Aeroelastic Analysis of Active Rotor Control Concepts for Vibration Reduction

The development and design of an active rotor control system to reduce aircraft vibration requires analytical tools which can accurately model the significant characteristics of the system. This paper details the development and initial evaluation of Sikorsky Aircraft's UMARC/S analysis, emphasizing its new capabilities to model active rotor control concepts. The UMARC/S analysis is first evaluated against Individual Blade Control (IBC) data obtained on a BO-105 rotor at NASA Ames Research Center. The metric of interest is N/rev hub vibratory loads, although blade bending loads and elastic deflections are also examined. In addition to IBC, on-blade trailing edge flap control and distributed twist control (e.g. internal blade twist actuation) are examined. Results show that the UMARC/S analysis accurately predicts vibration reduction trends resulting from the IBC inputs. It is also shown that the trailing-edge flap and distributed twist control concepts can yield benefits similar to the IBC system. All three concepts evaluated show significant increases in root torsional bending loads on the blade. These results show how the UMARC/S analysis can be an accurate and valuable tool in the design of an active rotor control system.