Excitement was in the air in late February 2022 in Shanghai, China, when a half-scale T1 model of the Pantala Concept H eVTOL started tethered hover flight tests, among many other types of testing.
It was a significant step forward toward eventual certification of this luxury eVTOL from China-based Pantuo Aviation.
The Pantala Concept H is intended for inner city transportation (airport shuttle) and intercity transportation but also public/emergency services, said Pantuo marketing director Louise Lu. These trips are expected to be mid-range or long-range, even for inner city transportation, she explained.
Development of the full-scale Concept H will kick off in late 2022, with the goal of certification and entry-into-service within five years of that point. Pantuo will begin in China and eventually seek certifications in the U.S. and Europe.
“At the beginning, we decided to target private charter service and we are also open to private buyers,” Lu said. “That’s why we emphasize the design and user experience of the aircraft a lot. But our business will not be limited in the private sector. We are working closely with fleet operators as well.”
Design and range
The sleek design of the Concept H features tilting wings and 22 ducted fans, which the company claims will provide precise and easy transition from vertical take-off to efficient high-speed, long-range cruising.
In fact, the Concept H is aiming for a range of 250 kilometers (155 miles) with five people on board. The aircraft flies at a maximum speed of 300 km/h (186 mph).
Lilium was a targeting similar range and speed — its eVTOL has ducted fans like the Concept H, but differs in primary propulsion, lift units and vehicle size, Lu said — but Lilium’s most recent battery study revealed that its current design can only achieve an operational range of 175 km (108 mi).
But while a short running landing capability was considered at the beginning of the Concept H development, Pantuo contends that the Concept H will be able to reach its range and speed goals using a nickel-lithium battery. This technology, Lu said, offers both decent energy density and high-power density. However, a hydrogen fuel cell hybrid, with its higher energy density, is a potential solution as well.
In terms of overall progress so far, Lu reported that during T1’s development period, the Pantuo team has carried out design, analysis, simulation, production and assembly, bench tests, static tests, vibration tests, tethered flight tests and more.
“We have been a self-funded startup to this point, but we are now seeking suitable investors to jointly develop the full-scale demonstration model,” she said. “We are in close contact with global Tier 1 suppliers and have established joint development relationships with some of them. Our team comes from diverse backgrounds, with abundant experience and expertise in aeronautics and electric vehicle industry.”
Both types of flight
Pantuo, like Eve Air Mobility of Brazil, is designing for both piloted and autonomous flight. Lu explained that to Pantuo, autonomy encompasses a range of solutions from today’s existing auto flight and advanced flight control systems to fully autonomous flight.
“We’ve always believed that when first generation of eVTOLs come into the market, they will be operated by pilots and this was confirmed by recent EASA [European Union Aviation Safety Agency] and FAA [U.S. Federal Aviation Administration] positions,” Lu said. “As regulators build up more confidence in advances in technology, more and more autonomy features will become standard until the arrival of full autonomy. We are confident that this will be the trend, and with Pantala Concept H, we are working to make sure that the core vehicle and systems architectures are ready for this multistage growth approach from day one.”
On the certification front, like all other eVTOL firms, Pantuo is constantly gauging regulatory directions from the Civil Aviation Administration of China (CAAC), the FAA and EASA to further refine the Concept H.
“Ultimately, we believe that under whichever set of regulations and means of compliance that this vehicle will be certified, the content will be close to a coherent combination of traditional Part 23/27 and a set of special conditions,” Lu said.
Perhaps the most interesting part of the Pantala Concept H design is the large-diameter ducted fans. Lilium’s design also employs ducted fans, which provide a wide range of benefits, Lu said.
Lu explained that in the very early stages of Pantuo’s existence, the design team analyzed different eVTOL configurations closely — and after examining benefits related to performance, safety, supply chain availability, technology maturity and growth potential, the choice of “tilt wing ducted fan” configuration was clear to the company.
“It offers lower overall drag during cruise, but the drawback of this aerodynamic configuration is of course reduced overall propeller disc area, which, during hover phases, requires an increase in power density requirements on the batteries,” Lu explained. “But with correct trade-offs, sizing and detailed design efforts, this increase in battery performance requirement is manageable.”
Indeed, the Pantuo team has found in many early experiments that a well-designed duct provides 40% to 50% greater static thrust performance compared to an open propeller of the same diameter at the same power. This can largely be attributed to the combined effect of suction on the curved duct inlet lip and the larger static pressure around the diffuser.
Lu points to other advantages of their design that may not be obvious.
“For example, our ducted fan wings have elevons on the trailing edge of the duct, which are powerful control effectors throughout all the flight phases,” she explained. “The T1 demonstrator’s flight test showed outstanding heading control capability in cross winds, which could be a challenge in some other eVTOL configurations, and this is mostly derived from simple elevon deflections in the back of the ducted fan.”
Lu pointed out that another performance benefit of these fans — which is often overlooked in eVTOLs — is the potential for very good performance at the low-speed end of the flight envelope.
“In our design, the ducted fan wing acts as a high-lift device that generates large amounts of lift even at very low forward speed,” she noted. “This in turn may enable the vehicle to have very good approach and take-off phase performance, such as very low approach speed, very steep approach angle and high climb out gradients, which means potentially it can safely go into less-accessible vertiports in more adverse conditions, which further enhance the operability and economics of this aircraft.”
Ducted fans also provide quiet operation and directional sound control. Greater safety for ground personnel is inherently provided by the enclosure of the propellers.
“The benefit of a ducted fan in a blade containment situation cannot be overlooked,” Lu said. “Also, with a with large number of fans, the individual blades tend to have smaller kinetic energy when such failures do occur.”
The distribution of powered-lift and propulsion over a larger number of propulsion units may also decrease the severity and criticality of vehicle-level effects after individual propulsion unit failures.
“This aircraft-level benefit will also be helpful in providing some relief in propulsion system criticality requirements,” Lu said. “Also, with eVTOLs having multiple critical systems packed tightly into a small fuselage, zonal separation and containment can be a challenge, and in emergency situations, the duct acts as a containment to prevent further damage to the airframe.”
Recently awarded with an ABC (Automotive Brand Contest) Award by the German Design Council in the transportation category, Pantuo has now started a financing program in China and is open to overseas investors as well. Lu said “in the next phase, we will continue with flight tests on the scaled demonstrator to accomplish transition and cruise mode.”