Propeller Designs: Week 8

As we we're going to test the first set of propellers that were printed in the diving pool, we encountered a drastic problem. The propeller was connected to the motor shaft through the use of a sleeve that slid onto the shaft. This sleeve held the propeller and was soldered to the motor shaft. However, the bond was obviously not strong enough since during the testing the port motor sleeve fell off of the shaft. We are working to correct this issue by carefully re-soldering the propeller sleeves onto the motor shaft along with another adhesive.
The two other propeller designs have also been constructed and sent to the rapid prototyping machine. The first set of propellers that were printed had a blade length of 10mm while the propellers provided in the kit had a length of 15mm. Therefore, to keep differences in blade lengths consistent, one model has a blade length of 15mm while the other has a length of 20mm. These are shown below in Figure A and Figure B, respectively.

Figure A: 15mm blade length

Figure B: 20mm blade length

James Esser

Daniel Stenger

Propeller Designs: Week 7

After looking at the designs, we reevaluated how exactly we would go about testing to see the differences in propulsion. Instead of testing two separate designs, we chose to modify Design A. Previously, the Pro/ENGINEER files had been in the wrong units and wrong magnitudes. These changes are displayed in the figure below.

We then sent these designs to the rapid-prototyping machine which fabricated the parts in hard plastic. In order to make sure that these propellers stayed on the motor shaft, a hole needed to be drilled in the center. This was done at the machine shop with the drill press and is depicted below.

The next step in testing submarine propulsion is to print out two more sets of propellers. The current propeller blades are shorter than the ones provided in the kit. Therefore, the next set will have the same blade length as the ones provided in the kit. Then the final set will be longer than those provided to us in the kit.

James Esser
Daniel Stenger

Water Capsule: Week 7

The purpose of this project was do use the modified Sea Perch to test water for pH, impurities, and other qualities. Sensors that we looked into for these measurements were all far over budget, and most of the ones available would not be able to operate under water. As an alternative to submarine-mounted sensors, we created a water capture device to retrieve a sample from a specific area in the water and return it to shore for testing.
The capsule is constructed of a three-inch long, half-inch diameter piece of PVC pipe. One end of the pipe is sealed with an end cap an PVC cement. The other end is covered by a sliding cap with a long sleeve that covers most of the pipe. The sliding cap is fitted with a rubber O-ring to prevent water leakage when the capsule is closed. Six holes are drilled into the sleeve, so that when the cap is lifted, water will enter the capsule. The idea is to mount a spring to keep pressure on the cap and keep the capsule closed. A small motor will be used to open the capsule and allow water to enter at the desired moment.

Brian Bucci

Tim Kaack

Justin Goebel

Propeller Designs: Week 6

In order to find the most effective propeller designs, we decided it would be a good idea to design two different propellers and then test the differences between them. To get a basic idea of how a standard submarine propeller looks, we conducted some research and constructed two models in Pro/ENGINEER, which are shown below.

Figure 1: Design A

Figure 2: Design B

The thought behind the Design A was to be able to move the most amount of water as possible. However, the issue with this design is that, theoretically, it will move faster in one direction than the other. Because of this, Design B is curved in both directions that will be able to move the water in both directions giving a better balance of forward and backward motion.

Brian Bucci
Tim Kaack
Justin Goebel
Daniel Stenger
James Esser

Motor Orientation Pictures: Week 5

The following pictures show the changes in motor orientation made to the SeaPerch. In order to remount the motors differently, the original zip-ties had to be cut. Also, more motor wire was required so the butyl rubber tape needed to be pulled back to expose more wire. Finally, the motors were re-positioned and then zip-tied  to the chassis.

Motor Orientations and Propeller Designs: Week 5

Now that the Sea Perch is assembled using all the standard parts, the next step is to optimize propulsion and maneuverability. Our first step was to adjust motor orientation. The two factors that are affected most by changes in motor orientation are the Sea Perch's turn radius and upward/downward movement. The propeller are capable of spinning in forward and reverse directions, but because of their shape, propellers provide more thrust in one direction than the other. The direction that provides more thrust will be referred to as the forward direction.
The vertical movement motor was originally mounted with the propeller's forward direction aiming down. We decided to reverse this for two reasons. The way the Sea Perch was constructed, it's average density was slightly greater than that of water, so it had the tendency to sink slowly. With the forward direction aimed up, the Sea Perch was able to overcome this tendency more efficiently than before. Also, in the original orientation, The propeller itself was located on the top of the Sea Perch, above the motor. When the Sea Perch would ascend to the surface of the water, this propeller would emerge from the water and splash around as it would spin on above the water. This caused instability and minor loss of control. The new motor orientation avoids this issue altogether.
The two side mounted motors are used to control the submarine through turns. Through first-hand testing, we determined that the when the motors were farther apart, the Sea Perch had a smaller turn radius. To implement this advantage into our design, we positioned the motors on the outside of the chassis, as opposed to the inside where the were originally. This added about 3 more inches of space between the two propellers (distance motor shaft to motor shaft), and should give the Sea Perch a smaller turn radius.
Our next approach to improving the Sea Perch is to increase the propulsion the motors are able to exert. To accomplish this, we will be using the 3D printer to manufacture new propellers. We are currently in the process of designing propellers in Pro ENGINEER. We are basing the designs off of research done on propellers and propulsion to come up with designs that maximize propulsion delivered by the propellers.

Brian Bucci
Daniel Stenger
Justin Goebel
James Esser
Tim Kaack

Motor Assembly Update: Week 4

A small packet of epoxy came included in the Sea Perch kit. This epoxy was supposed to be used to attach the metal caps that held the propellers to the metal rods that were spun by the motors. This epoxy, however, was would dissolve when in contact with chlorine, which was unacceptable due to our plans to test the submarine in a pool. We purchased marine glue that would hold up better than the epoxy in nonstandard conditions. This glue was applied to the pieces, and the propellers were tested in water. The glue wan unable to withstand the stress caused by the water resistance, and the pieces separated from each other.
To solve this problem and get the pieces attached once and for all, we decided to use solder to hold the propeller sleeves onto the motor shafts. We placed the sleeves one at a time into a vice, melted solder into them, and plunged the motor shafts into liquid solder, allowing it to cool and form a strong bond. All three propellers were then attached and tested in water. They held up to the resistance and were able to operate without fail.

Brian Bucci
Dan Stenger
Tim Kaack
Justin Goebel
James Esser

Electrical and Control System Update: Week 3

The correct instructions for how to put the control box together were received this week and the control box was assembled.  The two control sticks control the forward and backward motion of the sea perch.  The two buttons sticking out of the front of the box control the up and down motion, one spinning the motor forward and one spinning it backward.  The little box in the middle is the fuse that we thought we needed to find.  The black box is the Ethernet port. Upon completing the control box, it was found that there was a problem with the soldering, so a volt meter was used to find where the break was in the circuit.  We found that the problem was the soldering of the ground wire, so that was a very simple fix.  After that, the board was tested and moved the motors according to the plan.

Tim Kaack

Justin Goebel

Structure and Fabrication Update: Week 3

Following the completion of the chassis of the SeaPerch, the motors were fully constructed. First, the motor wires were soldered to the motor leads. The motor wires were from a CAT5 cable so to access them the cable needed to be stripped and then the individual wires needed to be stripped. Then, the motors were covered in electrical tape to prevent water from entering the motor and then encased in the film canisters. There were holes cut into both the top and bottom of the film canisters to allow the motor shaft to come out of the top while the wires came out the back. Once the motor was in the film canister, wax was squeezed into the extra spaces, waterproofing the motor.
The mesh bottom was then attached to the bottom of the chassis by using the small black zip-ties in the kit. The excess was trimmed off to eliminate drag. The motors were then mounted to the chassis, as shown in the picture below, using zip-ties and holes drilled into the side support beams.

After the motors were secured the CAT5 cable used to house the motor wires was waterproofed at the area where the wires were exposed. This was done using the butyl rubber tape which was then covered with electrical tape to fully waterproof the area. In order to make sure the cable would not run into one of the motors during usage, the cable was mounted to the side of the chassis in two places to completely ensure it would not move about during submersible usage.
The SeaPerch is now currently ready for the Philadelphia Science Fair where we will be showcasing our submersible.

Daniel Stenger
Brian Bucci
James Esser

Structure and Fabrication Update: Week 2

While having access to a saw in lab, the PVC pipes used to create the frame for the SeaPerch were cut. Thenecessary lengths included: two 2 1/2", two 4", two 4 1/2", four 1 1/2", and four 5". These pieces of PVC were then assembled using "Elbow" and "T" joints and foam tubing, as per the given directions. Then, holes were drilled in the corners of each of the joints using a 1/4" drill bit in a handheld drill. These holes will allow the PVC chassis to fill with water allowing it to sink into the river while the foam will give a buoyant force. Adding the battery will act as ballast allowing the motors to have full control over the positioning of the SeaPerch while submersed. The completed chassis is depicted in the photographs below, showing three different angles.

Future goals for the upcoming week are to complete the motors, attach them to the chassis, and finish the rest of the fabrication in order to be ready for the Accepted Students' Day Showcase that will be occurring on Saturday, April 21st.

-Daniel Stenger

-Brian Bucci

-James Esser

Electrical and Control System Update: Week 2

The SeaPerch probe comes with a basic control system that needs assembly. Week two was spent in focus on the control system: assembling pieces, taking inventory of the pieces, and planning the initial build of the control box. The kit gave specific instructions on how to build the control box, but the instructions were for a previous model, and no new instructions have been found. A lot of time was spent deciding how to best lay out the components of the control box. The kit also lacked an important fuse that is absolutely necessary for safety and function. The team will have to purchase this piece, or find it on campus. The goal coming into next week is to find updated instructions on construction of the control box and to move forward with assembly.

Timothy Kaack and Justin Goebel

Justin Goebel

jg923@drexel.edu

Materials Engineering

Control Systems and Sensors

Team Members

Timothy Kaack
tmk73@drexel.edu
Electrical Engineering
Head of Electrical Design

Team Members

Brian Bucci
bwb42@drexel.edu
Engineering Undecided
Navigation and Stability Designer

Team Members

Daniel Stenger

dys32@drexel.edu

Undecided Engineering

Head of Overall Design and Fabrication