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Punkin Chunk 2003: Mista Ballista's Story
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Operating Mista Ballista this year was exciting beyond our expectations. Some things worked great. Some things broke, and pumpkins flew!

When was the last time you saw a Ballista pull up for gas?



We drove from 9:30pm Thursday straight through till 6:30am Friday when we stopped and got breakfast. We came right to the field bright and early. Fibonacci and an outhouse are all that can be seen.

You can read more about our deployment strategy on the Mista Ballista Deployment page.


Eventually, the arms were installed, and the rope bundles twisted enough to hold the arms in position. We used hydraulics for the first time this year to tension the ropes beyond what is convenient to do with the come-along winch. You can see the cylinder on the bottom of this image as a few red pixels.

You can see more detailed pictures of how it works on the Mista Ballista Torsion page.


Once the bowstring was put on, Jeff (on the left in red) tested out the hydraulic lift. Last year we used the original pump from the dump truck with a 1.5 horse motor. That didn't work at all. This year the new pump system uses a 7 horse engine from a snow blower, and a special pump we purchased that was meant for a 6 horse engine. It lifted our multi-ton engine high into the air. Huzzah!


As the sun began to set, we had worked out the kinks in the torsion system, and prepared to fire our first test pumpkin. The orange passenger had no idea what was about to happen, and Dave was most pleased with himself.


After the launch, we learned much. The orange stain in the pumpkin pouch and bits of pumpkin skin scattered around the machine indicates the pumpkin was sitting a bit too low.


We also completely trashed our bowstring. We had to set to work immediately to fix it for our first competition shot. Fortunately it was going to be around noon on the next day. We had enough extra cable to fabricate 3 new strands. One of our four strands, though slightly damaged, was recycled into the next generation bowstring. In addition, big wooden sisal wrapped boards were placed in front of the uprights to prevent this happening again.


The short distance the pumpkin went also inspired us to get going and tighten up the rope bundles even more! It was about this time that the really exciting stuff started to happen.


Once we started pushing the cylinders to their upper limit, stuff started breaking. Here you can see where our 5000lb test chain was dented by our Clevis hook. You can also see a link originally welded onto the epizygis, and what it thought of the forces put on it. Lastly, you see the band-aid on Dave's hand where it had been whacked by flying metal bits while things were breaking. You can watch a video of one of the events.


When in doubt, weld more stuff on!


We did something right. The bowstring pullback on the ballista starts at the winch, goes out to a pulley attached to our Seacatch, and then comes back to this Dynamometer. The black needle shows current load. The red needle shows the load we just put on it while drawing back the arm. This indicates almost 3000 lbs of pullback. Wow!

This measurement was from our first successful competition shot which went 209 feet. Only our trebuchet Juggernaut2 had thrown so far before.


For our second contest shot, we opted to do nothing. Well, almost nothing. We had problems raising the dump frame past 25 degrees, so we examined the lifting cylinder, and discovered that it was hydrolocked. We drained the opposite side of the ram, and this time we got more altitude. Here we are ready to fire.


And Fire! You can watch the video of this shot from start to finish. The launch was about 250 feet.


As soon as our second shot was done, we set to work. We had earlier identified that our pouch was much too heavy. We hacked out chunks, thinned things up, and added wood in place of some of the steel beams. In addition, Jeff set to work tightening the rope bundles another 3 degrees or so.

The result, our longest shot for the weekend at 290.6 feet. We also managed to get 3400lbs of pullback on the pumpkin. Excellent!


Too bad the force was so great that the forward momentum of the arms caused it to buckle at the end of the reenforcement area near the bridge. Not altogether unexpected, but disappointing nonetheless.


And with that, the 3rd place trophy was ours! Huzzah!


Video

We were pretty busy at the chunk and didn't get much video. This first video was supposed to be an educational "how to" tighten hydraulically. Now it is an educational video on why you really don't want to do it this way.

No one was hurt during the flying metal shards stage of the video. After everything calmed down, however, the arm fell, and konked Dave and Jeff on the head.


Google Video Service
Mista Ballista - Failure of first torsioning system


Information:
At the 2003 Punkin Chunk, Mista Ballista was using a new hydraulic system for tightening the rope bundles. This shows the system in action, then breaking to disastrous effect.
8 sec - Nov 20, 2007

I have three videos of the launches we made. Our second 250ft launch had the clearest view with the least number of helmeted heads in the way.


Google Video Service
2003 - Punkin chunk - Mista Ballista shoots 250 ft


Information:
2003 Punkin Chunk. Mista Ballista shoots a pumpkin 250 ft.
14 sec - Nov 20, 2007


Additional Pages for Punkin Chunk 2003
Punkin Chunk 2003 The 2003 World Championship Punkin Chunk was a great year for Team Tormentum, and Mista Ballista, our competition Pumpkin throwing machine. After last year's tragic defeat at the hands equipment failure, our goals were simple, Shoot a pumpkin intact, and forward. In this, we succeeded, and the machine exceeded our expectations.
Punkin Chunk 2003: Mista Ballista's Story
(This Page)
Operating Mista Ballista this year was exciting beyond our expectations. Some things worked great. Some things broke, and pumpkins flew!
Punkin Chunk 2003: The Torsion Machines The torsion division is still small, with four machines entering. Everyone had something new to share.
Punkin Chunk 2003: Other Catapults There were 75 machines at this years chunk, and lots of nifty catapults were there to impress. We were pretty busy trying to get Mista Ballista to work right, so we don't have many pictures of cannons.


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