Fails when you want to go fast.

A plane that goes 80 MPH has no commercial viability for providing transportation. People can drive there faster door to door.

Tests with drone motors and props, which are optimized for essentially zero airspeed, don't really capture the trade offs needed for airplane propulsion.

Mike C.

Sure, but they're not aiming for jet speeds here.

It will be interesting to see what these new tilt-rotors do in level flight. With those huge props, they should be able to climb very well and have good fuel economy for their speed, in theory. The Grob Strato 2C weighed 24000lbs and had only 800hp (that's as if a C152 had only 30hp in comparison), but did 270kt TAS at 78000ft. Pretty impressive.

Fails when you want to go faster than a car.

Big slow turning props don't provide transportation by air.

Mike C.

Fails when you want to go faster than a car.

Big slow turning props don't provide transportation by air.

Mike C.

All those examples are powerful, not efficient per mile which electric aircraft need.

Solar Impulse 2 had 13 ft diameter props to be efficient, but it wasn't fast being driven by only 17 HP.

You need slow turning large props to be most efficient. That means a slow airplane.

Mike C.

Agreed. My only point was that it looks to me, that the props are not optimized in size for its designed speed, thus wasting efficiency. But it's hard to tell from an image.