Siege Universal Torsion Machine: VSpring Configuration

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Universal Torsion Machine: VSpring Configuration
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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.


To start, I needed a set of regulea.

First, I printed out some more plans that I could map onto the wood. I used classical mortise and tenon joints to join the frames together.

These then wrap around the square stanchions of the bundle.

A set of pins hold the tenons from coming out through the mortises.

On the torsion bundles themselves, I bolted on brackets that will hold the bundle in places against the regulea. Because the scutulas are wider than the stanchion mount points, that forms the brace on the far side.

Here is everything pinned together into a V spring engine

Adjustable Scapus

Designing a Scapus for UTM was a bit of a challenge. It needs to fit the inside of the narrow V spring, but also be usable for Hatra, and 4 bundle machines. It needs to be short, yet long. It needs a winch with a lock so we can take measurements. It needs to support compounding.

First, there is the long part of the Scapus that goes back to the winch (center). Then stand-off structure goes to another set of beams. Tgise are not attached in this picture, and are on either side of the scapus. These bolt onto the stand-off structures and clamp the scapus onto the regulea of the engine.

Here is the bundles upside down, but with the scapus now assembled, and attached to the bundles.

Still upside down. here it is with a stabilizer to prevent the bundles from twisting in the narrow clamp of the scapus.

Also note the stand mount farther back.

With this setup, 2 wing nuts disconnect the engine from the scapus. A single wing nut allows the mount point to slide around.

Winch Mount

The winch mount needs to handle the winch, the compounding anchors, and also be usable against different configurations.

Here are the fundamental parts of the winch. A simple boat which and a pair of curved compounding anchors, all mounted to a wood base that fits the end of the scapus.

Here is the winch mount assembled, and attached to the scapus, with a scapus extension in the middle.

The Stand.

The stand provides a pivot to mount the machine on at a convenient height.

The foot of the stand is a classic cross style. An extra long bolt connects the two in the center. A hole in the vertical part of the stand will slide over that, helping to anchor it in place.

A couple braces, and it is now very sturdy.

Throwing some Apples

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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