A tire pump is used to pump the bottle up to 60 psi. The lighter weight kids needed help getting the pressure up.
Note the boy on the left has a 3 bottle rocket. The longer rocket with fins doesn't tumble like the single bottles do.
FILE NAME: May21_147.JPG | DATE: 5/21/06 11:47 AM | CAMERA: Hewlett-Packard Company (HP PhotoSmart 315) | RESOLUTION: 1600 x 1200 | NATIVE FOCAL LENGTH: 5.88mm | FLASH: Flash did not fire | EXPOSURE TIME: 42/5000 sec | METERING MODE: Multi-segment | APERTURE: F9.8