The Future of Advanced Air Mobility

VerdeGo Aero's Hybrid-Electric Powertrain Will Drive Airflow's eSTOL Freighter

Airflow has selected VerdeGo Aero’s hybrid-electric powertrain system for the aerial logistics eSTOL aircraft that it aims to get into production during 2025. Through a partnership announced on December 1, VerdeGo Aero will provide its diesel (Jet-A) hybrid propulsion system, which combines a 180 kW generator with a high-power battery pack that the Florida-based company says reduces and emissions and fuel burn by 35 percent compared with conventional turbine powertrains.

California-based Airflow announced the launch of its program in June 2020. It says the fixed-wing aircraft will need only a 300-foot runway that could be built alongside a cargo warehouse to support so-called middle-mile connections of between 50 and 300 miles.

The start-up believes it can get the unnamed aircraft certified under FAA Part 23 rules. Since July, it has been flying a sub-scale model of an initial concept design as it finalizes the configuration of a full-scale prototype that it expects to start flight testing around mid-2023.

Airflow says that it intends to market cargo-carrying services directly to logistics companies and will sub-contract flight operations to Part 135 operators. It plans to announce partnerships with logistics and real estate firms to develop landing sites.

“Originally, we wanted to do an all-electric aircraft, but it wasn’t going to meet the requirements of our logistics companies,” Airflow cofounder and CEO Marc Ausman told FutureFlight. “We need to deliver a range of 300 miles and with no need for charging infrastructure [away from an operator’s base].”

VerdeGo Aero estimates that its propulsion system will support a range that is four to 10 times that of battery-electric eVTOL aircraft. “Airflow’s platform will be one of the first electric aircraft designed for aerial logistics, providing a higher payload at a lower cost than eVTOL cargo aircraft,” said the partners in their announcement.  

For Airflow, initial engineering work has been focused on developing key control algorithms to achieve safe and repeatable short-field landings and takeoffs. By mid-November, the engineering team was evaluating the second version of its autopilot with a series of trial approaches and landings. At that point, it had completed around 220 flights.

In the coming months, the company’s engineering team will be focusing on tasks such as completing the design of the aircraft’s "blown wing" configuration in which flaps in the wings are deployed to improve low-speed flight performance needed for the STOL capability. Other questions to be resolved include how many blades the propellers will have and how far they should be from the wing.

Ausman said that time has been spent on market validation, through talks with large logistics companies about requirements such as the size of the cargo bay, takeoff and landing performance, and the need for all-weather capability. He says that operating costs for the fixed-wing aircraft will be around one-third of those of comparable eVTOL aircraft.

“Our ability to rapidly move cargo from a warehouse directly to another warehouse helps e-commerce companies centralize inventory and reduce carrying costs,” said Ausman.

According to him, the prolific surge in demand for home delivery services during the Covid pandemic has bolstered the belief that e-commerce growth will drive demand for same-day deliveries supported by highly flexible and cost-efficient new aircraft. “Last year, FedEx carried around 50 million packages each day,” he explained. “[At that time] it predicted this would grow to 100 million by 2026, but now that projection has been brought forward to 2023. The trend is for faster and faster deliveries and that poses massive challenges for the logistics industry that will lead it to move to a regional distribution system rather than the current hub and spoke.”

In October XTI Aircraft selected VerdeGo Aero to provide a hybrid powertrain for its new TriFan 200 eVTOL freighter. The system is modular and is built around a common hybrid genset that can be installed in either a single- or twin-engine configuration, along with a scalable battery pack. So the generator/battery combination is essentially the same for both aircraft but each has its own configuration to fit the respective airframes and missions.

VerdeGo says it will start supplying powertrain hardware to both aircraft developers in 2021. The initial phase of its collaboration with Airflow will focus on optimizing the configuration for the aircraft, which features ten sets of wing-mounted propellers.

The propulsion specialist, which is targetting aviation applications requiring power output of below 1 MW, envisages numerous other applications of the technology on a variety of VTOL, CTOL, and STOL aircraft. It has had a full-scale iron bird test rig for the powertrain in operational test mode since mid-2020. Production hardware is now being assembled.