I’ve read some similar theories about electrostatic propulsion. What I’ve seen speculated is that some type of exotic energy principle enables a passive “antigravity“ effect, like a helium balloon, whereas a conventional jet or engine (of some kind) provides raw “thrust” for rapid acceleration on top of this. Allegedly the “antigravity drive” is powered by a miniaturized nuclear reactor.

I have no idea, but:

When it got super close, you could definitely hear some kind of weird noise- and I believe that noise was being generated by whatever was powering/propelling it. Kind of a hollow, muffled droning noise- it almost reminded me of a turbojet, but not quite.