A slider is a small rectangular piece of fabric with a

grommet Curtain grommets, used among others in shower curtains. A grommet is a ring or edge strip inserted into a hole through thin material, typically a sheet of textile fabric, sheet metal or composite of carbon fiber, wood or honeycomb. Grommets ar ...

near each corner used to control the deployment of a "ram-air"

parachute A parachute is a device used to slow the motion of an object through an atmosphere by creating drag or, in a ram-air parachute, aerodynamic lift. A major application is to support people, for recreation or as a safety device for aviators, w ...

. Also called a "reefing device." A ram-air parachute 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 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 Domina Cleophas Jalbert (1904–1991) invented the ram-air inflated flexible wing, often called the "Jalbert parafoil". Personal life Domina Jalbert was born in Saint-Jean-de-Matha, Quebec, Canada; his father was Onesime Jalbert (1856–1938) a ...

'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 and Montgomery counties. It includes both Wright and Patterson Fields, which were originally Wilbur Wr ...

Vandalia, Ohio Vandalia is a city in Montgomery County, Ohio, United States, and a suburb of Dayton. Its population was 15,246 during the 2010 census. In addition to being the city closest to Dayton International Airport, Vandalia lies at the crossroads of I ...

. Theodore Hulsizer, civilian prototype parachute manufacturer for the

United States Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Si ...

and

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

(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

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