The First Wind Tunnel Test of the Multiple Swashplate System: Test Procedure and Principal Results

In September 2015, the DLR completed the first wind tunnel test of its patented Multiple Swashplate System in the DNW's Large Low-Speed Facility in the Netherlands. During these tests, the potential of this new active rotor control system to effectively reduce noise, vibration, and power consumption using several individual blade control strategies, including 2/rev inputs, was successfully demonstrated on two different model rotors without using actuators in the rotating frame. For a Mach-scaled Bo105 model, rotor power reductions of up to 4% in level flight and reductions of the weighted 4/rev vibratory hub loads of up to 77% in a descent flight condition were measured, and BVI noise levels were reduced by up to 4.5 dB by the application of 3/rev higher harmonic control, confirming findings from the HART II test. For the second model rotor using a contemporary blade geometry, the maximum reductions were measured at 3%, 52%, and 3.9 dB for power, vibration, and BVI noise, respectively.