Vertical Aerospace plans VX4 eVTOL transition flights before year-end after successful Phase 3 tests
September 9, 2025
UK-based Vertical Aerospace has successfully completed the latest stage of flight testing for its VX4 electric vertical take-off and landing (eVTOL) aircraft (‘Phase 3’).
The company will now proceed to the transition phase of flight testing, where the aircraft will complete the lift-and-hover stage and transition into powered horizontal flight for the first time. It expects to hit this milestone by the end of the year.
A crucial period of flight testing of any new eVTOL aircraft being developed is the transition stage. Although lagging behind competitors such as Archer and Joby in this regard, Vertical is now set to press ahead with this stage, having completed several months of wing-borne flight testing.
This has included the VX4 taking off and landing as a conventional aircraft, using the lift created by its wing and propulsion from its wing-mounted propellers to fly horizontally through the air.
Vertical Aerospace reaches another milestone
In February, the company announced that it had completed Phase 2 in its piloted flight test program for its VX4 prototype eVTOL aircraft.
Known as the thrustborne stage of the testing process, this stage included the vertical take-off and hovering phase of the flight, as well as low-speed manoeuvres over a small, limited area.
Then, in May, Vertical Aerospace confirmed it had successfully conducted the first piloted flight of its VX4 aircraft prototype in open airspace.
The flight, which was pre-approved by the Civil Aviation Authority (CAA) of the United Kingdom, took place in the vicinity of Cotswolds Airport (GBA), near Kemble, in the southwest of England.
This flight represented the first ever piloted wingborne flight in Europe of a winged eVTOL aircraft in open airspace.
This was followed up by a flight between two different airfields in July, when the VX4 prototype (registered G-EVTA) flew from Cotswold Airport to go on display at the Royal International Air Tattoo at the RAF Fairford airbase in Oxfordshire, England – a distance of 17 miles (27.2 km).
During Phase 3, which has just concluded, the VX4 conducted flights flown by Vertical’s Chief Test Pilot, Simon Davies, as well as Test Pilot Paul Stone. These flights have included the switching between direct (manual) and flight (computer-assisted) control modes.
According to Vertical Aerospace, “The VX4 performed as modelled in the simulator, validating both the design and ease of handling.”
“Working closely with the UK Civil Aviation Authority (CAA), which is collaborating with the European Union Aviation Safety Agency (EASA) for their concurrent validation and certification of the VX4 to the highest safety standards required for commercial use, Vertical secured approvals for flight testing in open airspace by extending its Permit to Fly following a rigorous review of safety and technical documentation.”
Vertical’s VX4 eVTOL development is progressing
Since completing Europe’s first-ever piloted wingborne flight of a winged eVTOL in May, Vertical’s prototype has now completed piloted flight tests covering 250 miles (400 km), and has reached a top speed of 120 knots / 222 km/h, while climbing to an altitude of 2,000 ft.
Through conducting these test flights, the company says it has collected over 22 billion data points, validating aerodynamic models, acoustic levels, system reliability, and performance of the VX4 model.
With the wingborne phase of flight testing completed, Vertical is now looking ahead to its next milestone by completing the first transition flight.
This will test the VX4’s ability to switch between vertical lift (‘helicopter mode’) and wingborne flight (‘aeroplane mode’), which the company refers to as “the defining capability of a tiltrotor eVTOL aircraft, which means it can take off and land in a small space.”
“Completing wingborne flight is a historic milestone for Vertical and the VX4,” said Stuart Simpson, CEO of Vertical Aerospace.
“Each phase strengthens confidence among regulators, partners, and investors that our aircraft will meet the highest standards of safety and performance.”
“Now we enter the most exciting stage – transition testing, demonstrating the mode the VX4 will use in passenger service,” he said.
Simon Davies, Chief Test Pilot at Vertical, added, “Paul Stone and I have had the privilege of flying this machine through its wingborne test phase. It’s been incredibly rewarding, with the aircraft performing just like the simulator during our first flights in open air space.”
“With the high-quality data we’ve gathered and the ability to test at both high and low speeds, we are in the best possible place to explore transition with our proven tools and flight test team.”
Other recent developments for the VX4 eVTOL
As Phase 4 gets underway, Vertical is continuing to target type certification for the VX4 in 2028, working concurrently with the CAA and EASA, with validation across other regulators to follow.
Earlier in August, Vertical Aerospace announced that it had selected Spanish firm Aciturri to manufacture the airframe for the VX4 eVTOL aircraft.
The agreement reached between the companies covers the production of the entire VX4 airframe. This includes the wing, empennage, pylons, and fuselage.
The deal is set to extend beyond the certification stage, while Aciturri will also take responsibility for the design and engineering of several of the related key components.
Based in Miranda de Ebro, in central-northern Spain, Aciturri produces aerostructures for some of the world’s largest aircraft manufacturers and has been a supplier to aircraft programs such as the Airbus A320 and Boeing 737 commercial jets, as well as the Embraer KC-390 military transport aircraft.
On August 5, Vertical provided an update on its financial position – a topic that has troubled several eVTOL developers, with some, such as Lilium, exiting the race entirely over the past two years.
The company reported that its July fundraising round generated a gross total of around $69 million (£50.9 million), earmarked for further development of the VX4. Vertical also confirmed it holds approximately £104 million ($137 million) in cash and cash equivalents, extending its cash runway into mid-2026.
There was no change to guidance for the 2025 financial year, with net operating cash outflows expected to remain in the range of £90 million to £100 million ($110 million to $125 million). Looking ahead, the company forecasts net cash outflows from operating activities of around £106 million ($142 million) over the next 12 months, primarily to support the assembly and testing of VX4 prototypes.
