Chris's Visual Representation of tAble five's building process for the BSD Battleship Project

Project Intro

For all intents and purposes, our goal was to make a glorified potato cannon that fires off pressurized air, and a base that can set the cannon at varied angles of elevation and rotation. We began this project with the intent that we could collect data to consistently fire at different distances based on varying launch/fire angles and pressure. It was also supposed to incorporate Arduino in both the angling systems.

Building The Stabilizer

We begun the project by designing, prototyping, and printing out a stabilizer on the laser printer. Although it may not look it, I had to redesign the stabilizer several times to suit our needs, with the final result being shown in the two onshape screenshots above. While designing the stabilizer, our group went through a brainstorming process where I designed a variety of basic systems for adjusting launch angles. One of these ideas involved using strings and a pulley system to adjust a piece that would have connected to the stabilizer through the holes in its center (which we never removed albeit they had no purpose in the final design) allowing us to control the vertical angle of the cannon. Although several designs were considered for the base of the cannon, the stabilizer was only modified slightly for each design. It was designed to be modular, to take up a small amount of room while maintaining a strong resistance to any flexing of the cannon itself. It was designed so that the stabilizer could be easily incorporated into other designs and use less material than a traditional box. The hardest part of modifying the stabilizer was adapting the design for the cardboard prototype to the wood as the design of our stabilizer required very small tolerances. Thus we had to account for the slightly varying thickness of wood pieces and the kerf of the lazer(this is how laser should be spelled). One difference between the designs we used (bottom two) and the cardboard models is the triangular center piece that fits in the middle notches in the cross pieces. This was used to help prevent any motion that would cause stress on the PVC connecting the barrel, valve, and pressure chamber.

Arduino

Unfortunately, Adobe spark won't let me put a video in, but you can click the button to see one. For the arduino portion of the cannon project, we learned how to use various common components in circuits and were introduced to the arduino programming. The cannon was originally supposed to have analog controls that could be adjusted with the arduino, but a lack of resources did not allow this to come to fruition.

Cannon Assembly

This is the assembly of the cannon. We all took turns using the miter saw to cut the PVC to specifically marked lengths. We then used pressurized air to blow the dust out. We connected the PVC using different joints and mates secured air tight with PVC primer and cement. We then proceeded to use a drill and some hot glue to put a bike valve in the pressure chamber, which would allow us to pressurize the cannon. By installing a sprinkler valve we for all intents and purposes put an electronic trigger in our cannon that would allow the rapid release of pressure through the barrel to provide proportion to launch a projectile.

Base Design and Assembly

This is the final design of the base. It was changed again, and again, and again, until we finally decided to make a rectangular box shaped base. One of these ideas included a set of towers and pulley systems that provided an analog method of adjusting angles; this was eventually deemed it too unstable to handle the kick of the cannon. Another idea proposed an idea using incremental wedges, but it also got discarded because of its complexity and instability. Another idea (which was eventually incorporated in the modification of the final design) included a set of towers with holes or notches in it to create set heights and thus set angles. Additionally there were several other ideas that never got past the stage of concept design, and eventually we settled on the box because it was the most stable (and also because we took too long contemplating different designs before picking one and running with it). In the final design the length/depth of the notches were carefully placed to allow for incremental adjustments of angle, allowing us to increase the angle between two to three inches from starting at a 45 degree ending with nearly a 90 degree angle. One thing that we did not account for when designing this was air resistance and wind. Theoretically in a perfect situation, the same set of ranges for a projectile may be obtained from either 45 to 90 degrees or 0 to 45 degrees; however, air resistance and wind led to inconsistency when firing at high angles. This was modified by firing using the tabs originally meant to add a back to the box, as incremental heights which we could attach a bar for the cannon to rest on allowing it to fire at a set of angles. One flaw with this design was wood consumption, we never double checked the size of the measurements taken when this was being designed and transferred to onshape. The result of this mistake was a box that was to big for the cannon, wasted materials, and was much less balanced than intended (this is ironic because most of the other concept designs were discontinued on the grounds of instability. We also replaced the horizontal rotation design in the top right corner without simpler one better suited for the larger and heavier base.
Our team finishing the base cutting and assembly. We added modifications such as a baring and new rotation system to accommodate our larger design. We also added a shelf to help mount the turning system and allow us to fire at lower angles (shooting at high angles allowed the wind to change the path of the projectile too much). Custom notches were cut and chiseled out to help hold the cannon securely to the base.

Testing

After building the cannon we did some test firing and recorded the range of shots an different angles.

FAILURE LOG

  • When making the stabilizer we originally had only two cross beams, and eventually realized that it would need three to provide the necessary support to the cannon.
  • When making our final base design we did not double check measurements and when we did the conversion from the box making website to onshape. This heavily impacted material usage, weight, and balance.
  • When making the original turning system we made the mistake of making the hole for the turning system too small to fit the PVC

Project Grievances

Overall I hold a very large amount of disdain for this project. I understand that this project was new and there were a lot of shortfalls in the connect between concept and execution. That being said, the majority of my discontent arises from inadequately defined/constantly changing criteria, too much dictation and chunking of the design process (It would have been better to simultaneously create the designs of the stabilizer, arduino, and base so that a holistic and parametric design approach could be taken), lack of explanation of limitations and restraints of the project, and overall scarcity of guidelines as to what expectations were for both the project itself and this portfolio. Consequently the result of this was confusion and the need to rework designs. This required my group and I to spend more time on creating new designs. This was particularly stressful on me. I have done a lot of CAD in middle and high school, and even enjoy it to an extent. As a result I have become fairly familiar with Autodesk and Onshape, and my group decided I was the most suited to execute our designs in the CAD program. As a result I probably designed/redesigned about 30 or so parts and at least 5 assemblies, most of which were voted to be discarded as a result of confusion over the changing and unclear requirements and guidelines of the project. Personally this made me feel as if my time was wasted and left a very bad taste in my mouth for this project, especially because the final design our group decided to implement was based on poorly taken measurements and last minute decisions. Overall I feel that I invested a lot of time into design, which was mostly discarded in favor of an more easily executable design that required less thought and time because of a deadline that had to be met in conjunction with indecisiveness on our part as a consequence of unclear expectations. The result was a poorly constructed base that could not seemingly fire with the intended level of consistency. I understand that this project and portfolio are meant to show off what we are capable of and what we have learned, but in my honest opinion, I do not think that the final product our group put out is something to be proud of, and I don't believe it was educationally consummate with other school projects; therefore, I believe that if I do not feel proud of the final product I should not feel proud of the process of it's design and subsequently should not feel that this is worth including in any of my resumes or applications in the foreseeable future. The point of engineering is to create a solution to a problem. This isn't science, where failure is an acceptable part of the learning process. The way I see it is that the final product of engineering should not be a failure and I believe that the final product our group put out was a failure and thus little time and effort should be expended presenting it, instead it should serve as an explanation of why the end product failed and what attempts were made to improve it.

Created By
Christopher Evans
Appreciate

Credits:

Tbl5

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