operation of the aircraft,” Yutko said. “In an emergency, the pilot in command may deviate from any rule of this part to the extent required, and the reason that I point that out is autonomy inherits a significant discretionary authority to fulfill the safety mandate from regulations. That's very important.”
There are still many challenges to autonomy in aviation such as uncertainty and complexity which is why Yutko said there needs to be more testing of these systems in unstructured environments in order to make advancements.
Some companies building eVTOL aircraft are starting with a manned aircraft with the goal of later transitioning to an unmanned aircraft, Wisk is going straight to self-flying, Gary Gysin, CEO of Wisk, said.
In 2020, Wisk surpassed 1,500 test flights, entered a partnership with NASA, partnered with Boeing and Aurora Flight Sciences, and completed and flight-tested two new aircraft, Gysin said. The two new aircraft bring Wisk up to nine full-scale aircraft.
Wisk is currently working with regulatory bodies in the U.S. and New Zealand on autonomy developments for its gen six aircraft, Gysin said.
Honeywell is also working on a form of automation in its urban air mobility pursuits which it calls simplified vehicle operations (STO), Stephane Fymat, VP/GM of urban air mobility at Honeywell, said. This includes simplifying the user interface in the cockpit and a flight control scheme that reduces and simplified the control inputs required the aviate the vehicle.
“We've been developing and testing these concepts for several years now,” Fymat said. “We run hardware in the loop simulation systems in our labs. We've tried this kind of system, it's kind of a simplified interface, both with pilots and with nonpilots. What we found is with trained pilots, initially, they tend to over-control the aircraft. Now, this until they get the hang of it. Of course then once they get the hang of it, they complain it's too boring to fly, which is, in fact, what we exactly want. To nonpilots, on the other hand, this is very natural, more like a video game than a traditional aircraft.”
Fymat said the goals behind these innovations are also intended to bleed into innovations for commercial aircraft.
“We fully intend to do here is to replace the traditional aircraft glass panel that you might see in commercial aircraft with a brand new simplified user interface,” Fymat.
Vertical Aerospace will unveil and conduct the first test flight of its eVTOL aircraft the VA-1X prototype in 2021, Tim Williams, chief engineer at Vertical Aerospace, said. The VA-1X is Vertical Aerospace’s winged concept which they developed because of the design benefits like range, payload, cruise performance, and noise.
Williams said Vertical Aerospace is not looking to develop all their own technologies to use with the VA-1X. Instead, they are going to have lots of partners who are experts in their fields including the use of flight control systems and cockpit display systems from Honeywell.
“One of the approaches we're taking in our program is that we're not going to have a high degree of vertical integration like some of the other companies in this industry seems to be going for,” Williams said. “Our intention is to partner with some of the big names out there, some of the names that have the pedigrees in terms of safety analysis, safety management, supply chain management, and those sort of things. And we will be at any integrator, keeping up our cost down and utilizing their knowledge base.”
Airbus is looking at the development of eVTOL aircraft in three steps: maturing technology, including market knowledge, and then building certification capability, Joerg P. Mueller, head of urban air mobility at Airbus, said. The certification phase will not come until 2030.
They are currently currently working on two demonstrators as a way to learn and test different technologies while on a path to certification, Mueller said. Vahana is a tandem tilt-wing single passenger aircraft. CityAirbus is a VTOL demonstrator that can carry up to four passengers and fly autonomously for 15 minutes.
Airbus is working on a comprehensive approach to UAM that goes beyond just the aircraft to create public acceptance, Mueller said. These efforts include UAM traffic management (UTM), routing, noise mapping, and sound synthesis.
“If you're also allowed to start building the ecosystem around it to make the whole UAM at large, the whole efforts will lead into operations at scale, which will probably be at the end of the decade in 2030,” Mueller said.
Like Vertical Aerospace, Beta Technologies is not innovating on all fronts, Kyle Clark, founder of Beta Technologies, said. They are focusing their efforts on the foundational development in the motors, high power semiconductors, and batteries while outsourcing for other products.
“We recognized early that the foundational development has to happen in the motors, the high power semiconductors, and the energy-dense batteries because the batteries have to fail in a different way than they do in industrial and automotive applications, and the requirements for redundancy, power density, and torque density are significantly higher in the motors and the power electronics,” Clark said. “So that's where we've chosen to really focus our efforts.”
Beta’s aircraft has four rotors with multiple motors inside each corner. Clark said in terms of the number of motors, “it’s more than one and less than seven.” The tail also has a pusher motor. This configuration allows for optimized activity in what the aircraft is asked to do, Clark said.
The aircraft has about 325-kilowatt hours of batteries which gets it 250 nautical miles of range at a speed of 105 knots, Clark said.
Initial aircraft from Beta will be focused on cargo and fleet customers.
“Our objective here is to take a super pragmatic and simple approach to flight test certification and development of the aircraft and even the market entry strategy around focusing on cargo and fleet customers initially, and believing that, that will earn..our stripes so that we can go to the public and say we're going to carry your kid around in the seat next to you,” Clark said. ‘So we take that pretty seriously, and we're working hard to complete our mission.”
While the eVTOL industry is aiming to make some big moves towards development and certification in 2021, only time will tell.
“I think these are all aspirational dates,” Clark said. “Anybody throws a date out there, it's aspirational, right, and until a regulatory body certifies anybody, no one has flown any passengers in any vehicle. So it's got to be safe. It's got to be certified. So there can be aspirational dates, throw it out there, but until it happens, it hasn't happened. So it will take time. Until then it's incumbent on us to approve the safety case.”