German engineering firm Festo has created this flying manta ray. Dubbed the Air_ray, it’s a balloon made of an aluminum-vaporised “PET foil”. Inflated with helium, the Air_ray’s propulsion system is a flapping wing drive. Each wing has alternating pressure and tension flanks that are attached to an internal set of ribs. The flanks are connected to a remotely controlled servo motor. When pressure is applied to either of the flanks, the wing bends in the opposite direction. By alternating pressure on the flanks, the wings beat. The servos are powered by two 8V LiPo accumulator cells.
The total weight of the Air_ray including the balloon, propulsion system, power supply, and helium is 1.6Kg. Festo has more specs in this PDF.