Results and Conclusions

The final test of the SeaPerch, before one propeller broke, enabled the group to determine that the newly designed SeaPerch moved at a speed of .412 meters per second. The new design of the SeaPerch covered a distance of 12.8 meters in 31.1 seconds, whereas the original design covered this distance in 40.7 seconds. Furthermore, the original design of the SeaPerch moved at a speed of .314 meters per second. This proves that the group was in fact successful at altering the SeaPerch in order to make it more hydrodynamic. The SeaPerch was able to move more smoothly and efficiently through the water, allowing it to move at a quicker pace. The group increased the speed of the SeaPerch by 31.2%. This is calculated by taking the speed of new design, subtracting the speed of the original design, dividing that amount by the speed of the original design, and multiplying by 100 to get a percent.

.412 m/s - .314 m/s  x 100  =   .098 m/s  x 100 = 31.2%
         .314 m/s                          .314 m/s

Overall, the group was successful in completely the goal of making the SeaPerch more hydrodynamic. Unfortunately, the data is based on the assumption that the SeaPerch would have continued at the same pace across the rest of the width of the diving well. If the group had had more time to accomplish the task, more success could have been reached, and the propeller could have been repaired. The group was limited since the SeaPerch kit was not given to the group until the end of week four, which only left about five weeks of work time.

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

Final Design Built

Final Design of the SeaPerch: Construction

Figure 1: The front of the SeaPerch with added plastic top

Figure 2: The back of the SeaPerch with added plastic ring to hold the swim cap

Figure 3: The top of the SeaPerch with the three horizontal propellors

Figure 4: A side view of the SeaPerch with the swim cap on, finished product

Figure 5: The front view of the finished SeaPerch design. This is where water will flow in

Figure 6: The back view of the finished SeaPerch, the funnel shape in order to allow faster movement

Week 8: Overview

During week 8, the group finished the construction of the final design of the SeaPerch. Two pieces of plastic were added to the top and the back of the SeaPerch so the swim cap could be attached. One swim cap is stretched from the back of the SeaPerch to the middle, in order to create a funnel for the water. The three propellers all face horizontally, pushing water out of the smaller hole in the back. This will allow a greater push forward, making the SeaPerch faster. The group brought the SeaPerch to the Drexel pool in order to test if the SeaPerch was in fact more hydrodynamic. There were some flaws in the design that will be repaired before testing again. The SeaPerch sank to the bottom of the pool, which means more foam must be added. This is due to the fact that there is less surface area, so the weight was not distributed evenly. Also, the SeaPerch pulls left while it is being steered, and does not ride straight. This could be due to one motor being stronger than the other, or the propellors were not attached properly.

Week 7: Overview

During week 7, the group downsized the SeaPerch in every dimension. The purpose of downsizing the SeaPerch was to make it lighter and have a smaller surface area. With less surface area, the SeaPerch will not break as much water as it travels, allowing for less drag and faster movement. The group has come to the decision that copper wire will be used to construct two cylindrical structures that will be attached to the front and the back of the SeaPerch. This will funnel water through the SeaPerch, allowing it to move at a faster rate. The copper structures will be attached to two swim caps that will surround the entire SeaPerch, enclosing all materials inside. When considering the material options for enclosing the SeaPerch, the group fund that latex is the best material because it is water proof, water repellent, and inexpensive. Swim caps are made of 100% latex, and their shape is ideal for covering the SeaPerch. By enclosing the SeaPerch, there will be less friction ultimately causing less drag. These features will be added by the end of next week, in order to test the new design.

New Design

New Design:

• Smaller
  

• 3 Motor Propulsion System

• Modeled After Bullet

• Less Foam on the Side

• Stable

• Cap on the End

   

  Supplies Needed:

  • Mesh Casing

  • Cone

  General Idea of Design:

  To make the SeaPerch faster and more efficient in the water the group plans on lowering the dimensions of all of the pvc pipes. With the smaller frame the group plans on wrapping the outer frame with a water resistant material so that less drag is created as it drags through the water. The front and back will remain open where the motors will push the water through the holes. Two of the three motors will be placed in the back of the SeaPerch and the third will be on the middle bar slightly above the other two to push it forward as well. This will allow for the maximum volume of water to pass through the SeaPerch and create a stronger force to push it through the water. The group is also going to shorten the foam and move it into a more efficient place so that it doesn't protrude from the top of the perch. With that properly wrapped on the inside of the perch it will give more stability and create less drag than them passing directly through the water. Overall, the perch will have more power to direct it forward while created less disturbance through the water resulting in it moving significantly faster.

Week 6: Overview

The group tested the SeaPerch at the pool in the Drexel Athletic Center. It was found that on average the original SeaPerch moves at ...... This was determined by measuring the length of the pool (in meters) and dividing it by the average time it took the SeaPerch to cross the pool. The group plans to use this information to test the final design of the Perch to confirm whether or not the new design is more hydrodynamic. While testing the original design, it was found that the right motor was weaker than the left motor, causing the SeaPerch to turn slightly while moving. This slowed the SeaPerch down while testing since both motors were not running at the same time. Also, the cord connected to the battery was not long enough to cross the entire pool, so the person controlling the SeaPerch had to pick up the battery and walk the side of the pool. The tugging of the cord also contributed in slowing down the SeaPerch. The group then started to plan and design the new construction of the SeaPerch, and chose what modifications were to be made. These changes are displayed and described in the New Design post on the blog. The construction of the new design will begin in class this week, and will be finished by class in week eight. That will allow time for testing and alterations in week nine to finalize the final design and determine if the SeaPerch, is in fact more hydrodynamic.