Making a cardboard tube and balloon rocket is a fun and inexpensive craft for kids that allows them to be creative and provides a fun activity to enjoy upon completion. There are few critical dimensions for the rocket, but remember that the balloon is powering it, so heavy-gauge cardboard tubing will be self-defeating. A cardboard tube from a roll of paper towels is an ideal size to consider for this activity. Likewise, balloons come in a variety of shapes and sizes; consider one that is elongated and at least 4 inches shorter than the tube.
Cut card stock with scissors to make fins. The base of the fin should not exceed the diameter of the cardboard tube and the height of each fin should not be more than twice its base.
Glue the fins on to the tube in the desired locations and allow them to dry. Typically three or four fins are sufficient to provide some stability; they should be located near the base of the rocket.
Decorate the tube as desired. Here is where the creativity comes in to play; the decorating gives a feel of ownership to the user, so allow the kids to have some fun here.
Insert the balloon into the bottom of the rocket. This is easiest by holding the rocket upside down in one hand and sliding the balloon into the tube with the other while maintaining a grip on the end of the balloon for inflating it.
Inflate the balloon while holding the end of it in place just outside of the base of the tube. Once the balloon begins to inflate, the force of the air pressure will keep it firmly inside of the rocket.
Launch the rocket in a safe location by releasing the end of the balloon. Once the air has been expelled from the balloon, it will separate from the rocket and need to be recovered along with the rocket.
A cap or nose cone may be added to the rocket if desired. However, if the balloon protrudes from the end a bit when inflated, the resultant shape is actually more aerodynamic than an angular nose cone. Again, here is where creativity and just having fun should determine the design.