The Soda-Bottle Rocket Egg Launching Mission

Q-Focus (Rocket Science): Questions that we came up with included, 

"What is rocket science?" 

"How is this going to work out?" and 

"What will we need to consider in making these rockets?" 

The first question was kind of basic. The second and third one were more important. "How is this going to work out?" was answered. The rockets we made turned out to be great in the end, except for North Korea. We actually managed to launch the rocket in the air, get it to land at an adequate distance, and have the egg still intact. By pumping air into a compressed chamber (the soda bottle), and having the rocket blast off as water escapes out of the nozzle, we accomplished in exceeding the distance of 30 meters required by the guidelines. The third question was also answered. We had to figure out what materials we were going to use to make the rockets. That took a great deal of thinking and pondering but eventually it all worked out in the end.

Making the Rocket: It took us a few days to make three rockets. We already had the names of the rockets in mind; all we had to do was build the actual thing. 

In order to build the rockets, we used:

• Plastic 2 L soda bottles (fuel/compression chambers)
• Duct tape
• Safety cutter
• Foam board
• Scissors
• Ziploc bags
• Toilet paper
• Eggs
• Water
• Graduating Cylinder
• Printer (for rocket designs)
•  Construction paper
•  Aluminum

                                                                                  

Figure 1: Materials. Notice how we had separate pieces of soda bottles, which were taped to the whole soda bottles.

Figure 2: We had to cut the top part of bottles in this way. The piece would then be taped to a full soda bottle that's flipped upside down.

Figure 3: Cone shaped pieces placed on top of soda bottles.

Figure 4: Aluminum balls to be put in cones.

          The soda bottles were fundamental to creating the rockets. We used six bottles in the process; three for the body of the rockets, and three for pieces attached to the rocket. We had them washed and cleaned before utilizing them. The duct tape was necessary to securely seal different parts and support the rocket in general. The safety cutter was used to cut out the fins for the rocket. Accordingly, the fins were made of foam board. Scissors were used to cut out pieces of soda bottles that were to be attached to the rocket (see Figure 2). The eggs, provided by chickens from some farm, were kept in Ziploc bags in case they broke as to prevent a mess from happening. Toilet paper was used to absorb the impact made when the rocket hit the ground after launch, thus preventing the eggs from breaking. Construction paper was used to make cones that would make up the head of the rocket. This also helped in absorbing force in case the rocket made a skydive into the ground. Water was fuel for the rockets. It was pumped with oxygen (O2), increasing the pressure within the rocket. In addition, a graduating cylinder was needed to measure the amount of water that was to be placed in all three rockets. Lastly, the aluminum was essential. We took large sheets of aluminum and compacted them into small balls (see Figure 4), which we then placed into the cones (as mentioned, made of construction paper). This helped to support the cones as they hit the ground and absorbed some of the impact.

          

            In conclusion, the major decisions we had to make concerned how the rocket would look like, how we would make it reach the required distance, and how we would accomplish doing so without breaking the eggs inside the rockets. 

The Physics: Physics is a vital part of this rocket lab. Major concepts such as acceleration (velocity is changing), force, and velocity (measure of speed) are examples of things that we've learned that are all included. If we know the force and acceleration, we could find what the force is. This is where Newton's laws of motion play an essential role; Newton's second law (F=ma) is particularly useful. As the rocket is launched (person pulls pin), the rocket has a large amount of acceleration as the fuel (water) explodes out from the bottom, the nozzle. The pressure building up in the rocket helps it to increase in acceleration when the rocket is released. In addition, the rocket must "fight" against the force of gravity (9.8 m/s^2).

Other physics concepts that are considered:

• Inertia: resistance of an object to a change in its state of motion.
• Air resistance: forces that oppose an object moving in air.
• Projectile motion: object moves along a curved path due to gravity.

A visual representation of the forces enacted on the rocket:

 Key Info: With this in mind, we needed to find a way to utilize physics to our advantage in order to get the rockets off the ground, in the air, and far away from the launch site. To start off, we needed to have rockets that were sturdy and flexible. They couldn't be too light to prevent air flow from being a problem. They couldn't be too heavy or else gravity would take over. We had to have enough fuel to get the rocket to its destination. We had to have something that would cushion the egg when the rocket hit its destination, something that would absorb the impact instead of transferring it to the egg, causing it to break. And finally, the fins helped out in air flow when the rocket was in the air.

Practice Launch Photos: {Me with camera}

Kenneth doesn't look too happy. 

Kenneth isn't very good at this.

Rocket lands. Egg survives! Notice how the cone collapsed but the rest of the rocket was largely unaffected. 

Results: We made three rockets. "North Korea" turned out to be just like the actual thing: it failed. It reached the shortest (15m) out of all the rockets launched, including the ones from second period. Again, it was an utter letdown. The other two rockets were much better. Iran reached the farthest distance at 82 meters, China at 68 meters. So the average of the three turned out to be 55 meters. None of the eggs used were broken in the process. All three rockets were set at 35 degrees. All three rockets had 800 mL of water for fuel. We chose this number because we wanted to have a substantial amount of fuel and have some weight on the rocket. At the same time, we needed to make sure that there wouldn't be too much weight as to prevent the rocket from not reaching its maximum distance. Overall our choices for angles and water quantity were good. Two out of three of our rockets succeeded in meeting and exceeding the distance required. We believe that the only reason North Korea failed miserably is because we didn't structure the body of the rocket correctly, as we had done with the others. We later found out that it was loose and unstable, and this probably contributed to its malfunction.

Summary...

What went RIGHT:

•  Rockets were made on time
•  Average distance exceeded requirement (30 meters)
•   Eggs survived

What went WRONG:

•  North Korea       

What I learned: It's possible. It is actually possible to have something nearly made of plastic and water fly high into the air and land at a distance. Of course, this was more than just plastics and H2O; physics was part of the problem. Physics and concepts that are fundamental in physics, such as force and air flow, all played a major role in helping us get these rockets to work out the way they were supposed to. In the early stages of the project I thought that this was simply crazy, even bizarre. But I was mistaken. The results of our rockets were both surprising and satisfactory.