Most VTOL drones use multiple propellers for lift, but could they do without moving parts ?

One promising possibility is multistage atmospheric ion propulsion but that requires high voltage and high amperage. One way to store such energy is the Casimir battery proposed by physicist Robert L. Forward.

Since high voltage is available, one possible weapon for this drone is the Transversely Excited Atmospheric laser which can be build quite easily, but ambiant air versions are not powerful.

The result is a near-silent drone which can strike a (unarmored) target with pinpoint accuracy.