Water Bottle Rocket
Building your rocket
- 2l pop bottle (or other sizes, for experimenting)
- card board for nose cones and fins
- duct tape (preferably colourful!)
- (Optional) Sharpies and sticker to decorate the bottle
Fashion a cone for he top of the rocket (which is actually the bottom of the bottle). Fashion fins for the side. Tape in place.
(Discussion point - Do these just look cool or do they help the rocket fly?)
- Manual bicycle tire pump, or powered air compressor
- Cork with a sports ball inflation needle inserted through
- Shaft of a disposable pen (which fits into a tire pump / air compressor nozzle), wrapped with enough duct tape to fit snugly into the mouth of a pop bottle
Fashion some type of holder for the rocket. You don't want to be holding these things, that's not safe!
- Fill the water with 1/3 to 1/2 of water.
- Attach the compressor or pump to the nozzle.
- Secure the rocket in the launcher
- Be sure the area is clear, and that the rocket isn't pointed at anyone
- Start pumping, or turn on the compressor
- Yell "Oh... Ah..."
(Discussion point - how does the amount of water change the flight of the rocket? What's the best amount of water to put in the rocket?)
How does it work?
Basically, the compressed air forces the water out and that causes the rocket to be pushed up. This is Newton's third law of motion, for every action there is an equal and opposite reaction. The action is the water begin forced out of the bottle, the reaction is the bottle (rocket) being pushed up into the sky. Let's not make it anymore complicated than that!
(Discussion point - Which is the fuel, the compressed air, the water, or both?)
Can be done in association with these badges:
- Tawny Star A2 (Make a simple article such as a toy...)
- Tawny Star A4 (Make a working model and demonstrate its operation.)
- Handicraft Badge (Make a toy from recycled odds and ends.)
- Space Challenge Badge
- Space Exploration Badge (Draw or make a model of a rocket, or of a space craft of your own design. Tell about any special features you have included in your model.)