How to Create an Auto-Rotating Paper Helicopter (Whirligig)
Dual-Blade Rotor Craft that Spins Gently Down from Heights
What You Need Before Starting
Folding Instructions (5 Steps)
Follow each step in order. Press your folds firmly against the table using your thumbnail or a ruler for maximum performance.
Cut Paper Strip & Mark Guidelines
Cut a rectangular paper strip 2 inches wide by 8 inches long. Draw a vertical line 3 inches down from the top center (to divide the blades), and two 1/2-inch horizontal side snip marks 3 inches from the bottom.
Slit the Rotor Blades
Cut down the vertical center line from the top until you reach the 3-inch mark. This creates your two separate rotor blades.
Snip & Fold the Lower Stem
Make the two 1/2-inch horizontal side cuts along the middle guidelines. Fold the left and right lower flaps inward toward the center to create a narrow, reinforced central stem.
Fold Base Tab & Add Paper Clip
Fold the bottom 1/2 inch of the stem upward, and slide a small paperclip over the fold to lock it and provide base counterweight.
Angle Rotor Blades in Opposite Directions
Fold blade A forward at a 90-degree angle, and fold blade B backward in the opposite direction. Hold the helicopter high overhead and release!
Autorotation & Terminal Velocity
As gravity pulls the helicopter downward, upward rushing air pushes against the oppositely-angled rotor blades. The angled blades deflect air sideways, converting downward kinetic energy into rapid rotational spin (Autorotation). This spin generates upward lift that slows the descent.
Without the paper clip counterweight at the base, the helicopter tumbles chaotically. Weight at the bottom provides essential gravitational orientation.
Skills Your Child Develops with This Craft
Bilateral Scissor Control
Making straight, controlled partial snips along marked dotted lines develops fine cutting precision.
Counterweight Physics Understanding
Discovering how shifting mass distribution stabilizes spinning objects in freefall.
Observation of Gravity vs Drag
Timing descent rates from stairs or chair heights to analyze air resistance.
Fun Family Mini-Games to Play
Slow-Motion Descent Timer Contest
Drop two helicopters simultaneously from the same height. Modify blade lengths to see who can create the slowest, most graceful floating spin.
Reverse Spin Reversal Test
Flip blade A backward and blade B forward. Observe how the rotation immediately reverses direction from clockwise to counter-clockwise.
Parent Note:
Compare paper helicopters to natural maple tree seeds (samaras) that use identical autorotation to disperse across forests on the wind.
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