Base jump in cave

Skydiving, Le Base Jump est une discipline du parachutisme, qui consiste à sauter depuis des objets fixes et non des aéronefs. Il est souvent considéré comme la discipline reine des sports extrêmes. C'est un sport qui mêle en fait de nombreuses autres disciplines : chute libre, parapente, alpinisme, précision d'atterrissage, voltige, etc. La pratique exclusive du Base Jump depuis des falaises se nomme paralpinisme. Il y a en France environ 200 pratiquants réguliers, entre 8 000 et 10 000 dans le monde. La hauteur des objets sautables varie d'environ 50 mètres à plus de 1500 mètres (les temps de chute peuvent alors atteindre 1 minute 30 secondes). Le parachutiste accélère progressivement sous l'effet de la gravité, avant de se stabiliser aux alentours des 200 km/h par les frottements de l'air. "Base" est l'acronyme pour : pour Building, Antenna, Span bridge and Earth cliff Jump : saut en parachute à partir d'un immeuble, d'une antenne, d'un pont ou de falaise. close proximity to the object serving as the jump platform. Because BASE jumps generally entail slower airspeeds than typical skydives (due to the limited altitude), a BASE jumper rarely achieves terminal velocity (that speed achieved after twelve seconds of acceleration). Because higher airspeeds enable jumpers more aerodynamic control of their bodies, as well as more positive and quick parachute openings, the longer the delay, the better. Skydivers use the air flow to stabilize their position, allowing the parachute to deploy cleanly. BASE jumpers, falling at lower speeds, have less aerodynamic control, and may tumble. The attitude of the body at the moment of jumping determines the stability of flight in the first few seconds, before sufficient airspeed has built up to enable aerodynamic stability. On low BASE jumps, parachute deployment takes place during this early phase of flight, so if a poor "launch" leads into a tumble, the jumper may not be able to correct this before the opening. If the parachute is deployed while the jumper is tumbling, there is a high risk of entanglement or malfunction. The jumper may also not be facing the right direction. Such an off-heading opening is not a problem in skydiving, but off-heading opening that results in object strike has caused many serious injuries and deaths in BASE jumping.

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YouTube | November 11, 2008

Tags:. .immeuble. .voltige. .leffet. .partir. .antenne