META in the wind tunnel
As part of the National Aeronautical research project FTK-META-WK (advanced swashplate concepts – wind tunnel test of the multiple swashplate system), a test campaign spanning several weeks was successfully conducted in the Large Low-Speed Facility (LLF) of the DNW in the Netherlands.
Besides the first demonstration of individual blade control (IBC) realized with the multiple swashplate system META, the goal of the test was the investigation of the potential of active rotor control for the reduction of vibrations, noise emissions and power requirements under different test conditions (approach, level flight, and high-speed flight). In addition, a new set of model rotor blades with a modern blade geometry, manufactured by the DLR Institute of Flight Systems, was tested successfully in the wind tunnel for the first time.
To exactly measure the movements and elastic displacements of the new model rotor blades during operation of the model, more than 200 markers on the blades’ surfaces were optically tracked by a new Stereo Pattern Recognition (SPR) System of DNW using four high-speed cameras. Measurements of noise emissions also were carried out by DNW using a traversable microphone wing as well a microphone array consisting of more than 100 individual microphones.
During the wind tunnel test, significant reductions of vibrations, noise emissions, as well as required rotor power through the application of active rotor control were measured for simulated approach as well as in level flight.