J.: Wind-Tunnel Investigation of the Opening Characteristics, Drag, and Stability of Several Hemispherical Parachutes

An investigation has been conducted to determine the opening charac-teristics of several hemispherical parachutes at airspeeds up to 200 miles per hour and to study the influence of the parachute design variables on these opening characteristics. The effects of design variables on the drag and stability characteristics of the parachutes were also evaluated. The tests were made in the Langley 20 foot free—spinning tunnel and in the Langley 300 MPH 7 — by 10—foot tunnel. Some of the parachutes blossomed fully when opened in the air stream. Beneficial effects on the parachute opening characteristics were obtained when longer shroud lines relative to parachute diameter were used, when the floating hem lines were tacked to prevent the hem—line loops from pulling out under load, or when a strip of low—porosity fabric was provided around the canopy in the area immediately above the hem line. The drag characteristics of the parachutes were not appreciably affected by these changes in design. The stability characteristics of the para-chutes were affected somewhat adversely by the use of the low porosity fabric just above the hem line. It was indicated that, for a given para-chute, increased airspeeds impaired opening characteristics, lowered drag coefficients, and improved stability