Research on the safety of sled helicopter landing and sliding on snow-covered pavement

Sled helicopters, equipped with sleds on landing gear, can land on thick snow-covered pavement. However, existing research focuses on hard-surface landings, with little investigation into snow-covered pavement, hampering safety assessments. This study analyses sled helicopter landing characteristics on snow-covered pavement. Using the capped Drucker–Prager snow constitutive model and the coupled Eulerian–Lagrangian method, a multi-field finite-element model of the helicopter-snow system is established. Symmetrical and asymmetrical landing characteristics are compared, and the effects of initial landing velocity on landing and sliding safety boundaries are simulated. Results show that under identical symmetrical landing parameters, the maximum vertical overload at the centre of mass is 1.11 g, 25% lower than for wheeled helicopters. After an asymmetrical landing, the helicopter remains tilted, increasing load on a single landing gear. At a 5° roll angle, the peak load on the right landing gear is 22.88% higher than at 0°. Without rotor pitch moment, a heading velocity exceeding 3.8 m/s risks overturning during landing. Based on these findings, the velocity-moment safety boundary for the safe landing of sled helicopters is presented.