Core concept
CAD cannot prove fit: weigh the completed rocket, inspect fin retention, test both detachable interfaces, and use only a teacher-supervised, unpressurized launcher-fit check.
IED Unit 3 • Lesson 3.10
Physical Rocket Assembly & Fit Testing
Focus question: What does physical assembly reveal that cannot be confirmed from the CAD model alone?
Your lesson guide
Objective
Compare physical parts with the final digital assembly. Evaluate removable interfaces for alignment, retention, and serviceability. Verify laser-cut fin fit and alignment.
Materials
For the online work: a browser and your engineering notebook. Follow the activity’s materials list for any physical build, and get teacher approval before using equipment.
Plan your time
Suggested work block: 45–60 minutes. Physical builds and projects may span several classes; follow your teacher’s schedule.
IED Unit 3 • Lesson 3.10 Learning Studio
Understand the engineering, follow the examples, and document the result
Today's process
Inspect all manufactured parts; dry fit the nose, body and fin module; check the two removable couplers; weigh the completed rocket; photograph actual fit evidence.
Worked example
A real assembled mass of 120 g is under the 125 g limit, but the estimated filament mass alone does not establish compliance.
01 / Visual lesson
Physical Assembly and Fit Testing
CAD cannot prove fit: weigh the completed rocket, inspect fin retention, test both detachable interfaces, and use only a teacher-supervised, unpressurized launcher-fit check. This diagram is explanatory rather than a tested or dimensioned engineering artifact.
02 / Watch and research
Engineering tutorials and further learning
Fusion workflow review
Apply the useful modeling and assembly techniques to this lesson; sample parts in the tutorial may differ from your rocket.
Open the video on YouTube ↗Expert technical references
Read these Autodesk or NASA learning resources for the relevant design or aerospace fundamentals.
Primary technical reference ↗Additional learning reference ↗Learn independently: read, pause, apply the idea, then record the actual evidence.
03 / Follow the procedure
Guided engineering workflow
Steps for your project
- Inspect all manufactured parts
- dry fit the nose, body and fin module
- check the two removable couplers
- weigh the completed rocket
- photograph actual fit evidence.
What your result means
A real assembled mass of 120 g is under the 125 g limit, but the estimated filament mass alone does not establish compliance.
Example statements are not actual flight observations or substitute measurements. Use the original requirements and instructor approval.
04 / Independent checks
Review your evidence before submitting
Concept explorer: total finished mass
Not a measurement or GO authorization. For 3.14, only actual flight observations count.
Self-check questions
Does a printed mass estimate prove the finished rocket mass?
No. Weigh the entire complete rocket including fins and hardware.
Can students force the rocket onto the launcher?
No. Report binding during a teacher-supervised unpressurized fit check.
The existing “What to Submit” section below provides exact filenames and required proof.
IED Unit 3 • Lesson 3.10 • Learning Studio
Learn the concepts before completing the assignment
Engineering concept
Digital alignment cannot guarantee physical fit. Weigh the complete rocket, inspect fin retention and verify both serviceable interfaces before flight.
Today's engineering work
Inspect the printed and laser-cut components; dry-fit nose/body/lower couplers; verify full mass ≤125 g; check launch fit only on an unpressurized teacher-supervised tube; document photos.
Worked example
Illustrative full rocket mass 120 g is within the 125 g final limit. An STL slicer mass is not a substitute for a real scale.
01 / Illustrated concept
Physical Assembly & Fit Testing
What the diagram means: Digital alignment cannot guarantee physical fit. Weigh the complete rocket, inspect fin retention and verify both serviceable interfaces before flight. The example values illustrate the principle and do not replace actual teacher-assigned dimensions.
02 / Watch and research
Instructional video and technical resources
Fusion manufacturing and parts
Use the relevant modeling or assembly technique; the demonstration project may differ from the rocket assignment.
Watch directly on YouTube ↗Expert references
Use these official Autodesk or NASA guides when the video alone does not explain the underlying workflow.
Primary technical reference ↗Additional learning resource ↗Self-study: identify a key technique, pause the tutorial, apply the operation and verify the result before continuing.
03 / Step-by-step guide
From theory to your own project
Guided task sequence
- Inspect the printed and laser-cut components
- dry-fit nose/body/lower couplers
- verify full mass ≤125 g
- check launch fit only on an unpressurized teacher-supervised tube
- document photos.
Worked example and verification
Illustrative full rocket mass 120 g is within the 125 g final limit. An STL slicer mass is not a substitute for a real scale.
Important: Do not substitute illustrative numbers for actual CAD dimensions, real measurements or instructor approvals.
04 / Independent practice
Explore one key parameter
Interactive concept explorer
Illustrative values only; not a completed engineering inspection or teacher authorization.
Check your reasoning
How are detachable interfaces checked?
Assemble and separate each interface nondestructively, recording retention and fit.
Can the rocket be forced onto the launcher?
No. Stop if it binds; check fit only with instructor and no pressure.
Use the lesson's original assignment and “What to Submit” sections below for exact deliverable requirements.
Lesson Overview
What You Are Learning
Learning Targets
- Compare physical parts with the final digital assembly.
- Evaluate removable interfaces for alignment, retention, and serviceability.
- Verify laser-cut fin fit and alignment.
- Fit-check the rocket on the actual PVC launch tube without pressurizing the system.
Unit 3 Progression
This is where the assembly design meets real manufacturing variation.
ComponentsAssembleVerifyFabricateReviseFlight Test
Compressed-Air Rocket Challenge
Project Requirements
These requirements apply throughout Lessons 3.6–3.14.
1/2 in PVC Reference Tube
- The launcher tube outside diameter is 0.840 in (21.34 mm).
- Model the launch tube as a separate grounded Fusion reference component.
- You choose the rocket's internal launch clearance, but the finished rocket must slide freely over the actual PVC tube without binding.
- Before choosing the rocket's internal bore dimension, measure the actual unpressurized classroom launch tube. The 0.840 in (21.34 mm) diameter is the nominal outside-diameter reference, not the target bore size.
- The launcher itself is teacher equipment and is not modified as part of this project.
Modular 3D-Printed Rocket
- The structural rocket body is 3D printed in classroom-approved filament.
- Use at least 3 major printed modules: a lower launch/fin module, a main body module, and a nose/upper module.
- The rocket must have at least 2 removable printed-to-printed interfaces.
- Major printed modules must be disassembled without damaging the parts; permanent adhesive is not allowed between major modules.
Connection Method
- You choose how major modules connect.
- Examples include keyed/slip couplers with retention, twist-lock/bayonet features, screws/inserts, snap-fit features, or another approved method.
- The connection must keep the rocket aligned and secure during handling and flight-readiness checks.
- If a connection uses hardware or a tool, it must still be serviceable without damaging the printed parts.
Laser-Cut Fin Assembly
- Use 3 or 4 identical fins, equally spaced at 120° or 90°.
- Fins are laser-cut from 1/8 in acrylic or plywood.
- Use 3.175 mm as the nominal CAD thickness, then measure the actual stock and use that measurement for the final fin interface.
- Fins must use a repeatable locating feature such as slots, tabs, keyed pockets, or another approved feature. Surface gluing alone is not an acceptable locating method.
- Adhesive may be used to retain the fins after the fit/alignment check is approved.
Lightweight by Design
- Primary body walls should generally be 1.2–2.0 mm thick; 1.6 mm is the recommended target.
- Geometry thicker than 2.5 mm should be limited to local interfaces, couplers, fin mounts, fastener features, or other justified reinforcement.
- Total predicted 3D-printed material should be 100 g or less.
- The finished rocket should have a total mass of 125 g or less before the flight-readiness review.
Build for the Classroom Process
- Every printed component must fit the classroom printer build volume and be designed to print without support material.
- No support material may be required inside the launch bore or any mating interface.
- The nose must be rounded/blunt, and exposed fin corners/edges must be made safe before flight.
- Only the instructor operates, pressurizes, or changes settings on the compressed-air launcher.
Assignment
Assemble and Inspect the Physical Rocket
Do not modify the CAD first. Assemble the manufactured parts, observe what actually happens, and record evidence.
Step-by-Step Instructions
- Inspect every manufactured part: Check for warping, cracks, delamination, laser-cut defects, or incorrect scale before assembly.
- Measure the finished rocket mass: Confirm the complete rocket is 125 g or less.
- Test the lower/body connection: Assemble and disassemble the first major printed interface. Record whether it aligns, retains, and releases as intended.
- Test the body/nose connection: Repeat the same check for the second removable printed interface.
- Fit the fins: Insert the laser-cut fins into the designed locating features and verify equal orientation and secure positioning.
- Secure the fin subassembly: After instructor approval of alignment, use the approved retention method. Adhesive may be used for the fins if that was the chosen plan.
- Check the launcher interface: With the launcher unpressurized and under instructor supervision, slide the rocket over the 0.840 in / 21.34 mm OD PVC tube. It must move freely without binding and without excessive side-to-side looseness.
- Inspect the full assembly: Check centerline alignment, loose modules, sharp edges, cracks, and any other issue that could affect flight readiness.
- Disassemble the rocket: Confirm the major printed modules can still be separated without damage.
- Record every issue: Separate design/interface problems from manufacturing defects.
Before You Submit
- Finished mass is 125 g or less.
- Both major printed interfaces assemble and disassemble successfully.
- Fins are equally aligned and securely located.
- The rocket fits the actual PVC launch tube without binding.
- No major printed module requires destructive disassembly.
- Physical issues are documented before CAD changes are made.
Submission
What to Submit
Submit only the following assignment-specific deliverables in Google Classroom:
Resources
Lesson Resources
IED Unit 3
Return to the Unit 3 lesson map and project sequence.
Introduction to Engineering Design
Return to the IED course hub.
Build your lesson report
Checkpoint: is your evidence ready?
- Check calculations, units, labels, and measurements against the activity requirements.
- Record what actually happened, including unexpected results.
- Explain what you changed and why; attach required drawings, photos, CAD, or code in your classroom assignment.
Submit only the following assignment-specific deliverables in Google Classroom: Prototype inspection record (one PDF): LastName_FirstName_3_10_FitTest.pdf with a pass/fail and observations for both detachable interfaces, fin placement/retention, full assembly alignment, and unpressurized launcher sliding fit. Include measured assembled mass in grams. Photo evidence (in the PDF): at least three labeled photos: fully assembled rocket, disassembled main modules/interfaces, and installed laser-cut fin system.
A PDF download is not a submission. Review it, then upload it and any required attachments through your classroom assignment system.