Week 9: Overview

During week nine, the group altered the SeaPerch with corrections discovered during testing. More  foam was added to correct the SeaPerch's buoyancy. The size of the surface area was decreased when the dimensions were shortened, therefore the weight was not evenly distributed causing the SeaPerch to be heavier in the back and sink during the first test. New thicker and denser foam was purchased to aid in better floatation. The position and amount of slant of the propellers were slightly modified in the hopes of straightening out the movement of the SeaPerch.

Note: In addition to making changes in the the design of the SeaPerch, the group took into consideration the factors the environmental factors that affected the collected data. During the first test of the new design it was found that there was a current in the diving well of the pool at the DAC. As a result, the group made an effort to reduce the effect of the current by eliminating unnecessary motion in the diving well.

When the perch was tested a second time with the alterations, it covered half the distance of the diving well before one of the propellers broke; this distance was covered in 15.53 seconds. After the breakage, the SeaPerch began spinning in circles, and could not complete the full length of the pool, due to excessive power on one side of the SeaPerch. Assuming the perch would have continued at the same speed, it would have crossed the entire width of the diving well in 31.1 seconds. That means that the newly designed SeaPerch was moving at a speed of .412 meters per second. This is calculated by taking the width of the diving well, which is 12.8 meters long, and dividing it by the time it took the SeaPerch to cross the length of the pool. The original design of the SeaPerch moved at a pace of .314 meters per second.

Figure 1: A video of the movement of the SeaPerch once the propellor broke

Figure 2: The propeller fell off due to a error in the glue attachment and soldering

Figure 3: A closer view of the error in the attachment of the propeller