Ground control to southeast Michigan kids: Celebrate summer with a do-it-yourself bang! When i3 Detroit pitched us a water rocket project – one that shoots 100 feet into the sky – we grabbed our space helmets.
What’s i3? A cool “hackerspace” in Ferndale. This 8,000-square-foot former warehouse has loads of shop-type equipment, from welding to sewing to woodworking (heck, even robots). Packed with projects, it’s open to the community, and members are happy to show newbies how stuff works.
“The trick about i3 is we never do it for you,” says Nick Britsky, co-founder of this art/technology/culture collective. “We will absolutely sit down and empower you to do it.” Yep: Even kids.
Here, Britsky shares the scoop – from basics to fancy extras – for families to create their own water rockets. It’s sure to blast-off your summer fun right!
- Empty two-liter bottle (recommend one with straight sides; new, indented Coke bottles are tricky but not impossible)
- Corrugated plastic sheet (think for-rent/garage-sale signs), solid plastic sheet or luan plywood
- Fin profile template (click the link to print out; scroll to the very bottom of the page, where you’ll find 18 different templates, depending on the bottle you have)
- Electric drill with 1/8″ bit
- Construction adhesive
- Safety glasses
- Primer and spray paint (optional)
- Draw your fin shape using the profile of the bottle on the printed-out “fin profile template.”
- Cut out the fin profile template.
- Trace the template three times on the corrugated plastic.
- Cut out the fins with the knife.
- Drill a series of small holes, in a row, on the curved edge of your fin.
- Trim the extra plastic off the holes.
- Remove the label off the bottle (if it’s pesky, use some solvent to remove the glue).
- Lightly sand the bottle and fins. This will allow the glue and paint to stick. (Britsky recommends 400 grit.)
- Fill the bottle with water to keep it more rigid.
- With the adhesive, glue your first fin on the top of the bottle. Apply the glue to the curve, as well as the sides, then smooth out the glue. Make sure to cover the holes as these help adhere the fins.
- Repeat for the second and third fins, using your eye to keep them level and evenly spaced around the bottle.
- Gently empty the bottle of water.
If you’d like, paint and decorate the bottle.
Take a peek at Metro Parent’s video to see how we made our very own water rocket!
You can buy a variety of water rocket launchers – from sites like Amazon.com, to higher-quality (but still reasonable) varieties, like this launcher from ScienceKit.com. Or, if you’ve got a family of makers, try this how-to from i3 Detroit’s Nick Britsky.
Materials (all PVC must be Schedule 40):
- 1 o-ring (for outside of 1 1/4 collar)
- 1/2″ (ID) PVC Pipe, 2′-4′
- 1/2″ (ID) PVC cap (flat exterior, if you can)
- 1/2″ (ID) PVC elbow
- 1 1/4″ (ID) PVC Collar (for connecting 1″ pipe)
- Hose barb connector
- Valve stem from a tire
- Small radiator/hose clamp
- Vinyl tubing (3′-6′) to connect to valve stem and hose barb
- Wire hanger or similar wire
- 3 eyebolts
- String or twine (20′-30′)
- 3 tent stakes (metal ones are best)
- PVC glue and primer
- Electric drill and various drill bits
- Tap and die set (optional)
- Marker or pencil
- Slide the 1/2″ PVC pipe into a soda bottle – or your rocket about 3/4 into the bottle. A clear bottle is best for this. Make a mark on the PVC and remove the tube. Then cut a shallow notch (not all the way through the pipe) to seat the o-ring in. This is so the o-ring doesn’t move and makes a good seal with the rocket.
- Drill a 5/16 hole into the PVC end cap. If you can only find rounded ones, try using a center punch or awl to start a hole. Then screw the hose barb into the hole. You can use a tap and die for this, if you prefer. Just make sure to follow the instructions and drill a slightly smaller hole.
- Use PVC primer and glue to affix the elbow to the PVC tube. Glue it to the opposite end to which you put the o-ring on. Then glue the end cap with hose barb into the elbow. (Note: You may need a small piece of tube to connect these two, depending on the type of end cap you purchased.)
- Glue the piece of vinyl tube into the hose barb. It will probably hold without the glue, but this helps with the seal. Then, insert the tire stem into the vinyl tube. If there isn’t a good seal, use a hose clamp. If it is too big, trim it with the knife until it is a tight fit.
- Drill three holes into the bottom half of the PVC collar that are roughly equal distance from each other (eyeball it). Then, screw in your eyebolts loosely. Again, you can use a tap and die, if you like.
- Slide a soda bottle into the top half of the collar. Note where the lip of the bottle opening falls. You want to cut notches into the collar above where the lip is on each side of the collar. You can use a file to clean this up.
- Shape the hanger into a U-shape that will slide into the two notches you cut on the collar. This will hold the bottle down and act as your launch key.
- Slide the collar down the PVC tube so it covers the o-ring. Slide the bottle over the tube and place the collar so it covers the lip of the bottle and you can easily insert the launch key. Now tighten the eyebolts down. Don’t break the plastic – just make them snug.
- Tie 3′-6′ of string onto the bottom of the U on the launch key.
- Tie enough string from each tent stake to an eyebolt to reach the ground.
- Now you are ready to launch.
Once you’ve built your launcher, use these instructions – or simply follow the instructions that came with your store-bought launcher.
- Place the rocket launcher vertically with the elbow down.
- Hammer in each stake so that the tube is vertical and the lines are taut.
- Fill the rocket 1/3 full with water. (Experiment with soap and food coloring, too, for fun effects.)
- Quickly turn the bottle over the top of the launcher and insert the launch key to secure.
- Grab a tire pump or air compressor and fill to 60 PSI. (Make sure to wear goggles!)
- Stand from a safe distance and pull the string on the launcher. Your rocket should launch into the air – around 100 feet! If you’re having trouble pulling the launch key, loosen it up. Or use a broom handle to hold the launcher while you pull.
Good luck and experiment. Check out i3Detroit.com for more projects and see when the next Water Rocket Meet-up is happening.
Research online as there are hundreds of other variations on this and other water rockets. I’m currently working on a new launch pad using quick release garden hose connections. This focuses the water out a smaller opening which should get the rocket higher.
Bonus: Parachute Man
Adding a parachute is a fun add-on, too, Britsky says. “Skilled water rocket engineers use small circuits to launch the parachutes at the high of the launch,” he says. “You can use gravity, as well.”
- Another two-liter soda bottle
- Trash bag
- Spool of string
- Knife (if needed, to cut bottle)
- Make a nose cone out of an extra bottle: Just cut the neck off a bottle and rest it on the top of your rocket, so the rocket is now two bottles tall. Don’t glue them together or even push hard; just rest it on top.
- Now, you’ll make the parachute. Using a piece of trash bag, cut a circle out of the trash bag around 2′-3′ across. Then, cut 12 pieces of string 18″ long. Snip holes at 12 points around the edge of the trash bag circle. Tie a piece of string to each hole, being careful not to rip the trash bag (use hole reinforcers from the office store, if you like).
- Tie the other ends of the string together to make a parachute. Add another piece of string and affix it to the nose cone and the rocket body. Loosely insert the parachute into the nose cone and rest it on the top of the rocket prior to launch.
- If all goes well, your rocket will safely fall to the ground when it hits the height of its travel!