Bridles: As in skydiving, the bridle connects the pilot chute to the canopy, and is also involved in closure of the container, either through a pin or pins sewn to the bridle or an attached [][/] Velcro Closed shrivel flap. BASE bridles are generally made of square weave nylon (Type IV. MIL-T-5038, 550 LBS), but can also be made out of 725 pound Dacron line. The bridle is attached to both the canopy (or shrivel flap) and the pilot chute by a larks-head knot.
The typical BASE bridle measures 9 feet in length. This can be compared to a typical main skydiving bridle, which is 7 feet long, or a reserve free-bag bridle from a skydiving rig, measuring anything between 9 and 12 feet. The longer bridle used in BASE is the result of a lot of experimentation by jumpers and gear manufacturers, and is motivated by the (generally) lower airspeed at deployment and the absolute necessity of avoiding a “burbled” pilot chute.
When installing a bridle and closing the container with it, one of the most important things is to leave slack between all the points: (1) between the canopy attachment point and the top pin or top of the shrivel flap; (2) between the pins; and (3) between the lower pin or lower part of the shrivel flap and the extra folded bridle. It is also important that the bridle does not have any twists at any point. Bridles are cheap and very easy to make, and should be replaced at the first sign of wear; a broken bridle before canopy inflation will most likely result in death.
The “Multi”
The Multi bridle attachment, partially opened
Some BASE canopies are available with the “Multi”. The Multi consists of four dacron lines which are inserted between the shrivel flap (or bridle, on a pin-closed container) and the canopy. One of these lines goes to the usual canopy attachment point; the other three go to attachment points to the left, right, and rear of it. The Multi is generally enclosed in a velcro-closed nylon sheath to prevent entanglement with the jumper or canopy, and is stowed inside the container, near the yoke.
When deployment is initiated, just after the container has opened, the pilot chute and bridle are descending much more slowly than the jumper and canopy (which is still in the opened container). The packed canopy has considerable momentum relative to the pilot chute and bridle, and therefore resists being pulled out. On canopies attached only by the center cell, this leads to center-cell stripping (imagine lifting a table cloth up from the center), a phenomenon which is usually minor if the pilot chute used is appropriate to the delay.
The purpose of the Multi is to prevent center-cell stripping, and (in principle) give more consistent openings with better heading performance. There is no question that the Multi successfully accomplishes the first task. Whether center-cell stripping actually contributes significantly to heading performance with a properly-configured rig is a matter of some debate, though, and a single-attachment system remains the most common.
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