In recent years reserve parachute design has evolved much to the benefit of the overall safety for the pilot. Traditional round reserves have begun to be replaced by square reserves and a combination square/round design - both reduce the decent rate and oscillation tendency compared to the older round designs which make for softer and safer landings.
Previously the most common type of reserve used for paragliding was the round pull down apex (PDA) design. By pulling down the apex of a round reserve, the surface area is considerably increased, resulting in a decreased descent rate. The PDA design also helps to dampen oscillations, a major concern with round parachutes.
Another increasingly common reserve design is the steerable or “Rogallo” design named after Tony Rogallo who helped pioneer the first hang glider designs. It is triangular in shape and has a significant advantage in its forward penetration over round or square reserves. They also include a brake system that allows the pilot to flare for landing.
The reserves we use are specifically designed for use with paragliders. They are designed and packed to open quickly (4-6 seconds) and at relatively slow speeds. They are not certified for terminal velocity openings, although tests (using dummies) have shown that they can withstand them. The line lengths place the reserve below the paraglider, so that it gets first ‘crack’ at the airflow.