Modeling the inflation of ram-air parachutes reefed with sliders

Sliders are aerodynamic devices designed to reduce parachute opening shock by delaying the canopy spreading stage during inflation. Sliders are used o n almost all ram-air parachutes of 1000-ft(2) surface area or less and can be found on an increasing number of round and other cup-shaped canopies. Th e continued refinement and validation of an inflation model of slider-reefe d ram-air parachutes proposed a few years ago by Potvin (The Aeronautical J ournal. Vol. 101, No. 1007, 1997, pp. 299-313) are reported on. Model valid ation is accomplished by comparing its predictions with data recently colle cted from a large number of parachute jumps. The comparison shows good agre ement between theory and experiment. Additionally, a series of new scaling laws correlating opening shock and inflation time with descent speed, parac hute size, deployment altitude, etc., are derived and discussed.