2006-10-18

[Archive] 滑翔伞材料研究

Colour and Fabrics

We all want our paragliders to stay air tight, have beautiful colors and last a long time. The fabric and paraglider manufacturers consider this and more. Everybody has heard stories of gliders made from bad materials. Some gliders became porous prematurely while others seem to fade with every flight. These problems have been nearly eliminated with the thorough, constant testing of paraglider sailcloth. Textile mills constantly evaluate the fabric for porosity, stretch, weight and aging characteristics. The aging factors break down into color, UV, fatigue, abrasion and humidity resistance.

The choice of fabric is one of the biggest decision's a paraglider designer face. Textile mills supplying the paragliding industry include: Gelvenor, Toray (Edel, Swing, Trekking, XIX), Porcher Marine, and Perserveance (Swing). Sofifly is set to enter the market with Swing using their materials. Porcher Marine dominates the market. Over 70% of all the gliders made use their materials.

GELVENOR - #1 is the best (Aerodyne, Aeros, Airwave, Apco, Nova, Ozone, Sol)

#1 Purple, Dark Green, Red, Dark Blue, White

#2 Yellow, Violet (Light Purple), Turquoise

#3 Orange, Fluorescent Green, Fluorescent Pink, Fluorescent Yellow

PORCHER - 5-6 is the best (Advance, Aerodyne, Airwave, Firebird, FreeX, Gin, Gradient, Independence, ITV, MacPara, Nova, Ozone, Paratech, Perche, Pro Design, Sky, Skywalk, Sol, UP, U-Turn, Windtech, Wings of Change)

(from Porcher Marine)

5-6 Black, Deep Blue, Gold, Sunflower (Yellow), Dragon Red

5 Light Blue, Lhotse (Purple), Red, Grepon (Magenta)

4 White, Parma (Lilac), Orange

3-4 Lagoon (Light Green), Turkis (Turquoise), Grey

2-3 Dark Green

2 Prairie (Fluorescent Green)

1 Fluorescent Yellow

All of these fabric characteristics are interrelated. Improving one characteristic only comes at the expense of another. There is always the need to reach a compromise. For example, a heavier cloth will have better aging characteristics but at the expense of extra weight. The additional weight will cause a glider to have a slower and more dynamic recovery from a collapse. Designers generally use materials weighing 42-46 g/m2. One of the latest trends is for some gliders to incorporate a 36-38 g/m2 material for the bottom surface and cell walls. The lighter material eliminates the extra weight associated with V-rib technology. Some older gliders used a laminated 55 g/m2 mylar fabric on the leading edge and top surface.

Nylon is the most commonly used raw fiber for the manufacture of sailcloth. The properties of nylon include excellent strength, flexibility, abrasion resistance, ease of drying and resistance to attack by insects and microorganisms. Teijin alone uses polyester for their sailcloth. Polyester fabrics are more resistant to shrinking and stretching, dry quicker and less prone to wrinkle and crease. Used properly, both nylon and polyester have their place in paraglider construction. However, just remember that both types of material are very UV sensitive.

Nylon

Polyester (Dacron)

Tensile Strength 72° F @68% R.H.

7.0 grams/ denier

6.0 grams/ denier

Wet Strength

88%

100%

Loop Efficiency

85%

73%

Abrasion Resistance

6.0

2.25

Melting Point

482° F

480° F

Acid Resistance

Fair

Good

Alkali Resistance

Excellent

Fair

Mildew Resistance

Unaffected

Unaffected

Weathering Resistance

Fair

Fair

Elastic Recovery

Superior

Excellent

Flex Life

Excellent

Good

Sunlight (12 months)

Fair

Good

Specific Gravity

1.14

1.38

Elongation - Regular

30-37%

19-23%

Elongation - High Tenacity

21-38%

11-13%

Average Stiffness

0.77

Reg: .78 / H.T.: .50

Average Toughness - Regular

67,000-85,000

81,000-88,000

Average Toughness - High Tenacity

89,000-108,000

106,000-109,000

Moisture Regain

4% @65% R.H.

.4%@65% R.H.

Water Absorbency

8%@95% R.H.

2.5%@95%

A key component of a materials weight is the type of finish. Choices include coating, impregnation or laminated. The finish is subsequently a vital component of porosity. A majority of paraglider materials use either a polyurethane coating (Porcher Marine, Sofifly and Toray), a silicon coating (Perserverance) or both (Gelvenor). This provides the best balance between weight, flexibility and aging. Impregnation is a special type of coating process. Dipping the material in a bath results in coating both sides of the material. Mylar materials are laminated and provide resistance to stretching, absolutely zero porosity and good resistance to aging. However, mylar popularity has declined because of the extra weight and lack of flexibility.

A properly designed glider will use different materials in different areas; heavier, less porous fabrics for the top and maybe the bottom surface such as Porcher Marine 9017 or 9O92 ME or Gelvenor LCN066 OKS; Gelvenor LCN066 K54 or LCN517 K54 are intended for the bottom surface; stiffer, more porous material for the cell walls like Porcher Marine 9017 or 9O92 E29A. It is not unheard of for a glider to use up to five kinds of sailcloth. Manufacturers carefully select each material for optimum performance.

Fabric

Porcher Marine 9017 PU

Type of Finish

Side Coated (Polyurethane)

Yarn

PA 6.6 High Tenacity

Width

158 cm

Pattern

Ripstop

Unit

E38A - Medium

E77A - Water Repellant

E29A - Firm

Coated Fabric's Weight

g/sqm

40 +/-2

40 +/-2

40 +/-2

Tear Strength - Warp*

DaN

1.5 min

1.5 min

1.3 min

Tear Strength - Weft*

DaN

1.5 min

1.5 min

0.7 min

Elongation on Bias 3 lbs

%

8 max

6.5 max

1 max

Elongation on Bias 5 lbs

%

17 max

15 max

2 max

Elongation on Bias 10 lbs

%

28 max

27 max

10 max

Break Strength - Warp

DaN/5cm

38 min

38 min

38 min

Break Strength - Weft

DaN/5cm

33 min

33 min

33 min

Air Porosity**

***

40 max

40 max

100 max

End Uses

PG/Kite

PG/Fly Surf/Kite

PG Ribs/Kite

* ISO 4674 **ISO 9237 ***l/sqm/mn under 2000 Pa

Fabric

Porcher Marine 9092 PU

Type of Finish

Side Coated (Polyurethane)

Yarn

PA 6.6 High Tenacity

Width

158 cm

Pattern

Ripstop

Coated Fabric's Weight

g/sqm

45 +/-3

45 +/-3

45 +/-3

Tear Strength - Warp*

DaN

2 min

2 min

1 min

Tear Strength - Weft*

DaN

1.5 min

1.5 min

0.7 min

Elongation on Bias 3 lbs

%

6.5 max

6.5 max

2 max

Elongation on Bias 5 lbs

%

15 max

15 max

3 max

Elongation on Bias 10 lbs

%

27 max

27 max

10 max

Break Strength - Warp

DaN/5cm

40 min

40 min

40 min

Break Strength - Weft

DaN/5cm

33 min

33 min

33 min

Air Porosity**

***

40 max

40 max

100 max

End Uses

PG/Kite

PG/Fly Surf/Kite

PG Ribs/Kite

* ISO 4674 **ISO 9237 ***l/sqm/mn under 2000 Pa

Carrington

Carrington

Fabric

1080 N

1097/1098 N

Finish

PU

PU

Yarn Type

High Tenacity

Medium Tenacity

Thread Count

50x50

43x42

Weight (g/m2)

44 +/-2

44 +/-2

Tear Strength

40 N

18 N

Tensile Strength

450x410

350x350

Elongation On Bias

13%

25%








Line Attachment points

While all certified paragliders are shock tested to 8 g’s of the maximum recommended wing loading, the line attachment points still remain a critical area of the glider. The most common method is to sew a trapezoid or a semi-circle shaped piece of mylar to the cell wall. The mylar serves three purposes: improve inflation, aid in recovery and provide a stable and reinforced platform. Manufacturers sew a piece of polyester twill tape known as the V-tab onto the mylar platform. Lines attach to the V-tabs on the bottom surface of the glider. This is the method preferred by many companies. There are two variations: one is to use regular sailcloth instead of the mylar. A newer technique is to glue the mylar to the cell wall rather than sew it.

A few companies take another approach. Rather than possibly distort the cell wall with additional stitching, these manufacturers sew the V-tabs only into the bottom surface seam. This method produces a very clean top surface. Despite shock load testing, this method doesn’t appear to be the most durable in the long run.

The most unique method eliminate the V-tabs entirely. The lines are sewn directly to the glider. Folding the end of the line over several times assures that more than a single point of stitching catches each line. The result is a very clean finish on the bottom surface and an associated reduction in drag. However, every broken line requires taking out the seam and carefully sewing it again.

On the other end of the spectrum, another method foregoes the mylar platform and attach the V-tab all the way to the top surface. Pro Design builds all of their gliders with each line attached this way. UP does so only for the "A" and "B" lines since these lines support 80% of the pilot weight. If you have ever seen a picture of the bottom surface of a UP glider you can see where the V-tabs intersect and form a series of X’s along the leading edge.

Line Meterials

There has been quite a bit of discussion lately about the types of lines used in our paragliders: Spectra vs. Kevlar. Since every distributor has their own agenda, I decided to do some research myself. All of the following information is available from textile reference books and paragliding literature.

I am not associated with proponents of either material. My old glider had Dyneema lines, my current glider has aramid and the glider I am considering next uses both.

The terms Kevlar and Aramid are used interchangeably in this article as are Spectra and Dyneema.

KEVLAR & ARAMID

Dupont developed Kevlar in 1965 and introduced it to the market in 1972. Kevlar is an aramid (aromatic polyamide) fiber. Kevlar 49 is used for reinforcing plastic composites in aircraft, sporting goods, etc. Paragliding lines use Kevlar 29. Resin impregnated Kevlar 29 is used in the "bullet proof" applications. However, Kevlar can be easily damaged by abrasive dirt particles. Several coatings or treatments such as Teflon can improve abrasion resistance. Dupont supplies raw Kevlar material to Edelrid, Eulit and FSE. Teijin produces the Technora used by Cousin. Toray uses Twaron from Akzo Nobel.

Advantages

  • Three times the strength of nylon and polyester.
  • Half the weight and volume of nylon.
  • Can with stand high temperatures before losing strength.
  • Heat resistant to 750 degrees F.
  • Flame resistant.
  • Low elongation.
  • Resists most acids.

Disadvantages

  • Poor abrasion resistance.
  • Poor sunlight (UV) resistance.
  • 3-13% strength lose when wet.

SPECTRA, DYNEEMA & HIGH MODULUS DYNEEMA

Spectra is the trade name for a high performance polyethylene (HPPE) fiber manufactured by Allied Signal. Dyneema is manufactured by DSM (Netherlands) and is the same material. Originally introduced in 1985, there are two versions: Spectra 900 and Spectra 1000. The original Spectra 900 has a higher elongation and can not be sewn. The Spectra 1000 was introduced to overcome these drawbacks and is used today for paragliders. The two types of Spectra are the source for the myth "that all Spectra stretches".

Advantages

  • Highest strength-to-weight ratio of any fiber.
  • 40% stronger than Kevlar and four times stronger than nylon.
  • 7 to 20 times the abrasion resistance of Kevlar.
  • Low coefficient of friction.
  • High chemical resistance.
  • Cut/tear resistant.
  • Good UV resistance.
  • Low stretch properties.
  • Low weight/volume.
  • Low moisture absorption.

Disadvantages

  • Begins to lose strength at 230-240 degrees F.
  • Difficult to sew.
  • Can dramatically change length over time.

Kevlar can be distinguished by it's yellowish-beige color. While, Dyneema is always white.

So let's use a manufactures line material characteristics chart to compare lines using two different materials.

Sleeve material

Polyester

Polyester

Core material

Aramid

Dyneema

Diameter in mm

1.3

1.3

Weight per meters (total) g/m2

1.53

1.15

Weight per meters (core) g/m2

0.68

0.46

Weight per meters (sleeve) g/m2

0.85

0.69

Breaking strength min daN

120

130

Effective breaking strength daN

149

152

Single knot breaking strength daN

52

54

Strength after 5000 bending cycles daN

66

132

Elongation at

5 daN in %

0.1

0.1

10 daN in %

0.2

0.2

15 daN in %

0.3

0.3

20 daN in %

0.5

0.5

25 daN in %

0.6

0.6

50 daN in %

1.5

1.1

75 daN in %

2.2

1.6

100 daN in %

2.8

2.2

125 daN in %

NA

2.8

Elongation at max. breaking strength (%)

4.0

3.4

Inevitably, the first reaction is "This information is wrong! Aramid fibers do not stretch. Dyneema does." However, all of the above data is directly from one of the major line manufacturers. This company, along with their competitors, has invested literally thousands if not millions of dollars to develop both types of lines. So why would they have a "hidden agenda" to promote one over the other? If there are any lingering doubts, it is not THAT hard to contact the manufacturers and get the information yourself. Remember without data - it's just another opinion.

So what about the Superaramid and High Modulus Aramid fibers? A quick check of Cousin’s website (www.cousin-trestec.com) shows us that the correct name is Superaram and this is Cousin’s registered tradename for their Technora Aramide lines. While chemically identical to Kevlar and Twaron (aromatic polyamide), Superaram lines have improved UV and acid resistance, better flex characteristics and 30% better abrasion resistance. High Modulus Aramid is Edelrid’s tradename for their modified aramid lines. Despite the popular rumors, neither material is a hybrid of aramid and polyethylene.

The weave, density, sheath and construction (twisting or braiding) of the lines is just as important. Unless you fly a glider with unsheathed Spectra lines, sunlight is a major factor on the aging of the lines. The polyester sheath reacts differently to UV exposure than the lines do themselves. Unlike Kevlar and Spectra, polyester materials will began to shrink when not kept under constant tension. The end result is different for each type of line. Kevlar lines will withstand the shrinkage better because of the stiffer fibers. However, the fibers themselves become more brittle as they counteract the force of the polyester shrinking. Most line shrinking and breaking problems are the result of using different materials for the core and the sheath.

Some companies use both types of lines; Kevlar for the lower set and Spectra for the upper lines. It also not uncommon for a paraglider manufacturer to use lines from more than one supplier; a trend that is also growing with paraglider sailcloth. Different lines and materials are used for each separate model of glider.

So who uses what? Here is a quick summary: Edel uses Cousin and an unknown Korean factory. Sol and UP use Cousin. Advance, FreeX and Windtech use Cousin and Liros. Nova, Skywalk and XIX use Liros. Gin, Ozone and Swing are using Edelrid and Liros. Aerodyne, Airwave, Firebird, Gradient, Independence, Icaro, ITV, MacPara. Paratech, Perche, Pro Design, Sky and Wings of Change use Edelrid exclusively. Trekking and U-Turn use Teijin. I’m not sure about Aeros, Apco, and Pilot’s Right Stuff. Of course, all of these companies are always evaluating new materials and this can change at any time.

Then to confuse us even more, some companies are engaged in a kind of name game. They don’t use the name of the line factory - they use the name of the material or material factory. For example, Technora is the name of the aramid fiber from Teijin that Cousin uses for their line construction. Other companies simply call their lines Aramid. This is the technical name for either Dupont Kevlar, Teijin Technora or Twaron from Akzo Nobel.

Some companies will use different color lines to help with set up while other companies only use lines of the same color. Paraglider designers from the "same color" school believe lines of different colors will age at different rates. It is also cheaper to have an inventory of one or two colors compared to four or five. For safety reasons, different color stabilizer (stabilo) lines are convenient.

In summary, while both types of materials have certain advantages, both Kevlar and Spectra are accepted by the DHV, SHV, AFNOR and now CEN as suitable for paragliding. Considering there is a whole lot more to buying, flying and enjoying your paraglider, the type of line material is of secondary importance.

The important thing to remember is to care for the lines and glider properly. Don't daisy chain Kevlar lines since this abrades the fibers and the damage isn't visible. Protect Spectra lines from excessive heat. Keep your paraglider out of the sun when not in use since both types of material are UV sensitive. Have your paraglider professionally inspected once a year, after each 75 hours of use or whenever you may suspect that a hard whack or sloppy ground handling may have damaged something.

Paraglider material - the history

Recently there have been a number of postings on Internet forums asking about cloth quality, life expectancy and how to tell when your glider is past its sell-by date. Steady technological progress in the 1990s has made it possible for even relatively inexperienced pilots to rack up amounts of airtime that were unthinkable in the mid 1980s when people started hill launching paragliders first started in appreciable numbers.

Back in the late 1980s, technical progress meant that paragliders rarely saw more than two or three seasons, and their performance capped the number of hours one could fly. As the 90s came & went paraglider performance improved in leaps and bounds, to the point where ordinary pilots on intermediate gliders could ride to cloudbase and thus airtime possible for such pilots went up a large magnitude of order. In the early days, there were a number of scares where paraglider material was found to have been inappropriately chosen, or suffered manufacturing defects, but as time went on these types of problems disappeared and the more common occurrence was that the glider just got worn out.

In the search for more durable craft, pilots became more aware of the materials used in the construction of their gliders. During the 1990s we heard names like Carrington, Porcher Marine, Toray, Teijin, Unitika and Gelvenor. A major milestone came when Apco announced that they would guarantee their gliders for 250 hours or 3 years. This was the first long guarantee of any sort, made headlines for both Apco and Gelvenor, the material from which those Apco gliders were made. Apco had concluded that in order to get the cloth they needed their experience and that of the cloth manufacturer had to be combined. They entered into an agreement with Gelvenor to develop a cloth which would be based on paragliding needs as defined by Apco, using Gelvenor's expertise in cloth manufacture. The resulting cloth had a silicon layer over the PU [1] coating most other fabrics used as the final finish. Gelvenor acquired a reputation for longevity and durability. The heat was on.

With diagonal ribbing, and a reduction in the number of suspension points on gliders, the glider manufacturers wanted lighter cloths for undersurfaces, greater tear strength and resistance to elongation. Other long guarantees were instituted to rival Apcos', with back up from the cloth manufacturers. Rather than just using cloth from similar aviation sports, PG manufacturers were now dictating their own requirements. With PG companies selling 500 to 3,000 gliders a year this made a large potential market for the cloth manufacturers, who needed to supply cloth to exact requirements or lose custom to competitors.

Thanks to these advances we are now in a market where a 3-year/300 hour guarantee is the norm. Nova have now once again raised the bar by offering a one year free repair for accidental damage in addition to 3 year/300hours. New materials are being developed, with longer life spans, Swing are about to release details of the extensive testing of the cloth they offer on the Astral 3. Produced by a British company, Perseverance Mills Ltd, from Burnley in Lancashire, the material is a 6.6 filament rip stop nylon with a Silicon/PU coating. A new weave/construction promises weight similar to current cloths but an improved level of tear strength and resistance to elongation. The coating prolongs the life of the material, mostly by increasing resistance to porosity with age.

With the majority of paragliding sales being repeat business to established pilots in the post boom era of the sport, the interests of the pilot and the manufacturer get closer all the time, and the progress in cloth technology is one area with clear benefits for all.

Paraglider Material - The Players

Nylon is the most commonly used raw fibre for the manufacture of sailcloth. The properties of nylon include excellent strength, flexibility, abrasion resistance, ease of drying and resistance to attack by insects and micro-organisms. Teijin alone uses polyester for their sailcloth. Polyester fabrics are more resistant to shrinking and stretching, dry quicker and less prone to wrinkle and crease. Used properly, both nylon and polyester have their place in paraglider construction. However, just remember that both types of material are very UV sensitive.

Here's a brief look at some of the major players in paragliding fabric manufacture.

Carrington Novare [UK]: Carrington are based in Dewsbury, West Yorkshire in the UK. They have been a big player in the field for a long time. However, the profile and direction of their company and its target markets is changing. They issued us with this statement:

Carrington Performance Fabrics (CPF) was purchased from the IPT group in December 2000 by the British Millerain Company. The purchase of CPF and the subsequent incorporation of Millerain's Blake's operation enables The British Millerain group of companies to offer one of the widest range of coating techniques in Europe. Over recent years the paraglider market has become increasingly competitive with the pressure from manufacturers to reduce selling price. In such conditions it has become impossible to recoup the high cost of developing new and improved products. Without a continuing product development programme the ability to service the sector becomes increasingly difficult. CPF has therefore decided that it will no longer actively develop new paraglider fabrics but will continue to offer the existing range of fabrics whilst demand remains. It is with regret that with our long association with the paraglider sector we have had to take this decision, but our development efforts have to be focused on those sectors where a positive return can be obtained from the investment of resources.

Porcher Marine/NCV [France]: French group Porcher Industries is a worldwide leader in textiles for industrial applications, specialising in mechanically and chemically transforming yarn to produce glass, carbon, aramid and synthetic fabrics as well as non-woven and coated fabrics. Founded in 1912 by the SNC PORCHER Frères [brothers], by 1950 the company had started production of textiles for technical applications. Porcher started producing fabrics for spinnakers,gliders and parachutes in the mid 1980s. The Group reached a sales figure of 660 million Euros in 2000, with 4200 employees spread out over 19 industrial sites installed in 5 countries, ensuring the Group has a worldwide commercial presence. Paragliding cloth is made by the sport department of textile division NCV [Nebon Carle-Vassoilles] as well as the other cloths they make for sailing and parachuting, and to a lesser extent ballooning, windsurfing, hang gliding and microlighting. Paragliding cloth is produced in four different weights and with three different coatings. NCV do the whole manufacturing process in house [vertical integration]: preparation, weaving, dyeing and coating. NCV Industries is a fully owned division of the Porcher Industries Group, and produces other products like airbags and fabrics for protective clothing.

Porcher have developed a new water based [as opposed to solvent based] PU coating for their 9092 fabric that seriously reduces the effects of aging on the cloth and helps it retain its visual appearance. This development has come about as a result of EU requirements for reduced solvent use & emission, as well as customer pressure for longevity of both appearance and functionality in the cloth used in paragliding. Some manufacturers like FreeX are already using this new fabric [designated E85A] in their newest gliders. A lighter weight of material is also being developed for use with this coating.

Today, Porcher is one of the biggest players in the production of fabrics for paragliders.

Gelvenor Textiles [South Africa]:

Gelvenor Textiles is a leading global producer of high technology industrial, technical and specialised fabrics. They are also involved in production of specialty apparel for sport and leisurewear, satins and other high performance outerwear fabrics like those used in the protective textiles market and in corporate/school wear.

Gelvenor Textiles (Pty) Ltd was established in 1965 as a weaver and dyer of continuous

filament lining fabrics. In 1967 the company started producing nylon fabrics for the manufacture of parachutes and other military fabrics, mainly for the Defense Force. Textured polyester weaving started in 1968 and by 1970 Gelvenor were producing a wide range of industrial base fabrics for PVC coating, woven from high tenacity Polyester yarn. The late 1980's and early 1990's saw the transformation of the business away from finished commodity products to concentrate on fabric engineering and designing fabrics for specific niche market applications.

Gelvenor's OL-KS fabric range is manufactured from HT nylon 6.6 in a double-ripstop fabric base, which is coated with silicone, and polyurethane based compounds. This finish gives the fabrics a fuller, firmer and crisper handle to allow for easier inflation of the glider without sacrificing tear strength. The finish is an extremely durable and hard wearing polymer coating which gives zero air-permeability and sufficient fabric rigidity for good aerofoil maintenance. To give added protection against ultra-violet light and dirt adherence, the fabric is further treated on both sides with UV inhibitor and soil release agents. The company is involved in continuing research into new polymer coatings for a lighter weight glider fabric as well as alternative fabrics for bottom skins and ribs.

Perseverance Mills:

Perseverance have returned to the PG market after some time away from it with a new, exclusive contract with Swing for the top surface material of the new Astral 3. They also manufacture cloths for most outdoor garments and are very active in the promotion and sponsorship of outdoor activity sports that use the products they supply cloth for. They supply a number of parachute manufacturers like Parachutes de France with cloth.

Perseverance Mills Ltd was founded in 1901 as a weaver of specialist fabrics for balloons and typewriter ribbons. Since that time the company has become a world leader in specialist leader in specialist lightweight fabrics using man made yarns for the parachute, medical, and outdoor sports industries. As a vertically integrated manufacturer Perseverance Mills has complete quality control, not only over the weaving of fabrics but also the dyeing and finishing, ensuring that their products are fit for use in the most demanding environments.

The new cloth for PG is a 6.6 filament rip stop nylon with a Silicon PU coating. It is the same weight as other cloths commonly used in paragliding which do not have the same coating. This cloth has been developed in the last two years in partnership with Swing, with whom Perseverance have an exclusive contract for the supply of the cloth.

Toray:

Toray Industries is the largest fibre and textile manufacturer in Asia. The Toray Group factories are located in Japan, Malaysia, Thailand, Indonesia, China, and The Czech Republic. Their range of textile fabrics includes active sportswear, polyester & nylon taffetas and other linings. They also handle other kinds of fabrics such as polyester/cotton, casual/sportswear fabrics and specialised applications like paragliding.

The cloth Toray produce is also nylon based, with a PU coating. Some grades are water repellent, but not water-resistant.

Toray is currently increasing its textile production overseas as well as focusing on producing more "cutting edge" fabrics such as high performance textiles from Japan.

This isn't an exhaustive list. It just gives you an idea of where your cloth comes from. With the maturity of the sport and the pace of development, expect market shares to change and new fabrics to move the goalposts.

Reserve Parachute Comparison

Model

Maximum Weight

Surface m2

Sink Rate

Weight

Certification

Price

Apco

Mayday 16

<106>

23

6.3

4 lbs 1 oz

DHV

$415

Mayday 18

<120>

30

5.6

4 lbs 14 oz

SHV

$455

Mayday 20

<160>

37

5.6

5 lbs 15 oz

AFNOR

$515

Tandem

<200>

47

5.6

7 lbs 2 oz

AFNOR

$615

High Energy

QS 330

<150>

31

5.45

4 lbs 4 oz

NO

$575

QS 440

<200>

41

5.45

5 lbs 4 oz

NO

$625

QS 550

<250>

51

5.45

6 lbs 12 oz

NO

$675

Metamorfosi

Conar 16

64-109 kgs

22

4.43-5.78

3 lbs 11 oz

AFNOR

$650

Conar 18

81-138 kgs

28

4.43-5.78

4 lbs 7 oz

AFNOR

$750

Conar 20

100-170 kgs

35

4.43-5.78

5 lbs 11 oz

AFNOR

$800

Conar 22

121-206 kgs

42

4.43-5.78

6 lbs 14 oz

AFNOR

$950

Sol

33 PDA

60-100 kgs

33

4.91

4 lbs 3 oz

AFNOR

$530

37 PDA

81-138 kgs

37

4.3

5 lbs 5 oz

AFNOR

$530

36 CD

75-125 kgs

36

4.22

5 lbs 13 oz

AFNOR

$580

40 CD

90-145 kgs

40

3.98

6 lbs 7 oz

AFNOR

$580

64 CD

140-210 kgs

64

5.0

10 lbs 13 oz

AFNOR

$680

Sup'Air

Small

60-80 kgs

23.1

4.8

4 lbs 4 oz

AFNOR

$600

Medium

80-110 kgs

30

4.4

4 lbs 13 oz

AFNOR

$600

Large

100-140 kgs

37.8

5 lbs 12 oz

AFNOR

$600

Tandem

120-200 kgs

51.6

4.9

7 lbs 11 oz

AFNOR

$800

All specifications are subject to change at any time.

Risers

All paraglider use polyester or pre-stretched nylon webbing for the risers. Stretchy risers mean a glider will not stay in trim and could result in disaster.

The risers can be assembled with a series straight stitches, a series of bar tacks or with a box stitch. Straight stitching is the simplest method since no special machinery is required. Bar tacking is very strong but stresses the material at a single point or over a limited area. Box stitching is probably the best compromise when properly done. The stitching is spread over a larger area than the other two methods. A good manufacturer will use a computerized sewing machine to guarantee consistent results for each riser.

Beyond strength, there are a couple of small things a company can do to make the product more user friendly. Individually colored risers are an added bonus for quick sorting. They are also handy for quick identification of which riser to grab for big ears, "B" line stalls and killing the glider on the ground ("C" or "D" risers).

To attach your speed bar, the best method uses matching Brummel hooks on both ends of the system. The hooks are small pieces of metal with a hole and a slot that allows two hooks to mate without catching on anything else. Brummel hooks are also handy for attaching the risers to each other after flying.

A less convenient method relies on small quick links that screw together each time and are easy to lose. Under no circumstances should a system rely on miniature snap links or small carabiners. A line can cross the gate and snag. It has and will happen again until pilots quit using them.

Quick link keepers

Quick link keepers are easy to initially ignore. They are just little pieces of plastic that keep the lines sorted and the quick links closed. My friend tells a story about flying in Grindelwald when he sees another pilot with one hand on a riser and the other hand clutching his harness. It turns out that one of his quick links unscrewed itself and started stretching and separating under the load. One hand was actually covering the open quick link and lines. The other hand was on his reserve handle!

The most effective quick link keepers are the ones that actually fit inside the links. They are easy to remove, keep the lines bunched at the top and keep the gate from loosening. Advance, Airea, Edel, Gin, ITV, Pro Design like to use these little pieces of plastic to help keep us connected to our gliders.

Other companies use a small O-shaped ring twisted into a figure-eight and slipped onto the quick link. The idea is for the ring to keep the lines from sliding around. However, it does nothing for keeping the gate closed and they are easy to wear off.

A heat-shrink plastic sheath that covered the entire quick link was popular in the past. They are great until you have to replace a line and cut the thing off. Then you have nothing.

Paragliding Stitching

Blown Glider 1

Blown Glider 2

The inside of a glider slammed against the ground too hard.

This area is pretty straight forward. No manufacturer or the pilot wants to have their wing blow up in mid-air! All load bearing seams require double stitching for strength and durability. Fortunately, all manufacturers do this. Some companies go the extra length to triple and quadruple stitch the seams. For non-load bearing seams such as the partial ribs used on gliders, a single line of stitching is appropriate. There is no structural need to double stitch the seam and add unnecessary costs to produce the glider.

Most early paraglider manufacturers used one row of straight stitching and another row of zigzag stitching side by side. A zigzag stitch has more give and is less subject to breakage. Thread consumption is higher since the stitches lie diagonally across the fabric. The stress is not on a single line but apportioned across the span. Advance is an example of company that still believes in a straight stitch and a zigzag stitch for all seams. This maybe why they are also some of the most expensive gliders on the market. Other companies use a zigzag stitch selectively on line attach points and associated areas.

Bar tacks are a type of zigzag stitch. While perceived as being very strong (they are), bar tacks also have the disadvantage of creating many needle holes and concentrating the stress in one area. Manufacturers only use small bar tacks to reinforce the most critical areas. Mylar panels on the leading edge is one particular area.

Regardless of the type of stitching used, all seams should be even in length and thread tension. Incorrectly sewn gliders will have seams where the thread is loose or there is puckering of the material on one side but not the other. The large logos and color blocking on the top and bottom surfaces of many gliders can serve a hidden purpose. It is even better if the design covers the entire span. If all the panels are lined up correctly and sewn with the correct thread tension, everything should match within a tiny fraction of an inch. This is a very easy way to check the quality of construction.

Some common thread sizes and specifications used in paragliding equipment:

Size

#

Tensile Strength

Uses

B

46

5.5 lbs / 2.5 kg

Lightweight paraglider construction.

E

69

8.5 lbs / 4 kg

Standard paraglider construction.

F

92

11 lbs / 5 kg

Backpacks and accessories.

FF

207

16 lbs / 7.25 kg

Risers

3 cord

207

24 lbs / 11 kg

Harnesses

5 cord

346

40 lbs / 19 kg

Acro harnesses and high stress areas.

6 cord

415

50 lbs / 23 kg

Acro harnesses and high stress areas.

Trailing Edge

There are essentially two options at this point of construction: taped or hemmed. A taped trailing edge is finished by a piece of polyester tape binding the full length of the glider. For durability, a manufacturer will double or zigzag stitch the tape. The seam allowances should also be consistent from edge to edge along the tape for the entire length. Taped trailing edges are the least expensive to produce while also being the easiest to repair.

Hemmed trailing edges are generally stronger and more complicated to produce than taped trailing edges. They are also more expensive. Folding the trailing edge over on to itself twice hides the raw edge of the fabric. Sewing the hemmed edge flush with the bottom surface of the glider finishes the seam. Some companies will use a reinforcing tape inserted into the fold to stabilize the seam and for additional strength. The sewing machine operator has to be extra careful at this stage since the elliptical shape of gliders can cause the fold to occur on a diagonal to the material bias. Sloppy workmanship at this point will result in an unsightly trailing edge.

Nova has started to internally fold the material on the trailing edge. The finished product has no external fold on the bottom surface and produces the cleanest separation of air at the rear of the glider. There is also no edge to catch on debris when launching. As usual, this method does not come without additional cost and complication.

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