Using the nose cone and tail sections from this project, in addition to some easily accessible cardboard tubes and other supplies, you can build cheap model rockets that enable you to test a variety of fin configurations. These rockets are designed to work with standard Estes solid rocket motors (we recommend A8-3).
This project has been targeted at high school and middle school students, with a presentation that enables a physics or engineering class to hypothesize about the optimal fin configurations for height and compare the actual results to calculated ideals.
For a slow-motion video of the launch, I've attached the following video.
Variable per student specification
The tail cones do best printing upside down, with the fins pointing upwards - this keeps the tail cone free of FOD that will keep you from inserting the motor easily. The cones were processed with MeshMixer to print in this configuration, so support is not necessary.
The nose cone takes about 2 hours to print while the tail sections can take between 4 and 6 hours depending on your settings.
In addition to the 3D printed parts, each rocket will require the following parts (sourcing suggestions and construction instructions are at the end):
1 Toilet Paper Tube
1 Paper Clip (regular sized)
1 Eye Screw (5mm eye, minimum)
1 Recovery Parachute with Shock Cord
1 Estes A8-3 Rocket Engine w/igniter
8 pc. Recovery Wadding
Many of the parts are available in bulk packaging. To launch, a suitable launch platform (Estes 302215) and Launch Controller (Estes 302220 + AA batteries) are needed.
These models were all designed using #OnShape and are constrained in size to be printed on the #MakerbotMini. The nose cones and tail cones were sized to fit the cardboard tube found at the center of a roll of toilet paper. In case the tube that is found in your locally sourced toilet paper is of a different diameter, the OnShape document is linked here.
Overview and Background
The flight performance of unguided model rockets are determined by factors of aerodynamics, weight, and engine thrust. This project provides several different configurations to experimentally test these factors in a cost and time-effective manner.
In the context of a science classroom lesson, differing tail fin designs can be selected to influence the amount of stabilizing drag on a particular rocket. Two of the provided tail cone models induce spin for gyroscopic stabilization, similar to a spiraling football. They have the same planform as the “Shark Fin” model, so direct comparisons can be made. Modifying build parameters will affect the weight and center of gravity for a rocket. The thrust is standardized by use of a common rocket engine (An Estes A8-3 is recommended for classroom use).
Independent of the classroom setting, makers can construct their own model rockets for less than the cost of a typical rocket kit. More powerful engines (up to Estes C6 size) can be used for higher altitude launches.
Upon completion of this lesson, students will demonstrate an understanding of the impact of weight and drag on the behavior of rockets. They will gain an understanding of thrust, be able to demonstrate skills in reading thrust vs. time graphs, and understand the equations of motion and Newtonian physics as they apply to this topic.
This project is intended for middle to high school aged students. The topic and materials can be differentiated to accommodate the level of the students. Mathematics can be easily incorporated for students throughout the age range.
MS-PS1-6 Matter and its Interactions
Undertake a design project to construct, test, and modify a device that either releases or absorbs thermal energy by chemical processes.*
MS-PS2-2 Motion and Stability: Forces and Interactions
Plan an investigation to provide evidence that the change in an object’s motion depends on the sum of the forces on the object and the mass of the object.
MS-PS2-4 Motion and Stability: Forces and Interactions
Construct and present arguments using evidence to support the claim that gravitational interactions are attractive and depend on the masses of interacting objects.
MS-PS2-5 Motion and Stability: Forces and Interactions
Conduct an investigation and evaluate the experimental design to provide evidence that fields exist between objects exerting forces on each other even though the objects are not in contact.
Construct and interpret graphical displays of data to describe the relationships of kinetic energy to the mass of an object and to the speed of an object.
Construct, use, and present arguments to support the claim that when the kinetic energy of an object changes, energy is transferred to or from the object.
MS-ETS1-2 Engineering Design
Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
HS-PS2-1 Motion and Stability: Forces and Interactions
Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration.
Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.
- HS-PS3-3 Energy
Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.
To prepare for the lesson, acquire the additional non-printed parts and print the nose cones for each rocket before starting the lesson. Estes rockets, has a lot of helpful information, including standards-aligned lesson plans, at their website.
Introduce the general concept of how rockets work. NASA is a great resource with a pictorial history of rockets as well as the behavior of model rockets.
Model rocket use small solid fuel motors. For this project, the thrust provided will be the same for all rockets. The performance of a rocket will be determined by the apogee or maximum height that the rocket achieves from launch. Given a standardized motor with relatively uniform thrust output, the performance of each rocket will be determined by aerodynamic and mass factors. For aerodynamic variability, a tail cone with differing fin geometries can be selected by each group. Currently, there are five that are part of this project. The printing parameters can be adjusted to increase or decrease the weight of the printed tail cones.
For an inquiry-based Physics activity, your students can hypothesize about which fin design would result in a rocket traveling the highest. To conduct this lab, you can use the included presentation to support your explanations. Have your students identify the fin designs they feel would fly the highest and print those designs, with their specified infill (which will affect behavior). Once they have printed and assembled their rockets, they can measure the mass and determine the ideal height that should be reached by the rocket (as if it were flying with no drag and no losses). Once all students have reached their predictions, conduct a launch (or more, depending on your time and resources) for their rockets, with students using clinometers to measure the height reached. Make sure you have at least two students operating clinometers for every launch, in order to get more consistent results. Use trigonometry to determine the height reached (the presentation helps with this math) and compare the actual heights to the predicted. Students can be asked to identify likely causes for the differences between the two numbers.
In addition to physics applications, in both Math and Science, you can ask your students to:
- Calculate the surface area of the tail fins that the students selected to print. The surface area has impact on drag.
- Measure the mass of each rocket.
- Develop hypothesis on relative performance (apogee height).
- Observe the behavior of the rockets with twisted fins. Does the asymmetric drag help or hinder performance? (How is this related to the spin of a football?)
Rubric and Assessment
Students can be assessed on performing calculations with accuracy and in correctly applying precision and estimated units.
You can have students develop a lab report, highlighting observations, hypothesis, data collection and analysis, conclusions and future prospects and especially error analysis and communication of results.
Students can be assessed on using measuring tools with accuracy and precision. They can also be assessed on mathematical computations, graphing skills, and communicating their results. If you wish to use this project to launch a research project, assessment can be based on ELA standards as well.
Handouts and Assets:
Attached is a PDF Presentation that will help with walking students through the principles behind rocket flight and forces involved. It gives explanations of the forces and the equations of motion as well as calculations involved. Additionally, it shows how to use the clinometer and trigonometry to determine the height reached by the rocket.
After Printing the Tail Section
You have to add parts to the tail section to be able to insert and remove the rocket motors. You will need one standard paperclip for this part. First, unbend the paperclip.
Once it is straightened, fold it in half, over your needle nosed pliers
Curl over the bend by gripping about 1/8 of an inch (3 mm) of it inside the pliers and bending it over.
Move about 1" (25 mm) down from the first bend and bend the clip in the opposite direction from the first bend.
Clip off the remaining paperclip, retaining about 1/4" (6 mm) of clip to project through the body of the tail section.
Step by step, it should look like this:
This shows the progression of bending for the paper clip. The last on the right is an early version of the finished part. It is best to leave 1/4
After printing the nose cone
To assemble your nose cone, insert the 5mm eye screw into the center of the base of the nose cone and follow the directions on the package from the shock cord to attach the cord and parachute to your rocket.
To put it all together:
Use white glue to affix the tail section to the toilet paper tube and allow it to dry thoroughly before launch.
Remember to be safe, wear safety glasses, maintain a safe distance, and communicate with everyone around the launch area.