With the world becoming increasingly conscious of its ecological impact, how is the aviation sector following suit? Mark Broadbent explores some of the dif erent electrification initiatives under investigation.
Aircraft manufacturers have been exploring the potential for alternative fuels for more than half a century. In 1956, Convair successfully flew a modified B-36H Peacemaker equipped with a nuclear-powered General Electric J47 jet engine. A year later and north of the border, de Havilland Canada was 11 years into its 1,657-strong DHC-2 Beaver production run. The comparably diminutive, utility aircraft was powered by a Pratt & Whitney product – the R-985 Wasp Junior radial engine, first run in 1929. Remarkably, it is an example of the latter type that, 62 years later, has given the aviation industry a breakthrough in its bid for an alternative to internal combustion engines.
The white and yellow seaplanes of the Canadian airline Harbour Air undertake up to 300 flights each day around the Vancouver area. However, on December 10, 2019, one of the carrier’s DHC-2 Beavers, C-FJOS (c/n 1030), departed the Fraser River at Richmond and flew into the history books. The modified aircraft, nicknamed the ‘ePlane’ is described by Harbour Air as “the world’s first all-electric commercial aircraft” It is a major milestone in the carrier’s journey towards certifying the ePlane and becoming an all-electric carrier.
Making an impact
Harbour Air’s plan is just one example of the broader shift in technology and industry over the last decade or so, that has seen some parts of the developed world embrace electrification as a practical way to reduce reliance on fossil fuels.
Other examples of this trend are electric and hybrid-electric cars which have quickly shifted from curiosities to the motoring mainstream, along with initiatives in Europe and North America to electrify public transport and the introduction of more electric technologies into industrial production and national infrastructure, such as national power grids.
Ever-greater awareness and concerns about climate change – exemplified by the rise of ‘flight shaming’ in some Western economies over the last year or so – is ramping up the pressure on the aerospace industry to act faster to reduce its environmental impact.
According to the International Air Transport Association (IATA), aviation makes up 2.4% of the total global carbon dioxide emissions from fossil fuels. This seems insignificant, but a September 2019 report by the International Council on Clean Transportation, an independent nonprofit organisation, reported CO² emissions from commercial aviation rose by 32% between 2013 and 2018.
The International Coalition for Sustainable Aviation warns that without serious action, aviation could account for more than a fifth of global carbon emissions by 2050. The UN predicts global “human-caused” CO² emissions need to fall by about 45% from 2010 levels by 2030 and reach net zero by around 2050.
So far the industry’s efforts have typically involved researching alternative fuel sources – airframers such as Boeing and Gulfstream, and airlines including KLM, British Airways, Lufthansa, American Airlines, United Airlines and Virgin Atlantic, have operated demonstration flights with biofuels over the past decade. Manufacturers and research organisations have meanwhile worked on developing and trialling advanced materials and systems to improve fuel efficiency.
However, Valery Miftakhov, the founder and CEO of ZeroAvia, a US company developing a zero-emissions electric powertrain, believes more rapid change is needed.
In an article published by Forbes in late 2019, Miftakhov wrote: “We should make some immediate and fundamental changes in how we power aviation. If the industry ignores this, it faces the risk of regulatory pressure or severe growth headwinds from cultural and social changes.”
Electric technology in aviation is not new. As long ago as 1883, the French chemist, meteorologist and aviator Gaston Tissandier undertook the first electric-powered flight after fitting a Siemens electric motor to a dirigible. Starting in the 1960s, successive generations of aircraft have introduced more electrical systems.
So far, electric technology’s greatest impact on aviation has been fly-by-wire flight control, which arrived on a commercial airliner in the 1980s with the Airbus A320. More recently the 787 Dreamliner was the first airliner to have most of its key mechanical systems, including wheels, brakes, wing anti-icing equipment and the environmental control system, driven by electrical rather than pneumatic power.
Separately, numerous experimental manned and unmanned electric aircraft have flown, ranging from the Solar Challenger of the 1980s to the NASA Global Observer drones of the late 1990s and the Solar Impulse 2 that circumnavigated the world in 2015/16.
Today the aviation industry is in an electric age. Beyond what is already in use aboard airliners, electric technologies are a key aspect of future airliner studies under way at industry research organisations such as NASA and the Deutsches Zentrum für Luft- und Raumfahrt (DLR, German Aerospace Centre).
As AIR International showed in our December 2019 issue, this work has resulted in an array of futuristic concepts that use all-electric, turbo-electric or hybrid-electric technologies. An all-electric design involves engine fans being driven by electric motors and energy stored in batteries aboard. A turbo-electric architecture uses a conventional turboshaft engine to power an onboard generator that drives multiple distributed fans. Hybrid-electric relies on energy storage systems to generate additional power.
Research into these technologies can feel rather remote as it deals with visions of the future and speculative concepts that are years away from flight, but the electric aviation arena also includes projects that involve developing real aircraft.
Batteries, energy storage and power management are intrinsic to both ultra-long-endurance solar-powered unmanned platforms (such as the HAPSMobile HAWK30, see AIR International January) and electric vertical take-off and landing aircraft (see panel), which are in development.
Several start-ups are working on hybrid-electric passenger types. The Israeli company Eviation is progressing a nine-seat commuter aircraft, the Alice, powered by a hybrid electric engine, either magniX’s magni250 375shp (280kW) or the Siemens SP260D 349shp (260kW) powerplant. Eviation unveiled a prototype of the aircraft at last year’s Paris Airshow and aims to achieve certification and service entry in 2022. The US regional airline Cape Air has placed an order for an undisclosed number.
Meanwhile, a crop of developers is working on small passenger aircraft for short-haul flights. Swedish start-up Heart Aerospace has its ES-19 (it is working with several Scandinavian carriers including SAS), the DAX-19 is under development by the Spanish company Dante AeroNautical, and Los Angeles-based Wright Electric is working with easyJet on a regional passenger airliner.
Not all electric developments involve brand-new designs. Three examples flown last year were conventional types retrofitted with hybrid-electric engines. One was Harbour Air’s ePlane; the others were a Piper M250 retrofitted with a ZeroAvia hybrid-electric engine and a Cessna 337 with a hybrid developed by a Californian company, Ampaire.
General aviation types such as these, or smaller regional and commuter aircraft, are the focus for all these developments because their smaller airframe/engine size and payload/performance demands a more practical way of researching and introducing new technologies. Aircraft are, of course, also very weight-sensitive, which limits the size of batteries and the wiring systems and inevitably means smaller aircraft must be used.
In his Forbes piece, Miftakhov observed: “Realistically, I don’t believe that battery-powered aircraft will have any appreciable share of aviation anytime soon – and not by 2030. Extending battery range using fossil fuel generators is likely possible but challenging to scale.”
Airbus and Rolls-Royce
Even so, interest in electric aviation is strong, as shown by the many investments in the sector by large and established manufacturers.
Many large companies’ efforts are centred on converting conventionally powered aircraft into technology demonstrators. This year Embraer will fly an EMB-203 Ipanema modified with a hybrid-electric engine, and UTC Aerospace plans to test a hybrid on a DHC-8-100. Meanwhile, ATR is studying these technologies for its turboprops in conjunction with Air New Zealand.
Airbus has been active in electric aviation for the last decade or so, starting out with a tiny Colomban Cri-Cri retrofitted with electric engines before progressing through the subsequent e-Genius and E-Star aircraft. This early work led into the E-Fan programme, which after testing three smaller demonstrators will enter a more ambitious phase with E-Fan X.
The E-Fan X is a BAE Systems Avro RJ100 with its right inboard 7,000lbrated (31kN) Lycoming AF502 turbofan replaced by a single hybrid-electric engine, which has an electric motor and inverter in place of the turbine core, together with an AE2100 turboshaft and an AE3007 nacelle.
The testbed, G-WEFX (c/n E3379), was built at Woodford, Cheshire, in 2000 and previously flew with British Airways CityFlyer Express, CitiExpress and Connect subsidiaries as G-CFAC and later with Swiss as HB-IYU. The E-Fan X is due to make its first test flight from Cranfield in Bedfordshire later this year.
Rolls-Royce is working with Airbus on the E-Fan X, however, it also unveiled a rakish-looking electric technology demonstrator called ACCEL (Accelerating the Future of Flight) based on the Sharp Nemesis NXT in December 2019. Produced in conjunction with electric motor and controller manufacturer YASA and the start-up Electroflight, ACCEL is designed to break speed and performance records for an electric aircraft powered by reaching a targeted top speed of 300mph (480km/h). The airframe has previous pedigree – as the Safran SMA SR305-230-powered Big Frog, it became the first aircraft equipped with a diesel engine to win a race at Reno, Nevada, during the National Championship Air Races in 2011.
Rob Watson, Director of Rolls-Royce Electrical, claimed: “Building the world’s fastest all-electric aircraft is nothing less than a revolutionary step change in aviation and we are delighted to unveil the ACCEL project plane. This is not only an important step towards the world-record attempt but will also help to develop Rolls-Royce’s capabilities and ensure we are at the forefront of developing technology that can play a fundamental role in enabling the transition to a low carbon global economy.”
The Nemesis-based racer’s first flight is planned for the spring, subject to successful full-power and airworthiness checks. The company states that the aircraft will have the densest battery pack ever assembled for an aircraft, with 6,000 cells packaged to minimise weight and maximise thermal protection.
An advanced cooling system will directly cool cells during high-power speed runs. The aircraft will have three high power-density axial electric motors and, with its propeller blades set to spin at a far lower RPM compared with a conventional aircraft, the manufacturer hopes it will provide a more stable and quieter ride while still generating more than 500hp (372kW) thrust.
ACCEL enables Rolls-Royce to both test electric technologies and demonstrate a commitment to developing lower-carbon forms of power. These are perhaps reasons why Airbus is supporting Air Race E, a new, all-electric aircraft racing series. The partnership will, the race’s organisers claim, “help us to drive the development of cleaner and more efficient aviation, with the racing series providing a testbed for the trial of pioneering electric propulsion technology”
Jeff Zaltzman, CEO of Air Race E, commented: “The galvanising effect of a sporting competition should help to push the technology development of electric flight in the right direction.”
What are the challenges?
Despite all the ventures in electric flight, serious challenges remain. A 2017 report on the sector by German consultancy firm Roland Berger remarked that one major obstacle is “demonstrating whether there is market demand at a price that generates an acceptable return on investment to cover development and operating costs”.
New electrically powered aircraft must also “demonstrate considerable utility over and above zero emissions in order to be viable” the agency said. Noting how “the initial set of electrically-propelled regional aircraft appear to be targeted at the moribund smaller end of the regional aircraft market” it added: “the manufacturers will have to convince the airlines of the value proposition these new products will offer”.
Electric aircraft providing passenger services will also need to be able to quickly recharge or exchange depleted batteries within the time of the aircraft’s turnaround at the gate. Is battery technology mature enough?
The Roland Berger report estimates the current rate of lithium-ion battery development will improve power density to around 400-450 watts per hour per kilogram by the mid-2020s but says new chemistries are needed to reach 500 watts per hour per kilogram.
The company cautioned: “Even if batteries do reach this level, the energy storage density will still be a factor of 25 lower than the approximately 12 kilowatt hours per kilogram delivered by jet fuel.”
There are undeniably many technical challenges such as these to be overcome to make electric aviation truly mainstream, but it is felt overcoming them will be a necessity. As Miftakhov explained: “For the first time since turbines emerged 80 years ago, we are witnessing a fundamentally new propulsion technology take hold.
“We could see more electrified aircraft take flight and many records break as entrepreneurs and pioneers push the boundaries of what we think is possible. It will be up to manufacturers, operators and regulators to pursue zeroemission aircraft or risk playing a part in humanity’s inability to reach its CO² reduction goals.”
The emergence of eVTOL
Playing a large part in the electrification of flight are manned and unmanned electric vertical take-off and landing (eVTOL) vehicles, an emerging class of often radical-looking aircraft powered by either fully electric or hybrid-electric engines.
These systems are designed to provide urban air mobility – specifically air taxi and cargo delivery services intended to autonomously transport passengers and goods in urban areas.
The eVTOL segment involves ambitious start-up companies and established manufacturers alike. News from the segment arrives thick and fast, whether that involves research projects, technology trials or test flights of demonstrator aircraft.
Recent headlines include Airbus conducting a first untethered test flight of its CityAirbus demonstrator, Bell unveiling a striking concept aircraft with four ducted fans, called the Nexus 4EX, and Embraer subsidiary EmbraerX moving into commercial air cargo via a collaboration agreement with Elroy Air, a San Francisco-based start-up developing a hybrid-electric cargo drone.
Meanwhile, Boeing is working on an eVTOL called Cora with a start-up called Kitty Hawk in a joint venture called Wisk. Taxi firm Uber announced a partnership with Hyundai to produce an electric air taxi called the S-A1. The German company Volocopter demonstrated its air taxi in Singapore Harbour late last year, and the Chinese developer EHang – which has caught the eye with displays of automated eVTOLs flying in synchronisation – undertook its first demonstration flight in North America as it prepares to launch air taxi services.
The activity in the eVTOL segment extends to research and development work on internal systems and, crucially, technologies that will enable these aircraft to fit into the existing air traffic management network.
To give a few recent examples, BAE Systems has announced a partnership with an American company, Jaunt Air Mobility, to find out how to improve the efficiency of batteries for eVTOLs, and Honeywell developed a new version of its IntuVue RDR84K radar tailored to the urban market. Meanwhile, NASA and Uber collaborated on research to simulate large-scale eVTOL operations in a city centre to find out how to enable safe and efficient low-altitude operations by drones.
From seaplane to ePlane - Harbour Air
While Harbour Air and magniX have significant hurdles to clear in certifying their Electric Beaver, passengers could potentially be flying all-electric commercial aircraft before the middle of the decade.
The ePlane is a DHC-2 Beaver which has had its usual Pratt & Whitney R-985 Wasp Junior radial engine replaced by a 750hp (560kW) magniX electric engine. Harbour Air and magniX are now undertaking testing and pursuing the approval process for the engine.
A Harbour Air spokesperson told AIR International the company “anticipates that certification will take one to two years” of the initial test flight in December 2019, suggesting a late 2020 or 2021 debut for all-electric passenger services on the airline’s network. Following certification and initial service entry, the airline’s 40-strong fleet of DHC-2s will be retrofitted with the new engine.
Harbour Air and magniX announced the ePlane partnership last year. The modifications required to convert the Beaver involved installing the electric motor and its battery (plus the mounts for this equipment), inverters, cooling systems and wiring harnesses. Reconfiguring the cockpit, wiring-in a ground charging station and setting up supporting software was also required at Harbour Air’s base.
Roei Ganzarski, CEO of magniX, commented: “The transportation industry and specifically the aviation segment…is ripe for a massive disruption. Now we are proving that low-cost, environmentally friendly, commercial electric air travel can be a reality in the very near future.”