Kubicek Balloons is the only balloon company in the world who produces its own fabric; in fact it also invented this unique fabric for use in hot air balloons. Fabric is the most important part of a balloon envelope and having control of production means that we know precisely what will go into your envelope. Like all products our fabric is constantly being developed to improve the life, strength and brightness of our balloons. The latest version of our fabric is called Kubicek Polyester.
Polyester vs. Nylon (Polyamide)
When buying a new balloon, one of the basic decisions that you have to make is what fabric goes into the envelope. Just as fixed-wing pilots face the decision between dural or composites, our customers have to choose whether to buy a Polyester or Nylon (Polyamide) envelope. Although our recommendation would always be polyester, the client makes the final decision. Let’s take a look, and see why most of our balloons are made of polyester.
You can read more about the basic characteristics of Nylon, Polyester, and its comparison here. However please bear in mind that the thread (either Polyester or Nylon) is just one part of the story – although a very important one. In our opinion and experience the best fabric to build hot air balloons from is Polyester.
Balloon fabric is composed of two elementary components - the fiber itself and the coating. Some characteristics of the balloon fabric come from the fiber, some from the coating. Usually it is a combination of both. So let’s take a look at the pros and cons of a balloon fabric based on either Polyester and Nylon, not just the simple difference between Polyester and Nylon itself.
Please note: There are a lot of manufacturers of Nylon fabric used in hot-air balloons, some of the major companies are: Mayer Mayor, Coating Application, Lückenhaus, Gelvenor, Porcher and The British Millerain. Each manufacturer’s fabric has its own characteristics. For this comparison we will use an average fabric.
The Main Features of Polyester Balloon Fabric
High Temperature Tolerance
Polyester fabric is, in general, more resistant against overheating. When subjected to high temperatures it degrades very slowly and there is no risk of an immediate decrease in strength.
Lifetime and Temperature Endurance
Long lifetime cycle is the main reason for choosing Polyester fiber. In practice no polyester balloon flown correctly lasts less than 500 flight hours and many are still flying with more than 1,000 flight hours. This is the reason why we are happy to offer a standard warranty, on our Kubicek Polyester fabric, of at least 300-flight hours (400-flight hours for certain destinations) - talk to our sales representative for the warranty in your specific area.
In Polyester Fabrics Air Permeability Does Not Affect the Strength of the Fabric
Nylon fiber needs to be protected from moisture, because moisture allows the growth of microorganisms leading to increased permeability and a decrease in the fabric’s strength. A side effect is the distinctive odour of a Nylon balloon that has been packed damp and where the growth of these microorganisms has started.
Polyester fabric is more immune to moisture (hydrolysis) - you can leave your wet envelope packed for a lot longer period without losing any strength and without the smell that we have mentioned above. If Polyester fabric becomes more permeable then this may produce a slightly higher propane consumption, but this is not a flight safety issue.
It is more difficult to dye Polyester fabric than Nylon fabric, however it is worth the effort because Polyester has a slower colour tone decrease. The end result with Polyester is that the fabric starts bright and shiney and holds its colours through the years. Isn‘t this what we have always been looking for?
What is the maximum temperature that a balloon fabric can stand without failing?
It is difficult to give a precise figure, but 2 practical examples may help. Please note, we are not suggesting that you ever exceeding the limits set out in your balloon‘s Flight Manual!
- “Flower Power” balloon: piloted by Joschi Starkbaum, while setting a new world artitude record, the temperature inside the envelope exceeded an unbelievable 200°C (392°F). Despite this serious overheating, the balloon remained airworthy for several more seasons.
- “La Bonita” balloon: during a high-altitude flight the temperature exceeded to 175°C (347°F). The envelope was so hot that the pulley close to the parachute melted, however the fabric was undamaged and the balloon landed safely.
Both of these statements are supported by laboratory examinations of fabric samples from the balloons.
Why do Polyester balloons need bigger bags?
Coated Polyester fabric bends less than Nylon. That’s why the packed balloon takes a little more space - you simply can’t fold the balloon so easily. This does not mean it is more difficult to pack the balloon. Once packed it is much easier to move a polyester envelope around because it’s more solid.
Could we make a fabric similar to Hyperlast from Polyester?
Yes, we could. However you know how difficult it is to pack a Hyperlast balloon. Now, imagine packing a Hyperlast balloon made of Polyester, which has a more solid fiber. For the moment we do not make a Polyester version of Hyperlast but be assured that our engineers are working on the problem.
Is Polyester heavier than Nylon?
Yes, it is. The difference in density between Polyester and Nylon is 17.5 % (Polyester 1,34 g/cm3, Nylon 1,14 g/cm3). However, after the fabrics are coated, the final difference comes down to 6 % - Polyester is about 68 g/m2, and rip-stop Nylon fabric 64 g/m2. The surface of a “normal” balloon of 3,400 m3 (120,000 cu ft.) volume, is about 1,100 m2 (11,840 sq ft.) - so the resulting difference between the weights of the two different envelopes is an almost insignificant 4.4 kg (9.7 pounds). Not included in this calculation is the additional weight that comes from the Hyperlast fabric in the top of most rip-stop Nylon envelopes.
Is Polyester fiber harder to coat than Nylon?
In truth it is however Kubicek have found ways to solve this problem. Just as dying Polyester fabric is difficult so is coating the fabric. It is simpler to coat Nylon fabric than Polyester fabric however, if the coating foam/paste is made properly then the process of coating Polyester fabric works well. Kubicek both weaves and coats its own fabric and by doing so maintains complete control of the fabric as it is changed from rolls of thread to the final lengths of fabric from which we will build your balloon envelope. This is one of the reasons why Kubicek have recently invested into a new fabric coating production line - “czech” it out!
If you have safety concerns because of slightly increased permeability when your Polyester balloon has many hundreds of hours, then relax. Permeability and strength are two totally independent things,. Let’s look at propane consumption. According to tests that were run in a Swiss laboratory, permeability starts to influence fuel consumption when the porosity figure is around 20. Anything above this value (50, 150, 600 s) is irrelevant. New fabric has a value of around 600 and after many hundreds of flying hours your Polyester fabric porosity will still be above 250. At these anticipated levels there will be only the smallest increase in fuel usage after years of flying.
Is Nylon fabric stronger than Polyester?
It certainly is... when it is new. The initial strength of Nylon is better. However the important thing is how the two fabric‘s strength will decrease with time and flying hours. This is the thing that is critical to a balloon owner because what we are interested in is the strength of the envelope when measured by a “grab test”. The longer it takes before it fails the grab test, the better. So the initial strength is important only as a variable to the rate of degradation. And this is the main advantage of Polyester, where the degradation rate is much less. In the end Nylon envelopes fail the grab test a lot sooner than their Polyester cousins.
Unfortunately, it is very difficult to predict a balloon’s lifetime, as there are many variables in its flying operation. That’s why we have come up with our own method of measuring it. Results of our measuring could be seen in this chart, which clearly compares the relationship between initial strength of fabric and the rate of its degradation over a balloon’s lifetime.