Data and code supporting "Gravitational yaw stiffness of helicopter sling suspensions"

Data and code supporting “Gravitational yaw stiffness of helicopter sling suspensions” This repository contains the experimental data, computational tools, numerical results and figures supporting the research article “Gravitational yaw stiffness of helicopter sling suspensions”, submitted to The Aeronautical Journal (manuscript AeroJ-2026-0391). The research investigates the gravitational and elastic mechanisms responsible for yaw-restoring moments in helicopter sling suspensions, with particular emphasis on the influence of attachment geometry and suspension configuration. Repository contents The deposited materials include: Experimental data: Digitised measurements of sling wind-up resistance originally reported by Cicolani and Ehlers (2002). The corrected dataset contains 17 retained points from the published experimental curves. Supplementary Material S1: A description of the digitisation procedure, calibration, uncertainty assessment, extracted numerical values and limitations of the experimental interpretation. Analytical and numerical verification: Computational programs used to verify the gravitational yaw-stiffness expression for symmetric multi-leg suspensions and the elastic restraint of two-point configurations. Linearised dynamic analysis: Numerical results for representative single-point and two-point suspensions, including structural eigenvalues, the influence of suspension geometry and sensitivity to assumed aerodynamic damping. Suspension asymmetry: Calculations examining the effects of unequal sling-leg lengths on equilibrium configuration and the coupling between yaw and other rigid-body motions. Figures and supporting data: Numerical results and graphical materials used to illustrate the analytical and computational findings. Scientific scope and limitations The experimental data were digitised from previously published measurements and do not represent new experiments performed by the present authors. The structural dynamic calculations are based on simplified mechanical models with specified assumptions. They are not intended to constitute experimental validation of the complete helicopter–sling–load system in forward flight. The available wind-up measurements do not uniquely identify the individual contributions of gravitational restraint, friction, rope torsion and progressive bundle take-up. The repository is provided to support transparency, independent verification and reproducibility of the reported research results. Associated manuscript Podliesnyi, S., Sheremet, O. and Tomashevskyi, R. “Gravitational yaw stiffness of helicopter sling suspensions”. The Aeronautical Journal, manuscript AeroJ-2026-0391 (under revision).