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.

Philadelphia Science Festival

Clark Park Science Discovery Day 

April 29, 2012

The Clark Park Science Discovery Day is an event part of the Philadelphia Science Festival dedicated to introducing young students to a the world of science. At this event, there were more than 20 different hands on activities for students. This group found this event to be a great opportunity to test the general design of the Sea Perch and demonstrate its capabilities to the young scientists of the community.

Results from Testing:

 After testing the SeaPerch, it was found that the third motor, which sends the sub in an vertical direction was defective. What this means for the group is that the project has been setback because the group is unable to get accurate data that could be used in comparing the initial design to final. At this point, the group has to decide how this problem is going to be fixed and steps that are to be taken to accomplish this task.

Week 6: Goals

Heading in to week six the groups goal is to redesign the SeaPerch and test the new design at the Dac.

Week Five: In Overview

The goal for week five was to disassemble and redesign the SeaPerch. In addition to this, the group intended to gather the necessary materials for assembling the new design and by the end of the week hopefully test the design at the Drexel Pool (currently the group is waiting to hear back from the people in charge of running the pool.) If the team is unable to test the SeaPerch at the DAC, then the Perch will be tested on the Schuylkill River.

Construction of Original Design

During week four, the group assembled the SeaPerch according to the original design provided by the SeaPerch website. While doing so, several issues arose. Firstly, the kit lacked several pieces such as a sixth PVC pipe and nut. As a result the group compensated for the lack of the pipe and down sized the original design by about half an inch on almost every piece of pipe.

Figure 1: Standard PVC Pipe Dimensions

(when disassembled add a photo of the PVC pipes)

With respect to the lack of a nut the group had to discontinue working until it could be replaced.

The next problem to arise was during the mounting of the thrusters. Given to the group were three thruster mounts (Figure 3) that did not quite fit the thrusters properly. 

Figure 3: Two of the Three Thruster Mounts

Figure 5: Site of Attachment & Thruster Mount

Figure 4: Site of Attachment

To solve this problem, the mounts were bent and reshaped with needle head pliers. Once the thrusters were mounted onto the SeaPerch, the group finished assembling the original design. From here the next step in this process is testing it.