An accident last week involving an electric vertical takeoff and landing (eVTOL) aircraft could add a few suspicious glares to the wide eyes anticipating the birth of advanced air mobility (AAM) services.
On August 9, an eVTOL made by U.K.-based manufacturer Vertical Aerospace—a prototype of the company’s VX4, registered as G-EVTL—came down during an uncrewed test flight at Cotswold Airport (EGBP) in England. As reported by the U.K.’s Pilot, an airfield source claimed the aircraft was conducting inflight shutdowns when it impacted from about 20 feet high.
No injuries on the ground were reported. But photos circulating on social media platform X, formerly Twitter, appear to show significant damage to the prototype’s starboard wing.
Fire crews were called to the scene and were reportedly “concerned” about the lithium-ion batteries aboard the aircraft, which can be prone to catch fire. According to NOTAMs, the entire airport was closed for a few hours the morning of the accident, with a runway closure extending into the afternoon.
The U.K.’s Air Accidents Investigation Branch told Pilot it has opened an investigation into the crash.
Now, Vertical is reportedly pausing flight testing due to the investigation and the damage to its aircraft, which is the only VX4 prototype built for flight testing. It had anticipated the start of full-scale crewed flight tests in the coming days after what it dubbed a successful completion of the remote phase.
The five-seat aircraft features several components that were built in-house, such as its battery packs, electric powertrain, carbon fiber composite airframe, and eight propellers. Its avionics incorporate Honeywell’s F-35 jet technology to automate certain controls and make it easier to fly than a conventional aircraft, the company claims.
Vertical has yet to release any official communications regarding the incident. But it did confirm that the accident occurred via an SEC filing:
“On Wednesday August 9, 2023, Vertical Aerospace Ltd.’s experimental prototype aircraft was involved in an incident during flight testing at its flight test centre at Cotswold Airport, U.K.” the company said. “The aircraft was remotely piloted and there were no injuries. Our flight test programme is designed to establish the limits of the aircraft’s performance, and the incident occurred during an uncrewed test of the aircraft’s maneuverability during a motor failure test scenario, which is a key requirement to progress to crewed operations.”
It added that it was “working closely” with relevant authorities.
Given the reported delay in flight testing, last week’s loss could further prolong Vertical’s certification target, which was pushed back to 2026 in May after being revised from 2024 to 2025 a year earlier.
However, it’s not the only one in the emerging AAM industry to face a setback. One of the firm’s U.S. rivals, Joby Aviation, saw its own eVTOL crash in 2022 and has pushed back its entry into service. Another competitor, Germany’s Lilium, also extended its certification timeline last year.
Vertical did not immediately respond to FLYING’s request for more details on the accident.
The Outlook for Vertical
For Vertical, a lot is riding on the successful completion of crewed test flights with its current VX4 prototype. If it can’t get back in the air soon, the result could be a domino effect that puts the company in an uncomfortable spot.
The VX4 first took flight in September 2022 at Cotswold. In a preliminary test, the aircraft hovered a few feet off the ground while attached to a tether.
Then in March, Vertical received the U.K. Civil Aviation Authority’s first design organization approval (DOA) for an eVTOL company. The DOA—a necessary step before European Union Aviation Safety Agency (EASA) type certification can be achieved—authorized it to issue design approvals and expand flight testing.
The company released photo and video of untethered VX4 tests in July, confirming in its second-quarter shareholder letter that those flights had been taking place since June. In total, the aircraft completed 18 takeoffs and landings in which it lifted, hovered, flew, and landed using its electric propulsion system and Vertical’s proprietary battery packs.
The company said the eVTOL successfully hit its target speed of 40 knots and “demonstrated exceptional overall stability and control.”
“Across a multitude of hover and low speed flights, our VX4 prototype generally exceeded the performance targets we had set by 10 to 30 percent,” Vertical said. “Significant performance was especially impressive in sustained hover, typically the most challenging regime in a VTOL aircraft, where it maintained level flight for longer than we expected.”
The shareholder letter also updated investors on a second VX4 prototype, currently in development at partner GKN’s Global Technology Facility, to add to the company’s testing regimen. However, that design is not expected to be built until after crewed flights of the current prototype—which now appear likely to face delays.
“This second, upgraded full-scale VX4 demonstrator will have greater capabilities than our first prototype, including improved range and higher performance, particularly in hover,” the company said.
The new prototype will feature a fuselage made by Leonardo and battery cells from Molicel. Vertical is also working with Honeywell, Solvay, and others on its design.
A slowdown in crewed flight testing could do more than delay the second-generation prototype. Just days before the accident, Vertical announced it would seek additional capital this year to finance its future activities. But the added cost of repairs and potential revisions to its design could exacerbate the company’s cash flow issues.
Vertical says it is funded into the second half of 2024 with about $114 million in cash and cash equivalents on hand as of June. For the 12 months following August 1, it expects to use $101 million in funding.
“During this timeframe we will be delivering an uncompromising, rigorous and extensive flight test programme, with both our full-scale prototypes,” it said.
However, beyond next August, Vertical will need more cash. It currently has significantly less on hand than rivals Joby, Archer Aviation, Lilium, and others. And more funding could be difficult to come by—per SMG Consulting, Vertical trails all major competitors in capital raised, and its previous raise of $205 million was close to two years ago.
At that time, the company predicted it would need about $250 million in net funding for certification, developing a manufacturing plant, building out its commercial platform, and scaling production. That was enough to garner the interest of Mudrick Capital, which led the investment, as well as Kouros SA, American Airlines, Honeywell, Rolls-Royce, Avolon, and Microsoft’s M12. One of them may need to step up to keep the firm on track.
Vertical currently sits in 12th place on SMG Consulting’s most recent AAM Reality Index, a ranking of AAM companies based on their ability to mass produce and deliver certified aircraft. It ranks eighth in funding, trailing most major competitors, and is expected to enter service a year after Joby, Archer, and others.
Vertical does, however, own the second-highest order backlog in the industry, trailing only Embraer subsidiary Eve Air Mobility. It has an estimated 1,500 preorders from companies including American, Bristow Group, Japan Airlines, Iberojet, and most recently South Korea’s Kakao Mobility, which is expected to be a key launch customer.
