Wisk Unveils ‘Generation 6’ Production eVTOL
After 12 years of development, five generations of prototypes and more than 1,600 test flights, Wisk Aero has unveiled the electric vertical-takeoff-and-landing aircraft it intends to certificate with the FAA and use to carry passengers.
The “Generation 6” electric vertical-takeoff-and-landing (eVTOL) aircraft has cabin capacity for four passengers, plus a nose luggage compartment. It will be autonomous but supervised remotely by a human, and it will have a range of 90 mi., not including reserves.
- Aircraft to carry four passengers and luggage
- Company borrows Boeing expertise, intellectual property
For Wisk, whose employees have been developing eVTOLs longer than most while working for its predecessors, the production vehicle’s unveiling marks the start of the final leg of the journey. The startup does not say when it expects to certificate the aircraft with the FAA, although it anticipates operating by the end of the decade.
Wisk traces its origins to Kittyhawk Aero, an eVTOL startup founded in 2010 and backed by Google co-founder Larry Page. Boeing and Kittyhawk established Wisk as a joint venture in 2019. In 2022, after shutting down its own internal eVTOL projects, Boeing doubled down on Wisk and boosted the venture with $450 million in funding. Kittyhawk announced on Sept. 21, without explanation, that it was shutting down, but said Wisk was unaffected.
Wisk is not only trying to certify a novel eVTOL design, but its plans to launch autonomous passenger flights are a technical and regulatory feat to be sure. The Mountain View, California-based alliance of an aerospace giant and Silicon Valley disrupter asserts that its joint venture structure offers the best of both worlds.
“We think this is a huge competitive advantage to have the aerospace leader partnered with us,” says Wisk CEO Gary Gysin, pointing out that the startup is borrowing expertise from Boeing employees, including those working at subsidiaries such as research outfit Aurora Flight Sciences, developer of the Pegasus Passenger Air Vehicle eVTOL demonstrator.
Boeing intellectual property is up for grabs, too. “If it fits—if they’ve built something already that works in this program—then we can leverage that,” he says.
Given Boeing’s experience certifying aircraft and components with the FAA, Gysin says the partnership gives Wisk a leg up on the competition. “We’re able to accelerate our development timeline by being able to partner with Boeing,” he says.
Wisk tapped into Boeing’s database to pick an already certified material system for its Generation 6 aircraft. “That saves us at least a year,” he says. “It might save us 18 months to two years in terms of development.” Gysin did not name the material.
To demonstrate its progress, Wisk flew two of its fifth-generation eVTOL prototypes—from liftoff through transition to forward flight, back to hover and landing—at Hollister Municipal Airport in Northern California in late September, in front of a small group of journalists and industry analysts. Guests were shown a full-scale mockup of the Generation 6 vehicle, though the company did not say if vehicle assembly has begun. The company says it has started flight testing a subscale version of the production vehicle.
For Wisk Chief Technology Officer Jim Tighe, the unveiling of the Generation 6 aircraft has been more than a decade in the making. He was introduced to Kittyhawk predecessor Zee.Aero in 2011 when Scaled Composites, his employer at the time, agreed to do consulting work for it. Tighe, the former chief aerodynamicist for SpaceShipOne and chief engineer for SpaceShipTwo, says the battery energy density and power density then available, as well as the motor quality, had started to make the prospect of eVTOLs interesting.
“When I applied for this job I did a bunch of back-of-the-envelope calculations and it just barely closed, and that was exciting,” he says about joining the company in 2014. “That’s where I like to be.”
A progression of prototypes—as well as rapidly improving performance in batteries, motors, power electronics, composites and aerodynamics—has taken Wisk to a place where it feels ready to bring its air taxi product to market.
The Generation 6 vehicle builds on recent fourth- and fifth-generation prototypes, vehicles that started life as Kittyhawk’s Cora, a two-seat autonomous eVTOL with 12 independent electric-powered lifting propellers, a pusher propeller and a wing.
Whereas the fifth-generation prototype had a 36-ft. wingspan, the Generation 6 passenger aircraft’s wingspan will be about 50 ft. The production vehicle has a high wing, instead of its predecessors’ low wings. Longer booms also push the rotors farther away from the wing.
“By raising the wing, we’ve increased the aircraft stability and that brings more passenger comfort,” says Sebastien Vigneron, vice president of engineering and programs with Wisk. “By extending the booms, we’ve moved the propellers away from the passenger, which improves safety both on the ground and in the air.”
The eVTOL also has a new tail configuration. “We moved to a very simple, very lightweight cross-tail, which reduces aircraft weight and also allows us to optimize the location of the center of gravity,” Vigneron says. “That leads to better range and better performance overall.”
The Generation 6 vehicle’s 12 propellers will be mounted on six underwing booms. The production vehicle will forgo the fifth-generation vehicle’s pusher propeller. Instead, it will have six tilting propellers in the front for vertical and horizontal flight, and six fixed propellers in the back for vertical lift.
The aircraft should generate about 85 dB of noise at a distance of 100 ft. during takeoff and hover and will make about 40 dB of noise during its 120-kt. cruise phase. It takes about 30 sec. to transition to wingborne flight, and it has an operating altitude of 2,500-4,000 ft. and a payload capacity of 900 lb.
The rotors on the fifth-generation prototype had two blades each, but the Generation 6 eVTOL will have four. “That is really to reduce the disk loading,” Vigneron says. “That reduces the vibrations and the noise, especially during hover and transition.”
Wisk contends that autonomous control of its eVTOL is preferable to piloted control for operational efficiency, but also for safety reasons. The aircraft’s software is “logic-driven, procedural-based,” the company says. “We are leveraging existing and proven technology that accounts for more than 90% of pilot functions on today’s commercial flights,” Vigneron says.
The startup plans to have one “multi-vehicle supervisor” managing three eVTOL aircraft at once from a remote location. The supervisor can intervene at any time if there is a problem and will likely, at least at first, communicate with air traffic control on behalf of the vehicle.
Wisk plans to eventually offer high-frequency day and night operations using “ubiquitous autonomy,” including autonomous air traffic management, according to its concept of operations document. To achieve such highly autonomous operations, the company is proposing a “midterm state” for the urban air mobility industry as a “steppingstone.” The midterm state would adopt some automation, while retaining some conventional air operations concepts.
Over the longer term, Wisk foresees automated traffic management, flight planning and separation services that together will enable reduced aircraft separation and higher traffic density. It expects urban air mobility flight tracks will eventually be designated as urban air mobility corridors and enveloped in designated airspace.
The company also wants the number of aircraft a single vehicle supervisor can handle to grow beyond the initial three, enabling even more passenger-carrying capacity. “By making the aircraft and its systems responsible for the repetitive, time-sensitive tasks, we’re able to free up that human to focus on the more complex lower frequency tasks,” says Jon Lovegren, head of autonomy with Wisk.
Still, no eVTOL aircraft, much less an autonomous one, has ever been certified by the FAA. Rivals such as Joby Aviation and Archer are planning initial operations with a pilot as soon as 2024. Wisk is not predicting when certification will happen. “We submitted our G-1 [Certification Basis] earlier this year. And we’re heavily engaged with the FAA on the G-2,” Vigneron says.
The Generation 6 vehicle uses a combination of technologies for autonomous detect-and-avoid capabilities. “We expect to detect traffic through conventional transponders, like [automatic dependent surveillance-broadcast], Mode-S, etc., and leverage radar and optical [sensors] to detect less-equipped aircraft and flying objects,” the company says.
In simulated flights in restricted airspace above Honolulu, Wisk says its detect-and-avoid system is showing promise. “In many of these encounters, the system was able to detect the other traffic before the human pilot even had a chance to,” Lovegren says. “That demonstrates some of the potential that these technologies have for increasing safety.”
The company is also testing air traffic control interactions by flying in New Zealand using an uncrewed air vehicle from Boeing subsidiary Insitu. “Under the observation of the New Zealand civil aviation authority, we demonstrated flight under simulated instrument flight rules, including air traffic control interactions, proving that autonomous operations can be successfully integrated into existing airspace structures,” Lovegren says.
Wisk anticipates incorporating next-generation microweather data into its operations, but notes that the nature of eVTOL flights simplifies the issue. “The relatively short range on these flights makes predicting the weather and the conditions that you’ll have in any destination to be a relatively easier problem than a [Boeing] 787 flight,” Lovegren says. The company says its production-certificated vehicle will be able to handle a 30-kt. crosswind.
The Generation 6 vehicle is designed to have a one-in-a-billion probability of failure, Vigneron notes. The company says a triple-redundant fly-by-wire flight control system, as well as dissimilar hardware and software, should prevent catastrophic in-flight failures. The eVTOL can lose two rotors and safely land. It also can glide to land, though Wisk has not indicated its glide slope.
Despite some discussion in the industry about potential problems with vortex ring states—an issue that was fatal for the Bell-Boeing V-22 Osprey tiltrotor—Wisk is not particularly worried. “One interesting thing about multirotors is the pull field is messier,” Tighe says, referring to the airflow into the rotors. “So it’s hard to get into that steady-state, vortex ring state where you’re ingesting your own wake.”
The Generation 6 also has higher disk loading, meaning higher downwash velocities, which should help minimize the threshold at which vortex ring settling happens, he adds.
“So far, we haven’t seen that phenomenon, either in [computational fluid dynamics] or in any of the subscale or full-scale testing that we’ve done,” he says.
With plans to establish self-flying eVTOL operations from the beginning, Wisk published its “Concept of Operations for Uncrewed Urban Air Mobility” document on Sept. 20, setting out a road map for integrating its autonomous aircraft into the National Airspace System.
The document is the culmination of studies by Wisk, Boeing, Aurora Flight Sciences, Boeing-backed airspace management company SkyGrid and other industry partners. It echoes white papers and ideas published by NASA and the FAA that propose using eVTOL air taxis to move people between vertiports in dense urban areas.
Wisk names a price target of $3 per passenger, per mile—a cost partly determined by eliminating the expense of a pilot in the cockpit.
The company notes that it is trying to optimize passenger experience and has designed the cabin interior to reduce the likelihood of passenger motion sickness. Each passenger will have a digital display in front of them that will illustrate a flightpath ribbon to help people anticipate turns, climbs and descents. The display is also at eye level so that passengers do not lose sight of the horizon—a design choice intended to prevent motion sickness. Flight controls can be tuned to smooth the ride as well.
Wi-Fi, phone charging ports and cupholders will be featured at every seat, along with enough legroom to accommodate a 6-ft.-4-in.-tall person. Large doors on each side of the aircraft are meant to make it easier for passengers with mobility limitations to ride in the air taxi.
The company initially intends to be an original equipment manufacturer and operator of eVTOLs. “However, we will partner with airlines and other industries that have existing customers interested in our autonomous air taxi services,” Wisk says. “In the future, we would consider selling aircraft to airlines if it makes good sense for us and for that partnership.”
Wisk has not disclosed the number of life cycles the Generation 6 vehicle’s lithium ion batteries will have, but says it should be rechargeable in about 15 min., allowing for quick turnarounds.
“The nice thing about this class of vehicles is [that] because you have such high power requirements for hovering they also lend themselves naturally to charging at higher rates,” Tighe says.
If all goes according to plan, Wisk could find itself trying to meet a manufacturing demand of more than 1,000 eVTOLs per year, according to some industry projections. That would be unprecedented for the commercial aerospace industry, which at most produces hundreds of one type of large passenger aircraft annually, such as the Boeing 737 or Airbus A320.
Brian Yutko, Boeing’s chief engineer for sustainability and future mobility, says it is a task the aerospace industry is capable of tackling if the problem is reconsidered. “I get the rate question a lot at Boeing,” he says. “Clearly the rates will be different on an airplane like this because you’re going to be doing many more units. But the pounds per hour out of the factory is actually not a lot different.”