As the sands of time and money begin to run low for some eVTOL developers, Gideon Ewers argues that a fork in the road has been reached. As we unveil the findings of our third annual review of the eVTOL landscape, new entrants in the race to succeed are facing off against established players who are content to play a longer game.
This article was written in the February/March issue of RotorHub International. To recieve articles like this, apply for your complimentary subscription to RotorHub International.
The last six months have been nothing if not turbulent ones for the eVTOL industry, with two developers filing for insolvency, two showing signs of a pivot away from pure battery power and another only staving off an imminent demise though a debt restructure with its largest creditor.
The signs were there, of course. Despite multiple funding rounds with billions and billions of dollars raised, not one of the projects has flown a conforming prototype. I’ll say that again, despite billions in investment not one developer had flown a conforming prototype by the end of 2024.
Among the changes to this year’s review compared with previous years is the inclusion of hybrid electric aircraft for consideration in our top 10 countdown.
When considering the paths to development taken, there has been a fork in the road in 2024.
On one road there are the new entrant companies like Archer, Joby, Lilium and so on still rushing pell-mell to be the first to certify in the West. That drive has led them to consider alternative means of reaching this goal other than via their home regulator.
It’s a mystery why being first is an obsession among this group. After all, aviation history shows that having the right product is more important than being first. Consider the Comet vs the 707 or the Caravelle vs the DC-9 as examples).
Perhaps it has more to do with a need to keep the good news coming in shareholder letters than any wider business strategy.
Meanwhile taking the other road, you have the legacy OEMs such as, Eve, Sikorsky and Textron pursuing a more leisurely pace with their development. But then they can afford to, can’t they? They have healthy order books for their current products and time is on their side.
You will notice that one OEM is missing from that list. At the end of January, Airbus announced that it would “pause” development of its CityAirbus NextGen because the key technologies – batteries to you and me – are not sufficiently advanced in terms of performance to make the aircraft viable. Bearing in mind that all developers are using fundamentally similar cell designs, that’s a significant statement.
Event horizons
Returning to the new entrants, cash burn rate versus reserves is perhaps the most likely determinant of success. Before it is possible to get on with the business of selling and supporting aircraft – something the new entrant developers don’t seem to talk about – you have to be around long enough to get over the first hurdle, type certification.
Despite the breathless announcements of inward investments, the picture is a sobering one.
At present rates of cash burn and with no new investment, Archer will be out of money in 24 months. If the recent funds raised for hybrid/and defence projects are ringfenced wholly or partially, then naturally the day of reckoning moves closer.
For Joby, the event horizon is about the same – although if both tranches of the Toyota investment materialise, it moves to 36 months. But it must also be borne in mind that the developer/builder/operator model will have a longer time to recover the sizeable investment its supporters have made compared with a more straightforward new entrant OEM.
In Europe, despite the recent debt reschedule and cash injection, the lights will only stay on at Vertical Aerospace for another year.
(These predictions are made using a crude calculation based on average monthly cash burn rates versus those posted for the first nine months of 2024, dividing that by the cash and cash equivalent declarations in the latest SEC results filings, plus more recent funding announcements.)
The bulk of the year-end news was dominated by the insolvency filings of Lilium and Volocopter.
Lilium of course announced it had found a white knight in the form of Mobile Uplift Corporation (now renamed Lilium Aerospace), rather poetically on Christmas Eve.
At the time of writing, although approved by the creditors’ committee and the court, the deal – which includes a purchase of assets for an undisclosed sum together with an EUR 200 million cash injection – is yet to be finalised.
What this new investment means for the programme as whole is open to question and of course dependent on what Lilium Aerospace has paid to acquire the assets, but the fact remains that of the list prices announced at USD 7 million the Lilium Jet is the most expensive product in an already overpriced market.
In any case, the insolvency has had a significant impact on both the certification schedule and the Lilium Jet’s ranking in our top 10.
But for Volocopter, insolvent and with the search for a saviour just beginning, perhaps the writing is on the wall.
Broken promise after outlandish broken promise is likely to scupper their hopes, and so – pending a Lazarene resurrection – they have fallen out of the top 10.
Also falling out of our top 10 is Overair’s Butterfly. When we were compiling last year’s list, Overair had just completed building what it said would be its first flying full-scale prototype, with flight testing expected to start in early 2024.
Since that announcement there has been no update from the company’s Santa Ana headquarters, and so for financial or technical reasons Butterfly remains firmly on the ground and the company silent, and thus its prospects look increasingly shaky.
Still in California, both Joby and Archer have begun a pivot away from battery power and towards exploring hybrid options for their aircraft.
While Joby has travelled further along this path with a flying uncrewed aircraft, Archer has also doubled down and launched a defence-focused business unit.
But what of EHang and its S-216? Well, although it has been granted certification by China’s CAAC, that certification limits the usage of the aircraft to very short-range flights in defined areas – or as one commentator had it, “not much more than a ride in the fairground”.
Fairground attraction or not, my expectation is that certification outside China will take rather longer, if it is pursued at all – and in any case the aircraft’s payload and range do not make it a serious contender.
There are of course the outliers. Which is to say that although not an adjunct of an existing OEM, they are taking a long game approach to aircraft development.
Of these, the notables are Beta Technologies, which has continued to pursue development and certification of the CTOL variant of its Alia 250 aircraft before turning to the VTOL version.
Not in the top 10 but still worth mentioning is Dufour Aerospace, which plans to use the development of uncrewed small cargo aircraft to build regulator credence and revenue before moving on to larger crewed and passenger-carrying aircraft.
But as they say in the music business, there is a new “number one with a bullet”. Our list is topped by a new entrant, Unither Bioelectronics.
The company, a subsidiary of United Therapeutics, is working on the development of an STC for a fuel cell-powered variant of Robinson’s R44 airframe.
Unsurprisingly, given the turbulence of 2024, there are a lot of movers in our top 10 “most likely to” list, so it’s a good idea to recap the criteria we use for compiling the list.
1. Likelihood of reaching certification
Type and just as critically production certification is a complex, tortuous and long-winded process. Success never comes without its travails, but it is usually easier for those who have travelled the road before, understand the process and, critically, how to avoid the snags that lie in wait.
2. Technology
Regulators tend to skew to the conservative, and that’s no bad thing considering their role is to keep flight as safe as it is possible to make it. Accordingly, evolution will invariably be preferred compared with revolution and thus the use of existing technology is favoured.
Our rankings also give credit to speed and range. Accordingly, we give more credit to lift/cruise concepts. We are also mindful of the role that production scaling has in the success of a programme. So again, programmes with existing scaled aircraft production backing them are given credit.
Conversely, we mark down for autonomous or remotely piloted passenger aircraft, since we expect that these concepts will take longer to win acceptance by both regulators and the flying public.
3. Financing
It is a very fine thing to consider things like payloads, range, operating cost, and so forth. But what really makes things fly is money and plenty of it.
So well-funded projects have a leg up compared with their rivals.
4. Order book
A healthy order book is a very good thing, unless you are a customer with a long wait for your new pride and joy in prospect. The trouble is that most of the “orders” announced are in the form of letters of intent or memoranda of understanding, with at best a token amount of cash changing hands. History shows that these types of agreement can disappear without much provocation. Even so they are a factor, as some may translate to orders in the traditional understanding of the term, but not one given much weight.
Runners and risers … here are RotorHub International’s top 10 eVTOL rankings for 2025
10. Horizon Aircraft Cavorite X7
Type: Lift/cruise hybrid – piloted
Payload: Six passengers plus pilot
Speed: 240 kt
Range: 695 nm
Charge time: n/a
2024 ranking: New entry
Horizon Aircraft and its Cavorite X7 hybrid has a lot of promise from an engineering and technical standpoint, and as a result the company predicts impressive range and speed values. While the company has continued to raise financing, it would benefit significantly from a stronger investment stream – though we wouldn’t be surprised if one or two legacy OEMs are watching developments in Lindsay, Ontario, with more than a passing interest.
9. Lilium Aerospace Lilium Jet
Type: Tandem wing/vectored thrust – piloted
Payload: Four to six passengers
Speed: 120 kt
Range: Undisclosed
Charge time: Undisclosed
2024 ranking: 6
Last year, Lilium was the biggest faller in the rankings when it dropped from the number two spot to number six, primarily due to the erosion of company’s financial position. This of course worsened in November with a filing for insolvency. Although a new investor has been found with a proposal that has met the approval of the creditors’ committee, the detail of the rescue package is yet to be clarified. On the technical side, the company’s financial woes have had an impact on the construction of the conforming prototypes, two of which remain in build with work expected to resume once the rescue package has been confirmed. In the meantime, the company is still projecting a first flight in 2025.
8. Vertical Aerospace VX4
Type: Lift/cruise – piloted
Payload: Four passengers
Speed: 170 kt
Range: 100 sm (161 km)
Charge time: Undisclosed
2024 ranking: 8
On the technical front the VX4 programme bounced back rather well from the loss of its first prototype as the result of a blade failure during a hover test in 2023. The second prototype made its first crewed tethered flights mid-year, moving on to untethered crewed hover testing before year-end. Meanwhile, the financial progress has been rather less smooth, with a major restructuring of its debt with prime creditor Mudrick Capital Management completed in December. The structure of that deal will enable the company to continue to work toward certification, which it now projects for a 2028-29 time frame, with a commercial goal of “having 150 VX4s in service by 2030”.
7. Wisk Generation 6
Type: Lift/cruise – autonomous control
Payload: Four passengers plus carry-on baggage
Speed: 110 to 120 kt
Range: 90 sm (144 km)
Charge time: 15 minutes
2024 ranking: 10
A wholly owned Boeing subsidiary, Wisk has made slower than expected progress during the last year. This time last year the company said that the first flight for its Generation 6 aircraft would take place in 2024, but sadly that did not happen – although it has continued to carry out public demonstrations of the Generation 5 aircraft, notably at the EAA Air Venture Oshkosh. It’s hard to say what is impeding progress, the company has not said, although issues with battery performance or problems at the parent company over the last 12 months would be the top of our list.
6. Archer Midnight
Type: Lift/cruise – piloted
Payload: Four passengers
Speed: 130 kt
Range: up to 100 sm (161 km)
Charge time: 12 minutes (after 20 sm sector)
2024 ranking: 4
2024 passed without Archer flying a conforming prototype of Midnight, although it assured investors in its Q3 shareholder letter that conforming test flights would begin “early in 2025”. It’s worth noting that despite what has been slow progress, the company remains confident of an early service entry. Late last year the company announced the launch of Archer Defense in partnership with defence contractor Anduril. To support this expansion Archer has recruited an advisory board chock full of retired brass with enough stars to fill the firmament of a small galaxy. According to Archer, the plan is to develop a “hybrid powered Midnight-like aircraft” for military applications. On the finance side, the change of leadership at Stellantis, a major investor, rocked the boat more than a little and may have prompted Archer’s drive to find a new best friend. Cumulatively, however, the company has raised an additional USD 430 million over the course of the past year.
5. Joby Aviation
Type: Vectored thrust lift/cruise – piloted
Payload: Four passengers
Speed: Undisclosed
Range: 150 sm (240 km)
Charge time: Undisclosed
2024 ranking: 5
Much of 2024 for Joby seemed to centre on making unmanned demonstration flights. But worthy of note was the company’s exploration of a hybrid powertrain which advanced to carrying out extended flights on a closed circuit. Meanwhile, on the financial side, the company secured an additional USD 250 million of funding from Toyota with a further USD 250 million to follow provided certain conditions are met. This takes the automotive giant’s investment in the company to USD 823 million, and that is unlikely to come without certain conditions. But it does give Joby the largest war chest of the new OEMs. On the downside, CFO Matthew Field left the company in December “to spend more time with his family”, with CEO JoeBen Bevirt acting as Principal Financial Officer while Sergei Novikov, the company’s controller, will serve as acting principal accounting officer and treasurer. The markets did not react well to that news, prompting a nine per cent fall in the share price.
4. Textron eAviation Nexus
Type: Lift/cruise – piloted
Payload: Four passengers
Speed: 120 kt
Range: 100 nm
Charge time: Undisclosed
2024 ranking: New entry
Some might say Bell parent company Textron has been slow getting off the mark with its entry into the AAM space. But that involvement has ramped up considerably in the last few years, especially since the aerospace giant’s acquisition of electric aircraft specialists Pipistrel in 2022. The company is projecting first tethered flights of its technology demonstrator as well as moving on to an untethered flight test programme later in the year. Textron has the knowledge, experience and the pockets to make Nexus a leading contender in the sector.
3. Eve Air Mobility
Type: Lift/cruise – piloted
Payload: Four passengers
Speed: Undisclosed
Range: 100 km (at entry into service)
Charge time: Undisclosed
2024 ranking: 3
In 2023 Eve announced that its flight test programme would begin in 2024, but in the event the year passed without a flight, let alone the roll-out of an aircraft, although the company has made a number of announcements about the progress of the first airframe. In addition it continues to be active in signing infrastructure partnerships. On the finance side, the largesse of the Brazilian Development Bank (BNDES) has continued, with an USD 88 million loan to support the building of a production facility Embraer plant in Taubaté, São Paulo, as well as a further line of credit from the BNDES climate fund to support eVTOL development. Cumulatively, BNDES has extended cash and credit lines to Eve totalling USD 113 million. On top of that, the company secured a further USD 50 million loan from Citibank. The thing to bear in mind about Eve is that the company is backed by Embraer, and it is never wise to count out Embraer.
2. Beta ALIA 250
Type: Lift/cruise – piloted
Payload: Five passengers or 1,400 lb of cargo
Speed: 147 kt (272 kph)
Range: 250 nm (460 km)
Charge time: 50 minutes
2024 ranking: 1
Beta’s joint eVTOL and eCTOL development programme has the advantage of breaking down certification into bite-sized chunks, with early certification of the CTOL expected to bring in revenue. Certification of the CTOL machine was expected by the end of last year, but that failed to come to pass as expected. Inevitably, delays with the CTOL are in turn going to impact the VTOL, making the targeted end of 2026 increasingly unlikely. Even so, route-proving and trials are planned for next year in New Zealand and Norway. On the financial side, the company has secured another USD 300 million in equity funding.
1. Unither Bioelectronics/Robinson
Type: Hybrid electric helicopter – piloted
Payload: TBC but less than the R66
Speed: 110 kt
Range: TBC but circa 175 nm
Charge time: n/a
2024 ranking: New entry
Announced in August, Québec-based United Therapeutics subsidiary Unither Bioelectronics is partnering with Robinson on the development of hydrogen-powered helicopters based on the R44 and R66. The joint effort is expected to accelerate the development of zero-emission helicopters and, thanks to RHC’s engineering, technical and regulatory expertise, help smooth the path to TCCA and US FAA certification. The hybrid version is expected to take some hits in payload and range compared with the R66. According to Robinson, the “knee of the curve” the company is looking at concerns H2 containment volume versus customer needs. Likewise, useful load is yet to be defined but will be in line with the mission specification for the organ transplant containment system that United Therapeutics has developed. The organ transplant system weight is significant, so the aircraft is expected to offer a commercially valuable amount of useful load at certification. Robinson has a history of being agnostic when it comes to power source, and CEO David Smith, while a distributed power lift/cruise sceptic, is bullish on the prospects of new power sources for conventional design VTOLs. That, combined with the partners’ pursuit of an STC-based solution, means that the first of the zero-emission VTOLs could in fact be helicopter-shaped.
