When we embarked on this journey, we had little idea of the toils, hardships, and snares that would befall us. However, the fruits of our labor have also yielded many rewards, like watching our submarine glide through the water. The finished project was a result of many revisions, important decisions, and most of all, hours of working.

The evolution of our sub went through three main stages, but always with notion that it was going to be a wireless submarine, with the capacity to move horizontally and vertically. We got very far in constructing our first design, but ended up rejecting it for second design, with a more hydrodynamic design, consisting of three tubes connected by poles, with a wireless control system. The receiver was to sit in a watertight tube above the main tube and we were going to control it with a handheld radio. This would have been possible if two of our receiver chips hadn’t caught on fire, which led to our third design. We kept the same structure but hardwired the sub to switches which we could control from the surface. However, to this final and present design, we added a buoyancy system consisting of ping pong balls.

Our first design consisted of a 6” by 24” cylinder with two triangular wings on each side. The motors were to be in-between the tips of both wings, with the wires running from the motors to a hole in the top of the main cylinder. In this cylinder there would be a receiver for the radio, and batteries to power the motor. (Day 7) Unfortunately we realized the problems with this design after buying the materials. First of all, it was almost impossible to glue the wings at a consistent angle that would align with the edges of the sphere. Secondly, the design was too heavy since the tube was solid acrylic, and would have been too heavy for the motors to pull through the water. But since the cylinder had to be airtight, the volume of air inside of it was too large, and had to much positive buoyancy. We then decided on our second design . an idea that was radically different. It was much smaller and hydrodynamic. It consisted of one big long tube, and two short ones connected by poles to the long tube. At the ends of the short tubes were our two motors. The big tube contained the receiver chip, and the wires ran from the chip, through the poles, and into the tubes where the motors were. Then, tragedy struck.(Day 9)Right when we started working one day, we noticed that one of the wires was disconnected from the circuit board. After careful consideration and thought, we realized the only solution was to solder it back on to the circuit board. However, because of the lack of space to work with, we accidentally soldered onto another part of the board making the chip useless. At this point we couldn’t control the sub wirelessly. We bought a second model airplane(for the receiver, motors, and radio) and after a couple hours successfully dissembled it once again. (Day 10) However, when were testing our newly completed sub, a piece of styrofoam landed on the receiver and the whole chip went up in flames. Our dreams were crushed. Instead of dishing out another jefferson for a new plane, our parents told us to try a less expensive approach to powering our sub. After consulting with Mr. Harlan and Mr. Kerlin, we decided to hardwire our sub and have the switch and power on the surface, which is our present situation. At this point we were ready to test our sub (Experiment Day).

When we submerged the sub, it was leaned straight down. We figured out this was because all three of the motors were at one end. We moved the motor that controlled our buoyancy system (the ping pong balls) to the other end, and that balanced out the submarine. When we ran the motors, the sub promptly accelerated, but the only problem was the the sub would not stay at a consistent angle. It would either move towards the surface or to the bottom. It stayed pretty straight on a horizontal plane, but the vertical situation was enough to cause problems. We successfully fixed this problem by placing bits of cork by the motors of the sub, and we managed to get our first trial data. Our sub traveled 10 feet in 10 seconds. We were pretty happy after our first trial, but shortly after we ran into trouble. The starboard motor started shoring out, pulsing on and off, and we lost control of it from our switch box. This made the sub have a slightly circular path. Soon after, the faulty motor stopped working completely, for reasons that were pretty sure of. First off all, this was the first time my partner and I had ever worked on electrical circuitry. We weren't that good with soldering at the beginning of the project, and many of the solders that we had were put under a lot of strain. Inevitably, one of them snapped during our trials. We actually had three other snaps earlier, and were able to repair them by plugging in our soldering iron into the electrical outlets in a nearby classroom. But the snap that connected the switch to the starboard motor happened too late into the day, and we didn't have the time to fix it. This stopped us from conducting further trials on speed through water. We did run the sub with one motor for fun, and it actually worked really well. But we had yet to test our ping pong buoyancy system, which is where we ended up getting our data from. We tested how long it took for the sub to surface from a depth of 3 feet. See the Results Section. Our submarine surfaced at an average speed of .13 feet per second. In our opinion, this is pretty fast, because only one motor was pulling up our whole water-logged submarine (and that motor was only powered by two double-A batteries). Also, if it were coming up from the deepest spot in the pacific ocean (Marianas Trench), it would take only about 80 hours to surface (35,975 ft deep).

The percent error in our project was 7.3%. This isn't that bad, and the error that existed was due currents in the pool, and the motor was slowly draining the batteries. And because of all the variables involved in this topic, we can’t blame ourselves very much for this margin of error. This was a long, hard, and at times grating process for us, but the rewards more than outweigh the stress of it all.