Usage

How should I mix and use copper thermite?

Here's a quick list of the supplies and equipment you ought to have on-hand if you want to work with copper thermite:

How much should I use?

How much thermite is needed to light a given motor is NOT a completely "settled" subject; there is still room for experiment and debate.

A general rule of thumb that has been used, successfully, by quite a few rocketeers is to use approximately one gram of copper thermite for every 1000 Newton-seconds of total impulse.  So, for a K motor (between 1280 and 2560 N-s), use between 1.2 and 2.5 grams of copper thermite.  (An Aerotech K550, with about 1500N-s of total impulse, will light instantly with 1.5 to 2.0 grams of copper thermite.)

What about other metals?

Both magnesium and magnalium (a 50/50 blend of Mg and Al) powders have been tested instead of aluminum, and both worked just fine at 325 mesh.  If you can't get 325 mesh Al powder, substituting 325 mesh Mg powder or 325 mesh Mg/Al powder is acceptable, and performance is nearly identical.

You WILL need to adjust the mixture ratios to achieve a stoichiometric mixture, as the atomic weight of Mg is different than Al, and the reaction product (MgO instead of Al2O3) is different, as well.

What chemicals should I use?

The most commonly used (and therefore, the most well-understood and probably the safest) chemicals to make copper thermite for motor ignition are:

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