- Difficulty
- Beginner
- Build time
- 35-55 min
- Estimated cost
- $0-$5
- Age range
- 10-16
- Workspace
- A clear table about 90 cm wide
The finish line
What you will build
The parachute opens consistently and lowers a 20-gram payload through a 2-metre supervised drop at least 25 percent slower than the no-canopy control.
Learning goals
- Identify how release of a raised payload produces slower vertical descent.
- Construct and explain a gravitational fall opposed by aerodynamic drag system.
- Measure how canopy side length changes performance.
- Diagnose losses caused by canopy leakage and string tangles.
Before you build
Materials, tools, and safety
Reuse-material cost: $0-$3 with reused materials. Supervision: Adult help recommended for sharp or heated tools.
Tools
- Ruler
- Pencil
- Scissors
- Masking tape
Low-cost swaps
- Use clean recycled packaging whenever it has similar stiffness.
- Substitute paper clips, binder clips, or twist ties for specialty fasteners.
- Use paper napkins with reinforced tape corners and a large paper clip payload.
Project-specific safety
- Wear eye protection when stretched elastic, magnets, or spinning parts are present.
- Test at floor or tabletop height and keep the path clear of people.
- Perform supervised drops indoors at or below 2 metres, stand on the floor, and use an adult-held release pole rather than climbing furniture.
Orient the build
Place the build so release of a raised payload is on your left and slower vertical descent is on your right. Call the side facing you the front, the far side the back, the tabletop the bottom, and the opposite face the top.
Build it
Step-by-step instructions
Step 1
Prepare equal payloads
Build one 20-gram cup and mark four equally spaced tie points.
Use the same payload for every canopy.
Step 2
Cut three canopies
Make 20, 30, and 40 cm squares from the same material.
Reinforce each corner with equal tape patches.
Step 3
Attach equal strings
Tie four 35 cm lines to each canopy and join them evenly to the cup.
Check that no line crosses another.
Builder checkpoint: After attach equal strings, the first subassembly should stay aligned when handled gently.
Step 4
Set the safe drop
Mark a 2-metre release height on a pole and place a towel below.
Clear a one-metre radius.
Watch for: If this stage binds or drifts, inspect release variation before adding more parts.
Step 5
Run the control
Drop the payload without a canopy three times.
Time from release to first towel contact.
Step 6
Test each canopy
Release each size three times in the same orientation.
Redo any trial with an obvious string snag and record why.
Builder checkpoint: After test each canopy, operate the build slowly and confirm that slower vertical descent begins without binding.
Step 7
Calculate averages
Find the average descent time for control and each size.
Record opening behavior separately.
Step 8
Inspect and explain
Compare canopy area, average time, and swing.
Identify the best stable design rather than only the slowest single trial.
Builder checkpoint: At the final checkpoint, The parachute opens consistently and lowers a 20-gram payload through a 2-metre supervised drop at least 25 percent slower than the no-canopy control.
See the engineering
Why it works
- Input
- release of a raised payload
- Output
- slower vertical descent
- Motion
- gravitational fall opposed by aerodynamic drag
- Energy losses
- canopy leakage, string tangles, payload swing, release variation
Why this works
Drag-area tradeoff
A wider open canopy intercepts more moving air and creates more drag. The payload slows until weight and drag approach balance, though a short indoor drop may end before true terminal speed.
Look for: Watch the first half metre and note whether each canopy opens before timing most of the fall.
Where the energy goes
Efficiency and losses
The ideal model leaves out canopy leakage, string tangles, payload swing, release variation. These effects turn some input energy into heat, sound, vibration, or unwanted motion, so measured performance will be lower than an ideal calculation.
Look for: Run the build slowly and locate the first place where canopy leakage becomes visible or audible.
Math bite
Calculate canopy area
Formula: area = side × side
- Square side = 0.40 m
- The two perpendicular sides are equal
Substitute: area = 0.40 × 0.40 = 0.16 m²
Result: The largest square has 0.16 square metres of projected area when fully open.
More area can create more drag.
Wrinkles and tilt reduce the effective area.
Make it behave
Test, troubleshoot, and tune
Controlled test
Start here: Drop the payload alone three times as a control.
Success looks like: The parachute average is at least 25 percent slower than the control and opens in all three trials.
Measure: Descent time, opening distance, swing, and landing offset.
Change: canopy side length
Keep constant: payload, string length, material, drop height, release, and room
- 20 cm canopy
- 30 cm canopy
- 40 cm canopy
| Symptom | Likely cause | Confirm it | Fix |
|---|---|---|---|
| The canopy never opens | Strings are tangled or release is folded | Hold by canopy center and inspect lines | Separate lines and use a consistent open release |
| The payload spins | String lengths differ | Hang it motionless before dropping | Retie equal lengths |
| Times are nearly identical | Drop is too short or canopy collapses | Film the opening phase | Use the full safe height and lighter canopy |
| It drifts far sideways | Canopy is asymmetric or room air moves | Rotate and repeat with fans off | Square the canopy and balance ties |
Choose your tradeoff
A stable open canopy is more useful than the largest wrinkled one. Larger area increases drag but also increases sensitivity to uneven strings and indoor air currents.
Keep experimenting
Try another version
Two-size study
Compare control with one 30 cm canopy.
Lowest landing speed
Use video frames to estimate speed over the final 0.5 metre.
Canopy geometry
Compare equal-area circle and square shapes.
Build together
Classroom and access options
Classroom version
Teams can compare canopy side length while keeping payload, string length, material, drop height, release, and room. Assign builder, tester, recorder, and explainer roles; have each team predict the result before collecting three trials.
Access adaptations
- Offer pre-cut parts and tactile or high-contrast measurement marks.
- Split roles so one builder can hold, another assemble, and another measure.
- Use a pole-mounted clothespin release and assign timing and observation roles that do not require overhead reaching.
Reflect on the design
- How did canopy side length change the measured result?
- Where did canopy leakage affect the build most strongly?
- What evidence shows that drag-area tradeoff explains the motion?
- Which change would improve slower vertical descent without creating a new problem?
Glossary
- Drag-area tradeoff
- A wider open canopy intercepts more moving air and creates more drag.
- Input
- The action or energy supplied to a system; here it is release of a raised payload.
- Output
- The useful response produced by a system; here it is slower vertical descent.
- Efficiency
- The fraction of input energy that becomes useful output instead of friction, sound, heat, or unwanted motion.
Build your dreams
One build can start the next.
Share what you learned, change one variable, and help another builder understand what worked.
Explore more guidesSources and build notes
A familiar household engineering activity implemented with original instructions and controlled tests.
- Classroom engineering basis: A common educational challenge implemented with original dimensions, tests, diagrams, and instructions.
Written and edited by BrickLabClips. Published 2026-07-22; updated 2026-07-22.