SCIENCE AND ENGINEERING FAIR
Research Plan and/or Abstract for 2007

Category Award:   0 (GRAND AWARD)

Research Plan:

Abstract:
Abstract
A hot air balloon consists of three main parts: the basket, the burner and the envelope. The envelope catches the hot air rising, which in turn, lifts the balloon and its contents off of the ground. A science fair project was crafted in order to discover which of the four cloths—silk, nylon, rip-stop nylon, or polyester—would be best suited for the envelope of a hot air balloon. Currently, most hot air balloon envelopes are composed of rip-stop nylon. However, an occasional envelope is made of polyester and the first Chinese envelopes were constructed from silk.
Four qualities were selected to determine which fabric would be most appropriate. For each trait, a test was then conceived to ascertain how the textile would perform in each category. The first test, weight, is an important factor because the lighter the fabric, the less weight the balloon has to lift. After weighing the fabrics, rip-stop nylon appeared to be the lightest with polyester, silk, and nylon following respectively. Secondly, the durability of the cloth helps determine its strength. This test involved using a constant weight to drag the cloth across a strip of sand paper until completely worn through. The results were nylon first, then polyester, silk and, finally rip-stop nylon. The fabrics were then tested for tearing strength. In this case, the cloth was hung from a table and attached to a bucket at the bottom. Sand was gradually added into the bucket until the cloth ripped completely in two. It is important to note that the fabrics had slight cuts on each side to facilitate the tearing. Nylon took the gold once more by a large margin. Following were rip-stop nylon, polyester, and silk. The final attribute tested was their resistance to heat and how much they could endure. After being placed in an oven, the temperature was gradually increased up to 288º C, each cloth exhibiting different results. Their effects were recorded and graded on their appearance after being heated. Silk seemed to respond the best with nylon, rip-stop nylon, and polyester following.
After collecting and recording all of this data, charts as well as precision errors were completed. The tearing strength precision error had a variety of percents, with an average of 8% precision error. In addition to the tearing strength, the durability test had an average precision error of 10%. While not perfect, I believe the results accurately exposed the strongest textile.
The final step in this process was analyzing the results and determining which cloth deserved the gold. After much thought and consideration, a formula was designed to establish which fabric would be best suited for the envelope of a hot air balloon depending on which attributes were deemed most important. The durability was weighted the most because it is important for a long lasting envelope. Tearing cloth was also important because a torn cloth is not going to hold the air within the envelope at all. The weight was graded less due, in part, to the marginal difference between them. Finally, the heat resistance of the cloth was least significant. Hot air balloons only reach a temperature of about 120º C. Because all of the cloths could survive at that temperature, the amount of heat each cloth could endure was not as relevant.
After computing this formula, nylon came out victorious with a 1.556. Rip-stop nylon was second with 0.980 and polyester just behind at 0.922. Silk came in last, the weakest of the fabrics, with a 0.542. Seeing nylon well ahead of rip-stop nylon, the current fabric, it supports my hypothesis that a stronger textile could be used in the production of hot air balloon envelopes. It is obvious now why silk is no longer present in hot air balloon envelopes.