Links to competition classes

S3 Parachute duration

One of the great sights at a major championships is the sky full of rockets drifting down wind under parachutes, sometimes well over a meter in diameter. In this class the maximum flight time is five minutes and if there is even a modest wind blowing this can lead to recovery over a kilometer down range. Truly parachute duration is one of the events which favors large teams that deploy recovery teams in the expected landing area.

As with the other duration classes, the event is three rounds using only two models. This means you really must get your first model back. However don't try to ensure getting it back by having a short flight as typically there will be multiple competitors with three maximums at the end of the three rounds. The unlimited fly off may last for over 30 minutes or until the last model has drifted out of sight.

The parachutes themselves are often made of the lightest weight aluminized mylar that can be found. The minimum diameter used is typically 500mm, but most competitors will use parachutes much larger than that. Ian Dowsett has been known to use parachutes of 1200mm, but the issues with these large parachutes are firstly getting them out of the rocket body at apogee and secondly getting them to deploy fully. A half inflated 1000mm parachute is less effective than a fully inflated 750mm chute. John Jacomb, the British champion for the past couple of years believe the more shroud lines the better. A chute with 36 shroud lines seems to keep better shape than one with less lines. A hole at the top of the shroud is also used to let air bleed out and stop the risk of the chute rocking from side to side.

One final trick for parachute duration is to put lots of talcum powder on the chute to stop the mylar sticking to itself. For a good flight the parachute must open fully when it first comes out. Any panels that don't open will make a huge difference to flight times.