Much is being made of eVTOL, apparently offering the opportunity to fly at low cost from a local helipad to a downtown location in an electrically powered autonomous air vehicle. The reality is very different, says Ian Harbison, and other electric solutions may offer better opportunities.

The reality of eVTOL is that progress will take a long time and few of the current projects will ever enter service, as the costs involved in making the jump from a prototype to certification and to setting up a production line will be prohibitive for many initial investors – think back to the days of the Very Light Jet.

For those that do succeed, the air traffic management challenge is immense – free flying, small aircraft operating over urban areas, often on the edges of controlled airspace around airports.

And the introduction of fully autonomous aircraft will take even longer, only after a lengthy period of manned operations to ensure the concept is safe, followed by another period with a pilot monitoring the automatic operation.

Add to that resistance to the construction of those local helipads from the neighbours and it can be seen that eVTOL is an idea whose time is yet to come.

A more practical approach is to design a manned aircraft that can operate in controlled airspace. Inevitably, electric aircraft are short range, so an ideal application is the linking of smaller airports in remote areas.

Eviation

A start was made this year with an announcement at the Paris Air Show that US-based Cape Air had taken a ‘double-digit’ purchase option for the Alice electric aircraft from Eviation Aircraft.

Alice is claimed to be capable of flying on a single charge with nine passengers at 240kts to a range of just over 1,000km.

Cape Air currently operates a large fleet of nine-seat Cessna 402s and has just started replacing them with the 11-seat Tecnam P2012 Traveller, with 100 on order.

The airline’s network stretches across the US, from its local operations in Massachusetts, including Nantucket and Martha’s Vineyard, linking smaller cities with Boston, to the Caribbean and the Midwest, many services being government subsidised Essential Air Services.

Eviation says regional travel in the US is on the rise, with an increase in consumers flying short distances between 50 to 650 miles.

This growing segment offers the ideal scenario for Eviation’s all-electric Alice, which aims to undercut the cost of travel by making middle mile trips cheaper, faster and cleaner.

The shift to electric will reduce operating costs, eliminate greenhouse gas emissions, make air travel more affordable and connect communities like never before.

The all-composite aircraft will be powered by three magni 250 electric motors from magniX, each producing 375hp and driving a 165cm five-blade carbon fibre propeller from Hartzell. The rearward facing engine are mounted on the wingtips and in the aft fuselage.

They are driven by batteries that produce 920kwh of usable power and take up 60 per cent of the aircraft’s MTOW.

However, Eviation still faces all the challenges of eVTOL in terms of financing to get into production and into service successfully. It has yet to fly and there is an optimistic three-year flight test programme to achieve certification in 2022.

Project Fresson

A simpler step is electrify an existing aircraft and the UK government has just awarded a £9 million grant to Cranfield Aerospace Solutions (CAeS) (part of Cranfield University) to design, manufacture and integrate a hybrid-electric propulsion system into a nine-seat Britten-Norman Islander aircraft.

Again, this aircraft is often used in remote areas.

Called Project Fresson, the grant is provided through the ATI Programme: a partnership of the Aerospace Technology Institute (ATI), the Department for Business, Energy & Industry Strategy, and Innovate UK.

Other partners in the 30-month project include:

• Britten-Norman, providing the baseline aircraft and aircraft data/design support
• Delta Motorsport, providing battery packs
• Denis Ferranti Group, supplying the electric motors
• Rolls-Royce, supplying the power management system
• WMG (University of Warwick), performing battery testing and characterisation.

Following the demonstrator project, CAeS will go on to certify the modification through EASA to obtain a Supplemental Type Certificate.

This will then be immediately available in the global market, allowing the current operators of more than 400 Islanders to convert their aircraft to reduce operating costs and their carbon footprint.

In follow-on phases, the intention is to design and implement a similar modification, this time to a larger existing 19-seat sub-regional aircraft type, continuing with partners to design and build a new 19-seat aircraft.

The design of the new aircraft will be optimised for emission-free propulsion, making use of the certified propulsion systems architecture from the earlier phases.