Fly the finest fabric - Fly Kubicek Polyester
Why you should consider changing to a polyester balloon
There are two basic fabrics from which balloon envelopes are manufactured. The choice is either nylon or polyester.
In Europe we are most familiar with nylon because it is the material that both Carrington and
Luckenhaus make and these two companies provide the fabric for most of the European balloon manufacturers.
American balloonists are more familiar with the choice between nylon and polyester because at least two
American manufacturers use polyester.
Now that you can chose to fly a Kubicek envelope that is made from polyester it is time to look at the advantages
and disadvantages of the two fabrics. In our opinion polyester is the better balloon fabric, but you must make
up your own mind. Let's look at some basic facts.
Fabric properties
Nylon was first made in 1938 and its technical name is polyamide. Nylon absorbs energy well and it is elastic
and extensible and has a high resistance to tearing under shock loads. Because of these excellent properties
it is used extensively in the production of ropes, tyre cords and parachutes.
When European balloons were first manufactured, in England in the seventies, this fabric, probably because it
was already used extensively for parachutes, was used for the production of the first balloons. Unfortunately
nylon has a number of disadvantage, the greatest of which is that it is easily damaged by hydrolysis - it tends
to absorb water, attract micro-organisms and, as a result, decay. This decay often continues even when the
envelope is stored in its bag. Although modern coatings have reduced this susceptibility they have not removed
it. To disguise the poorer properties of some of these fabrics you may be offered a heavier nylon fabric for the
top of a nylon balloon.
Polyester was developed in 1941 and one of the best known brand names is Dacron. Polyester, when compared
with nylon, has a higher UV resistance, higher reversible deformation and it is less susceptible to damage by
micro-organisms. Polyester offers higher durability (life cycle), higher heat resistance, higher stability to UV
radiation and other weather conditions. Although Polyester is an ideal fabric for balloon envelopes it is more
difficult to dye and this has tended to deter most balloon manufacturers.
Coating
In addition to the chemical structure of the fibre the coatings applied to it and the way that the surface is finished will all effect the quality and the life
of the fabric. Coatings can be used to fix the colours, to increase impermeability (air-tightness), to reduce microbiological action and to slow the decay
of the fabric by reducing hydrolysis. The most frequently used coatings are polyurethane, acrylic and silicone. These coatings can be used individually or
as a mixture on both nylon and polyester fabric.
Coating thickness can be varied and a number
of different coatings may be applied.
We are often asked why Kubicek is the only
balloon manufacturer to use white demonstrators.
The answer is simple; our fabric is coated and
finished in a way designed to throw off dirt.
Kubicek Polyester is designed to stay brighter
for longer.
Heat degradation
Synthetic fabrics degrade gradually when they
are exposed to heat. As an example of the difference
between nylon and polyester, the Celanese
Fibres company presented a comparison of fabric
tensile strengths to the Industrial Fabric
Association International. In this study it was
shown that, after 500 hours of exposure to a continual 'dry temperature' of 149°C, the fabric made from nylon had degraded to 32 % of its original strength,
whereas the same fabric made from polyester retained 84 % of its initial strength. The same values measured over 1000 hours at the same temperature
were even more dramatic: nylon was down to 8 % of its original strength whilst polyester had retained 47 % of the original strength.
The durability (life cycle) of the polyester fabric is significantly higher than the life of a nylon fabric at comparable temperatures.
Because polyester fabrics stand up well to high temperatures the manufacturers who uses this fabric have the option of asking for their balloons to be
certified to fly at higher envelope temperatures than balloons made of nylon fabric. For example FireFly balloons are certified at to 149°C against an
'European standard' of around 121°C. This is a road that Kubicek has chosen not to take, preferring instead to certify its envelopes for 124°C, closer to
the temperatures adopted by European balloon manufacturers. By accepting this lower temperature the fabric will last longer.
Kubicek fabric
Since 1984 Kubicek has woven its own fabric. The looms that Kubicek own could produce either nylon or polyester fabric at similar costs, but the obvious choice was polyester. Kubicek's first fabric, called 'Urge' was used until 1997; it showed excellent laboratory results and lasted well. One of the oldest airworthiness envelope with 670 flight hours (autumn 2002) still flies in Vienna, Austria, pilot F-J. Rohrer. It's greate feature and tolerance of overheating was shown when 'Flower Power' balloon had set an altitude record during which it had been flown at a fairly constant 200°C and the fabric remain airworthy for many following years. In 1997 the weave density of the fabric was increased and the tensile strength increased to give yet longer life. This new fabric 'Kubicek Polyester' is expected to give even longer life than the excellent fabric that it replaces.
Leaflet about Kubicek Polyester [pdf document, 679 kB]
