Concurrent Aero-Structural Optimization and Mission Weight and Centre of Gravity Assessment for Weaponized Helicopter Conversion

Abstract

 This multidisciplinary approach seeks to determine how to upgrade a civilian helicopter to a weapons-capable design by optimizing both integrated aero-structural and mission parameters. The finite element analysis (FEA), computational fluid dynamics (CFD) and key parameters to assess the integrity of components (structure), as well as aerodynamic performance and operational feasibility. Structural analyses utilized forward crash loadings (9G) and downward crash loadings as defined in FAA Part 27 and MIL-STD-1290A. Stress concentration areas were discovered to be significant at the interface of the load transfer assembly, which exhibited a minimum margin of safety of 0.016.CFD was completed based on Reynolds-Averaged Navier–Stokes (RANS) flow theory at pylon/store junctions with flow separation detected. A grid independent solution was found over an approximate Reynolds number of 106 – 107. Structural modifications provided a reduction of approximately 30 % – 40 % in rotor vibrations in the 18 Hz – 24 Hz excitation range. Mission analysis performed confirmed the CG of the aircraft was within certified limits at different operating conditions. The proposed method will support a lightweight design while meeting airworthiness standards of both civil and military operations.