An illustration on white and blue graph paper of a hand holding a utility knife, several glass beakers and test tubes, a gear, and a pair of pliers with the words “Quick-n- Easy Water Rockets.”

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.

The first scene of the video showing an illustration of a hand holding a utility knife, several glass beakers and test tubes, a gear, and a pair of pliers with the words “DIY Science with Chevy.”

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

An illustration of a jug of water, a bike pump, an electric drill, a wooden ruler, a car tire stem, a cork, a pair of pliers, a roll of duct tape, a utility knife, a plastic bottle, a marker, a garden stake, and a cardboard mailing tube.

BUILDING YOUR WATER ROCKET

Two illustrations, one of a hand holding a bike tire stem and the other of a hand holding a car tire stem. Text over both illustrations reads “Look for old stems at bike stores and tire shops.”

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.

An illustration of a utility knife cutting away the excess rubber from a bike tire stem and cutting the top off a car tire stem. Text at the bottom reads “Adult supervision required.”

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.

An illustration of hands holding a cork in a pair of pliers and preparing to cut it in half with a utility knife. Text at the bottom reads “Adult supervision required.”

An illustration of a pair of pliers holding half of cork while the other half falls away after it’s cut with a utility knife. Text at the bottom reads “Adult supervision required.”

An illustration of a hand holding an electric drill and a close-up of a drill bit, with text reading “1/4-inch drill bit.” Text at the bottom reads “Adult supervision required.”

An illustration of a hand holding an electric drill and a close-up of a drill bit, with text reading “3/8-inch drill bit.” Text at the bottom reads “Adult supervision required.”

An illustration of a pair of hands holding a cork with a pair of pliers and drilling through the center of the cork with an electric drill.

An illustration of a pair of hands using a ruler and a marker to mark a line across a cork near one end. Text reads “1/8 inch - safe point.”

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.

An illustration of a hand holding a tire stem that has been inserted through a hole in a cork.

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.)

An illustration of a hand cutting a length of a cardboard mailing tube, with text reading “Approximately 7 inches.” Text at the bottom reads “Adult supervision required.”

An illustration of a length of cardboard mailing tube with a long garden stake and a roll of duct tape next to it.

An illustration of a garden stake duct-taped to the side of a length of cardboard mailing tube.

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.

An illustration of a jug of water, a 20-ounce plastic bottle, a length of cardboard mailing tube attached to a garden stake that is stuck in the ground, and a stand-up bike pump. A red arrow points down into the top end of the mailing tube.

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.

An illustration of a jug of water tipped up to pour the water into the 20-ounce plastic bottle. A mailing tube attached to a garden stake and a bike pump are at the side.

An illustration of a cork with a tire stem stuck through it inserted into the mouth of a 20-ounce plastic bottle. A jug of water, a cardboard mailing tube attached to a garden stake, and a bike pump are at the side.

A closeup illustration of a cork with a tire stem stuck through it inserted to a line marked “safe point” on the cork. A red arrow next to the bottle points down.

An illustration of a plastic bottle partly filled with water and plugged with a cork/tire stem plug inserted upside down into a cardboard mailing tube stuck in the ground with a garden stake.

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.

An illustration of a bike pump nozzle connected to the tire stem that’s sticking out of a cork plug in a plastic water bottle.

An illustration of a plastic bottle shooting out the top of a cardboard mailing tube with a puddle of water beneath it.

An illustration of a plastic bottle flying up and off to the right, trailing a stream of water.

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!