About skydiving

Skydiving: meaning, development, history, the present day

The Czech word for skydiving, parašutismus, comes from the French „para“, which means to protect or shield, and „chute“, which means fall. In English it is „skydiving“, a modern adrenaline sport from the family of air sports. It consists of free fall followed by flight under an open parachute and a landing. The history of skydiving The first attempts to slow down a free fall and survive it are connected with the invention of the hot-air balloon.

In practical terms, successful attempts date from the period at the beginning of the 20th century. The practical demand for a usable parachute grew stronger the moment powered flight spread in the 1920s. In that period the Slovak inventor Štefan Banič had his modified parachute design patented, U.S. Patent number 1,108,484.

After the Second World War, when skydiving became a common tool for rescuing shot-down airmen as well as a means of delivering supplies or troops behind enemy lines. Thanks to discharged military paratroopers, who had grown fond of the activity in the army, skydiving became a civilian sport. Today skydiving is practised all over the world. The professional use of skydiving is mainly in the army. Sport skydiving has seen a further boom.

It is widespread in economically developed countries, where purchasing power makes it possible to cover the high cost of running it. In recent years the popularity of what are known as tandem skydives has increased; almost anyone can make one with minimal preparation. The jump works in such a way that the "passenger" is attached by a special harness to an experienced skydiver — the "pilot" — who controls the jump. The price of jumps starts at 4,500 CZK (approx. €184). People interested in jumping go through basic training (approx.

10 hours). The jumps then take place first on parachutes with automatic opening, or by the AFF method (Accelerated Free Fall), where even the first jumps are made from an altitude of up to 4,000 m and two experienced instructors jump with the student, watching the jump and guiding the student. On the first jumps they even hold the student the whole time and, if needed, open the parachute for them.

A description of the jump On a jump the skydiver is equipped with a parachute assembly, which consists of a main and a reserve parachute, a harness and a safety device. The main parachute is usually of the ram-air type, and the reserve parachute is often of the ram-air type as well (on student assemblies it may also be round). The skydiver's equipment also includes a clearly legible altimeter, a helmet, a knife (for cutting free of tangled parachute lines) and sturdy ankle boots.

The drop takes place at altitudes from 700 up to 4,000 m above ground level. Jumps from higher altitudes require special equipment (oxygen masks, for example). The exit from the aircraft The aircraft flies into a designated area, mostly in the vicinity of the airfield, and at the designated drop altitude slows down to 250 to 120 km/h to make leaving the aircraft easier. After the exit comes free fall, which lasts until the parachute opens.

In the first seconds after the exit the inertial speed prevails, and only then does gravity take over. Stabilising the body in the air is achieved by arching strongly backwards. For a stable fall the symmetry of the body is the most important thing. It is possible to fall in a wide variety of positions. The basic and most important position in free fall is what is known as the "belly position" (as if lying face down). It is the basic position used in training.

The parachute has to be opened from this position, as that avoids contact between the skydiver's body and the straps and lines of the opening parachute. This position is used in disciplines such as RW or in large formations. In the "Free Fly" discipline it is possible to fall sitting, head down or feet first. In the "Free Style" discipline absolutely anything is then possible.

Depending on the drop altitude, the body position and the opening altitude, the resulting fall speed ranges from 180 to 300 km/h and the free fall can last up to a minute. The opening of the parachute The main parachute can be opened in several ways. Most often a small pilot chute is used first to release the closing pin of the harness. The parachute container is then pulled out of it, and the lines gradually unwind from the container.

Once the whole length of the parachute lines is deployed, the container opens and what is known as the canopy (the upper fabric part of the parachute) is pulled out. The parachute then unfolds and gradually inflates with air. Once the „slider“ (a small square piece of fabric) has run down to the skydiver's straps, it is fully ready for the flight itself. The parachute opens gradually, so that the fall speed is slowed smoothly. Sport parachutes open within a few seconds, with a loss of altitude of around 150 to 300 metres.

The opening altitude of the parachute If the parachute is opened at an altitude of around 14,000 feet (approx. 4.2 km) or higher, there is a danger that, because of the low air resistance at those altitudes, it will not open fully and will then stay „deflated“ for the whole of the fall. That is why parachutes are opened at a much lower altitude (roughly a quarter of that), that is around 1,000 m above the ground. In the event of a fault on the main parachute, that gives enough time to assess the situation and deal with it.

If the fault that has arisen cannot be remedied, the situation is dealt with by cutting away the main parachute and then opening the reserve parachute. This is where skydiving differs from paragliding, where the reserve parachute is opened next to the main canopy. Cutting away the main parachute is possible down to an altitude of roughly 300 to 500 m above the ground. After that it is definitely not recommended! The landing For the landing the skydiver chooses suitable open ground with a clear view.

Obstacles have to be avoided (high-voltage power lines, buildings, trees, roads and so on). These are dangerous not only for the landing itself but also because of possible turbulence (eddies of air). Eddies in such surroundings arise from the uneven heating and the flow of warm air. A few metres above the ground, turbulence like that can make a landing very unpleasant, and it can even be dangerous.

Before jumping over unfamiliar terrain it is a good idea to find out about the places that could be dangerous. As a rule you land into the wind, which slows down what is known as the parachute's forward speed relative to the ground. To determine the strength and direction of the wind, windsocks are therefore placed at the landing areas. At an altitude of about 5 m the skydiver starts to brake slowly and smoothly — to flare the parachute — by pulling down the steering lines. That changes the profile of the parachute and increases the lift.

The landing is made on a braked parachute, with the descent speed and the forward speed of a ram-air parachute reduced to zero. An experienced skydiver can land very precisely. This is used in the sporting discipline of accuracy landing. Safety Today's parachute assemblies already meet demanding international standards for the safety and reliability of the materials and the construction used. The statistical probability of a fault on a parachute is in the per mille range (one thousandth).

Most injuries happen through pilot error, by overestimating one's own abilities or underestimating the surrounding conditions, mainly the wind conditions or the weather and so on. Most of today's parachute assemblies are fitted with a safety device designated AAD (Automatic Activation Device). This device monitors the current altitude and the rate of descent in case it has to assess a critical situation according to the selected mode — student, expert, swoop and so on.

That mode opens the reserve parachute automatically.