Siege UTM: Universal Torsion Machine

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UTM: Universal Torsion Machine
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The UTM, or Universal Torsion Machine, is a small scale torsion engine designed to answer the oft asked question, "What is the best Torsion Engine configuration?"

We have built many different torsion engines at many different sizes, and each time we learn a little more, and make guesses about what is most efficient. In the end, however, each machine has minor advancements above previous machines, making the configuration differences hard to guess.

The UTM has been designed to take the variances in rope, torsion bundle size and tension, wear and other variables out of the equation, allow us to focus on the frame geometry. The idea is, if the same bundle at the same tension is put into different frame geometries, and operated with, then variances between eventual launch distance is a factor of the frame geometry, and not the bundle.

Our first completed configuration is for a traditional V-Spring ballista, and we used it to test configuration options for Mista Ballista.

Our intention is to also produce Hatra and onager configurations. Ideally, I'd also like to experiment with 2 4 bundle configurations, and answer the questions is 2 bundles better than 1? Are 4 bundles better than 2?

On Sept 20, 2008, UTM was taken outside during a local Home schooler catapult day. Small apples were launch at different arm length settings and different draw back distances.

Additional Pages for UTM
UTM: Universal Torsion Machine The UTM, or Universal Torsion Machine, is a small scale torsion engine designed to answer the oft asked question, "What is the best Torsion Engine configuration?"
Universal Torsion Machine: Torsion Bundles The UTM has four bundles. Two short bundles, and 2 long bundles. Each bundle was designed to have similar equipment, but there are two sets, each a different length.
Universal Torsion Machine: VSpring Configuration The V-Spring configuration for UTM models the classic Greek ballista. It was also set up to be able to model Mista Ballista's V spring configuration so we might determine ideal arm at-rest angle and arm length.
Universal Torsion Machine: Results Here are the hard numbers from various UTM runs we do.
Universal Torsion Machine: Software The UTM design was originally inspired by a MATLAB program I wrote. This program is able to simulate the geometric efficiency of different configurations. Since it doesn't model the actual effectiveness by measuring load on the bundle, we felt the need to create a physical model that could have the same flexibility.

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