Our mission was to build a full functioning submarine, capable of generating solid data and performance. To carry out this plan, Paul and I embarked on a priority to thoroughly design and build The Frog (our submarine). To do this, we took in all of the measures of underwater engineering, put them together in a logical way, and got to work. Our experiment was to test the over all performance of our submarine by incorporating neutral balance, buoyancy, speed and direction on a twenty foot, various depth course.
On the contrary, our submarine delivered very solid information as we expected. We were able to successfully send The Frog twenty feet with very minimal guidance from Paul. One of the most important parts of The Frog is the wiring. We were very fortunate to have our battery packs, and wire connections hold up when exposed to water. We were very satisfied with the neutral balance of The Frog. It was always capable of staying upright, even with the interference of the wires running to the control box. Our propellers propelled the ship a constant rate, thus delivering constant data. Despite all of these pros, we witnessed a fair amount of error, directly relating to the ship.
One of the most important concepts in underwater engineering is sealing. On our sub, we had two floatation devices (acrylic tubes) running parallel to each other. At the ends of each of these tubes, they were sealed with acrylic cement. Due to previous leaking, we ran each leaking area over with a silicone cement. Even with this extra layer, the tubes still leaked (not nearly as much though). This gave our sub a little weight on the port side, thus throwing off it’s balance my a minimal amount. See our leak diagram. We later learned if we had not put on that extra layer, our sub would not have delivered the same data we have now. Since our time at Long Beach was extremely limited, the last problem we needed had to do with wiring. Our battery pack had a contact problem with the engine wires. This delayed our experiment, leaving one of the ten foot trials blank. Since our submarine was not wireless, we had three long wires running from the engines to the control box. This is the what made the the submarine go approximently one foot per second. We also had to make sure that the wire laid directly in the middle of the submarine (keeping the balance neutral). Not only did the wire occasionally throw the submarine of balance but it sank the stern more than needed. This leads us into our next dilemma. We had very consistent and solid data, except for the surface trial. Instead of a 2% error, we got a 7% error. This was due to the wires (sub to control box) weighing down the stern, sending the bow of the sub out into the air. This was also influenced by the contribution of the two stern engines. See our Surface Error diagram. During a trial, this became a problem when we would have to deal with the elapsed time it took to reposition the sub. When we compare our Surface trial to the rest of the trials, they are in the twenties (seconds) while the others remain in the teens. See our results. The reason for this deviation has to do with density. When the submarine surfaced beyond the water line, there was no tension (density) to keep a constant rate of speed. On top of this, we would have to wait with the horizontal engines off, while the sub dove back to its starting depth. For the other depths, no matter how far the sub surfaced off of its course (no more than a foot)there was always a consistent supply of tension (density) pushing on the submarine in all areas.
If we had been exposed to unlimited time, we would have been able to correct a few minor mistakes on the submarine. First, we would have moved the vertical engine towards the back of the submarine. Since the vertical engine was towards the front/middle, when turned on, it would lift up the bow more than the stern. Therefore, if we had been able to relocate the vertical engine, it would have surfaced the sub in a even way. One problem we experienced was the leaks. We would have changed the flotation source to foam instead of unreliable tubes. This would of eliminated a potential disaster while giving us one less thing to worry about. It turned out our vertical engine was not as affective as we had hoped. If we had had a jet stream (a concentrated opening around the propeller) it would have been more effective. When we designed our sub, we didn't think about a weight carrier on the sides. This would have helped balance out the three wire weight problem. Another dilemma was the floatation issue. Adding floatation would have helped us make the sub neutrally buoyant, and then add weight to make it negatively buoyant. One of the most challenging portions of the construction of the sub, was the wiring. Instead of using wire connecters, we used tape. This, as we learned, was extremely unreliable. Had we followed through on all of these modifications, our submarine would have functioned at a higher performance, giving us even closer data.
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