"Sometimes the whole," wrote Aristotle, "is more than the sum of its parts." Like, say, macaroni and cheese, or gin and vermouth. Pair the right two things together and the emergent combination is awesome.
One of the awesomest pairings around is the stuff known as rocket candy. Made from a common chemical and powdered sugar, rocket candy is easy to make, impressive as hell, and a possible first step towards self-immolation if you don't do it right. Consider yourself warned.
Your childhood idols were Tony Stark, the Professor on Gilligan's Island, or you would just like say to your friends: "Well, yes, it is rocket science."
When a rocket, made minutes before with stuff you found in your garage and pantry, clears the launching pad on a belch of fire and smoke and ascends 200 feet in 2.9 seconds.
Finding a place remote enough and safe enough to launch without getting arrested.
- 6 grams powdered sugar
- 12 grams potassium nitrate (Places to legally purchase chemical grade, dirt-cheap KNO3 include Skylighter or United Nuclear. Some people use potassium nitrate-based stump remover, but it's expensive and the results are inconsistent.)
- Piece of kraft paper (cut from a paper grocery bag) 2.5-inch by 10-inch
- White or yellow glue
- Balsa wood dowel 1/8-inch diameter, 9 inches long
- Hardwood dowel, 3/8-inch diameter, 8 inches long
- Electric hot plate
- Non-stick pan
- Water putty
3 out of 10
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.
1. 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.
2. 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.
3. Sift the powder. Thoroughly mix the powdered sugar and potassium nitrate by sifting or screening the two into a single blend.
4. 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.
5. 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.
6. 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.
7. Crimp it.Crimp the open end so it makes a quasi-nozzle.
8. Mount the rocket. Glue the balsa stick to the rocket body. The stick is there to adjust your rocket's center of gravity so it flies true. To find the correct length of stick, attach the rocket to the stick and balance the two on your index finger, with your finger tip just behind the nozzle. Break or clip off small pieces of wood until it balances out.
9. Add the fuse. Insert the fuse through the nozzle and into the hole.
10. Prepare for liftoff. What goes up must come down. Launch your rocket in only in a safe place, where it won't land on a person, a roof, or anything that could be damaged. If you are in a place where you can't launch a bottle rocket safely, well, you can't do this either. Attempt at your own risk. Obey all local laws and regulations. Got it?
Insert a ¾-inch diameter iron pipe in the ground, pointing vertically. Place the rocket in the pipe. Light fuse. Get away. Marvel at your ability to make something fly. Iron out the kinks, do it again—and, if you're feeling confident, clock your time aloft on a stopwatch.
William Gurstelle is the author of Absinthe and Flamethrowers, The Practical Pyromaniac, and Backyard Ballistics. He is the Ballistics and Pyrotechnics Editor at Popular Mechanics Magazine and Contributing Editor at Make Magazine.