Intro: Fused Matchstick Rocket
How to make a fused matchstick rocket. Safer, and far more dramatic than the conventional kind! Still, exercise caution with these things - and remember, I'm not responsible if you blow your hand off with one of these things.
- A pin
- Access to a stove
- A paper clip
- Kitchen foil
Step 1: Make a Fuse
The first step is making a fuse. This is not difficult, but the smell is terrible. Cut the heads off around 50 matches. Now, put a small amount of water into a pan, and get it simmering. Drop the match heads into the pan, and swish them around. After around 5 minutes, drop the string in as well. Stir this around for another 10 minutes.
That's it! With care, take out the string and leave it to dry.
As you may notice in the comments, it's also possible to soak the string in nail polish or rubbing alcohol (or some other flammable liquid).
Step 2: Make the Rocket
Now to create the rocket! Cut out a square of foil, around 6 by 6 cm. Lay the match head on the foil as shown, with the pin resting next to it. Gently but tightly wrap up the match and pin in the foil, and fold over the top of the match with the excess foil. Cut off some if necessary.
Step 3: Prepare the Launch Pad
A launch pad is now necessary. Get the paper clip, and bend the metal on the side away from the main body. Then, twist up the main body as shown in the second image.
Step 4: Attaching the Fuse
Carefully tie your fuse around your rocket (make sure the pin is still inserted). Once it is tied, wiggle the pin around a bit to widen the exhaust pipe. You can then remove it.
Step 5: Launch!
Now for the fun part:
In a safe place, preferably outside, put the match rocket in the launch pad. Point it away from flammable objects (that includes people). Carefully light the fuse, and take a few steps back. If you've done everything right, your rocket should just manage to achieve escape velocity (just kidding) !
With this design, when the fuse is nearly burnt out , it can look like it has actually gone out. Don't be fooled and go up close - make sure that it really is out before shoving your face in front of it to relight the fuse. Plus, every once in a while, if you've messed up the design, the matck will simply explode. So be careful. But have fun!
Step 6: How It Works
(If I'm wrong about any of this, please, comment and correct me!)
A matchstick rocket is, in essence, a small rocket engine on a wooden stick. The head acts as the fuel, and the foil acts as both the combustion chamber and the nozzle.
The tip of a standard safety matchstick contains a chemical called potassium chlorate, which is a powerful oxidizer. When heated (in our rocket, this is done by the fuse), it decomposes into potassium chloride and oxygen:
2KClO3(s) + heat → 3O2(g) + 2KCl(s)
potassium chlorate (solid) + heat → oxygen (gas)+ potassium chloride (solid)
In doing this, it releases energy, which causes sulfur (another ingredient in the tip of the match) to burn:
S(s) + O2(g) → SO2(g)
sulphur (solid) + oxygen (gas) → sulphur dioxide (gas)
This, in turn, releases sulphur dioxide (which is the culprit behind the smell of burning matches) and more energy, setting the wood of the matchstick on fire.
We're mainly interested in the decomposition of the potassium chlorate, which rapidly produces hot oxygen gas. Gases take up a lot more volume than solids, and the oxygen is therefore at a high pressure while trapped inside the aluminium foil. The heat causes it to expand even more, thus increasing the pressure. The only escape for the oxygen is out through the small gap between the foil and the match - through which it shoots out at high speed. The resulting effect is described by Newton's third law, and is the basis of any rocket engine. As he puts it:
"LAW III: To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts. — Whatever draws or presses another is as much drawn or pressed by that other. If you press a stone with your finger, the finger is also pressed by the stone. If a horse draws a stone tied to a rope, the horse (if I may so say) will be equally drawn back towards the stone: for the distended rope, by the same endeavour to relax or unbend itself, will draw the horse as much towards the stone, as it does the stone towards the horse, and will obstruct the progress of the one as much as it advances that of the other. If a body impinges upon another, and by its force changes the motion of the other, that body also (because of the equality of the mutual pressure) will undergo an equal change, in its own motion, toward the contrary part. The changes made by these actions are equal, not in the velocities but in the motions of the bodies; that is to say, if the bodies are not hindered by any other impediments. For, as the motions are equally changed, the changes of the velocities made toward contrary parts are reciprocally proportional to the bodies." (see http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#Newton.27s_third_law:_law_of_reciprocal_actions)
So, when the hot gas is forced out through the nozzle, it is pushing downwards, towards the ground. So, that means an equal force is pushing the rocket upwards - towards the sky. Unfortunately, the potassium chlorate does not burn (and provide thrust) for long, and so the effect is sadly temporary. The thrust is only enough to allow the matchstick to undergo a brief, sub-orbital journey at best - for example, across a backyard.
But, to any aspiring rocket scientists, take heart! Project Mercury started out sub-orbital as well! Keep modifying and improving the design, and you may well be the first to get a matchstick - powered rocket into low-earth orbit ;) .