Rocketship Launcher

Did you see us at Maker Faire in San Mateo? Here's the video for making the rocket launcher project that we had available at our booth!

Materials

  • Four 1-1/4" slip 90o elbows
  • One 1-1/4" slip cross
  • One 1-1/4" slip cap
  • Three 16"long by 1-1/4" diameter PVC pieces
  • Two 6.5" long by 1-1/4" diameter PVC pieces
  • 3" long by 1-1/4" diameter PVC piece
  • One reducer that goes from 1-1/4" PVC slip to 3/4" threaded
  • One reducer that goes from 3/4" threaded to 1/2" slip
  • 1/2" PVC union (see video for specific type - it needs to be adjustable)
  • One 1/2" slip-slip 90o "street" elbow  (male-female)
  • One 1/2" diameter by 18" PVC piece
  • One 1/2" slip end cap
  • One 5" long by 1" diameter PVC pipe
  • Two 1" slip caps
  • One 1/2" male adapter (female slip, male threaded)
  • One 1/2" threaded cap
  • 3/16" brass tubing
  • PVC glue
  • hot glue
  • 9V battery
  • SPST momentary on button
  • Soldering equipment
  • Car tire valve
  • 3/4" inline sprinkler valve (orbit brand)
  • newspaper and rubber gloves (to protect your space)

Never used PVC glue before? Here's an important video for you to watch on how to make strong joints without primer using Red Hot Blue Glue:

After the initial fun, you may start to wonder about how you can use this as a science fair project or something that really does some real science. This is a great setup for this type of experimenting, since you can do repeated launches and measure your results. This experiment can show the effect of gravity of different masses of rockets, since the speed of the rocket is the same at all angles fired at (if you launch with the same amount of pressure each time).

You can also vary the launch angle and measure how far the rocket goes horizontally each time, or make the vertical measurement tool shown in the video as well. You can experimentally figure out the best angle to launch at, since if you launch completely vertical, all the energy goes into making the rocket move vertically and it doesn’t travel any vertical distance, and lets drag stop the rocket while it’s still in the air. If you aim it near the horizontal, there’s less energy available to overcome the pull of gravity, so it doesn’t fly nearly as high and it hits the ground and drags to a stop, wasting energy. There’s a “best launch angle” that balances these two effects to make a parabolic trajectory (path) that the rocket takes when launched.

Other ideas including carrying the nose-weight of the rocket. You’ll need to be able to measure the nose before you attach it to the rocket (in grams) and see what effect this has on flight as well. Try a rocket with very little hot glue in the nosecone and see how it flies! Use a pencil tip or an edge of a ruler to balance each rocket and find it’s center of gravity, and measure this from the nose and record this with your data in a table.

What happens if you change the size, shape, and location of the fins?  What if you put fins in the front, middle or back? Use big or small fins?

You'll need to make a couple of rockets that work with this launcher. Here's what you need for the rockets:

Materials

  • Two straws each in two different sizes
  • two sheets
  • index cards
  • scissors
  • tape
  • hot glue gun
  • air compressor or air tank with spray-nozzle
  • metal tubing that fits just inside the larger straws

Make a very long straw by joining two straws with tape.  Roll an 8½x11-inch sheet of paper into a long tube and tape it shut. Cut triangle fins out of the index card and hot glue to the base end of the rocket.

Construction Tip: Younger kids can roll the paper around a dowel to help.

To make the nosecone, cut a circle out of paper.  You can trace the inner diameter of masking tape roll to get a good circle. To make a flat circle into a 3D cone, begin to cut the circle in half, but stop cutting when you get to the center.  Slide one flap over the other to form a nose for your rocket and tape it shut.  Pile a lot of glue inside the cone insert the long straw and wait to for it to dry. Slip the straw inside the tube and seal the nosecone to the rocket body.

When dry, blow into your straw to check for leaks.  It should be impossible to blow through.  If you have a leak, go back and fix it now.  Otherwise, slip a metal tube slightly larger than the straw over the straw and blow hard. Tip: Check a hardware store for the metal tube.

Repair Tip: If your straws come loose, simply cut the rocket body just below the nosecone and rebuild the straw-cone assembly, fastening it in place when dry.