Originally Posted by
cattletruck
I hear it suffers from the dreaded 35 engine approach.(someone wants their computer cooling fans back).
That's funny. Except it should be "the dreaded 36
motor approach".
Unfortunately, there are quite a few practical issues with this concept that they do not seem to have fully resolved yet.
First, relying solely on differential thrust produced by speed changes of (36?) small diameter fixed pitch rotors to provide satisfactory pitch/roll/yaw control authority, plus the required lift in hover, is a very inefficient approach for VTOL operation.
Second, their claims of "simplicity" and "high redundancy" may be rather optimistic. Having 36 individual motor driven fans does not make the propulsion safer or more reliable if there is some single point in the motor control/power system which if it fails would disable enough motors to cause loss of lift/control of the aircraft. This means several isolated/separate systems for power/control of those 36 motors.
Third, using 36 electric motor-driven fans does not reduce the maintenance requirements or increase reliability versus a conventional commercial helicopter drivetrain. In fact, the most failure prone part of this system will be the high-power motor control electronics. A good helicopter gearbox and turboshaft engine will last >2000 hrs. But an air-cooled aircraft-weight electric motor and high-power control system will likely have an MTBF of a couple hundred hours at best. Consider how worse the situation gets with 36 motors.