Paper helicopter lab
01 // Question
How does the length of a paper helicopter's rotor blades change how long it takes to fall?
A testable question names one thing you change about the design and one thing you measure.
02 // Variables
Independent
Rotor blade length- Short (3 cm)
- Medium (6 cm)
- Long (9 cm)
Dependent
Fall time- Seconds, to 0.1 s
- Average of 3 drops
03 // Hypothesis
IF a paper helicopter's rotor blades are made longer, THEN it will take longer to fall the same distance, BECAUSE longer blades push against more air as they spin, and that extra air resistance slows the helicopter's descent.
04 // Procedure
1. Cut the template
Cut three helicopters from the same template, changing only the rotor blade length on each.
2. Fold and clip
Fold the rotor blades in opposite directions and attach a paper clip to the base of each helicopter.
3. Mark a fixed height
Stand on a chair or stairwell and mark a consistent drop height, such as 2 meters.
4. Drop and time
Release each helicopter rotor-side up and time its fall with a stopwatch. Repeat 3 times per design.
5. Average and compare
Average the 3 trial times for each blade length and compare the results.
05 // Data table
| Blade length | Trial 1 (s) | Trial 2 (s) | Trial 3 (s) | Average (s) |
|---|---|---|---|---|
| Short (3 cm) | ____ | ____ | ____ | ____ |
| Medium (6 cm) | ____ | ____ | ____ | ____ |
| Long (9 cm) | ____ | ____ | ____ | ____ |
Formula Average fall time = (trial 1 + trial 2 + trial 3) ÷ 3
06 // What to expect
Longer rotor blades usually produce a slower, longer fall time, because the wider blades create more air resistance and catch more air as they spin, which is the same drag effect that lets a real helicopter's rotor generate lift.
A helicopter that is too heavy for its blade length falls fast and barely spins, while one with blades too long for its weight can flutter unevenly instead of spinning cleanly — the paper clip weight and blade length have to be matched.
07 // Lab notes
- Drop from the exact same height every time — even a small height difference changes the fall time more than the blade length does.
- Release the helicopter the same way each drop (fingers open, no toss) so your hand doesn't add extra speed.
- Use a stopwatch app that shows tenths of a second, and start it the instant the helicopter leaves your hand.
08 // Remember
Spinning blades push against air. More blade means more push-back, and a slower fall.
09 // Questions people ask
Why do longer rotor blades make a paper helicopter fall more slowly?
Longer blades sweep out a wider circle of air as they spin, and pushing against more air creates more drag pointing upward against gravity. That extra resistance slows the helicopter's rate of fall compared to a shorter-bladed design.
Why does a paper helicopter spin at all?
As the helicopter falls, air pushes up against the angled blades unevenly, creating a small sideways force on each blade. That force starts a spin, and once spinning, the blades behave like a slow-motion propeller, generating drag that fights the fall.
Why time three drops instead of just one?
A single drop can be thrown off by a small gust of air, an uneven release, or a timing mistake. Averaging three trials smooths out that random variation and gives a more reliable number to compare between designs.