Based on the past two sections of the rocket project, we partnered up and planned a final rocket. I wanted an extra challenge, so I gave myself one: We made our entire rocket out of balsa wood. Why? I wanted this rocket to be extremely large, and yet incredibly light, while not losing structural integrity. The blueprint for our rocket is below.
The balsa wood was cut into .5 inch wide, three feet long strips. Then we glued them down onto three slices of a wooden dowel. This kept the rocket cylindrical all the way down. We used super glue, because of how strong of a hold it has. We also used super glue to seal the creases between the strips. On one end, there was a strip that had been cut a little bit too thin. So, we cut a new piece to put right there that filled in the spot. |
Next, we made a nose cone using another also wood dowel. We drilled a hole into one end, and then used a screw to attach the dowel to the drill press. Next, while the dowel was spinning, we used sandpaper wrapped around a block to shave the dowel down into the shape of a nose. We left the end cylindrical, so it can be inserted into the rocket. We also made a parachute that we attached to the nose cone. This was made out of a heavy duty plastic garbage bag, which was cut into an octagon. We attached fishing line to each corner, and tied that together in the middle. using a thick rubber band, we attached the nose cone and parachute to the rocket. |
We then measured the rocket for it's center of mass, and then center of pressure. Each side of the center of pressure needs to equal each other in surface area. Based off the surface area of the front, we figured out how large to make the fins for the back. After lots of calculations, we realized we would need six fins, all of which would give fifteen square inches of surface area. We sanded them down after cutting them, so they would be as close to exactly identical as possible. Then, after painting them, we super glued them to the base of the rocket. A picture of the final rocket is below.
Our next challenge was to figure out how to create an ejection of the nose cone. Normally, as a motor finishes, a second amount of fuel is lit and pushes upward through the rocket, pushing off the nose cone. However, our rocket had pieces of wood in the middle of it, which meant the ejection wouldn't have worked. We talked it through with Andrew, and decided to put a small capsule full of fuel in the top section, next to the parachute. A fuse with attached, and put through a hole in the side that then ran down the side of the rocket. This was twice the size of the fuse that would be used for the motor, which would be lit at the same time. That way, when the rocket launched, the fuse leading to the nose would be halfway through, and (hopefully) pop the nose off just as the rocket finished its acceleration. We put the piece in the rocket, and hoped for the best. |
Finally, we headed off to Fiesta Island to launch our rocket. using pieces of straw, we created a launch lug, so that when the rocket launched, it would follow a wire until it was going fast enough to keep itself straight. Below are videos of our launch.
Our rocket performed a lot better than I expected. I was worried that the balsa would rip apart, but it stayed intact, and went even straighter than I had planned. It also went super high. However, as you can see, the nose cone didn't eject until after the rocket crashed. The rocket flew nose first into the ground, and ripped itself to pieces. Below is a picture of what the crash site looked like. We collected what we could, and left the smaller pieces in the dirt. When we got back to class, I duct taped the rocket back together, so that we could present it later for exhibition. However, what's left of the rocket is only two feet long; one foot shorter than the real rocket.
Project Reflection
- Now that this project is complete, how do you feel about it? What things stand out?
- What, if any, science or technological things did you learn from doing this project? What is necessary to understand to build a successful rocket?
- What, if any, metacognitive knowledge did you gain? (what did you learn about yourself as a learner - work habits, work ethic, tendencies, etc.)
- How did you collaborate with others in this project? (Who did you work with? What did you contribute? How did you operate as a group or unit?)
- If you could do this project again, would you do anything differently? What advice would you give to the next class of rocketeers?
- Based on your responses above, what advice or suggestions would you give to Andrew to help him design a better rocket project?