Vertiflite May/June 2021

VerdeGo Aero plans to certify the hybrid-electric generator set under US Federal Aviation Regulations (FAR) Part 33 rules governing stand-alone piston and turbine engines. “That obviously simplifies certification of the [customer] aircraft because you’re using a known quantity for the engine.” Current plans begin with the first pre-production units delivered for early-adopter flight testing within 18 months to two years. Low-volume production to support customer flight testing and non-certified applications will run in parallel with US Federal Aviation Administration (FAA) certification testing using fully conformal hardware. VerdeGo Aero will integrate the new generator sets in its own production facilities at a site to be announced. “We will make the final unit,” said Bartsch. “Röder is the vendor for the diesel engine that’s inside. We have [a research and development] facility now where we’re doing low-volume production.” The VH-3-185 uses the SR305 engine, created by SMA Engines (Société de Motorisations Aéronautiques) in 1997, located in Bourges, France. The company was acquired by Safran in 2005, but sold to Egelsbach, Germany-based Röder Präzision GmbH in September 2020. VerdeGo Aero found that most electric aircraft programs prioritize lower cost of ownership, reduced noise and better efficiency. “You need a hybrid that can operate quietly,” noted Bartsch. “Small turbines are expensive, loud and burn a lot of gas.” VerdeGo Aero chose a previously aircraft-certified diesel-cycle engine for its attractive power-to-weight ratio and compatibility with common jet fuels. “Of course, this hybrid system is going to be used in the general market for electric aircraft, so emissions are important,” said Bartsch. “Compatibility with jet fuel gives us compatibility with all the biofuel alternatives that are available. We want to be sure future carbon-neutral fuel sources are compatible with the VH-3.” TheVH-3-185 is VerdeGo Aero’s third-generation hybrid generator set, progressing from iron bird research tool to low-volume pre- production system to production and certification hardware. Bartsch said, “You can basically think about it as each time we went forward, we cut the weight and size in half and increased the power output.”The company is working with the FAA defining Part 33 and equivalent requirements. Bartsch observed, “In order to get the full benefit of a hybrid- electric aircraft, it’s important [that] the aircraft design leverage the new powerplant, either with distributed propulsion, active aerodynamics or all manner of things you can do with that electricity.” He noted that retrofits or conversions of traditional aircraft are not terribly attractive markets for hybridization. “You can make it fly and make it work. [But] it doesn’t make the aircraft better… I think a vertical takeoff aircraft where you’ve got eight propulsors instead of one, that’s something you can’t do with conventional propulsion. Those are great examples of where you’d like to have something like the VH-3.” General Electric Meanwhile, turboshaft engine manufacturers are also developing solutions for hybrid-electric aircraft. GE Aviation’s Catalyst turboprop engine is nearingflight tests onamodifiedBeechcraft 350 King Air. Called “the first new, clean-sheet turboprop developed for the Business & General Aviation market in more than 30 years,” the Catalyst can produce 850–1,650 shp (630–1,230 kW). The company

has said that installing a permanent magnet generator in lieu of the propeller would create a 1-MW hybrid-electric powerplant for advanced air mobility solutions, such as electric vertical takeoff and landing (eVTOL) aircraft. The Catalyst was selected by XTI Aircraft as the engine for its Trifan 600 (see “XTI Aircraft’s TriFan 600 Development Continues,” Vertiflite , March/April 2020).

Honeywell Honeywell Aerospace announced that it is developing a power source for hybrid-electric aircraft, planned for demonstration later this year. “At 280 pounds [127 kg], the Honeywell 1-Megawatt generator weighs about the same as a motor scooter but delivers enough energy to power an entire neighborhood block,” the company said inaMarch 8 press release.This generator is combined with the Honeywell HGT1700 auxiliary power unit, currently flown on every Airbus A350 XWB, to form a turbogenerator 2.5 times more powerful than the version the company unveiled in 2019. That system was based on the company’s HTS900 engine with two generators, each providing 200 kW of power. In December, Honeywell signed a memorandumof understanding with British startup Faradair Aerospace to collaborate on systems and a turbo-generation unit that will run on sustainable aviation fuel to power Faradair’s Bio Electric Hybrid Aircraft (BEHA). Faradair intends to deliver 300 hybrid-electric short takeoff and landing (eSTOL) BEHAs into service by 2030. Honeywell says it is in advanced discussions with several other potential turbogenerator customers, working to help define power requirements based on mission profiles required by various manufacturers. LaunchPoint EPS Goleta, California-based Honeywell announced its 1-MW generator, based on the HGT1700 auxiliary power unit, in March. (Honeywell)

LaunchPoint Technologies, which has been developing power-dense Halbach-array electric motors since 2009, spun off a hybrid-electric propulsion company last year. LaunchPoint Electric Propulsion Solutions, Inc., is commercializing the motors, hybrid-electric generator sets and control software developed by LaunchPoint, as well the Modeling Advanced Aircraft Propulsion (MAAP)

May / June 2021

LaunchPoint’s HPS400 uses a Rotax engine to generate 40 kW. (LaunchPoint)

software, which can be used for designing electric aircraft propulsion systems. LaunchPoint was an Uber Elevate partner;

65