Balloon Design Project

The fundamental goal of this project was to design a makeshift balloon to remain airborne for at least 20 seconds. The balloon and all attachments must fit within a 2-meter cube and all materials must be less than 30 dollars in total cost. While there was a set list of materials, teams could request other materials to use.

In the consumer marketplace, this product will be used by farmers who need to deposit seeds or pesticides over their farmland. It will be a cheaper way to maintain farmland compared to using a crop-duster, as the balloon will cost is a fraction of the price of renting a crop-duster.

Our design consists of a 3ft long triangular prism, with a 1.5 ft triangular pyramid on top. The bottom will resemble another 1.5ft triangular prism, with the top point (0.5ft) cut off. Each face of the balloon will be 4ft wide. The overall shape vaguely resembles a diamond.

While the manufacturing process is relatively hazard free (care should be taken to safely use scissors and X-acto knives), the inflating and heat process of the balloon poses some risk. For instance, the heat gun used to heat the air must not touch the edge of the balloon while heating, as the plastic drop cloth may catch on fire. To help prevent this, multiple people will be present to hold the balloon flaps away from the heat gun exit. Also, special care should be taken to ensure that no body part comes in contact with the heat gun, as burns could occur.

The balloon will primarily be made up of a high-density polyethylene drop cloth that is 0.7mm thick. The sides will be fastened with packaging tape. The total cost of the drop cloth and tape was $7.45.

The mathematical model calculated the mass and number of moles of the air in the balloon using the calculated volume of the balloon. Using the mass of the balloon, the quantity of heat loss during time aloft was found. Then, using the equation given in class, the Time of Heat Loss (tascent) was found. Finally, the model found the total time afloat by adding the tascent and tdescent (0.5 tascent ).

The model predicted a time afloat of 36.6s. Upon testing, the balloon floated for 54 seconds. This was likely due to the high winds that were present during testing, carrying the balloon higher in the air. Other sources of error include the convection coefficients used in our model. These were rough estimates based on limited experience with convection, which could have impacted our predicted time afloat.

The design was formulated after a Chinese lantern. While we recognized that the cylinder would be the best shape for the balloon by increasing volume while maintaining a small surface area, we chose to take a risk on a balloon that could potentially perform better. The pointed top of our balloon decreases downward air resistance as the balloon ascends, increasing the height the balloon ascends to, thereby increasing the amount of time the balloon floats.

The team functioned well, with each member contributing to the team by playing to their strengths. Aarya and Venkie took lead roles in designing the balloon, obtaining materials, and documenting meetings in the design notebook. Umesh manufactured the mathematical model with Aarya and Venki’s assistance. Finally, Xuanzhuo wrote the design process.

In order to launch the balloon, we had to create a schematic design, a mathematical model, and document our work in a lab report. Attached is a copy of the mathematical model and a video of the balloon flying.