Introduction: How to Make Rocket-Candy Engines

    This step-by-step tutorial will teach you how to make candy rockets, including the casing, propellant, wick, and rust.  These rockets have highly varied results and are in no way perfect.  Using this tutorial is at your own risk.  Do not expect an immediate success due to the various ways that the rocket could become faulty, whether it be an accidentally miscalculated ratio, a bad wick, etc...

Disclaimer:  the intention for this instructable is for educational purposes.  Deciding to use this instructable is your decision and you cannot, therefore, hold me responsible for any legal issues.

Make SURE that your local laws do not prohibit you from performing this experiment or it could result in going to jail.

This project is suggested for teenagers or younger kids with parent supervisory.

Step 1: Gathering Ingredients

The ingredients which you will need to collect are:
   For Casings:

   For Rust:
        Steel Wool

   For Wick:
        Stump Remover (Potassium Nitrate)

   For Propellant:
        Stump Remover (same as above)

        Drill (or forming mandrel)

Step 2: Creating the Propellant

    First thing to do is to grind up the stump remover and sugar in a mortar, using a pestle.  After they are both ground finely, put them together in a mixture of 65% stump remover (your oxidizer) and 35% sugar (your fuel).  After they are together, mix them up a bit so they the two ingredients are evenly spread.  Pour the mixture into water, and then let it sit there for a while.  After a few minutes, put it on the skillet at 200 degrees fahrenheit until you have thoroughly gotten rid of any water left.  Once the water is gone, take your hardened propellant and smash it into bits.  Grind this up and you have your propellant.

Step 3: Creating the Rust

    To make the rust, simply put a large chunk of steel wool in a cup, pour vinegar into it along with a small amount of bleach.  Make sure that the steel wool is completely under the fluids.  Let this sit near a ventilated area for a day and come back to it.  Use a coffee filter to separate the fluid from the newly formed rust.  Now your rust is complete.  Take the water out of the rust and then grind it into fine bits (just like the propellant).

Step 4: Creating the Casings

    This step is very short and simple.  First, take a rod with the approximate diameter that you want your casing to be.  Then, cut paper strips that are roughly 8/3 inches by 11 inches.  Wrap these pieces of paper tightly (very important that they are tight) around the rod, making sure to glue the entire outside of paper so that all the layers stick tightly.  After you have wrapped at least 3 (could be more) of these pieces around the rod, take the glued paper tube off of it.  This is the completed casing.

Step 5: Creating the Wick

    First thing to do is to gather a small portion of cotton and swirl it into a thin line that is roughly 3-4 centimeters.  Take this and soak it in the sugar water for at least 30 seconds so the cotton fully absorbs the solution.  Stir the cotton strips while in the water.

    The sugar water is simply made by adding a 60% stump remover & 40% sugar mixture to water, stirring the water with the mixture in it until dissolved well enough.  The potassium nitrate and sugar do not need to be ground in this specific step.

    Once the cotton strips are soaked, take them out of the water and heat them up at 200 degrees fahrenheit.  Allow them to turn black, and take them out once they are completely stiff.  Your wick is now complete.

Step 6: Putting the Parts Together

    First, take your casing.  Pack the casing with 95% of the propellant, and 5% of the rust.  Then, use a hammer and pen to pack it tightly.  Next, take a power drill and drill a hole about halfway through the filled casing.  Edit: this can be very unsafe, so I suggest the use of a forming mandrel instead, setting it in place where the hole should be, and then putting in the propellant + rust.  Make sure that the hole is wide enough for the wick to fit in.  Next, stick the wick into the hole that was just made.  Lastly, attach this engine to a stick and fire it.

Step 7: Cautions and Safety Concerns When Constructing

1)  Be aware that you do not mix up your stump remover and sugar while grinding; although they smell different, they can look fairly similar.
2)  When making the wick, do NOT shorten the dipping of the cotton strip.  If this step is overlooked, your rocket may not ignite at all (or at least may not burn through much of the propellant).
3)  As common sense should provide, do not launch these inside or near buildings with windows that you (or your neighbors) would not like broken.

Safety Concerns:
1)  When heating the propellant, beware that it will be VERY hot.  On top of it being hot, it may still be sticky and painful to get off.
2)  I suggest using goggles for anything that you are heating up.
3)  When igniting the rocket, make sure not to stand over it or in its path (if not shooting it straight up).  These rockets can take off fast enough to the point that you lose trace of them the instant that they are ignited.
4)  Although I have not extensively researched this, another user has stated that using the power drill for creating the hole could result in igniting the fuel.  If you do not want to take this risk, I suggest finding a slower but safer way to make this hole (its just a matter of taking more time).  Be creative, but be safe!