Wing, harness, and instruments
The paraglider wing or canopy is usually what is known in engineering as a ram-air airfoil. Such wings comprise two layers of fabric that are connected to internal supporting material in such a way as to form a row of cells. By leaving most of the cells open only at the leading edge, incoming air keeps the wing inflated, thus maintaining its shape. When inflated, the wing’s cross-section has the typical teardrop aerofoil shape. Modern paraglider wings are made of high-performance non-porous materials such as ripstop nylon.
Structure of paraglidider
In most modern paragliders (from the 1990s onwards), some of the cells of the leading edge are closed to form a cleaner aerodynamic profile. Holes in the internal ribs allow a free flow of air from the open cells to these closed cells to inflate them, and also to the wingtips, which are also closed. Almost all modern paragliders follow a sharknose design of the leading edge, by which the inflation opening is not at the front of the wing, but slightly backwards on the underside of the wing, and following a concave shape. This design, resembling the nose of a shark, increases wing stability and stall resistance. In modern paragliders, semi-flexible rods made out of plastic or nitinol are used to give extra stability to the profile of the wing. In high-performance paragliders, these rods extend through most of the length of the upper wing.
The pilot is supported underneath the wing by a network of suspension lines. These start with two sets of risers made of short (40 cm (16 in)) lengths of strong webbing. Each set is attached to the harness by a carabiner, one on each side of the pilot, and each riser of a set is generally attached to lines from only one row of its side of wing. At the end of each riser of the set, there is a small delta maillon with a number (2–5) of lines attached, forming a fan. These are typically 4–5 m (13–16 ft) long, with the end attached to 2–4 further lines of around 2 m (6.6 ft) m, which are again joined to a group of smaller, thinner lines. In some cases this is repeated for a fourth cascade.
Speed range of paraglider
The top of each line is attached to small fabric loops sewn into the structure of the wing, which are generally arranged in rows running span-wise (i.e., side to side). The row of lines nearest the front are known as the A lines, the next row back the B lines, and so on. A typical wing will have A, B, C and D lines, but recently, there has been a tendency to reduce the rows of lines to three, or even two (and experimentally to one), to reduce drag.
Paraglider lines are usually made from UHMW polythene or aramid. Although they look rather slender, these materials are strong and subject to load testing requirements. For example, a single 0.66 mm-diameter line (about the thinnest used) can have a breaking strength of 56 kgf (550 N).
Paraglider wings typically have an area of 20–35 square metres (220–380 sq ft) with a span of 8–12 metres (26–39 ft) and weigh 3–7 kilograms (6.6–15.4 lb). Combined weight of wing, harness, reserve, instruments, helmet, etc. is around 12–22 kilograms (26–49 lb).
The glide ratio of paragliders ranges from 9.3 for recreational wings to about 11.3 for modern competition models, reaching in some cases up to 13. For comparison, a typical skydiving parachute will achieve about 3:1 glide. A hang glider ranges from 9.5 for recreational wings to about 16.5 for modern competition models. An idling (gliding) Cessna 152 light aircraft will achieve 9:1. Some sailplanes can achieve a glide ratio of up to 72:1.
The speed range of paragliders is typically 22–55 kilometres per hour (14–34 mph), from stall speed to maximum speed. Achieving maximum speed requires the use of speedbar, or trimmers. Without these, and without applying brakes, a paraglider is at its trim speed, which is typically 32–40 kilometres per hour (20–25 mph) and often at the best glide ratio, too. High-performance paragliders meant for competitions may achieve faster accelerated flight, as do speedwings, due to their small size and different profile.
For storage and carrying, the wing is usually folded into a stuffsack (bag), which can then be stowed in a large backpack along with the harness. Some modern harnesses include the ability to turn the harness inside out such that it becomes a backpack, saving weight and space.
Paragliders are unique among human-carrying aircraft in being easily portable. The complete equipment packs into a rucksack and can be carried easily on the pilot’s back, in a car, or on public transport. In comparison with other air sports, this substantially simplifies travel to a suitable takeoff spot, the selection of a landing place and return travel.
Tandem paragliders, designed to carry the pilot and one passenger, are larger but otherwise similar. They usually fly faster with higher trim speeds, are more resistant to collapse, and have a slightly higher sink rate compared to solo paragliders.
The pilot is loosely and comfortably buckled into a harness, which offers support in both the standing and sitting positions. Most harnesses have protectors made out of foam or other materials underneath the seat and behind the back to reduce the impact on failed launches or landings. Modern harnesses are designed to be as comfortable as a lounge chair in the sitting or reclining position. Many harnesses even have an adjustable lumbar support. A reserve parachute is also typically connected to a paragliding harness.
Harnesses also vary according to the need of the pilot, and thereby come in a range of designs, mostly:
- open harnesses, ranging from training harness for beginners to all-round harnesses
- pod harnesses for long-distance cross-country flights
- competition harnesses, which are pod harnesses with the capacity to carry two reserve parachutes
- acro harnesses, a type of open harness, designed for acrobatic paragliding, with the capacity for two or three reserve parachutes
- hike&fly harnesses, which are designed to be lightweight and compact when folded away for hiking
- harnesses for tandem pilots and passangers
- kids tandem harnesses are also now available with special child-proof locks
Expert harness for Cross country flying
Harnesses have a substantial influence on the flying characteristics; for instance, acro harnesses lead to more agile handling, which is desirable for flying acrobatics, but may be unsuitable for beginners or XC pilots looking for more stability in flight. While pod harnesses offer more stability and aerodynamic properties, they increase the risk of riser twist, and are hence not suitable for beginners. The standard harness is an open harness, which features a sitting, slightly reclined body position.
Instruments in paragliding
Most pilots use variometers, radios, and, increasingly, GNSS units when they are flying.Variometer
The main purpose of a variometer is in helping a pilot find and stay in the “core” of a thermal to maximise height gain and, conversely, to indicate when a pilot is in sinking air and needs to find rising air. Humans can sense the acceleration when they first hit a thermal, but cannot detect the difference between constant rising air and constant sinking air. Modern variometers are capable of detecting rates of climb or sink of 1 cm per second. A variometer indicates climb rate (or sink-rate) with short audio signals (beeps, which increase in pitch and tempo during ascent, and a droning sound, which gets deeper as the rate of descent increases) and/or a visual display. It also shows altitude: either above takeoff, above sea level, or (at higher altitudes) flight level.
Various variometer for paragliding and hanggliding
Radio communications are used in training, to communicate with other pilots, and to report where and when they intend to land. These radios normally operate on a range of frequencies in different countries—some authorised, some illegal but tolerated locally. Some local authorities (e.g., flight clubs) offer periodic automated weather updates on these frequencies. In rare cases, pilots use radios to talk to airport control towers or air traffic controllers. Many pilots carry a cell phone so they can call for pickup should they land away from their intended point of destination.
GNSS is a necessary accessory when flying competitions, where it has to be demonstrated that way-points have been correctly passed. The recorded GNSS track of a flight can be used to analyze flying technique or can be shared with other pilots. GNSS is also used to determine drift due to the prevailing wind when flying at altitude, providing position information to allow restricted airspace to be avoided and identifying one’s location for retrieval teams after landing out in unfamiliar territory. GNSS is integrated with some models of variometer. This is not only more convenient, but also allows for a three-dimensional record of the flight. The flight track can be used as proof for record claims, replacing the old method of photo documentation.
Increasingly, smart phones are used as the primary means of navigation and flight logging, with several applications available to assist in air navigation. They are also used to co-ordinate tasks in competitive paragliding and facilitate retrieval of pilots returning to their point of launch. External variometers are typically used to assist in accurate altitude information.
One of GNSS for competition