But that hasn't stopped one Swiss firm from working hard to make it a reality.

Skye Aero is a project to build 10-foot helium-filled balloons, with small propellers attached to give better control than your average blimp. The benefits are a much bigger aircraft—useful when you want to advertise to people—and one that won't crash the second it loses power, or bumps into anyone.

It's not a totally new design—British band Muse have been using a fleet of similar drones on their most recent tour—but Swiss firm Aerotain's design stands out, due to its soul-sucking practicality. The company thinks Aerotain will be a perfect, audience-engaging advertising platform, which is probably true, but a little too consumerist to get excited about.

Moving away from its role as a replacement for the Goodyear Blimp, lighter-than-air drones are an interesting and underutilized concept. Provided they're not filled with hydrogen, they offer increased safety for flying over crowds, and a much greater payload than traditional quadcopters. Hopefully, someone will find a better application for them than giant floating billboards.