SKAT - A LuFo V-1 Project on Scaling Techniques for Rotorcraft Design

The LuFo V-1 project SKAT (Skalierbarkeit und Risikominimierung von Technologien bei innovativem Design) aims on the scalability of the main rotor system with respect to aerodynamics, acoustics and structural dynamics aspects to expedite the kit and platform approaches within the aeromechanics topics. The project includes two independent proposals. One proposal was made by Airbus Helicopter, which will be discussed in further detail in this paper, and the other one by DLR FT (Institut fur Flugsystemtechnik), dealing with effectiveness of higher harmonic control and individual blade control for five bladed rotors. To push the approach with respect to scaling within the rotorcraft design domain several subtopics are addressed for main rotors within the LuFo V-1 project SKAT. The first large topic is dedicated to the enhancement of methodologies to predict scaling effects in pre-design. This task comprises the investigation on aerodynamics phenomena for scaling, an improved rotor pre-design process and the definition of design spaces of dynamics parameters for pre-design phase. The second area, which is addressed, is methods for innovative rotor design, including main rotor scalability investigations with respect to aerodynamics, aero-acoustics, performance and limitloads as weil as transition investigations, scaling laws for aeroelastics models and the establishment of an improved blade design process. The third part of the project deals with similarity of interfaces of the main rotor. The influence of the overall system on scaling of fatigue loads and existing load spectra was investigated. From an interfaces point of view the drive train was taken under closer considerations by modelling of low and high frequency torsion oscillations, investigations of the influence of the drive train, gear box suspension and roter controls on the main rotor. For easier modelling of main roter interfaces studies on model reduction were made. Also scalability with respect to aeromechanics stability, vibratory hub loads, active roter control and vibro-acoustics transfer was investigated. Finally, the results obtained within the project will be assessed with respect to its industrial applicability especially for pre-development tasks, roter aerodynamics and the overall main roter system.