Analytic Essay

  Background Essay

Analytic Essay

 Method & Materials












 St. Matt's Page


  First of all, the submarine was a bigger success than we thought it would be. It went up and down(sometimes), it turned(with a little help), and it went forward and backward. It did everything we wanted it to do.
The first time we put the submarine in the water we did not add or do anything other than what the book said. We had three big problems. The submarine tipped down, and the motors wouldn't push the sub straight, and the wires created a drag. In the method and materials you will notice there is a section for first change, second change, and so on. These are for the changes we made after the sub did something wrong. The first change we made was for the back tip in the submarine. We tried cutting of the back, which did absolutely nothing. The submarine still tipped the same amount. This was because of the way the frame was constructed. When water flooded the pipes it weighted the back. So by cutting off the back we allowed the water to not weigh down the back, but we found that the pipes the motors were mounted to weighed it down. Next we tried to weigh the front of the sub to level the sub and give it neutral buoyancy. We do not know why we could not achieve neutral buoyancy. Everything seemed right, but still the submarine floated or sank. To completely fix these problem we would have to design the frame differently. So we decided to only test the sub on the surface (floating). We tried to make the sub go six feet. That was not an easy task either. One motor rotated faster than the other, thus every few seconds one motor had to be shut off to straighten out the sub (see video). Another problem we had was keeping the cords from affecting the hydro drag and balance. The way we had the wires hooked up to the ROV created a drag in the water. Think of a big parachute on the side of a car, the parachute would make the car turn depending on what side it was on. That is exactly what the wires did. The wires were connected to the top right of the sub, which made the drag to the right, in which made the submarine turn to the right. We fixed this problem by connecting the wires to the back of the sub.
The book we used to make the sub talked about how the motors cannot ever be fully water proof. Also that if the propellers were too long the motor would not be able to take the pressure and density of the water and they would burn out. We found that both of these were true in the motor that made it rise and lower. That was the only propeller that we didn't cut and after a while that motor only went in one direction. This was around the time that we decided to test the submarine only at the surface, so that motor was not used anyway.
Using the results we can find the average speed of the sub. The distance we made the sub go was six feet. So using the formula for velocity (Distance divided by average time equals the speed), the average velocity is .28 ft per sec.
If we were to redesign the experiment we would change the frame-work of the sub. If the frame was set up in a way that the two motors that propelled the sub were angled exactly right, and the back did not tip down. We might be able to conclude more than subs are difficult to build. We might also be able to work on the hydrodynamics of it by building a frame, or figure out how to build better motors. Also we would make the sub radio controlled rather than have it remotely controlled.
From this project we learned that maybe we should leave the sub building to the NAVY. If we had maybe a month more and no school on the side, we might be able to do everything that we want to do. Now that we know the sub will work if the sub is done right.
We can conclude from the error that while the engines are meant to be air tight they do gather some amounts of water inside. This may be the reason why one propeller moves faster than the other. It could also be concluded that the lamp battery which we used to power the submarine thrusters was low on energy. The buoyancy problems in which our project faced could be best solved with more exact and smaller weights which would give us a closer measure to perfect buoyancy. With the results of this sub it shows exactly why the Navy uses funds of trillions of dollars to build and power their giant submarines.



 This graph shows the results of when we tried to make the sbmarine go straight six feet.



 This is the results in spread sheet form.

 Time it took in sec. to go 6ft.  
  26.14   trial 1
 20.17  trial 2
 20.21  trial 3