Numerical Study of Aerodynamic Characteristics of No-Swinging and Free-to-Swing Cross Parachute

During wind-tunnel experiments on parachutes, it is common to either fix the apex of the canopy to maintain a specific angle of attack or only fix the confluence point of the suspension lines to allow the canopy to move freely. These no-swinging and free-to-swing conditions affect considerably the aerodynamic characteristics of the parachute. This paper investigates the influence of these conditions on the aerodynamic characteristics and dynamic motion characteristics of both symmetric cross parachutes with eight equal suspension lines, and asymmetric cross parachutes with two (of eight) shortened suspension lines. The research reveals that the canopy of a no-swinging cross parachute exhibits a spinning motion around its axis. The free-to-swing parachute undergoes a conical swing motion around the suspension-line confluence point. The frequency of spin and conical swing increases in proportion to [Formula: see text]. The magnitude and direction of the lift force varies periodically owing to the conical swing of the free-to-swing parachute. Conversely, the no-swinging parachute, at a fixed angle of attack, maintains a comparatively stable lift force. The free-to-swing asymmetric cross parachute produces a stronger lift force because of the larger swing angle compared to the symmetric parachute. The resultant asymmetry in the aerodynamic shape caused by the shortening of suspension lines has minimal effect on aerodynamic characteristics.