• 18 Apr 2024 11:39 AM
• 1

Doroni’s H1-X Personal eVTOL

By Pat Host
Vertiflite, May/June 2024

Doroni Aerospace pushes drone, electric vehicle and aviation technology with new model

Since establishing Pompano Beach, Florida-based Doroni Aerospace in 2016, founder Doron Merdinger has pushed the bounds of possible between uncrewed and crewed aircraft, and his newest electric vertical takeoff and landing (eVTOL) platform pushes that envelope even further.

Unveiled on March 1, the H1-X Hummingbird is a two-seat, ducted propeller, tandem wing design weighing 1,850 lb (839 kg) with a 500-lb (22kg) payload. The aircraft has eight contra-rotating, coaxial vertical thrusting propellers for lift and two ducted fans for cruise.

The H1-X is an evolution of the company's previous H1 model, which had two side-by-side ducted propellers on each wing and two ducted propellers at the rear for forward thrust.

Featuring a lightweight and durable carbon fiber frame, the new design has a top speed of 120 mph (193 km/h), a 95-mph (153-km/h) cruise speed and a 60-mile (97-km) range, which the company expects to increase with advancements in battery technology.

The H1-X has a 45-minute flight duration and can be fully charged in 25 minutes. The aircraft has an 18.2-ft (5.5-m) wingspan, so it can fit inside a two-car garage.

The H1-X can start, takeoff and land with a button push and features an autonomous navigation system with 360-degree anti-collision coverage. The aircraft features an intuitive joystick, simplifying the flight process and reducing a pilot's learning curve. The aircraft features a ballistic parachute system to land safely in the unlikely event of a critical failure.

Merdinger told Vertiflite that, similar to uncrewed aircraft, the only moving parts will be the propellers. There is no tilting of the wings or the thrusters. “It's a natural progression of drone technology, electric vehicles and aviation,” Merdinger said. “It's like the expected compelling next step.”

Early Developments

Futuristic movies and uncrewed aircraft inspired Merdinger's interest in “flying cars” since he was young. The Jetsons got people thinking about personal vertical flight, he said. But while others gave up on their dreams, Merdinger did not.

After moving from Israel to the United States in 2013, Merdinger was stuck in traffic and saw a young boy playing with a drone. This was Merdinger's “Aha Moment” and demonstrated to him the future of aviation technology.

Merdinger spent 2017–2020 developing a one-seat, open-cockpit, motorcycle-style aircraft, a Y6 configuration with two sets of propellers in each of three ducted fans. This platform, Doroni's first full-scale aircraft prototype, weighed 643 lb (292 kg) without a pilot on board. But after hovering the aircraft, Merdinger realized that this aircraft would not result in a sustainable business model.

Doroni researched other aircraft designs before developing a two-seat, roadster-influenced platform, originally dubbed the X8 (two propellers in each duct at the corners of the vehicle).

The company redesigned this roadster into what would become the H1, attracting potential customers wanting to fly for pleasure and commuting (see the VFS World eVTOL Aircraft Directory at www.eVTOL.news/aircraft for entries of each of Doroni’s prior concepts.)

Merdinger designed the H1 around an uncrewed aircraft and made it an octocopter for redundancy. Merdinger said Doroni designs airframes around the flight control system. Autopilot technology, he said, is becoming more stable and user-friendly, easier to control and safe.

On the H1 demonstrator, the upper propellers are comprised of two stacked, non-orthogonal, two-bladed propellers and the lower set uses a pair of stacked three-bladed props. The non-coplanar, asymmetric configuration also helps lower and broaden the noise spectrum; this specific design is not seen in the H1-X renderings, but the propellers appear to have some asymmetry.

After many years of development, including subscale, component and propeller testing, Doroni made the first tethered liftoff of the H1 demonstrator in February 2023. Within a few days, the company had completed two dozen more tests, and was flying regularly inside its South Florida warehouse. On July 3, Merdinger flew the aircraft in the hangar; the company said this was “the first-ever US manned test flight of a personal 2-seater eVTOL.”

In November, the company received its Special Airworthiness Certification from the US Federal Aviation Administration (FAA), which will allow the company to conduct flights outdoors.

For now, however, Doroni continues flying the H1 indoors, gathering data for its new H1-X. By March, the company had completed more than 70 tests on the H1, including about 10 manned flights.

Why Ducted Propellers

Doroni chose a ducted propeller design for the H1-X for many reasons, Merdinger said. One is that ducted propellers provide better lift efficiency. Ducted thrusters, or shrouded propellers, typically produce greater static thrust compared to an isolated propeller of the same diameter and power loading, according to a 2002 study by the US National Aeronautics and Space Administration (NASA) entitled, “Performance Study of a Ducted Fan System.” Andrew Mearns, a sales coach and consultant with Multicopter Aerospace Consulting, told Vertiflite on March 1 that the winged design of the H1-X provides one of the few “freebies” in aerodynamics — free lift. Mearns liked the ducted propeller design as it provides additional efficiency, about 20% more than aircraft without ducted thrusters.

Another reason for the ducted propeller design is that the ducts provide an added level of safety compared to exposed propellers. Merdinger said the safety provided by the ducts will be appealing to families who want to use their aircraft for personal use.

Mearns said the ducted propeller design makes pilots and passengers far less likely to come in contact with a spinning propeller because the blades are fully enclosed and obvious to people around the aircraft. Additionally, Mearns said the H1-X provides a big positive with a clear ingress and egress in between the wings with a safety buffer between the passengers and the thrusters.

Mearns said other eVTOL aircraft, such as the EHang autonomous aerial vehicle (AAV), do not have a defined walkway or pathway of safety, requiring crew to wait until the propellers stop spinning to safely exit. There could be situations, he said, where the crew must exit an aircraft in an emergency and cannot wait for propellers to stop spinning.

Merdinger said the ducts also hide the motors and reduce noise from spinning compared to the exposed blades. Lastly, Merdinger noted the sleek design of the ducted propellers.

Doroni is promoting the H1-X for a variety of personal and professional missions including cargo, military operations, emergency medical services (EMS), and search and rescue (SAR). The aircraft can take off and land on any private or public property where permission is granted, allowing it to be used for daily commutes or pleasure flights.

The H1-X is capable of remotely piloted flight, but Merdinger did not provide further details. Merdinger said the H1-X's reduced noise levels and heat signature would make it attractive to militaries.

“It can rescue other people by remote control as well,” Merdinger said. “Just take it five miles out of the [danger] area and bring them to a safe [place].”

Multiple Missions

A Doroni advisor believes the H1-X's compact design will bring utility, functionality and convenience to the market. Johnny Doo, president of International Vehicle Research, Inc., and co-lead of the VFS Transformative Vertical Flight (TVF) working group on public service, told Vertiflite on March 13 that being able to fit the H1-X into a two-car garage will provide utility in firefighting and EMS missions. Increased sales of the H1-X, he said, will reduce the platform's total unit costs.

Militaries can use the H1-X for reconnaissance, personnel transport and other critical missions. EMS providers can use it for medical evacuations and transporting professionals and supplies. The H1-X announcement video presented on March 1 showed a stretcher entering through the front of the cockpit for EMS missions. The H1-X is also useful in SAR missions for navigating challenging terrains and ensuring quick responses.

Designing the new aircraft over the last year, Doroni knew it wanted the H1-X to use the same propulsion system as on the H1 model, but that it should have wings with more lift and lifting surfaces than the H1. The result is that the H1-X has more efficient wing designs and gains extra lift from having the patented landing gears embedded in the tips of the anhedral surfaces, which Merdinger called an engineering challenge.

Doroni ran multiple digital simulations and tests on a motor test rig, which Merdinger said showed the company was moving in the right direction with the design. He said Doroni spent a lot of time and money redesigning so it would not resemble a typical airframe, but instead, a combination of a drone and an aircraft. The H1-X has an aerodynamic fence on the top and bottom of the wings to prevent the air from flowing from the wing into the ducts in forward flight.

This will reduce drag, Merdinger said. The H1-X's extra lift from the wider wingspan allows more efficient battery usage. Merdinger said that to fly vertically, the H1-X constantly pushes air down with its vertical propellers. An aircraft with a larger wingspan or more wing surfaces, he said, must use less of the ducts or propeller to fly forward.

Doo called the H1-X's tandem wing design a more modern version of multi-lifting surface designs found in vintage bi-plane and tri-plane aircraft. The tandem wing design, he said, generates as much cruise lift out of the wing as possible while still limiting the platform's wingspan and its overall size and packaging.

Retro Design

Doroni drew inspiration for the H1-X's design from jet fighters from the 1950s and ‘60s. Doo said he was blown away with the H1-X's design as it looks more like a sports car than a utility platform in a market with many unattractive designs. Aircraft for recreational or personal use, he said, not only need to be a good product at the right price, but also look good.

Doroni wanted the H1-X to maintain the simplicity of the H1 with fewer points of failure and minimized opportunities for pilot error. Merdinger said it’s easy for engineers to make aircraft more complex as they progress in aircraft design, but Doroni resisted this with the H1-X.

The 10-thruster design also provides redundancy. Merdinger said the aircraft will continue to safely land if there is a problem with a single propeller in up to three separate ducts.

Both the H1-X and the previous H1 design are two-seat vehicles. Merdinger said he likes two-seat designs as they are easier, faster and cheaper to certify. Doroni plans to certify the H1-X as a Light Sport Aircraft (LSA) in the US under the FAA’s proposed Modernization of Special Airworthiness Certification (MOSAIC) rules (see “Washington Report,” Vertiflite, March/April 2024).

Doroni designed its charging system to be compatible with standard electric vehicle (EV) charging infrastructure, ensuring the aircraft can be conveniently charged. The H1-X's battery packs are also swappable. Merdinger declined to say what type of batteries Doroni uses but said that the company is developing its own battery packs.

Doroni does not yet have a prototype of the H1-X, but has performed digital testing, such as computational fluid dynamics (CFD), on the platform. Doroni has raised close to $6M with over 430 preorder requests. Merdinger wants the H1-X to have their first delivery in the second half of 2025.

Doo, in his time as a Doroni advisor, said the company has accomplished much with a small team. Not only does Doroni learn and move fast, he said, but it also moves logically with a safe approach. Doo said this is critical for smaller companies developing innovative products.

“They ask all the right questions necessary to be successful,” Doo said. “I think the ability to innovate and to learn and to develop quickly in a logical manner is probably a strong suit for Doroni. That will enable them to be one of the more likely to [succeed] in the marketplace.”

About the Author

Pat Host is an experienced Washington media relations and news professional. He’s previously covered aviation technologies for Janes, Defense Daily, Rotor & Wing and other news sites, and his work has appeared in publications such as Vertical and Aerospace America.