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Vents

This page is a chapter in 'BASE Wiki Canopies'

Many modern BASE canopies are “vented” on the bottom skin. A vented canopy is generally recommended for a jumper who intends to jump slider-down or slider off on a regular basis.

Vents are small cut out openings covered with mesh, on the bottom skin, usually towards the nose, which serve two primary functions;

First, they give faster top skin inflation. A ram-air parachute catches air and begins to fly in two stages:
  • The bottom skin catches the air, snapping quickly open and decelerating the jumper;
  • The canopy inflates, the top skin takes shape, and the parachute begins to fly as a wing.
Vents will reduce the time between the first and second stages, giving the jumper a flying canopy sooner — a characteristic which is particularly desirable in lower altitude jumps or in the event of an off heading opening.

Second, vents help keep the canopy pressurized and inflated even when it is decending in or near a stall, for instance during a steep accuracy approach or when the canopy is nose-in during an object strike. In such scenarios, vents help maintain a reasonable decent rate and predictable flight, reducing the risk of injury.



Vents can be configured in a variety of ways, depending on the manufacturer and the users needs. You can have anywhere from one to seven vents total (one vent per cell desired).

Early vented canopies lacked any device to prevent air spilling out of the canopy through the same openings designed to allow it in. These canopies, though still in common use today, tended to have a lower glide ratio and poor flare as a result. Newer vented canopies include a valve of some sort which prevents air from spilling out through the vents.

One thing to keep in mind is that even valves are not leak-proof. Hence, depending on variables like design, wing loading, usage, and skill, there may be some degradation in performance especially in the flare “department”. Most users say they are willing to trade off a bit less flare power for a faster inflation.

There are some conventional canopies that pressurize better than some valved ones. The most important thing to keep in mind is not to get a false sense of security because you are jumping a valved/vented canopy.




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Categories: Category:Gear

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