Egg in Rocket Project

Our final project for Intro to Aviation and Aerospace was to design our own rockets. The requirements for the rocket were that it 1) had to protect a quail egg (land without breaking the egg) and 2) had to reach 40ft. We could make the rocket whatever size, shape, or material as long as it met the two requirements mentioned above. In the google drive above, I have uploaded pictures and videos of our process/launch and files we used to carry out our design.

Materials:

- Copy paper

- Gummed tape

- Cylinder shaped object to form the shape of the body tube

- Launch lug

- Card stock

- Stretchy string

- Parachute material

- Shroud line/strong thread

- PLA

- Engine tube

- Cardboard

- A8-3 engine

- Marshmallows

- Quail egg

Tools:

- Razor blade

- Scissors

- Pencil

- Wood/Super glue

- Tape

- 3D printer

- Laser cutter

Design:

The first step of the engineering design process is research. My partner and I began researching the best ways to protect the quail egg. However, the major difference between this project and the regular egg drop contest is that the egg must be contained within a rocket. One of the most helpful resources we used was a video by Mark Rober. He explains a little bit of the physics behind the drop itself and what works best and why. One of the main takeaways was that it is important to direct as much of the energy from the impact away from the egg. He gives several examples of how to do this. Another thing we had to keep in mind while designing our rocket to protect the egg was our recovery method. Were we going to use a parachute? If so, where would we put the egg? The rocket motor we had previously used (A8-3) had a delay time of 3 seconds between the end of the thrust phase and ignition of the ejection charge. If we used such a motor, we wouldn't be able to put the egg above or below it (egg must be ejected) because it would either fly out the bottom or be ejected out the top. However, if we used an A8-0 motor, we wouldn't be able to use a parachute because motors ending in zero have no ejection charge. We decided to enlarge the nose cone to fit the egg and cushiony material which meant we had to enlarge the body tube as well. We modified the Pitsco rocket to fit our needs and incorporated our experience with the 3D printers and laser cutter.

Preliminary design:

Workflow:

1) Taking measurements:

Because the Pitsco rocket was not wide enough to fit the egg, we chose to increase the diameter and keep the length at 11 in. We measured the egg using a micrometer and found that it had dimensions of 1.06 in. x 1.36 in. Subsequently, we decided to make the diameter of the body tube and capsule 2.95 in. (needed room on both sides for padding around egg) and the nose cone 3 in. so that it would rest flush against the body tube. We also decided the height of the capsule would be 1.5 in. and the height of the nose cone would be 3 in.

2) Constructing the body tube:

We followed the same steps for making the airframe as the Pitsco rocket except we made the diameter bigger. Instead of one sheet of copy paper, we had to tape together 2 pieces of paper so that it could wrap around 2.95 in. diameter glasses we had at our house. The glasses served the same purpose as the plastic tube in the Pitsco rocket.

3) Adding the fins:

We followed the same procedure for the fins as was laid out in the directions booklet. We made three fins from card stock material and cut them out using a razor blade. We then glued them equal distance apart 5/8'' from the bottom of the rocket.

4) 3D printing the nose cone and capsule:

We used 123D Design to make the nose cone and capsule. For the nose cone, I added a cone from the primitives menu and entered the dimensions. Then, to hollow it out, I clicked on the "shell out" tool and clicked on the bottom face of the cone. For the capsule, I added a cylinder from the primitives menu and entered the dimensions. Using the same "shell out" tool, I clicked on one of the circular faces, which made the inside hollow. The STL and the 123D Design files are in the google drive.

3D printing cone:

Cylinder uploaded into Cura software:

3D printing cylinder:

5) Laser cutting the spacer rings:

We designed the spacer rings for the engine mount assembly in Inkscape. The actual design was simple: a smaller circle inside of a larger circle. The larger circle had a diameter of 2.90 in. (which we discovered was too small) and the smaller circle had a diameter of .73 in. (the diameter of the engine tube. The PDF of the file is in the google drive folder above.

Screen shot of file:

When cutting, the lines should be hairline and the speed = 10, power = 100, and frequency = 10.

6) Making the parachute:

Making the parachute for this rocket was not much different from making the parachute from the Pitsco rocket. In fact, we used a parachute from a Pitsco Rocket Kit and cut out the 6 small holes and the large hole at the top. We used strong, clear thread instead of the black thread we used on the Pitsco rocket. We gathered the ends of the thread and tied them to the shock cord at the end near the nose cone.

7) Assembling the shock cord:

Similar to the Pitsco rocket and The Viking, we attached the shock cord to the nose cone by super gluing one end to the bottom of the 3D printed capsule and attached it to the inside by first gluing the shock cord inside an "anchor" and gluing the anchor to the inside of the body tube.

8) Assembling the engine mount:

For the engine mount, we had to glue the spacer rings around the engine tube. One ring went 1'' from one end and the other ring went 1/4'' from the other end. In addition, we added an engine lock, which we did not do for the Pitsco rocket. To make the engine lock, we unraveled a paper clip and super-glued it to the side of the engine tube before gluing on the spacer rings. Below is what it looked like inside of the rocket.

(The green stuff around the spacer rings is just tape to make the fit better since the spacer rings were a bit too small).

Launch results:

For our first trial, we used an A8-3 rocket motor. The altimeter read 18 ft, which didn't reach the requirement, but the egg did not break. The lack of height didn't give the parachute enough time to deploy, but it eventually did pop out (see video below). For our second trial, we used a more powerful rocket motor (B6-4) since our rocket was so heavy. This time the altimeter read 25 ft. and our egg still did not break.

Success!

Issues/Challenges:

This was definitely the hardest project we had done since there was no direction whatsoever. From designing the shape to deciding the recovery method, it was all up to us. It took us a big chunk of time to thoughtfully plan out what we were going to do and figure out how we were going to execute it.

The first challenge we encountered was remembering how to use 123D Design and figuring out which tools to use to make the nose cone and capsule the way we wanted. Furthermore, when we laser cut the spacer rings the first time, they didn't cut through all the way. We had to laser cut them again at a lower speed.

Another setback we encountered was the capsule not fitting in the body tube correctly. It was a tight fit and we were worried that it would get stuck when trying to be ejected, which would mean our parachute would not deploy. Therefore, we had to remake our body tube a little bit larger. We wrapped the paper around the first body tube so it was slightly bigger and then wrapped gummed tape around it (just like the other body tubes). Unfortunately, we made the second body tube a little too big and had to make the body tube for the 3rd time, smaller than the 2nd but larger than the 1st. The third times a charm and the capsule fit snugly but not too tight. However, we had to add tape to the outside of the spacer rings because they were too small and didn't press against the side.

Conclusion:

All in all, I am very content with the results and learned a lot throughout the process. Making a custom design of a rocket required a thorough understanding of the parts of the rocket and it forced us to think innovatively. Moreover, when things weren't going the way we wanted them to, we had to adapt and persevere.

This project taught us that there will always be trade offs. Although our design was well-thought out and all of the parts fit nicely together, we forgot to consider the weight aspect. We tried to use light-weight material for the padding, but even lighter material could have been used, such as Rice Krispies or popcorn. These material, however, might not have been as protective as the marshmallows were. We weighed our rocket after the fact and it weighed 182.2 grams. This may not seem like that much, but the rocket was pretty top heavy and the rocket motor was not that powerful. A bigger rocket motor might have overcome the heaviness of the rocket.

Finally, I feel proud of the work that we did on this project despite it not being perfect. We did the research, planning, prototyping and testing, which are the first 4 steps of the engineering design process. If we had more time, we could go back, make changes, and test it again. Overall, I thought we came up with a solid plan and constructed a very early stage of a plausible rocket to keep the egg safe while reaching the height requirement.

**Although we should have simulated the rocket before launching, we simulated it after because we were curious what it would predict. The results are located under the RockSim tab on my site.