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I am doing a project in chemistry at the moment to build a rocket out of materials that can be easily bought and that react strongly to create thrust. I was wondering if anyone knew a good chemical formula for my rocket fuel? I know lots of good fuels and reactants used in amateur rocketry however commercial fuels have been banned from the project. Any help would be appreciated.

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  • $\begingroup$ I remember school days where sodium chlorate NaClO3 has been widely used as total herbicide called Travex . We used as the solid propelent the filtration paper, soaked by concentrated Travex solution and dried. It had to be kept dry, as sodium chlorite is hygroscopic. Not sure if it is still available. Generally, in context of terorism, public access to resources for violent chemical reactions are rather limited. For similar purposes could be used KNO3, but solution must be hot because of solubility. Other option could be classical black gun powder. $\endgroup$ – Poutnik Dec 18 '20 at 8:16
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    $\begingroup$ See this excellent site about all things rocketry-related for suggestions. There are also other answers on this site so poke around. $\endgroup$ – Todd Minehardt Dec 18 '20 at 17:59
  • $\begingroup$ en.wikipedia.org/wiki/V-2_rocket used oxygen and climate neutral ethanol. Whatever you use, it must burn fast enough to be a good propellant, but slow enough not to burst your rocket. A cardboard rocket for new years day will need different propellant from a high performance steel casing. $\endgroup$ – Gyro Gearloose Dec 18 '20 at 23:10
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Put some potassium nitrate $\ce{KNO3}$ plus powdered charcoal and sulfur in a mortar. Wet it carefully and grind the whole until you get a black homogeneous paste. Let it dry overnight in the mortar. The obtained black gun powder may be detached from the mortar with a wooden spoon. It is a safe rocket fuel. The proportions of the powders are defined by stoichiometry. They must allow the chemical reaction : $$\ce{2 KNO3 + 3 C + S -> K2S + 3 CO2 + N2}$$

I have done it many times with my students. It's a good exercice of stoichiometry. Never had an accident ! And remember : Never ! Never grind dry powders ! Grind as wet powders as possible ! In case of doubt add more water ! Pastes are even a better choice for grinding purposes !

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The chemistry is a safety issue, but the mechanics of rocket guidance is important too. Take it easy with grinding: I was grinding a little mass (maybe 10 grams) of propellant when it ignited (did not explode!), and I jerked back and banged my head.

I made small rockets by winding paper around a pencil, then filling the tube with $KClO_3$ + sulfur + sugar. Ignited in a copper tube about 2 feet long, they would fly straight out and go about 200 feet, except one that made a right angle turn right out of the tube and sailed right by an observer, hitting a garage door, where the rest of the propellant exploded, leaving a clean spot on the rusty door about 6 inches in diameter. It probably burned thru the paper tube unsymmetrically, deviating the thrust from a straight flight. The propellant burned well, but had an unexpected impact sensitivity.

With the high energy reactions, scale-up is problematic: you know that at some point, your mix may change from burning fast to exploding very fast. Do things cautiously, small scale at first and do not scale up too fast. Have several layers of safety measures, because you know that you will not stop building bigger rockets until you have a catastrophic failure. Plan to have the catastrophe some considerable distance from you and others.

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try 65g of KNO3 per 35g of sugar. Dissolve the mix in the smallest possible amount of hot water on a pan, and boil off the water, once you start seeing large bubbles and it turns into a paste start mixing. Make sure it stops sizzling when you push it down with a spatula. Sounds dangerous but really it's reliable, just do it outside. Coalesce it into a large blob with the spatula while it's still hot. It will harden within a few minutes so you better put it into the motor immediately.

Push a pencil in the middle of the fuel to create a hollow cyllinder, that will make it burn much faster.

Also, it's much easier to set off with an ember than flame

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