Homemade rockets are a fun family activity for the holidays, for science fairs or to teach your kids about Newton’s laws of physics. Recycle two-liter soda bottles and make a craft that will give your kids hours of fun.
This is cheap fun. The cost to make a single rocket is about a dime. Unfortunately, you can’t buy only 6 grams of sugar or just 12 grams of potassium nitrate, so your startup cost will be a bit higher.
Roll the casing. Spread white glue evenly on one side of the kraft paper. Wrap it tightly around the 3/8-inch dowel to form the shape of a cylindrical rocket motor casing. Remove the dowel and let the glue dry.
Make a plug. Mix a small amount of water putty with water according to the directions on the can. Insert the dowel back into the now-dry paper cylinder until it comes to within 1/3-inch from the top. Place the water putty in the remaining space at the top of the paper cylinder, so it forms a plug. Remove the dowel. Let the plug dry completely before continuing.
Make rocket candy. Do this step outside. If 18 grams of rocket candy accidentally ignites in your kitchen, there will be a lot of smoke. Also, you can’t go wrong keeping a fire extinguisher close by and wearing safety glasses here.Turn the hotplate to medium. Place the pan on the electric burner and then add the sugar-KNO3 mixture. Soon the mixture will melt into a brown, sweet-smelling goo. Stir with spatula constantly and don’t let the mixture scorch. When it reaches an even, slightly runny consistency you’re ready for the next step.
Pack the casing. Let the brown slurry cool slightly in the pan, just enough so you can handle it but it’s still soft and pliable. Congratulations: You have made rocket candy. Insert the rocket candy into the open end of the rocket body and compress it with the 3/8-inch dowel. Stop adding the fuel mixture when there’s about 3/4-inch of cylinder space left at the top.
Bore the core. Take a 6D nail or 1/8-inch drill bit and make a hole down the middle of the fuel mixture. This step turns your engine into what rocket scientists term “a core burner” which will provide more surface area for burning and allow your rocket to lift off more quickly.
Crimp it.Crimp the open end so it makes a quasi-nozzle.