Powering air travel with greener, high-efficiency electric power systems

Author : Kevin Noertker, CEO, Ampaire & Andy Maughan, Director of Business Development, Industrial, Vicor

01 July 2022


Escalating concerns over the environmental impacts of fossil fuel consumption, air pollution & rising CO2 emissions is driving worldwide demand for pure-electric vehicle (EV) & hybrid-electric vehicles (HEV). This reflects an acknowledgment that electric power is essential to reducing the carbon footprint of automotive transportation. The aerospace industry is also starting to undergo a similar evolution, analysing the cost & performance benefits of electric-powered aviation.

This case study was originally featured in the July 2022 issue of EPDT magazine [read the digital issue]. And sign up to receive your own copy each month.

In this case study, Kevin Noertker, CEO at electric aircraft pioneer, Ampaire & Andy Maughan, Director of Business Development, Industrial Broad Market at power component specialist, Vicor explain how proven modular power-delivery solutions are simplifying aerospace design & reducing time-to-market…

As electrification of automotive vehicles continues to gather pace, the airline industry is now starting to undergo a similar evolution, analysing the cost and performance benefits of electric-powered aviation – potentially leading to significant market expansion. If air travel infrastructure costs can be driven down, then it becomes more feasible to expand air travel to underserviced and remote geographies. With ubiquitous short-haul ‘air taxi’ services available across an increased number of regional airports and connection points, the future of air transportation will look radically different than it does today.

California-based Ampaire is committed to making flying more accessible to more people, and from more airports, by developing electric aircraft that are environmentally cleaner, less costly and quieter.

Electric EEL in Hawaii
Electric EEL in Hawaii

Ampaire aims to achieve a 90% reduction in fuel costs, a 50% reduction in maintenance and a 66% noise reduction during takeoff and landing (compared to traditional combustion-engine-powered aircraft), with an all-electric aircraft with zero tailpipe emissions.

Ampaire estimates that switching to electric propulsion could expand the number of viable airline destinations by 10x, from 500 to 5,000 airports in the US alone, and similar expansion can be achieved across the globe.

People living in remote areas will have far easier access to regional airline transportation, and regional airlines struggling to achieve profitability due to high operating costs will be well positioned to thrive.

Greener, cleaner power  for air travel

Currently at the prototyping stage, Ampaire has developed a dual-powerplant architecture, to enable redundancy during initial test flight scenarios for evaluation and development of techniques for dividing the power and propulsion load between the fuel and electric power sources according to payload, cruise speed and flightpath needs.


The present Ampaire prototype – a retrofitted Cessna 337 Skymaster – features a standard internal combustion-engine-powered propeller in the rear of the aircraft and an electric-powered propeller up front, comprising an inline, parallel-hybrid architecture. In-flight power can be dynamically shared across both propulsion systems to optimise for speed, power, fuel consumption and noise.

In future development phases, it is anticipated that the combustion engine will be mainly used during takeoff and climb, with the electric engine serving as the primary propulsion mechanism during cruising. In time, ongoing engineering innovation is expected to yield a fully-electric aircraft, providing short-haul air transit with no petroleum-based fuel dependencies, or carbon dioxide (CO2) emissions. Parallel innovations will help to reduce the size and weight of battery and power storage technologies to ensure greater power efficiency and longer-distance flights.

High-density power-component solutions essential to rapid prototyping

The power delivery system for the Ampaire prototype plane consists of a high-voltage battery pack with a source voltage range of 500 – 738V. Typical avionic control and monitoring systems operate from a 28V supply, so a DC-DC converter solution capable of operating from a wide-range input and tightly regulating to a 28V output was required. The high-voltage battery necessitated isolation, and load parameters required a power rating of up to 500 watts.

The Ampaire design team also requested a compact size for the solution, high efficiency, a simple thermal management solution, rapid prototyping and short time-to-production. The design team also did not want to have to design or use circuit boards for the power converter.

With this design brief, the Vicor engineering team recommended that the power conversion and regulation be accomplished in two stages to optimise the efficiency and power density, and to simplify thermal management. In the first stage, a fixed-ratio bus converter (BCM®) isolates and down-converts the battery’s high source voltage, and in the second stage, a low-voltage DC-DC converter (DCM™) regulates the output of the bus converter to 28V.

With the 500W power level, and a strong desire by the Ampaire team to not use circuit board mounting, the chassis-mount and thermally-adept VIA™ package was selected. The VIA package incorporates filtering, overvoltage and thermal protection, as well as a PMBus® control interface to simplify overall power system command. This modular approach assured rapid prototyping and short time-to-production for this highly integrated solution.

The ultra-high-voltage (UHV) BCM4414 VIA was chosen for the first stage, and combined with a companion DCM3414 VIA for the second stage. Both devices were co-located in a compact, die-cast aluminium subsystem enclosure, and then chassis-mounted and thermally bonded to the enclosure, to enable passive cooling and protect against the significant shock/vibration inherent to aerospace applications. The BCM and DCM components enable quick and easy parallel capability that will help Ampaire designers scale to higher power levels in future aircraft.

Electric EEL Aerial
Electric EEL Aerial

A modular approach that scales & meets stringent aviation requirements

The overall modularity and scalability of the Vicor modular solution enabled Ampaire engineers to achieve key design advantages compared to bulky, conventional ‘silver box’ power supplies. These power technology advantages were complemented by the proven Vicor heritage of providing military- and aerospace-grade quality and reliability. In the highly regulated aviation-technology domain, this helps streamline validation and certification cycles. This ease of component certification will prove to be a great asset as Ampaire transitions from its current modified-hybrid powertrain architecture to a fully-electric propulsion system.

The future of electric-powered flight

Ampaire is among the leaders in the electric-powered aviation market to fly an aircraft demonstrating commercial viability. Its prototype aircraft is slated for testing by Hawaii-based Mokulele Airlines, which hopes to employ next-generation, commercial-production Ampaire aircraft for short-haul flights across the Hawaiian Islands. The future Ampaire production plane is expected to carry from nine to nineteen passengers and travel the 90-mile range from Honolulu to Kahului.

Vicor high-density BCM VIA and DCM VIA converters have helped equip Ampaire to achieve a highly efficient, aerospace-grade power chain targeted for a new era of environmentally friendlier air travel and transport. As Ampaire prepares for take-off, the entire aviation industry is watching closely, anxiously anticipating its ascent…

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