The Bottle Rocket

  • Luke Larsen, 7, clamps the bicycle-pump head to the stopper assembly, preparing for lift-off. Luke’s twin sister and father built the rocket together.
  • Building a rocket. Illustration by Alex Griendling/Project plans courtesy of William Gurstelle
  • The DIY family: Michael Larsen with his twins, Ada and Luke, 7, and wife, Tracy Talbert.
Date:25 July 2012 Tags:, ,

THE EARLY ADOPTER
NEVER HAS LEARNING NEWTON’S THIRD LAW OF MOTION* BEEN SO MUCH FUN. MADE FROM A 2-LITRE SOFT DRINK BOTTLE AND PROPELLED BY A PLUME OF AIR AND WATER, THIS EASY-TO-BUILD ROCKET IS A FAMILY PROJECT THAT TURNS ANY AFTERNOON INTO A BLAST.
* To every action, there is an equal and opposite reaction. Here the rocket rises due to a focused, downward release of water and pressurised air.

BUILDING THE ROCKET
TOOLS AND MATERIALS

  • Electric drill with 2-, 4-, and 6-mm bits
  • One No 4 size rubber stopper (25 mm long, 25-mm diameter at the fat end)
  • One 20-cm length of 5-mm (outside diameter) copper tubing
  • Bicycle pump with infl ation needle
  • Heavy card stock
  • One 2-litre plastic bottle
  • Duct tape
  • One drinking straw, minimum 6-mm diameter
  • Four 25-mm-square wood blocks
  • One 12-mm plywood board, 300 to 400 mm square
  • One 6-mm threaded steel rod, 450 mm long
  • Four 6-mm nuts
  • Two washers, 6-mm hole, 25-mm diameter TOOLS

 

SAFETY FIRST: parental supervision strongly advised for build and launch.

MAKE THE STOPPER ASSEMBLY
1. Drill a 2-mm hole through the middle of the stopper.
2. Widen the hole by drilling the 4-mm bit about 12 mm into the top (wider part) of the stopper.
3. Insert the copper tubing into the 4-mm hole.
4. Push the inflation needle into the hole in the bottom of the stopper so that it feeds into the copper tube.

BUILD THE ROCKET
5. Make fins from card stock; attach to the bottle with duct tape.
6. Tape the 20-cm drinking straw to the side of the bottle (oriented from top to bottom).

BUILD THE LAUNCHPAD
7. Attach square blocks to the corners of the launch platform (plywood), using quick-setting glue or 30 mm wood screws.
8. Place the rocket in the centre of the launch platform and mark the spot directly below the plastic straw.
9. Drill a 6-mm hole through the mark; insert the steel rod into the hole, and ? x in place with nuts and washers.

PREPARE THE HYDRO-PUMP ROCKET FOR LAUNCH
10. Attach the bicycle pump to the inflation needle.
11. Fill bottle one-third full with water, below top of copper tube.
12. Push the stopper assembly firmly into bottle’s mouth.
13. Invert the rocket and slide the soda straw on to the rod.

LAUNCH THE ROCKET
14. Pump air into the rocket. The amount of pressure required to fire the rocket will vary, depending on how clean the seal between the rubber stopper and the rocket is and how firmly the stopper is placed.
15. After several pumps, the pressure inside the rocket will be great enough to overcome the friction holding the stopper in place. Now comes the cool part, as the stopper releases from the rocket, and the rocket launches high into the air, shooting a trail of water behind it. Zoom!