US Patent 10518187 Lighter than air hovering drone

A lighter-than-air toy drone assembly that stays aloft using a balloon that is filled with a lighter-than-air gas. The balloon is inflated and deflated with the gas through a remote control vent valve. A ballast chamber can be provided that is filled with and drained of ballast through a purge valve. Controlled flight is achieved by selectively controlling motorized propellers, the vent valve and the optional purge valve. The motorized propeller provides horizontal movement. The purge valve and the vent valve change the buoyancy of the drone assembly and therefore control vertical movement.