I still haven't built the spear holders as I'd need to modify the handles and order some leather, but the spears themselves are simple.

Also, I don't think it's really legal (where I live at least, France) to share mechanisms and stuff regarding weaponry so I won't explain how to make an explosive charge and the firing mechanism, but I'll still go through detailing the propulsion process.

You'll need:

- a 1.5cm long, 5cm wide steel tube

- sugar

- potassium nitrate

- random metal and wood

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Most hobby rockets are using **rocket candy**. It's the usual name for a potassium nitrate / sucrose fuel combo (the potassium nitrate acts as the oxidizer and the sucrose acts as the combustible). From the reaction equation:

**5**(C12H22O11) + **48**(KNO3) -> **24**(K2CO3) + **36**(CO2) + **55**(H2O) + **24**(N2)

As you can see, it's quite oxidizer-hungry. It also releases lots of nasty gas so you might want to be careful when firing hobby rockets. **Needless to say, firing a 1.5m tall metal tube with homemade rocket fuel isn't a good idea in a urban area. Do it in a safe place.**

Basically, mix up 48 moles of potassium nitrate with 5 moles of sucrose, cook it in a sauce pan on medium heat for a while, and you get a kinda dough-looking burning hot fuel paste. Fill the tube with it (there are different ways to do so, some configurations work better than others, you might get more thrust from specific configurations).

Once your tube is filled, it needs a cap. a 2.5cm high cone with a 2.5cm radius base will work. The engine nozzle will then be attached in the same way, I still haven't figured that part out.

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Note that this is **highly experimental. We're talking about actual weaponry, stuff that here in France would get you banned if you were to walk around with in public places. Do not take this lightly, I recommend you build them without any fuel in them.**

I'll report back later (in a few weeks, but before the 22nd of April) with details concerning the thunder spears. I only have hand drawn blueprints at the moment, but I'll have working prototypes sooner or later.

Good luck!

[Hand drawn blueprints](http://i.imgur.com/DxhxDpx.jpg)