- 26 Oct 2021
- Fabrizio Poli
- Development & Certification
Fabrizio Poli concludes his overview of the electrical Vertical Take-Off & Landing (eVTOL) market, similar flying machines, and how they fit into the future of business flying.Back to Articles
Previously, we considered some of the similarities when it comes to eVTOL development with the Very Light Jet (VLJ) craze at the start of the millennium. We also discussed where eVTOLs might fit into the market once the leading projects in development overcome the many barriers to certification.
With hundreds of eVTOL programs being developed, last month we profiled three of the leading programs. Following, we outline a few more…
Based in Bristol, UK, Vertical Aerospace says its VA-X4 model, priced at roughly $4m, is zero emissions and very quiet, and will be able to carry four passengers and a pilot more than 100 miles at more than 200mph.
Aircraft leasing company Avolon will be the biggest launch customer, with a conditional order for as many as 500 VA-X4s, valued at $2bn.
Virgin Atlantic also has options to buy 150, with a view to establishing a branded network within the UK. According to Shai Weiss, the Chief Executive of Virgin Atlantic, the airline will be exploring a joint venture “to bring short-haul, electric vehicle connectivity to cities and our UK airport hubs, starting with London Heathrow as well as Manchester and London Gatwick”.
The aircraft could be used to transfer passengers between home and airports, Virgin believes. It would be able, for example, to make the 56-mile journey from Cambridge to Heathrow in 22 minutes, compared with a 90-minute drive.
American Airlines has also placed a conditional order for as many as 250, and will work on similar infrastructure in the US.
Having formed strategic partnerships with firms such as Honeywell and Rolls-Royce, Vertical Aerospace plans to float after merging with Broadstone, a special purpose acquisition company (SPAC), with a value of $2.2bn. Microsoft is among its other investors.
More information from www.vertical-aerospace.com
PteroDynamics is currently developing a transwing eVTOL aircraft incorporating a patented folding wing design, where propellers on propulsion pods are distributed down a set of wings that can fold back on dihedral pivot points along the wing.
The folding mechanism is operated by control rods attached to actuators on the main body. When the wings are completely folded, the props point upward, in a similar configuration to a basic multi-copter design. Transwing aircraft have much greater range, endurance, and cargo carrying efficiency when compared other VTOL aircraft designs.
One of the most important metrics for evaluating alternative VTOL aircraft is “cargo carrying efficiency”, the measure of how efficient an aircraft design is at carrying a payload, whether goods, passengers, and/or cameras and other sensors.
PteroDynamics’ patented design is truly a breakthrough for distance VTOL aircraft. The company is adopting a step-by-step approach to market by first developing its drone (designed to carry a 5lbs payload). The drone is 18% smaller, flies more than six times as long (100 minutes vs 13 minutes) and more than twelve times as far (80 miles vs 6 miles) than the otherwise most performant VTOL aircraft of a similar size.
Moreover, PteroDynamics already has a working prototype with a four-foot wingspan (Parus4), and has hovered the first of its two Parus12 aircraft (with 12-foot wingspans, which are a quarter scale of the two-passenger vehicle).
Soon, the Parus12 aircraft will embark on full flight, complete with in-flight wing transitions.
More information from www.pterodynamics.com
Dufour Aerospace has over 30 years’ experience in Swiss commercial helicopter operations, allowing the company a thorough understanding of the real-world requirements of VTOL aircraft.
By combining its helicopter experience, with its electric aircraft know-how, Dufour developed the aEro 2 – and in July 2020 the company announced its engineering team had finished initial phase-of-flight testing of its VTOL technology demonstrator aircraft.
Dufour attracted considerable attention when it released video footage of its large-scale tilt-wing eVTOL demonstrator performing unmanned flight testing, including full transitions between hovering and wing-borne cruise flight. The demonstrator has a wingspan of around 4.5 meters.
Over the course of more than 500 test flights, expanding the flight envelope incrementally, Dufour has demonstrated a high degree of stability and control in all conditions, including transition from hover, to cruise, and back again.
Jasmine Kent, Chief Technology Officer (CTO) of the project explained that the company’s goal is to ultimately develop a vehicle that is a helicopter replacement, particularly for medical transport. Dufour sees a big opportunity in the market for an aircraft that can do medical transfer flights faster, and at a lower cost than a helicopter.
In October 2020, additional video footage was released of the demonstrator, this time including sound, making Dufour one of only a handful of eVTOL developers that have shared audio of their prototypes.
Dufour Aerospace received additional funding in April 2021 and is now preparing to launch the build of its hybrid-electric, tilt-wing aEro 3 prototype. The aEro 3 is a piloted tilt-wing aircraft for medical transport and regional air mobility missions, with a hybrid range of 620 miles.
Construction of the aEro 3 prototype has already started, and flight testing will begin in 2022. Meanwhile, the company is refining avionics and flight control laws using its in-house simulation platform, which will be further developed to serve as a pilot training tool. Certification and market entry is targeted for 2026.
More information from www.dufour.aero
The team at Craft Aerospace is certainly experienced in building sophisticated transport. CEO James Dorris was a primary designer on Virgin Hyperloop’s propulsion system, and his Co-Founder Axel Radermacher helped build Karma Automotive’s drivetrain. You may have noticed that neither of those companies makes aircraft, but Dorris considers this a plus.
Craft is also relying on partners with some serious aerospace clout. Among its advisers are Bryan Berthy (once Director of Engineering at Lockheed Martin), Nikhil Goel (one of Uber Elevate’s Co-Founders), and Brogan BamBrogan (early SpaceX employee and Hyperloop faithful).
Craft’s aircraft offers a unique design, with the main fuselage looking like a small, traditional airliner. However, things start getting really interesting when you get to the wings. The front wing joins to the bottom of the cabin, sweeping back at a fairly familiar angle. At their tips, though, the wings curve upwards to meet the rear wings, which are joined to the top of the rear of the cabin.
Thus is formed a kind of box, or blown wing, with a diamond shape. This new VTOL technique, redirects the flow of air from its engines using flaps, rather than turning them, making for a much more robust and controllable experience.
“Our tech is a combination of both existing and novel tech,” Dorris says. “The box wing has been built and flown; the high flap aircraft has been built and flown. They’ve never been synthesized like this in a VTOL aircraft.”
So far, Craft Aerospace has demonstrated a limited scale model that shows the principle is sound (it doesn’t claim there’s a full-scale craft ready to go – that’s years down the line, but willing partners will help them move forward).
The fifth-generation prototype (perhaps the size of a coffee table) hovers using the blown wing principle, and the sixth will introduce the transitioning flaps.
Eventually, the aircraft will carry nine passengers, and up to two pilots. It’ll fly up to around 30,000ft at approximately 300kts. While slower than a normal passenger jet, whatever time you lose in the air ought to be regained by skipping the airport. The range of the cleaner hybrid gas-electric engines should be around 1,000 miles.
Craft Aerospace recently announced a letter of intent from JSX, a small airline serving local routes, to purchase 200 aircraft with the option for 400 more. Dorris believes that, with its position and growth curve, JSX could make a perfect early partner when the aircraft is ready, probably around 2025, with flights beginning in 2026.
More information from www.craft.aero
What Impact Will eVTOLs Have on Business Aviation?
If we apply the 95% failure rate the Very Light Jet (VLJ) projects had, we will see around 25 out of 483 of the current VTOL projects succeed.
There are many applications for eVTOL aircraft, whether solving the ‘last mile’ or ‘door-to-door’ challenge by moving people quickly from a company office, to meetings in city centers that are near existing heliports or newly constructed vertiports, or to outlying airports so passengers can depart on a business jet or scheduled airline flight.
An eVTOL is a lot cheaper and more efficient than a helicopter. I could see UHNWIs having one of these eVTOLs parked in a hangar next door to the house and using it to fly to the local airport, perhaps jumping into their Gulfstream G800 or Falcon 10X and flying to the other side of the world.
Urban areas will need the right infrastructure in place to serve the eVTOLs. Starting with existing heliports, as they have the operating certificates and air rights to begin stationing eVTOL aircraft immediately. Some heliports would need to undergo modification to offer recharging stations, hybrid vehicle refueling facilities, passenger shelters, and other amenities.
However, the cost to retrofit a simple landing pad into an eVTOL vertiport would be very affordable. Heliports currently in use will likely see the addition of, and transition to eVTOL aircraft, and those heliports not in use — a goldmine in economic opportunity sitting idle — will obtain revised operating certificates and air rights for Urban Air Mobility (UAM) use.
And, with airlines such as United, Virgin, and American Airlines already having ordered fleets of eVTOLs, various airports will seek to blend UAM with conventional airport operations to maximize the utility and convenience of its facilities. Airports are the logical point of entry for eVTOLs into an urban transportation network.
Another great area for eVTOLs to help businesses is in cargo transport. Areas of the world with little infrastructure, like Africa or the islands of Indonesia, will benefit from this. It will allow them to move freight a lot quicker, and at a fraction of the cost of flying by helicopter. This no doubt will result in lifting economies in remote locations, and help businesses prosper.
There will be a few growing pains along the way, but these new flying machines will change the way we travel short distances. Overall, eVTOLs will increase our speed, lower our transportation costs, and simultaneously keep the air clean.
Read eVTOL and the Future of Business Flying (Part One)