2020-09-16 | Chevy New Roads Magazine
DIY Science with Chevy
Quick-N-Easy Water Rockets
The whole family can aim for the stars with this fun project that brings science to life.
Learning from home can be extra exciting with hands-on DIY projects. In this installment of our “DIY Science with Chevy” series, learn about the thrilling world of rocket propulsion, but on an approachable scale that doesn’t require an astronomical budget. Experiment with water and compressed air to see how high you can fire your rocket! Then, check back soon for other DIY projects.
This series is designed for children ages 7–13. For outdoor use only. All activities should have adult supervision with proper safety precautions. We recommend always wearing gloves and safety glasses while conducting experiments.
Why You Want to Build It
Water rockets are an excellent place to start exploring rocketry and flight. This design is easy to build, with no valves, no firing mechanisms, and self-regulating pressurization fail-safes. It’s safe (just water!), cheap (most supplies are kicking around in your junk drawer), and fun, especially on a hot day.
MATERIALS AND SUPPLIES
BUILDING YOUR WATER ROCKET
STEP 1: GET A TIRE STEM. Bike shops and tire stores are a reliable source for old tire stems. Tell them that broken stems are OK. A broken car tire stem usually just has its bulbous end snapped off (that’s the round end on the top of the stem seen in the illustration; you don’t need it anyway). A broken bike stem is one that’s been separated from the bike tire inner tube, which will save you some work later. If the bike or car tire stem is missing its valve, don’t worry; we don’t need it.
STEP 2: TRIM YOUR TIRE STEM (IF NECESSARY). If you’re using a bike tire stem, cut away all of the surrounding rubber. A car tire stem can be used as is—although if the bulbous rubber end is in the way, you can cut it off with your utility knife.
STEP 3: DRILL YOUR LAUNCH PLUG. To build your launch plug, cut the cork in half horizontally, and then drill a hole through the middle big enough for the tire stem. Cork is a little trickier to work with than other materials, since it tends to tear apart and is hard to grip. Test to see which end of your cork fits best into the bottle you have, and measure 1/8-inch from that end of the cork. Mark this “safe point.”
DRILLING TIPS & SAFETY: For safety’s sake, hold the cork with a pair of pliers. Running the drill fast, drill a 1/4-inch hole through the cork. If you’re using a bike tire stem, this should be fine (although you may need to generously ream the hole, or even bump up to the 19/64-inch bit). For a car tire stem, switch to the 3/8-inch bit to expand the hole.
STEP 4: ASSEMBLE YOUR LAUNCH PLUG. Insert the threaded end of the tire stem into the “safe point” end of the cork and push it through. It should be a snug fit (important for pressurizing the bottle). Twisting as you go will help. All of the brass threads should be pushed entirely through the cork, as shown. (You can use a utility knife to trim down the cork if it ends up being a little too long.)
STEP 5: BUILD A LAUNCH TUBE. Cut a 7-inch length from the mailing tube or canister and duct tape the garden stake to its side. While a tube is not strictly necessary, if you have a stand-up style bike pump (like the one shown in Materials and Supplies above), having a launch tube frees up both hands to operate the pump.
STEP 6: PREPARE TO LAUNCH. You’re ready to launch! Head outside with your bottles, launch tube, launch plug, bike pump, and a jug of water. Make sure you have plenty of space and a clear landing zone for your rocket (no one wants to get hit by a water bottle). Stick the launch tube stake into the ground, leaving enough open space at the bottom for you to attach the bike pump.
STEP 7: CHARGE YOUR ROCKET. Fill the bottle one-third full with water, and then stick the launch plug in the mouth of the bottle so that the threaded end of the valve stem sticks out. Insert the plug at least to the safe point or up to halfway into the mouth of the bottle.
STEP 8: PUMP AND LAUNCH! Slide the rocket into the launch tube, connect the pump to the valve stem, and start pumping vigorously. After a dozen or so pumps (depending on the quality of your pump) the cork will pop, and we have liftoff!