Under Siege (Catapult)

Title Paragraph:
This project was focused on building a machine that would be able to launch a strong projectile. We had the option to build either a catapult, a ballista, or a trebuchet. My partner, Sara, and I chose to build a catapult. Our catapult needed to launch a marshmallow. One type of launch with the marshmallow would be for distance, as large as possible, and the other type of launch would be for accuracy, so that we could shoot the marshmallow into a bucket. This project applies to the study of technology because we formulated and built a machine that would perform a specific purpose.

Technological Concepts:
One technological concept associated with this catapult project is force. The more force we pulled on the launching arm with, the more force it applied to the marshmallow. The large force allowed for marshmallow to have increased speed in the air and increased distance of travel. We were able to reach the farthest distance of 23 feet. Our other goal was for good accuracy, and by changing (raising or lowering) the amount of force we applied on the launching arm, we could change the distance the marshmallow needed to go to get into the bucket. Also, we adjusted the aim of the projectile by shifting the launching arm from left to right.

Learning Goals:
Our goal for this project was to figure out the most practical ways for the different parts of the catapult to be put together. There are several different ways the launching arm, rubber bands, and other pieces can interact, but we wanted to learn how to build a strong catapult. Neither my partner nor I had ever built a catapult or a wooden project like this before, so we hoped to figure out the ways that good catapults work.

Description of Our Project:
Our project was held together by a wooden pole that went through the side blocks and the launching arm. The arm was able to be pulled back and launch forward when released because of four rubber bands which were strung around two nails on the side blocks and two nails on the back of the arm. We placed a wooden bar across the whole machine, and its purpose was to stop the launching arm's motion after it was released. At first, after several test launches, we discovered that the launching arm was stopping too late to allow the marshmallow to go very far. We moved the wooden bar down further, and that allowed for the arm to stop closer to a 45 degree angle when launching. We know that a 45 degree angle allows for the farthest projectile distance.

Positive Feedback:
The catapult held up very well in terms of distance and speed of the marshmallow launches. It did so probably because it was a very sturdy machine, and the four rubber bands and our own arms that pulled the arm allowed for it to move with great force. These construction and testing elements performed well. The design element that we were proud of was the wooden bar that helped the arm to launch the marshmallow at almost 45 degrees.

Redesign Paragraph:
If we were to do this project again, we could have figured out an even stronger way to use the rubber bands so that the marshmallow could be launched further. Also, we could change the overall design of the catapult so that it could launch the marshmallow not only far but higher up into the air. This would allow for the marshmallow to fall into the bucket more easily. One way we could do this is by adjusting the machine so that the wooden bar could be placed even further down.

Technological Resources:
I never realized that Elmer's glue is strong enough to hold a wooden machine, like our catapult, together. This was quite convenient, as there were many parts we had to glue together. Also, the wooden pieces we were able to choose from varied in thickness and in length, and that was very convenient because we did not have to cut and carve many pieces of wood. The only big machine we used was the chop saw, which we cut the biggest, thickest blocks of wood with. For the thin pieces of wood, we used a simple hand saw. The convenience of the technological resources allowed for us to put more focus into the design of the catapult rather than laborious construction.

Biggest Challenge:
The biggest challenge for us was the design process. We did not have much experience with catapults at all, so it was hard to even think of one design, let alone several designs. Eventually, we were able to put a plan together, and we even redesigned parts as we went along, like the rubber band placement. And although our catapult design may have seemed quite simple, it was effective, and effectiveness in distance and accuracy was the main goal.

What We Learned:
All in all, we learned how catapults actually work. In order to launch with strength and a good projectile, they require strong elastic components (we used rubber bands), sturdy materials, and a specific launch angle. The only type of catapult we were familiar with before this project was a simple plastic spoon. From our struggles of designing it, to our epiphanies while building it, all the parts of our catapult came together and we felt successful and more knowledgeable about catapults and projectiles in the end.

Aerodynamics

Title Paragraph
This project focused on the concepts of aerodynamics. We learned how to use wind tunnels to help us calculate the drag of two airfoils and our CO2 car. We designed our car by keeping in mind the factors of aerodynamics that would possibly help or prevent our car from having a high speed when it was in action. We built our car using pine, wheels, and rods to connect the wheels. We designed the shape of our car to have two bumps and a small, pinched front end. By streamlining our design, we hoped that drag would be reduced as much as possible, allowing the car to move fast.

Technological Concepts
The technological concepts of aerodynamics were related to this project. We had to make sure that when a thrust- a push suddenly or violently in a direction- was applied from the puncturing of a CO2 cartridge, our car would travel fast along the fishing line. We tried to reduce the amount of drag, that would work against our car, as much as possible.

Learning Goals
Our goals in this project were to figure out the best design for a CO2-powered car that would allow it to travel as fast as possible. We had to learn which designs worked best by testing everyone's different models. I was wondering how the slightest differences in shape would affect the cars' performances. Also, I hoped to better understand how drag will be affected by the shape of a car, including pointed tips, curved tops, and more.

Description of Project:
Our car had a pretty basic design in the way that it was not shaped in an abnormal way, but we did include a bump in its front and then a curve that rose towards the back. We figured the air would be able to accelerate down the bump and then rush up the ramp. At first, the car we made was pretty big and heavy, and its race time was slow- about 3.5 seconds. We decided to sandit down a ton in order to make it smaller and lighter, and that really improved its performance- its final time was 2.9 seconds.

Positive Feedback

The best thing about our car was that it was the result of our problem solving. We built the car, tested it, and realized that it moved extremely slowly because of its large mass. We decided to sand as much as we could, and helped the car to have a reduced mass, a lower time, and a greater speed. Although our design seemed simple, it performed pretty well. I was quite relieved that our car's performance matched up very closely with that of the other cars, because they had such different, rounder, and smaller designs.

Redesign Paragraph

If I were to do this project over again, I would try to make the car even smaller. My partner and I tried to follow the size requirements in the first place, but our car was still much bigger than everyone else's. If we had built it to be smaller, it could have gone faster. Also, I would like to try to make a more different design for the car and see how that fares, compared to the original design. This probably would include a pointed tip and maybe a hollowed-out section.

Technological Resources

We used tools like the drill press, hand saw, and sander to make our car. We had never used the hand saw before, and it really helped us to shape our car the way we wanted while we cut it out of the wood block. In addition, the sander was our savior when we made our car smaller and lighter. It shaved down a great deal of mass.

Biggest Challenge

The biggest challenge about this project was following the size requirements while also making our car fast enough compared to others. There were length and weight requirements and we also had to be smart about the shape of the car. Our car was much bigger than the other groups', but once we shaved it down, its speed compared closely to those of the other cars.

What I Learned From This Project

I learned that when you want something to have speed, design is important, but mass may be even more important. A wooden car will not roll speedily if it is really heavy. Now we know that we must always take size into account when working on projects. Also, I learned about the many different concepts of aerodynamics and how they affect airfoils.