Study on Influencing Factors of Parafoil Maximum Opening Force

In order to explore the opening force variation rules and influencing factors of parafoil opening process， a dynamic model for parafoil opening process is established in this paper. The performance of the parafoil opening process is calculated using the Runge‑Kutta method. The calculation results are consistent with the patterns of the existing literatures， showing a maximum opening force error of 4.8%. Based on this， simulations are conducted for 20 different operating conditions of the parafoil system， and the rules governing the changes in system motion speed and parafoil opening force are obtained. The influence of the parafoil parameters and opening conditions on the opening force is also investigated. The results indicate that the opening force is positively correlated with the load mass， the opening speed， and trajectory angle， while it is negatively correlated with the opening height. The peak time of the opening force is affected by aerodynamic force and decelerating inertia force. As the weight and the opening height increase， the system deceleration becomes slower， and the peak time of the opening force is delayed. The aerodynamic force increases with the canopy area and the opening speed， leading to an advancement in the peak time of the opening force. Finally， the Sobol global sensitivity analysis method is employed to obtain the first‑order sensitivity and total sensitivity coefficients of the parafoil parameters and opening conditions on parafoil maximum opening force. The results show that the opening speed and the load mass significantly affect the maximum opening force. The first‑order sensitivity coefficients of 0.410 7 and 0.313 6， respectively； and the total sensitivity coefficients of 0.477 5 and 0.375 2， respectively. The sensitivity of the canopy area is at a moderate level， with the first‑order and total sensitivity coefficients of 0.074 9 and 0.085 1，respectively. The sensitivity coefficients for the opening height and the opening angle are close to zero， indicating that fluctuations in their values have little effect on the maximum opening force.