Analytic Essay
What our results show?We started with our large pipe as our fuselage, but underestimated the weight we would have to add in order to make it neutrally buoyant. When we were “done” with the body of the submarine, we began to add weight. We tested it in the extra guppy tank, which did not have any guppies in it, of course. We added metal washers to the inside and outside of the submarine. We thought we only needed about 750 grams in order to make the submarine sink, but we later discovered that we needed closer to 1,800 grams (four pounds), which would have required about 130 washers, far more than what we had. The reason for the miscalculation in needed weight was we had assumed that the pipe itself was not buoyant. We later discovered that because the pipe was slightly positively buoyant, we would have to add more weight. We used a four pound (1,800 grams) dive weight, and placed it in the center of the sub.
Another issue we had to work with was center of gravity. We could not have the submarine tilt to one side or the other when not moving. This would cause it to be unstable, and not “fly” straight underwater. In our sub, Kevin used bubble wrap to keep the weight in a stationary position inside the sub. Kevin could change the amount of bubble wrap on each side of the weight, front or back, to change the center of gravity. But our biggest problem was waterproofing. We had believed that small amounts of water would leak through the front cap, but we later discovered that a large amount of water was coming through the holes where we installed the fins. We had used hot glue to seal the servo and fin holes, but because that was found not to be waterproof, we re-sealed everything using silicone. We believe that this will fix all of our water leakage issues. |
What would we change in our design?If we were able to start our project over again, we would probably make the fuselage smaller. The large fuselage made it difficult to created neutral buoyancy. A larger body would mean we could use smaller weights, and it would be an overall more compact design which, would be easier to use, work on and transport. We would also use a 2.4gHz radio system instead of the 27mHz system we are currently using. 2.4gHz would required three times the wiring, but it would be worth it in the long run, as 2.4gHz is more reliable, easier to use and more programmable.
What would happen if our submarine dove deeper?We believe that greater depth would have little to no effect on the performance of the submarine. The increased depth should not cause any leakage, increased drag or stress on the motor. The only issue with depth is the fact that our sub can only dive about 15 feet. Once it dives more than 15 feet, it would begin pulling the antenna down under the water’s surface and we would start to lose signal.
Other Ideas to further experiment or study: We would like to install a 2.4gHz system, which would make programming and ease of control much better. We would also want to dive to our maximum depth of 15 feet, which we have not been able to achieve yet due to the spontaneous combustion issue.
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Explain what you learned by doing the experiment?
We learned a lot about different types of problems you can run into when working underwater. The issues that we learned from, which do not only apply to our project, were buoyancy and waterproofing. Both of these things are issues when using objects underwater, especially electronics, which are moisture sensitive. If we were ever to use a underwater case to hold a camera, we would have to make sure it was watertight, and would sink, if we wanted it to sink, and float if we wanted it to float.