3D Rockets

In this project, you will be introduced to aerospace engineering through rocketry. You will create air-powered rockets with 3D-printed nose cones and self-designed fins to carry small payloads.

In this step, you're on a desert island.

What? We just went from rockets to a desert island? Don't worry, just stick with me here.

You're going to be stranded on an island for a year as part of a reality TV show and you can select only 5 things to take with you. You and your group mates have to talk about the top 5 things you should take to the desert island.

For each of these items, consider:

1. Why are you bringing this item?

2. What purpose does this item serve? Can it serve multiple purposes?

3. How does this item contribute to the survival of the group?

4. Do you need other items to keep this item functioning? (i.e. do you need to bring fuel if you have a generator?
 

After five minutes, share this list with your class!

In this step, you will be introduced to the Engineering Design Process. As part of this, you will cover the fundamentals of rocketry. 

To the right is the Engineering Design Process. You first start off by defining your goal. Your goal in this project is to design a rocket and launch the rocket with a payload. We will get further into the process as the project progresses.

Note, the two important statements at the bottom.

1. The Engineering Design Process is iterative. This means that you can repeat these processes again and again to improve on a design. Engineers use lessons learned from past versions of a prototype or product and apply them to future versions.

2. Failure is always part of the process. No rocket design is perfect on the first try. Robert Goddard, the granddaddy of modern rocketry, built and tested the first liquid-fueled rockets. Here is a good, short article about his ventures. Goddard was ridiculed for how often his rockets didn't work. Goddard, on the other hand, considered each failure as “valuable negative information.”

Goddard also famously said to his nay-sayers, "Every vision is a joke until the first man accomplishes it; once realized, it becomes commonplace.”

A more modern example is the Falcon 9 rocket.  It took the engineers at SpaceX 5 tries before successfully landing a rocket on a boat without exploding, but they did it in the end!

 

To the left, you can see the main forces that affect a rocket in flight. Thrust is the force used to propel the rocket. During a conventional rocket launch, either solid or liquid fuel is burned and the expanding gas forced out of the end of the rocket creates thrust. Your rocket will use compressed air as the source of thrust.

Weight is the mass of the object combined with the gravitational force pulling it back to Earth. The more mass, the more thrust is needed to overcome that force.

Drag is the air resistance on the rocket. Air molecules have to move out of the way to let objects through. A rocket is moving very fast so it must quickly push those molecules out of the way as it flies. A rocket is designed to be long and slender to decrease drag and increase the effect of the thrust.

Lift is the smallest component of the forces on a rocket. The lift force is generated on the fins and helps with the control surfaces that help stabilize the rocket. 

 

 

In this step, you will design the fins of your rocket. 

Collect the materials your teacher has available for designing and making your fins. Also, collect the nosecone and fuselage pieces.

The purpose of fins on a rocket is to provide stability. Think of a rocket like an arrow. An arrow has fletching on the back. The fletching keeps the point of the arrow going in the same, relative direction. Much like a rocket, you want the point going up toward space. If it does not point in that direction, your rocket is having a very bad day.

Things to think about when designing your fins:

1. What shape would you like to make them?

2. Will that shape look really cool on your rocket?

3. Will the fins create drag?

4. Will the fin placement create unequal forces that may affect flight?

 

Create your fins and attach them to your rocket fuselage! Then we will look at the Center of Gravity and the Center of Pressure!

In this step, you will find the Center of Gravity and the Center of Pressure for your rocket.

The Center of Gravity is the point on your rocket where both ends are balanced and your rocket won’t topple over mid-flight. tie a small loop in your string and put your rocket fuselage in it. Where does the string need to be to hold the rocket level?

When you find the center of gravity, mark it on your rocket fuselage. 

Was the center of gravity in the middle of your rocket? Explain why or why not.

 

The Center of Pressure is a little harder to visualize. Imagine that you're trying to balance the rocket on the same point but inside a wind tunnel with the wind blowing down on the rocket. The point where you can balance the rocket will be determined not by the weight of the parts of the rocket, but, instead, by how hard each part is pressed by the wind. The CP balance point will be in a different place than the CG balance point (Rocketreviews.com).

To find your Center of Pressure, create a profile/silhouette of your rocket out of cardboard. Then, try to balance your cardboard cutout on the edge of a ruler or another piece of cardboard. 

How do the Center of Gravity and Center of Pressure compare? How do you think these two points will affect the performance of the rocket?

Now that we understand some of these mechanics, let's discuss the rocket payload! 

 

In this step, you will decide what resources you will take into space and attach those resources to your rocket.

Remember the Desert Island/Colonization thought game from earlier? Well, it is back. But, this time, we are looking at 6 categories of materials to send into space:

food/water     - Limit 5
tools              - Limit 2
scientists      - Limit 3
medicine       - Limit 3
fuel                - Limit 1
plants            - Limit 2

Why are each of these important to have in space?
 

You must choose wisely and decide which of these resources you think the colonists will need the most. Each of these materials has a different mass value. Your rocket can only carry so much before it loses its center of gravity and becomes too heavy to fight against our gravitational pull. 

You must select 10 items for your rocket's payload. You can select any combination, within respective limits, to include in your payload. For example, you could have 5 food and water, but you cannot take 7 plants, because that is above the limit for plants.

After you have your 10 items for your payload, why did you select these items? How do you think they will affect your colony's chances of survival?

 

Once you’ve decided on your materials, tape them to your rocket.

How might these new materials affect your Center of Gravity? How do you think they will affect your Center of Pressure?

Once your payload is secured to the rocket, it is time to launch it into space!

In this step, you will launch and take measurements of your rocket's flight.

For the sake of safety, please follow all instructions from your instructor. Plus, use common sense and be observant. A random gust of wind can significantly change a rocket's trajectory! 

As a student observer, watch the other launches. From launches that went really high, what things do you think went well? For the launches that "provided valuable negative information," what factors led to that failure?

Continue to observe launches. When it comes to your turn to use the altitude measurer, remember your teacher's instructions!

When you are ready to launch, remember that the rocket is designed to leave the launchpad in a very fast manner. Do not be in front of the rocket at any point in the launch process!

 

If you have the opportunity to do multiple launches, what do you think you can do to increase the stability of your rocket? Can you move your payload to different locations on your rocket to increase performance?

Whether you have a rocket that flew or you had a rocket that provided negative information, you still succeeded in rocket science today! Congrats!

In this step, you will reflect on your 3D Rocket experience.

What we did today is what companies like Boeing are innovating right now. We use the engineering process, science, and physics to invent technologies to do great new things, like traveling to other planets! Who would want to live on Mars? Believe it or not, I’ve heard rumors that by the time you’re 32, it’ll be possible to book a ticket to Mars. 

1. What parts of this project were easy? Which parts were more difficult?

2. Did you run into any problems during constructing your rocket? Were you able to find a solution on your own?

3. What did you learn about aerodynamics?

4. What did you learn about rocketry in general?

7. From your testing, how well did your rocket fly? What height did it reach? What changes did you (or would you) make to your rocket? Did those changes improve launch height?

8. As a result of this project, please share one new idea or new question you may have come up with or encountered.