US startup Wright Electric has announced the launch of the Wright Spirit, a 100-passenger, all-electric, zero-emissions retrofit of a BAe 146 aircraft that the company is targeting for an entry into service in 2026. While other new propulsion startups are working on programmes to bring smaller-sized commercial aircraft – up to 19-seats – to market initially, Wright believes focusing on the 100-passenger segment is where airline demand lies, with one-hour flights accounting for the world’s busiest city pair routes. Mexican low-cost carrier Viva Aerobus has now joined easyJet to support Wright’s development of zero-emission passenger aircraft. At the core of Wright’s technology is a high-efficiency, high-power density inverter and a 2MW (2,700 HP) motor to replace each of the BAe 146’s conventional hydrocarbon-powered four engines. Earlier this year, Wright unveiled its design concepts and the start of an electric propulsion development programme for a flagship 186-seater electric plane with an 800-mile range, named Wright 1, which is slated to commence operations in 2030.

The focus on 9-seat and 19-seat aircraft by novel propulsion startups is driven by regulations prescribed by the US FAA to govern all aviation activities and promote safe aviation. Part 23 contains airworthiness standards required for issuance and change of type certificates for airplanes with nine or less passengers and a MTOW of 12,500 pounds or less, as well a commuter category of multi-engine airplanes with 19 passengers or less and a MTOW of 19,000 pounds or less. Companies like Heart Aerospace, with its all-new ES-19 electric airliner slated for commercial flight by 2026, and ZeroAvia and Universal Hydrogen with their retrofit solutions for existing aircraft, are all targeting the commuter market as an initial step.

Wright Electric, on the other hand, is leapfrogging this segment and going for a higher passenger capacity – Part 25 – market served by the likes of Airbus and Boeing aircraft. It points out that 95% of the carbon footprint of aerospace comes from Airbus and Boeing sized planes – Boeing itself has estimated each of their airplanes will generate 1 million tonnes of emissions over a 20-year lifespan. Around half of A320 and 737 flights are shorter than 800 miles and the single-aisle market represents nearly half of the industry’s carbon footprint, says Wright.

Wright’s Founder and CEO Jeff Engler told GreenAir: “Airlines have told us repeatedly that what they want are planes that fly at jet speeds and altitudes, and carry more than 100 passengers. A 19-seat airplane flying slow, low and unpressurised dramatically changes their business models. That’s not to say this particular market is impossible, in fact there are huge opportunities.

“The electric and hydrogen aircraft industry is highly collaborative right now and there’s a lot that can be done by companies working together. While we aren’t focused on the 19-passenger market, we think we can do our part with larger airplanes and we can support those companies that stay within Part 23 as well.”

The BAe 146 will be familiar to those who followed the Airbus/Rolls-Royce/Siemens E-Fan X electric flight collaboration that was launched in November 2017 before being cancelled in April 2020, with Airbus deciding to focus instead on hydrogen propulsion through the launch of the ZEROe programme. The E-Fan X demonstrator aimed to use a BAe 146 and replace one of its four jet engines with a 2MW electric motor. Wright Electric is now going down the same path and is already proceeding with ground testing and final selection of the propulsion system. Following testing in an altitude chamber, it is expecting to begin flight testing on the 146 aircraft – which Wright is still to acquire – with the one all-electric propulsor in 2023 and then with two propulsors the following year.

The four-engined 146 makes it an interesting configuration, said Engler, and as of 2019, around 100 out of the 400 that were built are still in service. For the proposed entry into commercial service in 2026, he said it was not certain just yet that the aircraft would be powered by four electric motors from the start and could be a combination of electric and conventional jet engines. There are two ways you could do a hybrid configuration, he added, either two jet engines and two electric motors on the wings or all four electric motors on the wings and a turbogenerator for fuel reserves or range extension. “We’re evaluating both of those,” he said.

The plan, he revealed, is to start services on one route that is highly concentrated and served by more than one airport, say between London and Paris. “This allows us to start small and build up our operational capabilities, and then we can expand from there,” he explained. “By just focusing on one- or two-hour single-aisle flights, we will be covering a meaningful segment of the industry’s carbon footprint. That’s what we’re guided by more than anything else.”

Regardless of whether a new-concept aircraft or a retrofitted existing aircraft type, certification of an all-electric passenger aircraft will be a critical step. “We’ve built an extremely structured process from a data gathering and safety perspective into our company from day one,” said Engler. “We’ve had familiarisation discussions with regulators and a lot of the work that is already happening on the Part 23 side will be applicable to the Part 25 side as well.”

With a philosophy Engler describes as “start small, start simple, then grow through increasing complexity and difficulty”, Wright began its megawatt-scale electric motor programme for a single-aisle commercial airliner in January 2020, and in May 2021 began testing its next-generation inverter technology. Whether a future airplane is battery-electric or powered by a hydrogen fuel cell, an inverter is a key component in high voltage aircraft electric systems as it converts the DC power from batteries to the AC power required by the propulsion system’s electric motors, explains the company. Wright claims its inverter has a 99.5% level of efficiency and targets a six-times improvement in heat loss over current in-production aviation inverters, resulting in significantly lower thermal management loads. In contrast to today’s technology delivering a 10-20 kw/kg power density, the inverter is targeting 30 kw/kg, which on a single-aisle aircraft would result in weight savings equivalent to adding an extra 5-10 passengers per flight.

Claiming it to be perhaps the largest propulsive aerospace motor in existence today, Wright has begun testing its 2 MW motor, which is being designed to be scalable from 500 kw to 4 MW for different applications without requiring a big change in the system’s architecture. The two-times improvement compared to available aircraft propulsion motors allows application of the motor up to single-aisle class aircraft to enable electric and hybrid-electric flight with little (from jet fuel, for example when a turbogenerator might be necessary) or no emissions.

The company claims a two-motor system could power a 50-seat aircraft such as the ATR-42. However, ten 2 MW motors would be required to power the 186-seater Wright 1 aircraft.

Wright is currently evaluating energy storage solutions to pair with the propulsion system, with two options under consideration: hydrogen fuel cells and aluminium fuel cells. The main conclusions so far are that the former provide a longer range but smaller payload, harder operations and higher costs compared to the aluminium fuel cell.

“Our two biggest challenges are the propulsion system and energy storage but there’s a chicken and egg situation here,” said Engler. “No one is going to build a really big motor unless there is an energy storage system for it and no one is going to build a really big ultra-lightweight storage system unless there’s something to use with it. We started with the propulsion system because we didn’t see anyone else working on this. On the energy storage side, however, there’s a lot of people quietly working behind the scenes and making incredible advances, including on hydrogen fuel cells and aluminium fuel cells. What we need to do right now is to take the technologies they’ve been building and integrate them into an aircraft.

“One of the reasons why we’ve been able to build our motor is that we weren’t building a brand new technology. We were taking multiple technologies and combining them in a clever way to build the world’s most powerful propulsion system, four times more powerful than anything else in the aerospace industry today and with an incredible power density.”

The company has just launched the Joint Technical Assessment Phase (JTAP) of the development programme, which, in collaboration with Honeywell Aerospace and EaglePitcher Technologies, will explore various technologies, including turbogenerator and fuel cell offerings, as well as the utilisation of Honeywell’s test facilities and other support. EaglePitcher will bring to the programme its experience in high-capacity battery technology and advanced cell chemistry. The JTAP programme plan and aircraft launch path are expected to be completed by October 2022.

European low-cost carrier easyJet has been working with Wright since 2017. “We believe zero-emission aircraft are key to addressing aviation’s environmental impact and so we fully support them in their ambition to bring a zero-emission aircraft to market,” commented David Morgan, Director of Flight Operations at easyJet, on the launch of the Wright Spirit programme.

Added Juan Carlos Zuazua, CEO of Viva Aerobus, which operates a young fleet of 43 Airbus A320 family aircraft: “We are excited to support the development of the Wright Spirit as a member of the advisory board. As the greenest airline in Mexico, we are focused on aviation’s commitment to greenhouse gas reductions. We look forward to collaborating with Wright to analyse the integration of a zero-emissions 100-passenger aircraft into airline operations.”

Founded in 2016 by a team of aerospace engineers, powertrain experts and battery chemists, Wright has development contracts with NASA and the US Department of Energy’s ARPA-E and has been funded through Y Combinator, the Clean Energy Trust, venture funds and family offices.

Engler firmly believes electric power is the true path to fully decarbonising short-haul routes and has doubts about liquid hydrogen propulsion. “The problem with hydrogen combustion is that even though technically it’s zero carbon, because there are emissions like water and NOx, studies have suggested the actual reduction in global warming equivalent might be as low as 50% compared to today’s airplanes,” he said. “With new engine and aircraft designs, it might be possible to get close to that 50% anyway without the huge investment in hydrogen that is required.”

Although he sees a major role for carbon offsetting and sustainable aviation fuels, he does not see them as any more than stop-gap solutions and that there is a longer term requirement for zero emissions technology.

Image: The Wright Spirit

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