By Joe Jennings www.skydive.tv
Parachuting, or skydiving, is the action sport of exiting an aircraft and returning to earth with the aid of gravity while using a parachute to slow down during the final part of the descent. It may or may not involve a certain amount of free-fall, a time during which the parachute has not been deployed and the body gradually accelerates to terminal velocity. The history of skydiving starts with Andre-Jacques Garnerin who made successful descents using a canvas canopy and small basket, tethered beneath a hot-air balloon. The first intentional freefall jump with a ripcord-operated deployment is credited to Leslie Irvin in 1919 ; however, the stunt jumper Georgina "Tiny" Broadwick claimed to have made earlier freefall jumps simply by cutting her static-line and manually pulling the remaining cord-end after falling away from the aircraft. The military developed parachuting technology as a way to save aircrews from emergencies aboard balloons and aircraft in flight, and later as a way of delivering soldiers to the battlefield. Early competitions date back to the 1930s, and it became an international sport in 1952.
Parachuting is performed as a recreational activity and a competitive sport, as well as for the deployment of military personnel Airborne forces and occasionally forest firefighters.
A skydiving center can be a commercial operation or a club, usually operates at an airport, and provides one or more aircraft that takes groups of skydivers up for a fee. An individual jumper can go up in a light aircraft such as a Cessna 172 or Cessna 182. In busier drop zones (DZ) larger aircraft may be used such as the Cessna 208, de Havilland Canada DHC-6 Twin Otter, GippsAero GA8 Airvan or Short SC.7 Skyvan.
A typical jump involves individuals exiting an aircraft (usually an airplane, but sometimes a helicopter or even the gondola of a balloon), at anywhere from 1,000 to 4,000 meters (3,000 to 13,000 feet) altitude. If jumping from a low altitude, the parachute is deployed immediately; however, at higher altitudes, the skydiver may free-fall for a short period of time (about a minute) before activating a parachute to slow the landing down to safe speeds (about 5 to 7 minutes).
When the parachute opens (usually the parachute will be fully inflated by 800 meters or 2,600 feet) the jumper can control the direction and speed with toggles on the end of steering lines attached to the trailing edge of the parachute, and can aim for the landing site and come to a relatively gentle stop. All modern sport parachutes are self-inflating "ram-air" wings that provide control of speed and direction similar to the related paragliders. Purists in either sport would note that paragliders have much greater lift and range, but that parachutes are designed to absorb the stresses of deployment at terminal velocity.
By manipulating the shape of the body in freefall, a skydiver can generate turns, forward motion, backwards motion, and even lift (relative to other jumpers, not the ground).
When leaving an aircraft, for a few seconds a skydiver continues to travel forward as well as down, due to the momentum created by the aircraft's speed (known as "forward throw"). The perception of a change from horizontal to vertical flight is known as the "relative wind", or informally as "being on the hill". In freefall, skydivers generally do not experience a "falling" sensation because the resistance of the air to their body at speeds above about 50 mph (80 km/h) provides some feeling of weight and direction. At normal exit speeds for aircraft (approx 90 mph (140 km/h)) there is little feeling of falling just after exit, but jumping from a balloon or helicopter can create this sensation. Skydivers reach terminal velocity (around 120 mph (190 km/h) for belly to Earth orientations, 150--200 mph (240--320 km/h) for head down orientations) and are no longer accelerating towards the ground. At this point the sensation is as of a forceful wind.
12-way formation with videographer seen in upper-right corner
Jump with Russian flag
Many people make their first jump with an experienced and trained instructor -- this type of skydive may be in the form of a tandem skydive. During the tandem jump the instructor is responsible for emergency procedures in the unlikely event that they will be needed, therefore freeing the student to concentrate on learning to skydive. Other training methods include static line, IAD (Instructor Assisted Deployment), and AFF (Accelerated Free fall) also known as Progressive Free-Fall (PFF) in Canada.