Overtest Results for the 7.3-m (24-ft) Diameter Hybrid Kevlar=29/Nylon Ribbon Parachute

Abstract

The design of a 7.3-m (24-ft) diameter hybrid Kevlar-29/nylon ribbon parachute is presented. The results of six Nike rocket-boosted overtests of the parachute are discussed. Four tests were successful with the parachute being deployed unreefed from the 345-kg (760-lb) test vehicle in free flight at a Mach number of about 1.5 and a dynamic pressure of about 125-kN/m2 (2600 lb/ft2). A peak deceleration of 240 #'s was measured. The use of Kevlar-29 in construction of the parachute has resulted in 2.25 times the drag area of a 5.2-m (17-ft) diameter allnylon ribbon parachute with the same pack weight and volume. Nomenclature CD. = parachute drag coefficient based on S D = parachute constructed diameter, m £max. = maximum deceleration, g's h = altitude, m L = reefing line length, m M = Mach number q = dynamic pressure = 1 /2p V2, kN/m2 R = reefing ratio = \QQ(CDSr/CDS), % S = parachute constructed area = (ir/4)D2, m2 t =time, s V = vehicle velocity, m/s WT = weight of test vehicle and parachute system, kg A = incremented value \G = geometric porosity of canopy, % p = air density, kg/m3 Subscripts