Zunum Designs Electric Power Trains with a Software Approach

Dean Sigler Electric Powerplants, Hybrid Aircraft, Sustainable Aviation Leave a Comment

Zunum is a startup electric airliner firm, helmed by former leaders in aerospace, electronics and software companies.  It’s no surprise, then, to see their design and manufacturing efforts following a path that blends those disciplines.

Aviation Week reports Zunum just received an $800,000 matching grant from Washington State’s Clean Energy Fund,its size proportionate to funding already raised from Boeing HorizonX and JetBlue Technology Ventures.”  It’s also the second largest of five such awards.  Zunum CEO Ashish Kumar describes the grant as, “a significant amount, a significant endorsement and a significant investment at a national level in electric aviation” that “supplements funds from out-of-state sources and will go toward prototype building.”

Zunum presses forward on an aggressive schedule, with plans to certify its 10-to-19-seat hybrid electric regional airliners “in the early 2020s.”  Founder and Chief Aero Engineer Matt Knapp describes the organization as “mostly a propulsion company with some aircraft development on the side.”  Zunum will develop its power system through a series of version, much like software, with updates released “every six months of so as technology matures.”

Considering that light aircraft go through tough regulatory oversight to manage even simple modifications to existing systems, Zunum is taking a bold step to reconfigure not only the powerplants, but the process for upgrading them incrementally.  As with various bus architectures, Zunum’s propulsion system will allow components to be upgraded over time, as improved motors, batteries, and electronics become available.  Such changes could enable expanding range from 700 nautical miles (805 statute miles) at the launch of the first airplanes to 1,000 nm (1,150 sm) by 2030.

Waleed Said, Chief Technology Officer, led development of the power electronics and control systems for the Boeing 787 and Lockheed Martin F-35.  He will start with Zunum by analyzing assumptions already made in the design of propulsion architecture.  Recent “help wanted” notes on the company web site indicate the need for a Lead Electric Motor Design Engineer, a Lead Power Electronics Design Engineer, and a Lead Power Systems Design Engineer.  These and other hires in aircraft configuration and performance and fan development would grow the current work force from 10 to 20 or 25.  That may seem small, but many wildly successful companies started in garages with a few entrepreneurs.

Ashish Kumar has a goal of having the “copper bird,” a full-scale ground test rig for the hybrid-electric powertrain, running by year’s end.  Then, within the next year, he anticipates having a flying testbed on an existing twin-turboprop aircraft “that will be modified in stages to demonstrate the hybrid-electric propulsion system.”  This development process is similar to what NASA has done with the X-57 Maxwell project, ground testing an off-the-shelf motor from Pipistrel to prepare for a next-step flight article.

Yohan Lin prepares Pipistrel motor on AirVolt test stand – roughly equivalent to Zunum’s “copper bird” ground test rig

With the goal of producing a “family of regional airliners… optimized for shorter ranges than today’s turbine-powered aircraft, and therefore suited to electric propulsion,” Zunum plans to work with an airframe builder for the actual final aircraft, while it works on powerplant development.

Opting for the simplicity of natural laminar flow to reduce drag and energy consumption, Zunum will craft its copper bird starting point with the same dimensions as the projected final design, but with heavier, available motors.  These will power ducted fans on both the ground and flight test versions.  Kumar’s approach is to take the hardware from tests, through several iterations, until the system is ready for certification and production.  In his words, “We will have aggressively matured the system.”

Zunum’s features show exciting possibilities

To keep initial costs low, the firms will use an off-the-shelf turbine, possibly used, as a range extender.  Zunum will work with suppliers to improve on the early baselines.  One desirable feature, quick start capabilities, could allow shutdowns in flight, with rapid restarts as needed.

As might be expected, Zunum will work closely with regulators to meet reserve requirements, first with the requisite fuel supply for the range extender, but finally with a third battery pack to meet the 45 minute reserve.

If the group is able to meet its schedule, find an airframe supplier to mate an airworthy design with their hybrid power system, and maintain good relationship s with regulators, this new company may well see its ambitions fulfilled.  Certainly returning the use of regional airports and making airline flight less stressful will be a welcome re-introduction to the economy.  We wish them luck.

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