And while we're talking engine efficiency, at the same time Heart Aerospace fly the largest electric airliner to date in the shape of this 30-seat regional aircraft. It began with two motors and has grown two more, and all of it in Sweden before decamping ~ as you must with these things ~ to California.
The founder did attend M.I.T. in fairness and some seven years ago teamed up with Y Combinator to develop what you see here. He does suggest in the promo vid that jet engines are equally as costly and burdensome to build and maintain compared to electric motors, which simply isn't true.
I say that because tiny jet-turbines have made remarkable strides in recent years whilst remaining relatively affordable, and turbo-propeller engines are as reliable and as fuel-efficient as ever... as witnessed by the ongoing success of the ATR-42 and -72 that I flew for a spell.
It'll be a while before they've the range to compete as well: in one ill-advised foray* I flew an ATR between Stansted and the Canaries on behalf of drunken oil-rig crew, albeit with a fuel-stop in Faro. Nonetheless in terms of economy and ease of maintenance electric airliners are looking inevitable going forward.
My one reservation relates to the under-floor battery-storage. Turbo-propeller types rarely include a central fuel-tank in order to simplify manufacture, therefore storing fuel in the wings. Any damage here and though you might get a fire it is at some remove; whereas battery fires once begun are practically inextinguishable. So it may get a little hot underfoot, but then we'll be used to that from cars by then.
At the end of the day however its a numbers game, and so we can afford a few fry-ups.
* Titan Airways, before they got posh, operated turbo-props on contracts that would include ferrying oil-rigs workers from work-base to home-base. Having spent three months dry they would stock up in duty-free to consume onboard i.e. during those eight hours we spent enroute the Canaries. The toilet was at the rear on the ATR, where I'd be told by any number of Rob C. Nesbitts that I was their 'best mate'. On arrival in Tenerife one of them stood on the top air-stair and perhaps thinking he was at home, stepped sideways onto the tarmac six-feet below.
