Interesting to ponder energy use. Suspending a human mid-air requires ~1 kJ/sec, or 3 MJ / hr Typical energy densities for things like LPG are ~50 MJ / kg. Of course, many losses & safety issues (I wonder what's powering it here?) But a priori seems energetically okay.https://twitter.com/balajis/status/1479264202023858176 …
exhaust velocity / reaction mass and buoyancy are the critical factors. a gas generator might be 20% efficient, maybe future tech like a hot rodded fuel cell could hit 3x that, but the key for efficiency is to displace a lot of air; jets are much more wasteful than wings
