Quick connector snap. A large hook-shaped, spring-loaded snap, two of which are used to quickly attach the chest-type parachute to the two D-rings on the harness.

Radial seam. A seam extending from the skirt to the apex, joining two gores. A portion of the suspension lines may be concealed in the tube formed by the radial seam.

Ram-air parachute. Generally, a rectangular, double-surface canopy with airfoil shaped ribs inflated by the air flowing into the front openings to produce an airfoil shape.

Rate of descent. The vertical velocity, in feet per second, of a fully-opened parachute.

Rating. A statement that, as a part of a certificate, sets forth special conditions, privileges, or limitations.

Ravel (unravel). To separate, untwist, or unwind, leaving a frayed or ragged edge. “Unravel” is often used with the same meaning, although grammatically incorrect.

Raw edge. The unfinished edge of the material; liable to raveling.

Reefing. A temporary restriction of the skirt of a parachute to a diameter less than the fully inflated diameter. Reefing is used to decrease drag area and/or to obtain stability.

Reinforcements. Commonly strong tape or webbing used to strengthen parts of the canopy, container, or harness.

Relative humidity. Ratio of the amount of water vapor present in the air to that which the air would hold at saturation at the same temperature.

Repack cycle. The time that a certificated parachute is considered to be airworthy before being inspected and repacked. The current U.S. repack cycle is 180 days.

Reserve parachute. The second or “auxiliary” parachute worn by a person making a premeditated jump.

Reserve static line (RSL). A backup device for activating the reserve after a cutaway. Usually a line, webbing, or cable that connects the main risers with the ripcord handle, housing, or cable.

Restitching. The process of sewing directly over base or broken stitching.

Retainer band. A rubber band used to hold folded suspension lines or static lines to the parachute pack.

Rig. 1. To pack. 2. A set of sport parachute equipment. 3. To assemble a parachute.

Rigger roll. To prepare an unpacked parachute for storage by rolling the canopy into a ball with the suspension lines around it.

Ripcord. A locking device that secures the pack in a closed condition and by which the release of the parachute is effected. It may consist of a handle, cable, locking pins, and a cable swage.

Ripcord cable. A flexible cable joining the locking pins and the ripcord handle.