3 The flapping wing in motion case enables Air_ray to deploy the full power of its flapping wing. The structure is supplemented by a torsionally resistant central spar developed by Rainer Mugrauer. Mounted to its exterior end is a servo drive unit that enables the flapping wing to rotateaboutitstransverseaxis,sothatAir_raycanfly backwards. The pitch elevator is also designed as a Fin Ray structure driven by a servo unit. With this project, Festo demonstrates how nature can serve as a model to inspire new technical solutions. Air_ray’s movements already closely approach those of the biological model, and it can even execute birdlike light manoeuvres. Camera images can be transmitted live from Air_ray, and diagnosis of its operating parameters can be carried out online. The application of structures modelled on nature can also give rise to new solutions in automation. Air_ray is modelled on the manta ray, which with its flanks akin toflappingwingshasbeenplyingtheoceansforthousands of years. The contours of the manta ray have undergone continuous refinement over the course of many stages of evolution. Air_ray is a remote-controlled hybrid construction comprising a helium-filled ballonett and a flapping-wing drive mechanism. The ballonett is a gastight bladder of aluminium-vaporised “PET foil” with a specific mass of 22 g/qm; it can be filled with up to 1.6 cbm of helium. Since 1 cbm of helium generates approx.1 kg weight of buoyant force, Air_ray’s overall mass must not exceed 1.6kg. Air has a density of 0.0012 kg/m3 at 20° Celsius at sea level; by comparison, the density of water is about 1 kg/dcm3. In the design of Air_ray, the difference in density between these two media necessitates an extremely light construction. This enables Air_ray to almost hover in the air by means of the buoyant force of the helium ballonet, floating through a sea of air just as the Manta_ray does in water. The propulsion is effected by a flapping-wing mechanism. The wing module, which can be moved up and down by a servo drive unit, has a structure like that of the tail fins of many fish. This structure consists of two alternating pressure and tension flanks flexibly connected by ribs.When one flank is subjected topressure, the geometrical structure automatically bends in the direction opposed to the force applied.This concept,named FinRay Effect®, was developed by Leif Kniese. In Air_ray it serves as an active structure. A servo drive unit pulls on the two flanks longitudinally in alternation, thus moving the wing module up and down. What at first sounds complicated is in fact a simple principle, which in this
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