Materials

• Plastic two liter bottles (3 // $1.00)
• Cardboard ($0.00)
• Shoelaces ($2.00)
• Duct Tape ($3.00)
• Golf ball ($1.00)
• Old batteries ($0.00)
• Poster Paper ($1.00)
• Car Sponges ($0.00)
• Trash Bag ($0.10)

 

Procedures

1. Planned out and drew out rocket design, considering the parachute, egg, and height requirements
2. Listed out materials and purchased them (listed above)
3. Cut out one bottle from the bottom to hold the egg and parachute
4. Left another bottle un-cut to act as the fuel cell
5. Cut out a circle from the trash bag
6. Reinforced the edge with duct tape
7. Cut out four holes around the edge evenly spaced for the string
8. Cut four holes out of the bottom of the cut bottle and tied the shoelace through and attached the parachute
9. Traced out a triangular wing on cardboard with a ruler and cut out one wing
10. Used the first wing as a template to cut out the other three wings
11. Reinforced the wings with duct tape and trimmed excess duct tape to make sure the wings were durable and would not get soggy in the water
12. Taped on the wings to the uncut fuel cell, evenly spaced and slightly bent to create a spin when the rocket was launched
13. With the poster paper, cut out a square and then rolled out a nose cone
14. Reinforced the nose cone with duct tape to make it more sturdy and durable
15. Attached the nose cone to the top of the cut bottle with more tape
16. Inside of the cut bottle with the parachute, we placed a golf ball and batteries at the bottom to weigh it down
17. Then put a layer of car sponge over the weights
18. Cut a slit in one sponge for the egg to rest in to be sandwiched between the other sponges
19. Placed in the egg sponge with one more sponge on top
20. Rolled up the parachute and placed it over the last sponge
21. Gently slid the un-cut fuel bottle face down, under the parachute bottle with the cone to form the full rocket 
    
    
    
    
    
    
    
    Results
    Overall, I do not think that our rocket preformed as well as we would have liked. Our main problem was that our parachute did not deploy, causing the rocket to fall down very fast and have a rough impact with the ground. As a result, our egg did not survive either. I think that this was mostly a design malfunction problem, because even though we had barely placed the parachute capsule on top of the main fuel bottle, it still failed to come off and deploy the parachute. Also, our design was very top heavy, which may have caused the parachute capsule to push down and tighten against the fuel cell as launch may have pushed it down. In hindsight, with the limited time and height the rocket had in the air, our design, which intended to flip the rocket over after apogee and deploy the parachute, seems flawed. There was not enough time and height for the rocket to completely flip over and separate, and our parachute only came out as the rocket was hitting the ground. Our egg protection with the sponges also proved to be of little help, as the egg completely shattered within its pouch of sponge inside the rocket. Although, despite our failed parachute, our rocket still managed to be one of the highest fliers. I believe this can be attributed to the shape of our nose cone, and the precision and symmetry of the exterior of our rocket, as it was very even and clean cut.
    
    
    
    
    
    
    
    
    
     Conclusion
    
    
    Based on observations of the performance of our rocket, along with some other successful rockets in the class, there are a few things that I would change in our rocket design. First, I would make the parachute and egg capsule much smaller and rest on top of the rocket and weigh the bottom of the rocket a little more than the top. This would make it much easier for the parachute to separate and deploy as the rocket starts coming down, as the bottom would pull away and the parachute would deploy without having to flip over. With the short amount of time that the rocket is in the air, I believe that this design would be much more effective. Additionally, making the rocket more bottom heavy and having the egg on top would be more likely to protect the egg if the parachute does not deploy, as it will not fall egg first into the ground as ours did. Finally, I would make the strings of our parachute a little shorter. The shorter strings means the parachute is less likely to get tangled and that it can deploy faster in the limited time it has to do so.
    
    
    
    
    

    Calculations

    
    Δy = V_it + ½ a_g · t²
    Δy = 0 + ½ (9.8 m/s²)·(3.04 s)²Δy = ½ (90.568 m)
    Δy = 45.283 m
    Δy = 45.283 m  · 3.28 ft / 1m
    Δy = 148.52 ft
    
    The height given by the teacher was 75. Our calculated height was larger, and I would assume more accurate, as the teacher gave an estimation based on looking at it, and we used math to thoroughly prove our height.
    
    Δy = V_it + ½ a_g · t²
    Δy  - ½ a_g · t^{2 =} V_it
    V_i = (Δy  - ½ a_g · t²) ∕ t
    V_i = (148.53 - ½ (-9.8 m/s²)(3.04s)²) / (3.04 s)
    V_{i =} (193.893 m) / (3.04 s)
    V_i 63.754 m/s
    
    
    

     Force Body Diagrams