Feasibility studies for a bionic propulsion system of a blimp based on dielectric elastomers

Abstract

After having successfully integrated Dielectric Elastomers (DE) in a cross tail for flight control, a novel biologically inspired propulsion system based on DE is envisaged. The basic idea is to mimic a fish body motion by deforming a) the envelope of the rear lifting body and b) flapping an aft-tail. In both cases, planar DEs are used, either fully integrated in the envelope (for a) and/or arranged as an active hinge (for b). In a theoretical study the specifications of a steady-state horizontal indoor flight of 1 m/s were defined. In an experimental work the concept of an active hull element, which consists of a balloon hull material and several layers of DE actuators was verified. The specific boundary conditions of a slightly pressurized elliptical membrane body were simulated in a biaxial test. It could be shown, that the necessary active strains to reach the specified body deformations were reached. In a second study an aero-elastic fin was designed. Based on fluid-dynamic similarity principles the size, shape and stiffness of the fin were determined and tested in preliminary flight test with a three meter long blimp. The main goal of 1 m/s flight velocity could be shown.