As we were devouring our pizza, the talk naturally to what all young TEP's minds turn to in the spring...no, NOT THAT...WATER WAR!!! We commented on the fact that there had not been a drastic increase in water war technology in a while...backpack-mounted fire extinguishers, 3 man funnelators, water weenies were becoming commonplace. So we were trying to think of a new weapon to be used. Somebody (Leper?) suggested a pneumatic water balloon cannon. We were skeptical of the feasibility of such a weapon, but then Schmooz whipped out a greasy napkin and a pen, and started doing some calculations. Using our universal gas law, and estimating the size of a tank, and arbitrarily setting the pressure of the tank to be 100 psi, we got a really rough idea of what the velocity of a water balloon would be coming out of the tube. The answer? 200 miles an hour. 1/3 Mach. This was deemed to be MORE than satisfactory even taking into account the losses introduced when we actually built the thing, and so it was decided to attempt to build the cannon. Due to its lowly beginnings, sketched on the back of a greasy napkin at Newbury Pizza, and due to its awesome power in comparison to anything before seen in Water War, the cannon was immediately dubbed: The Newbury Project.
After some parts buying at Slum Lum, we adjourned to the basement of TEP and started building it. This was a week or so later on a Saturday afternoon if I remember correctly. The idea was to use pieces of 5 inch wide PVC pipe for both the barrel and the tank, with some pipes to connect them and a big ball valve in between. Eventually it was constructed mostly by Schmooz and Leper, and mounted on a stand for aimability. Then the moment of truth. Would the thing work? or would it be just a cool idea that was impossible to do in reality?
The initial test: The Newbury Project was moved into the back lot with its barrel pointed at our large steel metal dumpster. Various and sundry TEPs and hangers-ons flooded the back lot and the windows on the back of the house in anticipation. We loaded the holding tank to 100 psi using our air compressor, loaded a water balloon into the barrel, and opened the large ball valve.
The air made this amazing noise as it rushed out the barrel; sadly, the balloon didn't...it exploded in the barrel, and a little trickle of water dribbled out the end of the barrel. This was, to say the least, anticlimactic. We tried it again with another balloon - same result. The balloon couldn't take the acceleration or something and exploded in the barrel.
After a couple more disappointing tries with balloons (soaping them up for less friction etc), somebody suggested trying something that wouldn't explode in the barrel. Like a potato. This was deemed to be a good idea, so somebody grabbed a potato and carved it down to exactly fit inside the barrel, and slid it into the barrel. The cannon was pressurized once again, the muzzle was lowered til it was aimed at the dumpster, and the ball valve was turned once again.
The crash into the dumpster happened about half a second after the FWOOSH. The steel dumpster now had a large dent in its side. There was no potato to be found. Instead, lots and lots of little pieces of potato, none bigger than an inch across were found in our back lot, in the back lots of both our neighbors, up to 40 feet away. We had to clean off our neighbor's cars where they were spattered with potato bits. Meanwhile, all the TEPs were going "HOLY S@#%!!! OH MY GOD!! WE COULD _KILL_ SOMEBODY WITH THIS!!!" Needless to say, the Newbury Project was now an official win. We did a few more potatoes and oranges to impress ourselves some more with how well it worked, then returned to the problem of how to launch water balloons with it.
Somebody (Schmooz?) suggested making sabot rounds - that is, a casing to hold the water balloon til it cleared the barrel, and then fell away. This was quickly improvised, by sticking two plastic cups bottom to bottom, and placing the water balloon inside the outer cup. This worked GREAT! The rounds came flying out of the barrel, the plastic cups fell away as soon as the air hit them, and the water balloon continued onward at great velocity. By this point we were pretty psyched, and wanted to get an estimate of what our actual muzzle velocity was. So being the good nerds that we were, we took a balloon and fired it as near to straight up as we could, and timed the hang time. We had spotters on the roof, who claimed it went about 50-70 feet higher than TEPs roof (which is already 6 floors up from the back lot). The water balloon splattered, the different digital watch readings were compared, some quick calculations were done, and it was concluded that the muzzle velocity was approximately 60 mph. This was considered good enough.
The War: By the day of the war, we had bought extra CO2 tanks for use as portable fillers for the cannon, and practiced with them on the Esplanade shooting various sundry objects into the Charles. Since the PKT's never appeared til late afternoon, we set up the Newbury Project in the early afternoon, on Killian Court between the flagpoles. Then we started testing its range. From the flagpoles, we were able to hit Great Dome with our water balloons...for reference sake, the Great Dome was about 100 yards away, and 100 feet up from the ground...twas quite impressive. Later on a lone PKT showed up with a two-liter bottle launcher - one of the things where you load it halfway up with water, and then pressurize it, and launch it at which point it takes off in a totally random direction and sprays water back at you. While he was trying to launch this bottle, we were testing accuracy of the cannon. He looked up, saw the big 5 inch barrel staring at him, and started to run...the water balloon crashed on his heels. We got a couple more to hit right on his heels as he ran away. So in addition to having incredible range, it had incredible accuracy. This was getting better and better. You can see how impressive the cannon looked here. I'm the tall dorky-looking rightmost TEP in the picture with the funky looking glasses (which are dark-green-tinted safety goggles - I kid you not) and wearing a Danger shirt.
When more PKT's appeared, the war shifted to extinguisher-to-extinguisher combat for a while, cuz the cannon had too long a reload time and could HURT somebody at close range. Eventually, we all got tired of this, and the PKTs came over to get a closer look at the Project. Meanwhile, the "Student Revolutionary Government" was trying to get their Yearbook picture taken on the steps of Killian Court. They were cheering us on, shouting countdowns for the cannon, and generally mocking us. After a few minutes of test firings, a message was relayed to our cannoneer/ex Minister of War Velcro(tm), that a woman that was part of the SRG had said that "You don't have the balls to hit us." Now Velcro takes enormous pride in his primary organ, so this insult hit home pretty hard. He immediately switched targets, and shot a balloon WAAAYY up in the sky. Since we'd been firing for a while he had a good idea of the wind, and shot off to the right of where they were. It was a tiny dot in the sky, when it started blowing back to the left, slowly, and we watched the SRG people all turn their heads skyward. The balloon started appearing larger as it dropped, headed directly for the center of the group of people on Killian Court's steps. As it dropped even more, the group started to scatter wildly, everybody running off in all directions, except for a few stalwart individuals who were sure it couldn't hit them. At the last moment, those individuals also dived off to the side, as the balloon exploded dead center where the group had been standing just moments before. Afterwards, they sent their leader over to apologize and ask us not to bomb them anymore. Twas quite fun.
Eric Nehrlich's WWW home page / firstname.lastname@example.org