The altitude integration test was completed at NASA’s NEAT facility in Ohio

July 19, 2022

FARNBOROUGH, England—GE reported that it completed the world’s first test of a megawatt (MW)-class and multi-kilovolt (kV) hybrid electric propulsion system in altitude conditions that simulate single-aisle commercial flight.

GE made the announcement in July at the Farnborough International Airshow, describing the test as “a major milestone toward hybrid electric flight for commercial passenger air travel.”

The test of the high power, high voltage system—including electric motor/generators, power converters, power transmission, and power control systems—successfully demonstrated performance and operation of the components in a replicated flight environment, GE said in a release. This helps validate the architecture of the hybrid electric propulsion systems GE is developing. It’s also said to be an important and necessary step in GE’s technology programs with NASA to develop a hybrid electric propulsion system for flight tests later this decade and for entry into service in the mid-2030s.

The altitude integration test of the system began in June 2021 and was completed earlier this year at NASA’s Electric Aircraft Testbed (NEAT) facility in Sandusky, Ohio. To represent the right and left engine side of an aircraft, two sets of a hybrid electric system were operated in conditions up to 45,000 feet, simulating the electrical loads required to help optimize the engines and propel and power an aircraft.

“We’re making aviation history by developing the technology to help make hybrid electric flight possible for everyday commercial air travel,” said Mohamed Ali, vice president and general manager of engineering for GE Aerospace, in the release.

“GE is proud to be a longstanding partner with NASA for development of new aviation technologies. Together, we just passed a key milestone by successfully concluding the world’s first test of a high power, high voltage hybrid electric system at altitude conditions. We appreciate the collaboration to make this possible. This is one of many milestones in our journey with NASA towards demonstrating a hybrid electric aircraft engine system for a more sustainable future of flight,” Ali said.

The NEAT facility, where testing took place, is a NASA reconfigurable testbed used to design, develop, assemble, and test electric aircraft power systems.

“NASA’s unique NEAT facility is the only testing location capable of simultaneously providing both high-electric power and high-altitude conditions in an area large enough to fit an entire electric powertrain, and we are proud to see this test with GE come to a successful conclusion,” said Bob Pearce, associate administrator for NASA’s Aeronautics Mission Research Directorate, in the release. “This facility has become highly sought after by GE and others across the aviation community, and it is critical to supporting the agency’s goal of developing technologies that will enable and support future climate change adaptation initiatives.

“At NEAT, we are able to test a high-voltage powertrain system in flight altitude conditions without leaving the ground, thereby reducing major safety risks in a timely manner,” Pearce added. “With the ground testing completed, we are now well positioned to move to the next phase of our agreement with GE, an actual electric aircraft flight demonstration.”

The altitude integration test

Components were tested independently and as an integrated system. Additionally, multiple operational modes were evaluated, including power transfer from side to side, power assist to a simulated engine, and aircraft power generation. The implementation of energy storage was also simulated, according to GE.

Megawatts (MWs) measure electrical power, and kilovolts (kVs) measure the difference in electrical potential between two points, equivalent to the pressure used to drive fluid through a pipe. A kV-class system enables high efficiency and specific power. Successfully testing a kV system in altitude conditions is significant because the interaction of voltage and the environment is different at higher altitudes than on the ground. The kV-class systems are significantly more difficult to manage at altitude, GE said in the release.

What’s next for hybrid electric flight

Future tests will continue as part of the Electrified Powertrain Flight Demonstration (EPFD) project that was announced by NASA in September 2021, including testing of the hybrid electric system connected to GE’s CT7 turboprop engines. Eventually, this will lead to a flight test later this decade of the hybrid electric system on a CT7-powered Saab 340B plane, the company said.

Boeing is partnering with GE to support the flight tests for EPFD. Boeing and its subsidiary,  Aurora Flight Sciences, are providing the aircraft, aircraft modification, aircraft integration, and flight-testing services. That work includes nacelle manufacturing, flight deck interface design and software, aircraft-level performance analysis, and systems integration, the company said.

Hybrid electric propulsion technologies can help reduce fuel usage, reduce CO2 emissions, and optimize engine performance. The electrification technologies under development by GE are also compatible with sustainable aviation fuel, hydrogen, advanced engine architectures, such as open fan, and new compact engine core designs, according to the release.

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