The thread is turning into a technical one.
The participants in this thread, and logic, appear to agree that using ducted fans for lift is verboten, at least for the foreseeable future. However, IMHO, electric drives and control have a very promising near-term future.
As you have said Mart, existing brushless motors have no moving parts, except for a couple of bearings. These bearings could be air or magnetic bearings in the future, thereby creating a motor with no components to wear out.
Additional safety is available now, by simply connecting the windings of a single motor into two or three separate groups (in addition to the 3-phase grouping). Each group will have its own controller and power supply. In a motor with three groupings, if one of these highly reliable electric groups was to fail, the motor can still produce 2/3 of its nominal torque. Also, electrical motors can deliver 3x to 10x their nominal torque for a few seconds without damage.
Axial flux motors produce high torque at slow rotational speeds. An axial flux motor can be directly coupled to a helicopter rotor. The weight of a mechanical transmission, plus its safety concerns, are totally eliminated. The power/weight ratio of electric motors is also improving by the use of existing
Halbach magnets and the potential of
carbon nanotube wire.
The storage of electrical power is the main obstacle, however billions of dollars will be spent to overcome this problem.
Here is one of many current research projects. Initially the benefit will be realized in ground vehicles, then airplanes, and eventually rotorcraft.
In the early days of helicopters, at least one aspirant waited for a sufficiently powerful engine to come along before starting to develop his rotor control concepts. I suggest that this time around electric rotorcraft research and development should be conducted now, so that there is a timely marriage of motor, battery and integrative helicopter.
Anyone want to participate in the development toward man's first electrical rotorcraft flight?