Electric dreams

ONE OF the most active areas in the aerospace industry right now is the development of electric aircraft.

Cora, designed and built by Kitty Hawk Corporation, is one of dozens of electric aircraft projects.
Kitty Hawk Corporation via Boeing

There are no fewer than 170 diff erent electric aircraft development projects around the world, according to a May 2019 estimate by consultancy Roland Berger, which it says is an increase of 50% since April 2018. The consultancy says there could be around 200 such projects by the end of this year.

Electric aircraft projects span various areas in the commercial aviation market. There are electrically powered unmanned systems designed for urban air mobility, a catch-all term for the growing ecosystem that includes air taxis and cargo delivery drones to transport passengers, goods and supplies around urban areas.

There are electric aircraft planned for the business aviation and general aviation markets, small commuter aircraft providing short to medium-haul services for regional airline requirements, and electric aircraft demonstrators from major aircraft manufacturers designed to study and prove the technologies of batteries and electrical power distribution systems.

According to the Roland Berger research, air taxis account for more than half of the 170 electric aircraft development projects and regional and commuter aircraft for around a tenth.

The consultancy identifies Europe and North America as key areas for electric aircraft development. Out of those 170 projects, it counts 72 in Europe and 67 in North America, the remainder made up by sprinklings of projects across Asia-Pacific and South America.

The quickening pace of development activities around urban air mobility has been partly due to the entry into the electric aviation area by some major aerospace original equipment manufacturers.

In January 2019, for example, Boeing announced the successful first test flight of its autonomous passenger air vehicle (PAV) prototype developed by its Boeing NeXt division and Aurora Flight Sciences. The vertical take-off and landing PAV can carry two passengers and has a range of up to 50 miles (80km).

Another electric aviation project in which Boeing is involved is a strategic partnership with Kitty Hawk Corporation to use that company’s Cora twoperson air taxi to research safe urban air mobility.

The Roland Berger research says: “That urban air taxis and general aviation projects dominate in fully electric propulsion remains unsurprising. Not only are smaller developments easier to fund and test, but current electrical systems technology still favours lower power and shorter distance flights.”

There are grander plans, though. The recent Paris Air Show turned out to be a focal point for announcements in the electric aviation segment. Especially striking news was Rolls-Royce announcing it is to acquire the electric and hybrid-electric aerospace propulsion activities of Siemens, a deal expected to be completed later in 2019, to advance the development of all-electric and hybrid electric propulsion solutions for aerospace.

Rolls-Royce and Siemens have already been involved in the E-Fan X demonstrator project with Airbus to showcase electric propulsion at the scale required to power regional aircraft.

Paris also saw the Israeli company Eviation Aircraft show a prototype of its Alice nineseat commuter aircraft powered by a hybrid electric engine and announce the US regional airline Cape Air as the aircraft’s first customer, although no details were released about the size of the order.

Another start-up developer, VoltAero, showed a mock-up of a hybrid power module. VoltAero is planning to start flight testing of a demonstrator called Cassio 1, based on a Cessna 337, with the front engine replaced by electric motors. The company is planning a new-build aircraft, the Cassio 2, based on the Cassio 1’s configuration but using an all-composite airframe and a fully hybrid engine.

Separately, as reported in the July 2019 issue of AIR International, Airbus, Dahler and Safran also used Paris to announce the EcoPulse initiative to develop a hybrid engine for testing on a TBM 700.

It is, however, unlikely people will be flying long distances on an electric aircraft any time soon. Energy density of battery systems is an issue. Roland Berger’s analysis notes: “A battery gravimetric density of ˜500Wh/kg would be required as a minimum for viable aircraft that could one day be competitive with today’s propulsion systems for regional and large commercial flight; this is not expected before 2030.”

Starting with smaller hybrid aircraft and then scaling the technology up is the most obvious path forward for electric technologies

Beyond battery technology however, there are many other practical issues facing electric aircraft, whether the goal is introducing autonomous air taxis or a larger commuter aircraft. What infrastructure adjustment or energy generation is required to accommodate electric aircraft? What will be the model for organisations operating them? How will developers and operators make money?

Regulations and certification are crucial pieces in the jigsaw. There will necessarily have to be a lot of work into standards and operations. Detailed safety cases, risk analyses and testing regimes will need to be developed (for example, around the health of batteries, the safety of high-voltage cabling and power distribution systems) and protocols agreed and implemented across the industry and proven to work.

This area is especially crucial for the area of urban air mobility, if the vision developers like to portray when they release CGI renderings of futuristic-looking autonomous systems whizzing over cities delivering people and cargo, is to become a reality.

It is clear all areas of the industry will have to work together to move electric aircraft from curiosities to platforms of relevance to daily life. Although this is a big task and will inevitably take some time, it makes electric aviation an interesting area to watch.

Mark Broadbent