A New method for the calculation of static flight loads of rigid fuselage of rotorcraft

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2016
Gül, Seyhan
The loads acting on a rotorcraft fuselage in pull-up, push-over, and yaw maneuvers and gust conditions are required to be calculated by civil and military standards. For each maneuver and the gust condition, different flight and rotor speeds, mass states, altitudes, and temperatures are required to be analyzed. This may add up to thousands of conditions. Calculation of fuselage loads for all these conditions with transient analysis is not only computationally expensive but it also requires a lot of engineering effort. Moreover, a stability augmentation system model is required for the transient analysis. In order to reduce the computation time and engineering effort and to eliminate the need for a stability augmentation system model, an approach named as ROFLOT (ROtorcraft Fuselage LOads with Trim) has been developed which represents the transient analysis by trim point(s). Fuselage sectional axial force, shear force, torsional moment, and bending moment diagrams have been generated by using both transient analysis and ROFLOT approach and the results have been compared. It has been observed that the results are generally in good agreement except from Mx and Mz obtained from high-g forward flight trim method which is one of the two methods developed to represent the high vertical load factor in a pull-up maneuver. Furthermore, the loads are slightly underestimated with ROFLOT approach when the overall comparison of the gust conditions is considered. 

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Citation Formats
S. Gül, “A New method for the calculation of static flight loads of rigid fuselage of rotorcraft,” M.S. - Master of Science, Middle East Technical University, 2016.