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World Championship Chunk 2013: Mista Ballista
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Mista Ballista returned to Delaware for the 2013 Punkin Chunk. After proving that compounding worked pretty well, we brought that back again this year to see if we could improve. We did not, however, want a repeat of the 2011 broken trailer leaf springs, so we replaced the front axle (the axle not replaced when the spring broke last time) and also rewired the trailer to improve reliability.
Missing launch content goes here. The travel bolts on the back of the ballista were left in, and we couldn't lift the ballista up to full launch angle. Combine that with the sloppy bowstring, and our big launch was 538.98 ft. Half of what we can normally do. Repairs were needed for tomorrow.
We threw 840.94 ft, beating our previous compounded pumpkin throw.
The team, unsatisfied with an 800ft launch decides to switch back to a straight up bowstring. Last year this pushed us into the 1200ft range, and because the only compounding change we made was to the bowstring, and we did not make corresponding changes to the length of the Scapus and shortening the arms, we decided this was the only way to get back up into the 1000ft range. This resulted in late-night splicing, and then an early morning rushed set of splices to make up for the fact that we had a measurement error at night.
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Contact: Team Tormentum Copyright © 2000-2022 Eric M. Ludlam All rights reserved. Twas' brillig, and the slithy toves did gyre and gimble in the wabe... | Last Modified: 05/10/09 |
This year Forrest Clifton offered his truck to tow 
It didn't take long to lift 
We made a quick trip down to the pumpkin source and found a sea of orange pumpkins. There sure were a lot of pumpkins, and while some fit in the 8-10 lb range, none were of the strong white lumina or other of the sturdier varieties. I brought a few back to the pit, but we knew we'd have to go out and bum some punkins off our competitors.
I then stood in line for a little over 3 hours in order to get badges for the team. By the time I picked up our badges, it was dark out, and the ballista was assembled and mostly wound up and ready to go. Except that we ran out of gas for the hydraulic unit and didn't finish winding the right bundle.
The team continues working while I'm stuck in the badging line.
First things first on Friday was to finish winding the bundles. We twisted each bundle up to 2500psi on the hydraulics giving us a nicely balanced system.
We put on the bowstring, and then pulled back so we could set the arm-stop ropes. The arm-stops are the heavy white ropes that catch the arms and are tied to the back of the machine. What we learned was that the bowstring was incredibly loose. In this picture you can see the bowline is pulled back quite a ways, but the arms have hardly moved. We made some minor tweaks to an adjustable part of the bowstring, but it wasn't enough to get the slack out of the system.
Once other systems were set, we installed the punkin. Thanks team chunky for "lending" us a spare pumpkin heavy enough to throw, but small enough to fit in our throwing pouch.
Day 2 of the competition. The sloppy bowstring was respliced, and here you can see that it is setting nice and tight while at idle. In this case, I needed to make some minor lengthening adjustments, and we used ratchet straps to pull the arms back to fit the bowstring on. This was going to be good....
Unwinding the winch to the pouch is a drag, so to speak. We need to pull it out by hand and hook it onto the throwing pouch. In this picture, 
To celebrate not breaking the machine on our 2nd competition shot, 
The video camera flew beautifully. Here you can see the little orange tail put on the pumpkin to stabilize the flight. The video preview we saw on the gopro camera was gorgeous. I can't imagine they won't use it in the Punkin Chunkin show.
The camera survives! The pumpkin, not so much.
Again, 
And another successful launch, this time reaching out to 1059.8 ft.
Our results for the weekend written on the side of our machine.
The bowstring survived, but the arm developed a bit of a crack. Too much power. Fortunately, this is something we know how to fix...
And with that, the sad disassembly process begins as we convert the ballista back into travel mode.
The torsion class enjoyed some weather ranging from cloudy with a bit of rain, to sunny and warm. There was a new torsion engine joining the group, and team Chucky who has dominated the torsion line for years was dethroned as Onager joins the 3000ft club for 1st place this year.