| >Is the efficiency the number of amps required to gain/maintain a particular rotational speed? Thrust, not RPM. Efficiency for any actuator is defined by (work done)/(power in). You could replace the Archimedes screw with a simple axle, and it would be much easier to maintain RPM - however it would move no air no matter how much power you dumped into it, and so would have 0% efficiency. > So given rotational speed 4k conventional is 50g thrust and DaVinci 75ish g, if conventional costs 10amp then DaVinci would be less efficient if it uses more than 15 amps? Not quite. Thrust / power for disk-shaped actuators is not a constant ratio, but a curve - an x^(3/2) power law, to be exact. You need exponentially more power to maintain a linear increase in thrust. So while it's correct that thrust/amps[note] describes the efficiency, it's not fair to compare conventional at 50g and DaVinci at 75g. However I guarantee you if you put the same power into this rotor, you'll get less thrust than if you put it into a regular prop. [note] Watts, really, but same thing if voltage is held constant |
Fun pedantic correction, it would move air via the Magnus effect [1], but of course it would be orthogonal to the direction you want it to be moved!
See the Turbosail [2] for a fun application of that effect.
[1] - https://en.wikipedia.org/wiki/Magnus_effect
[2] - https://en.wikipedia.org/wiki/Turbosail