Dacron® , Mylar® and General Sailcloth Information

With respect to sail materials, the term Dacron® is commonly used to refer to a woven cloth made of polyester fibers. More correctly, Dacron® is a registered trademark of DuPont, and refers specifically to a DuPont developed polyester fiber.

In a similar manner, with respect to sail materials, the term Mylar® is commonly used to refer to a polyester film, and, again, Mylar® is a registered trademark of DuPont, and refers specifically to a DuPont developed polyester film.

There are basically two types of sail materials used in hang glider sails - woven polyester fabrics and composite laminated fabrics that use some combination of polyester film and polyester reinforcing fibers. Wills Wing uses premium fabrics made by Dimension-Polyant, widely recognized as the leading sail cloth manufacturer in the world.

V170 4.0 Ounce Woven Polyester Fabric

This is the most basic, commonly used sailcloth. It forms essentially the entire sail on gliders like the Falcon and the Eagle, and is typically used in the bottom surface and mid-chord top surface of other model gliders. It comes in white and in colors, and it is a very tight weave of small diameter polyester fibers, which is subsequently "stabilized" by the hot-press impregnation of a polyester resin. The purpose of the resin impregnation is to provide "dimensional stability" which is the resistance to distortion or stretch of the material along the "bias" - in other words, at some angle to the two perpendicular directions of the threads that form the weave. This resistance to bias stretch is important in maintaining the aerodynamic shape originally designed into the sail, when the sail is placed under varying loads. The material is relatively light in weight, moderately elastic, and has good durability. It provides the best combination of light weight and durability in a sail with the best overall handling qualities.

Try the Glider Color Selector to see colors and sail patterns.

205MT and 240MT

These are two heavier woven fabrics, which utilize a ripstop pattern of larger diameter fibers woven into the regular cloth. These materials come in white only, and are typically used on the trailing edge of higher performance gliders, or other gliders where the trailing edge is subject to higher loads. 205 MT, which has a weight of 4.9 ounces per sailmaker's yard, is the standard trailing edge fabric on the T2and U2. 240 MT, which has a weight of 5.7 ounces per sailmaker's yard, is the standard trailing edge fabric on the Falcon Tandem. These fabrics provide greater durability and increased resistance to stretch under heavier loads, allowing for better control of spanwise twist on high performance gliders.

HYDRA-NET® 200

Hydra-net® is a trademark of Dimension-Polyant, and refers to a tightly woven high tenacity fabric with an integrated ripstop pattern of Spectra® fibers. The use of these Spectra® reinforcing fibers in a relatively light-weight cloth provides the structural performance and durability of a heavier cloth with the superior handling of a lighter weight material. Hydra-net 200 comes in white only, and is an upgrade option for the trailing edge panel or leading edge panel on the T2and U2.

PX & PM Polyester X-Ply Laminates

These are two types (with several subtypes) of what are commonly called "Mylar®" sailcloth. They are not available in colors, and will be either "mostly clear" or white depending on cloth construction. Laminated sail materials using polyester film have been used for many years in hang glider sails. The original inspiration for the use of these fabrics was an attempt to achieve superior performance by using a lower stretch material that was still relatively light in weight. In high performance hang gliders, limiting spanwise twist is a key component of performance, and twist is generally controlled by sail tension. The disadvantages of the polyester film fabrics have been that the reduced elasticity under load has generally resulted in "stiffer," less responsive handling qualities, and that the polyester laminated fabrics have been, historically, not as durable or long lasting as woven fabrics. The current generation of laminated fabrics are vastly improved over those of even ten years ago, however it is still generally the case that a premium woven fabric will outlast even the best laminated materials.

The PM Laminates are a three layer laminate in which two outer layers of polyester film sandwich an inner layer of scrim (open net of polyester fibers).

The PX Laminates are a four layer laminate in which a 6 degree X-ply layer of black polyester yarns is added in between the polyester film layers.

PX10

PX10T, Black Xply® version with taffeta backing, shown for clarity. The laminates without taffeta are somewhat transparent, and the 'PM' types do not have the Xply layer.

Polyester X-Ply® Laminate construction. The PM series cloths are made without the X-Ply layer, and the PM--T cloths feature a layer of Taffeta fabric, for durability, ouside of and behind the film sandwich.

In either type, a thin, lightweight layer of taffeta may be bonded to one side, on the outside of the film sandwich, for added durability. These variants are designated with the addition of a "T," as in PM05T, or PX10T.

UVM10T - NEW!

Falcons and Sport 2s

Falcon and Sport 2 sails (excluding the Falcon Tandem) are normally made entirely with V170 4.0 ounce w fabric, for light weight, good durability, and optimum handling. The only sail cloth material option in the Falcon line is the option for PX05 in the #3 and #4 panels on a Falcon 3 170 or Falcon 3 195. In the Sport 2 line, as of January 2008, you may select 205 MT or Hydranet 200 in either the top surface leading edge panel (#1) or trailing edge panel (#4) or both. You may also select either PX10T or UVM10T in the top surface leading edge panel (#1). The upgrade from the normal V170 to 205 MT or PX10T costs $75 per panel, and an additional upgrade to either premium fabric (Hydranet or UVM10T) adds an additional $75 per panel upgraded. For example, an upgrade to UVM10T on panel #1 and Hydranet on Panel #4, would add $300 to the total price. With regard to color choice options, the top surface leading edge (#1) and bottom surface (#5 on the Falcon, #5 and #6 on the Sport 2) are normally made with either colored or white V170 material, and you can select your own colors for these panels when you elect the "Customer choice of colors" upgrade. If you upgrade to any of the premium cloth options, there are no color choices for those panels.

Falcon Tandem

All of the above paragraph applies to the Falcon Tandem except that the #4 trailing edge panel is always made from 240 MT and therefore is only available in white.

T2s and U2s

The T2 and U2 come standard with PX10T in the top surface leading edge panel, 205 MT in the trailing edge panel, and V170 4.0 ounce in the top surface midchord (#3) and bottom surface panels (#5, #6). The bottom surface panels are normally available for color choice when you elect the "Customer choice of colors" upgrade. It is also possible to have color in the top surface midchord (#3) panel, for an additional charge.

Hydra-Net 200 is an extra cost upgrade option for the trailing edge panel of either a T2 or U2. Hydra-Net 200 and 205 MT are, in our experience, essentially equivalent with respect to performance and handling when used in the trailing edge panel of the U2. Hydranet is just slightly lighter at 4.7 vs 4.9 ounces, and has a slightly softer "hand."

An additional option on the T2 and U2 is to select a woven material - such as Hydra-Net 200 (extra cost), 205 MT (no extra cost) for use on the top surface leading edge panel. The advantages of using a woven material here include the superior durability of woven cloth, and the fact that the glider's performance is less likely to suffer significant degradation if flown in the rain. A sail made with a leading edge using woven material will last about twice as long as one made with a "Mylar®" leading edge. In the rain, water droplets tend to bead up on the slick surface of a laminated cloth - polyester film leading edge, which disrupts the smooth airflow and leads to an increased stall speed. This effect varies from glider model to glider model, but in the worst cases it can cause the stall speed to increase above 30 mph, making landing in light winds difficult and even dangerous. A disadvantage of the woven material leading edge is that it will more easily become stained by dirt, and is more difficult to clean.

On the T2 and U2 you can upgrade the leading edge panel (#1) to UVM10T fabric for an additional charge.

On theT2 only, you can also upgrade the midchord and trailing edge panels (#3 and #4) to Mylar® fabric for an additional charge. (with PX10T it is referred to as the "Mylar®" sail upgrade, with UVM10T it is referred to as the UVM10T complete sail upgrade). This is the typical sail configuration for competition pilots. Mylar® upgrade sails will feature PX10T in the leading and trailing edge (#1 and #4 panel) and PX05T in the midchord. The UVM10T complete sail upgrade features UVM10T in panels #1, #3, and #4. The flight qualities and durability of the woven materials are generally superior to those of the laminates, so if you are not competing we recommend that you stay with the standard woven materials in this application.

Note On Visibility Issues with The UVM10T Complete Sail Upgrade

The UVM material is only available in one color - which is a sort of gray/green. One disadvantage to this color is that it tends to disappear against a background of trees or brush. Consequently, a glider which has a full top surface of UVM can be very difficult to see against such a background if you are at the same altitude or slightly above it. Pilots flying with gliders that have full UVM top surfaces should be especially vigilant, and recognize that these gliders will be more difficult to see. Pilots flying gliders with full UVM top surfaces must also be especially vigilant, and recognize that other pilots may have more difficulty seeing you, so you will bear a greater responsibility to "see and avoid."

Pilots have asked about modifications or alternate options to make gliders with UVM top surfaces more easily visible. One idea that has been suggested that doesn't really work is to make the leading edge out of normal PX10T (white) material, and make the rest of the top surface out of UVM. This will certainly increase visibility, but it also negates the value of the UVM material. The sail will only last as long as the shortest lived component - so the longer service life of the UVM on the rear portion of the sail will be of no benefit after the shorter lived PX10T degrades due to UV exposure.

One thing we are happy to do on request on new glider orders, for no extra charge, is to offer a contrasting nose cone in some more visible color. Since the nose cone can easily be replaced, it doesn't matter if it deteriorates before the remainder of the sail. Pilots who already own gliders with the full UVM top surfaces can, if they wish to, replace their nose cones with something more visible.

We don't recommend applying stickers to the leading edge as a solution, as we have found in the past that even the very slight disruption in airflow that can occur due a a slightly raised edge on an applied sticker can cause a noticeable premature stall and stall hysteresis on a high performance glider.

See Also: Sailcloth Options Article by Steven Pearson

NOTE: Sailcloth images shown with dark backgrounds to show fiber details.

Last Modified: 12 June, 2008