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| Mista Ballista | |||||||||||||||||||||||||||||||||
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Mista Ballista is Team Tormentum's Torsion Division competition catapult. We started construction in 2000 with our first purchase of two very large steel donuts that now make up the lower scutulas. The different pages documenting Mista Ballista focus on different aspects of it's construction and do not go in chronological order.
That's approximately 22700 foot pounds at the base of the arm, and perhaps 26800 foot pounds at the point where we had a catastrophic failure last year. To put in that tension, we had about 7000 lbs exerted by the hydraulic ram which was running around 800psi at the pump.
Thanks to Jim Goodwin for these two great pictures.
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Mr. B just before launch at the 
Mr. B getting ready to launch at the 
Sproing! 670 feet!
Preparing for our first competition launch at the 
Ouch! Things didn't go so well for us.
Preparing for a test launch at the 
Sproing!
Preparing for a launch that goes 250 feet at the 
Fire!
After winding rope bundles late into the night Thursday before the 
Our first shots broke pumpkins, but they did go forward about 100 feet with minimal tightening of our rope bundles.
The Modiolus and Epizygis used in Mista Ballista account for a majority of the
time spent. The size and detail needed to construct these items in a way
that could reliably contain the force of so much rope worried us, and we
over engineered them.
The rope bundles are the main engine of the machine. The framework that holds
everything together is about 24 ft long, and 6 feet tall.
At the 2004 chunk the main stanchions for the torsion frames were bent by the impact of the arms.
You can see the animation of when this happened on the 
In 2005 we broke our fancy fiberglass arms. In 2006 we got the 
The framework for the Ballista had to be built strong enough to resist the pullback, and to hold up
the 2500 pounds we currently estimate of our engine. It must also push it up 16 feet in the air!
Building an arm for a torsion machine this large has been very challenging.
A 
One of our goals for the 2003 season is to acquire a dedicated trailer for Mista Ballista.
All winter during 2003 we have been collecting the parts we need to accomplish our 2003 chunk goals.
Here are a bunch of pictures of these random parts. Can you guess what they are for?
To travel to different chunkin' locations, we need to pack the system down onto our trailer.
Deploying from the folded up position is challenging and time consuming, taking a day and a half
at the 2002 chunk. This year at the 2003 Punkin Chunk, we were done in about 4 hours.
Mista Ballista's engine operates with torsion from twisted rope bundles. One of the biggest challenges
of torsion for this machine has been adding the twist. An onager is pretty straight forward in that a large lever and gravity can be used. With our ballista, the direction of twist is sideways, so
alternate means of twisting is needed.
Mista Ballista uses hydraulics for lifting the engine to a 45 degree angle for firing, and also for winding the cord bundles.
We also like having electricity on hand since Mr. B has a tendency to break, and need on-field repairs. This page describes
what we are using to power up the system.
Building an arm for a torsion machine this large has proven to be very challenging.
Based on the experiences of our competitors, who also keep breaking arms, we find that
we are not alone in this dilemma.
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Contact: Team Tormentum Copyright © 2000-THISYEAR Eric M. Ludlam All rights reserved. Twas' brillig, and the slithy toves did gyre and gimble in the wabe... | Last Modified: 12/24/07 |
