What explains the result?
Longer rotor blades interact with more air and can increase drag, slowing the fall.
PHYSICAL SCIENCE · GRADES 4–8
Paper helicopter blade-length test
INVESTIGATION QUESTIONHow does blade length affect fall time?
● ILLUSTRATIVE SCIENCE MODEL
ENGLISH CAPTIONS
Cut matching rotor designs. Blade length is the independent variable in this comparison.
0.0 / 3.0 s
Where does this matter?
Rotor design connects to helicopter blades, parachutes, and drag in sports equipment.
What should you keep in mind?
Paper mass, fold quality, release height, and air currents must be held as steady as possible.
DEDICATED MOTION INVESTIGATION · GRADES 4–9
Paper helicopter
flight chamber
Build a folding rotor, keep the release height steady, and time how long it takes to land as you test blade length.
VERTICAL WIND TUNNEL · RELEASE HEIGHT 2.0 mREADY
2.0 m0 m
LD
LANDING GATE · TIMER STOPS
LAST FLIGHT— —
BLADE SPAN5 cm
PAPERCLIPS1
FLIGHT LOG
Compare descent times
Your first drop will create a record here. Repeat runs so one lucky spin does not decide the conclusion.
WHY THE ROTOR SLOWS DOWN
Air pushes against the angled blades. As the paper body spins, the rotor creates drag and an upward force that slows its descent. Paper mass, fold symmetry, blade angle and air currents also affect a real fall.