Introduction: How to Make Rocket Candy

Picture of How to Make Rocket Candy

What is rocket candy?
Rocket candy is a type of fuel used for model rockets that is made from sugar and an oxidizer. Rocket candy, aka caramel candy, is called such because of its sugar content and appearance of caramel. Because of its oxidizer content it obviously should not be consumed.
Materials
-Scale/Balance
-Table Sugar
-Corn Syrup
-Salt Peter
-Beaker/ Heat safe container
-Hot Plate/ Electric Skillet
-Mortar and Pestle/ Grinder
-Used rocket motors
-Drill and Drill bits
-Dowel Rod
-Model Rocket, Igniters, Launch Pad, etc
-Safety Gear (goggles, gloves, etc)
Warnings
Making rocket fuel is dangerous. There is potential for personal injury including poisoning and burning. This is to be conducted outside under adult supervision and in an open air environment. The creator of this instructable is not personally responsible for any injury resulting from the creation or use of this rocket candy. All safety precautions should be followed including those of the manufacturers of the rockets themselves. Take care, while fun, rockets are still dangerous.

Step 1: Ingredients

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This specific type of rocket candy calls for 3 ingredients. An Oxidizer, Potassium Nitrate (KNO3, aka "Salt Peter"). And two types of fuel: Sucrose (table sugar), and Fructose (Corn Syrup). Ideally the oxidizer and fuel should be in a ratio of around 65:35. In order to account for the water in the corn syrup, the ingredients should be in the following amounts:
62% KNO3
17% Sucrose
21% Fructose
Sugar and Corn syrup can be purchased at your local grocery. KNO3 can be found in commercial stump remover which can be purchased at most hardware stores or online.
Weigh out the ingredients on the scale.

Step 2: Heat

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Turn on your hot plate to around 350 F and allow it to heat up.

Step 3: Add the Ingredients

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Add your ingredients to the beaker. Stir continuously until the mixture is a uniform consistency. Then stir occasionally so that the sugar doesn't burn. 

Step 4: Turn the Heat Up

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Once the mixture has thinned out a little (after about 5-10 mins) increase the heat to 500-600 F. Stir more often than before.

Step 5: Remove From Heat

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Once the mixture stops bubbling and has turned a caramel color (after about 15-20 mins) turn off the hot plate and remove the beaker from the heat. Pour your mixture onto wax paper and let cool.

Step 6: Cool Your Fuel

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Once the fuel has cooled and hardened break it into smaller pieces. You will notice the fuel has lost some weight due to water boiling off.

Step 7: Grind Your Fuel

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Using a mortar and pestle, grind your fuel into a powder. This step is important. The fuel must have a small grain size so that it can be properly mixed and packed.

Step 8: Add Metal Oxide

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Add 5-10% by weight of a metal oxide. This increases the burn rate of your fuel turning it from a smoke bomb into a rocket engine. The easiest metal oxide to use is Iron oxide (rust). There are plenty of great tutorials on Instructables.com on how to make rust. It follow the instructions and add the rust to your fuel and mix.

Step 9: Pack Your Motors

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Take the motor casing from a used rocket motor and fill it with your fuel. I used the B size rocket motors which take around 6g of fuel to fill. While packing you should periodically pack down the fuel in the motor. Do this by sliding the dowel rod into the open end and tapping it down with a hammer.

Step 10: Drill a Nozzle

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Once the motors are packed, use a drill to drill a nozzle down the center of the motor. It should be slightly smaller than the hole in the motor casing nozzle and about 2/3-3/4 the depth of your fuel.

Step 11: Blast Off

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You are now finished. Put your motor into an appropriate size rocket, install an igniter, and fire it off.

Comments

PaulA23 (author)2017-07-12

Best Rocket Candy instructable I've read so far. It is detailed with specific information, & easy to follow. Good job! :-)

Daddy42 (author)2016-12-23

Is rust easy to grind into a powder once you rust a metal object? (I'm new to these kinds of things sorry).

chris.harding.560 (author)2015-03-24

R-Candy won't ignite by grinding it. I think the comment below about fingers being blown off is probably referring to Potassium Perchlorate flash powder which you'd have to be a moron to grind!
Unless confined, R-Candy will just burn (rapidly). This stuff is popular because it's relative cheap, safe and easy to make and can be cast when hot meaning that you don't have to grind it.
NOTE: If you don't make the particle size small enough or don't compress the granules enough into the motor casing then your rocket could cato (catastrophically fail) on ignition because gaps between the particles allow a much larger surface area to deflagrate (burn). Casting the propellant avoids this.
When the particle size of this stuff is is about 3mm it is referred to as R-Explosive! It's a low explosive which will still just burn quickly in open air but can be extremely dangerous when confined. Bottom line: cast it when it's hot and avoid injury.

Alex_T (author)chris.harding.5602016-02-04

Preach this stuff

Kiteman (author)2014-04-09

Judging by the sudden rush of rocket-fuel instructables, it looks like a class are all posting their work. Could you do me a favour, and ask the class teacher or group leader to contact me?

They can reply to any of my comments on these projects, but it would probably be better if they send me a PM.

Kiteman (author)2014-04-09

Aside from the legal issues (this project would get you locked up in the UK), the recommended method is highly dangerous!

Grinding the finished fuel and using a power drill to form the combustion chamber could both very easily generate enough heat to ignite the fuel. I know of at least one case where somebody lost fingerx whilst grinding a mixture like this in a pestle and mortad

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