Procedure: 

Attach the balloon to the removable collar.  Blow up the balloon and pinch off the neck.  Attach the collar back to the helicopter fins.  Release and watch the rotation.  Note: Either round or long balloons will work.

References: 

• Yee-kong Ng, Se-Yuen Mak, and Choi-man Chung, "Demonstration of Newton's Third Law Using a Balloon Helicopter", TPT, Vol. 40, #3, Mar. 2002, p. 181.
• George Gerhab, "The Balloon-O-Copter", TPT, Vol. 32, #4, Apr. 1994, p. 215.
• "A Simple Aerial Toy", The Boy Mechanic Makes Toys, p. 176.
• Janice VanCleave, "64. Right or Left?", Physics for Every Kid - 101 Easy Experiments in Motion, Heat, Light, Machines, and Sound, p. 150 - 151.
• Janice VanCleave, "63. Helicopter", Physics for Every Kid - 101 Easy Experiments in Motion, Heat, Light, Machines, and Sound, p. 148 - 149.
• Robert Ehrlich, "C.11. Water Rocket, Rocket Balloon, and Balloon-Powered Helicopter", Turning the World Inside Out, p. 33 - 34.