Project Outline
Personal Project
As apart of a first year design project, me and 3 other group members were tasked with designing a toy from scratch
The skies were the limit, literally.
The idea of "Armageddon" was meant to be a toy for children 10-13 years old, taking inspiration from popular toys such as stomp rockets.
As a first year, designing a projectile launcher with no prior knowledge of aerodynamics proved to be quite the challenge.
What is Armageddon?
Second Iteration of Armageddon
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Armageddon is a pressurized gas launcher designed to launch a single projectile before needing to be reloaded again. It is meant to be fastened to ones forearm using Velcro.
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Once the launcher is fastened to the users arm, a bike pump is used to pump air into a ABS piping chamber. Once the gas pressured is built up enough, it is ready to launch.
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Once ready to launch, one of two different projectiles are loaded onto the launcher. A rocket, or a plane. Then the user simply clicks a button connected to a valve which releases all the air through the barrel of the launcher, launching the projectile.
Project Outline
Design
After choosing the toy idea I wanted to do, the first step was to start making it. The goal was to finish in under 4 months, while handling all our normal academic responsibilities.
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I started from the beginning. I want to make a projectile launcher, how will I launch projectiles? How will they be loaded? How will the mechanism be activated? These were all important questions to consider when designing this toy
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Due to time and budget constraints (starving first year engineers trying to pay tuition. We were all broke), the following design decisions were made:
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Material would be cheap, PVC and ABS piping
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The energy input would be gas pressure due to us having access to a free, old bike pump
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Initially we would use a solenoid valve (which would change has the project went on)
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And so we ventured out to Home Depot to buy piping for the structure of our gun. After we bought what we needed, I then machined all the piping to the desired shapes, as well as created a hole for the bike pump valve to interface with the pressure chamber.
First Iteration of Armageddon & Sketch
Design Decision Making
After testing Armageddon with the solenoid valve, we were disappointed in the distance we were able to launch our projectiles. It appeared that the valve was opening to slow, releasing the energy from the air pressure at a slow and controlled rate, rather then rapidly.
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To combat this, I brought up the idea of using a ball-valve. This valve was opened by the user, meaning that if you were strong enough, you could rapidly open the valve. This allowed us to reach the 7th floor of E7 (roughly 30 meters or 98 feet).
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Although this appeared to be a good solution, it came with its own issues:
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It required too much force to turn the valve due to how much internal friction there was. A 10-13 year old child would not be able to turn the valve effectively
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There were safety hazards regarding the speed and distance the projectiles could go
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As a result, this version of Armageddon was only a prototype, later being adjusted to fit the boundaries of the project.
Second Iteration of Armageddon Being Launched
Projectile Design
A small addition along the way was the introduction of multiple projectile types. Initially I didn't think the design of the projectiles was going to be complicated, so I focused all my efforts into the launcher itself. The two projectiles I wanted to make fly were a rocket and a small plane.
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I had no idea how difficult it would be to make a projectile fly properly.
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After doing research on wing chords, I designed a small plane using cardboard for the fuselage and foam for the wings themselves. I had hoped that the dimensions I purposely chose for the wings would lead to the pressure distribution across the entire wing to be reduced to a single lift force to provide stability.
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I then added weight to the front of the plane by using paper clips, so that the planes would land on their nose cone, and so that it wouldn't fly upwards and flip over after being launched
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As seen in the video, the plane flies pretty well.
CAD Model of Rocket Projectile
Plane Projectile Being Launched
Final Design Decisions
Finally, I ended up opting for a more expensive solenoid valve. Being able to push a button to have the valve open was too attractive of an idea for me. This valve was bigger, and opened much quicker, eliminating both the problem of the valve being hard to open and the force from the air pressure being too minimal.
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Both a plane and rocket were designed. Initially each projectile featured a 3D-printed nose cone, but it was found that the nose cone would often shatter on impact.
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Using a simple arm brace (purchased off the shelf) and some Velcro, Armageddon was now easily mounted to any wrist of any size due to its adjustability.
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Piping cement was used on all the connections in order to prevent any fluid leakage, allowing for a much greater force being applied to the projectiles
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And finally, we all had a blast making it. Truly an introduction to engineering!
Final Armageddon Design
Results
Overall, this project was extremely rewarding and fun to do. It does hold a special place in my heart because it as the first real exposure I ever had to engineering. In such a short span of time I gained so much knowledge, plus my TA bought me a cookie because we managed to hit the roof of Engineering 7 at our max pressure. Some results from this project were:
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Hitting the 7th floor of E7 (roughly 98 ft)
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Achieving a 92% for the project
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A large crowd on symposium day
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Learned about aircraft structure
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Kept the budget under $100
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A cookie from my TA!
