WATERPRESSURIZED ROCKET
It’s pretty amazing to watch NASA rocket launches from Cape Canaveral. It's even more amazing to watch rocket launches when NASA is in your own backyard. And you won't need a billion-dollar budget. With just a few materials repurposed from around the house—a plastic soda bottle, a cork, and a bike pump—you and your kids will be launching flights high into the atmosphere in no time. Roger that.
DIFFICULTY LEVEL: Easy
TIME INVOLVED: a couple of hours
MATERIALS:
Wine bottle cork
Plastic 2-litre soda bottle
Bike pump with ball needle and long hose
(2 to 3 ft / 60 to 90 cm)
Water to use as "rocket fuel"
TOOLS:
Utility knife
LAUNCH PAD (OPTIONAL)
MATERIALS:
One 6 ft / 1900 mm 1x8 / 25x200 mm redwood or pine fence board
FASTENERS:
2 in / 50 mm wood screws (10)
TOOLS:
Circular saw or chop saw
Handsaw
Drill with 1/8 in / 3 mm bit
INSTRUCTIONS:
1. Make sure the cork fits the opening of the soda bottle. If you’re having trouble finding a cork that fits, check with your local hardware store. They should be able to help you out.
2. Measure the cork against the needle and use a utility knife to cut off enough of it so the needle just sticks out of the end of the cork when you push it through. See Cutting the Cork and image a.
3. Now push the needle lengthwise through the center of the cork. See image b.
4. Attach the needle to the end of the bike pump hose.
5. Fill the soda bottle one-third full of rocket fuel—I mean, water.
6. Here is where we seal this baby up. Push the cork into the bottle as hard as you can. See image c.
7. Make some sort of launch stand that allows you to prop the bottle upside down. A huge cardboard or PVC tube will work well. Even propping it up against a couple of bricks will work. Just make sure the bottle isn’t aimed at the middle of someone’s forehead. (If you want to make something more official, see the instructions for building a launch pad on page 24.) See image d.
8. Have a flight technician (or a kid) start pumping, and count the pumps as the launch sequence progresses. The bottle should fill with bubbles, and the cork will hiss a bit. After 20 or so pumps, you’ll reach ignition. (Once you’ve learned exactly how many pumps it takes, the next time you can start the countdown with that number.) The cork will explode out of the neck and the rocket will blast skyward. Keep an eye on it!
9. Now it’s time to send out the recovery team. If you built the rocket right, it will be far away from the launch base. If you had a successful flight, head back to mission control, break out the bubblegum cigars for your crew, and “refuel” for your next flight. If not, head back to the drawing board!
BUILDING A LAUNCH PAD
For optimal flights, build a launch pad to make rocket launches easier.
1. Using your circular saw or chop saw, cut your fence board into two 61⁄2-°—-61⁄2-in/16.5-°—-16.5-cm pieces.
2. Now cut two more pieces that measure 51⁄2 °— 61⁄2 in/14 °— 16.5 cm. These will be the SIDEWALLS.
3. Cut another piece that measures 61⁄2 °— 2 in/16.5 °— 5 cm. This will be the FRONT LIP of the base.
4. Predrill all screw holes in this project with a 1⁄8-in/3-mm bit. With two wood screws, attach the two large pieces together at one edge so that they form an L shape. This is the beginning of the base. See image a.
5. Attach the SIDEWALLS to the L-shaped base to form a three-sided box, driving two wood screws per side through the bottom of the base. All the edges should be flush with one another. See image b.
6. Connect the sidewalls to the rear wall by driving one wood screw through the back of the box on each side, about 1 in/2.5 cm down from the top edge.
7. Using two wood screws, attach the LIP to the front of the box. Again, make sure all the edges are flush. See image c.
You now have a stable base from which to launch the rockets. You can try to aim them, but they’ll pretty much go where they want. Start collecting soda bottles now to build up your fleet of H2O bombs!