A slider is a small rectangular piece of fabric with a grommet near each corner used to control the deployment of a "ram-air" parachute. Also called a "reefing device." A ram-air parachute / parafoil has a tendency to open very rapidly. At high velocities, the opening shock from a rapid deployment can cause damage to the canopy or injury to the jumper. The slider was developed as a way of mitigating this. During deployment, the slider slides down from the canopy to the risers. Air resistance slows its descent. The slider holds the lines together, which slows the parachute inflation. The slider also deflects some of the rising air column away from the center of the canopy as it inflates. This also helps moderate the speed of opening. This invention solved the rapid deployment problem with ram-air designs. Sliders also reduce the chance of the lines twisting to cause a malfunction. In

BASE jumping BASE jumping () is the recreational sport of jumping from fixed objects, using a parachute to descend to the ground. BASE is an acronym that stands for four categories of fixed objects from which one can jump: buildings, antenna (radio), antenna ...

a rapid canopy deployment is desirable. The slider may be constructed of mesh, packed so that the slider is at the base of the lines and does not inhibit the opening ("slider down") instead of up by the canopy, or removed completely. Slider down and slider off both allow the canopy to open with no resistance and are identical in performance. In 1971, Domina Jalbert's ram air parachute was designed and tested at

Wright-Patterson Air Force Base Wright-Patterson Air Force Base (WPAFB) is a United States Air Force base and census-designated place just east of Dayton, Ohio, in Greene County, Ohio, Greene and Montgomery County, Ohio, Montgomery counties. It includes both Wright and Patte ...

in Vandalia, Ohio. Theodore Hulsizer, civilian prototype parachute manufacturer for the

United States Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...

and

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

(1947–1973), made the first working parafoil parachute. While testing his prototype in the wind tunnel at Wright-Patterson Air Force Base in Dayton, Ohio, USA, Theodore realized its drag was stronger than any other parachute he had tested in his 25 years of experience. He believed others' attempts ripped to shreds, because of the drag. To slow the opening of the parafoil, Theodore ran the cords through rings he designed that were slid to the top while packing the parachute. As it opened, the rings had to slide down, slowing the opening. Theodore personally made the first full-size parafoil, which worked in its first drop.

References

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External links

* http://adventure.howstuffworks.com/skydiving4.htm * http://www.skydivewestpoint.com/skydiving-information/Soft-Parachute-Deployments.aspx Parachuting