Poster Presentation

Development of a Stratospheric Rube Goldberg Machine for a Potential Ballooning Competition

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Abstract

The Stratospheric Ballooning Association is considering running a nationwide stratospheric ballooning competition. One potential challenge under consideration is the “Stratospheric Rube Goldberg” challenge in which teams are tasked with building a Rube Goldberg device to fly on a weather balloon mission, at least some aspect(s) of which can only operate in stratospheric conditions. To test the feasibility of this idea, the MN Space Grant ballooning team at the U of MN Twin Cities set out to build and test such a device. Spoiler alert: it was hard! The proposed rules for the challenge state that the machine and its enclosure must weigh no more than 3 pounds and measure no more than 12 inches in any one dimension. It must have at least one transparent side or a window so that the Rube Goldberg machine can be monitored by a camera from outside the enclosure. A microcontroller may be used to trigger the machine once the balloon gets above 80,000 feet but, once started, the machine must run on its own with no additional microcontroller input/control. Once triggered, the machine must execute of at least four steps, the last of which is supposed to promote the school (think – deploying a school flag). The machine must finish all steps before the balloon bursts. The Rube Goldberg machine we built to test these draft rules had five independent steps and its operation was recorded by an external 360-degree camera. The Rube Golberg device was mounted in a 12 x 12 x 12 inch payload enclosure with one fully-transparent side (rather than just a window). The device used a PADL flight computer with gps, backed up by a pressure sensor, to determine the payload’s altitude. Once the machine reached 80,000 ft ASL, the PADL triggered the heating of a nichrome wire to cut a string which released a ball. The ball rolled down a spiral tube and set off a mouse trap, the arm of which pulled a ring magnet out of place allowing a second magnet to fall through a copper pipe. Lenz’s law slowed the fall of the second magnet. As the second magnet fell, it pulled on a string that raised a multi-spiked object. The payload enclosure contained a partially-inflated balloon which expanded as the machine ascended and ambient pressure decreased. Ultimately, the spiked object popped the balloon, releasing University confetti. It was this step with the balloon that satisfied the “can only operate in stratospheric conditions” rule. The device was built, ground tested, and flight tested (more than once, with mixed results), suggesting that this stratospheric Rube Goldberg challenge, though novel, might be somewhat too difficult, especially for teams that are new to stratospheric ballooning and/or only will be able to do one flight test.

Keywords: Rube Goldberg machine, stratosphere, stratospheric ballooning, weather balloon

How to Cite:

Ali, M., Raby, K. & Flaten, J., (2025) “Development of a Stratospheric Rube Goldberg Machine for a Potential Ballooning Competition”, Academic High Altitude Conference 2025(1). doi: https://doi.org/10.31274/ahac.20150