Many hobby stores sell model rocketry supplies, but I think making your own rocket engine from scratch is a more meaningful and exciting experience. In this project, we’ll build on the work of rocket pioneer Jack Parsons (see MAKE Volume 13, “Darkside Rocketeer,” for more about this fascinating character). It was Parsons who invented “castable” rocket fuel, which starts as a soft, pliable material and slowly hardens, allowing it to be cast or molded into a high-performance motor.
In this project, you’ll combine two commonly available substances — granulated sugar and potassium nitrate — to make a powerful engine that can propel a small sugar rocket to impressive heights. This method involves melting a mixture of sugary fuel and chemical oxidizer (the potassium nitrate) over an electric hot plate and then pouring it into a paper rocket body where it solidifies into a rock-hard casting containing an incredible amount of chemical energy.
CAUTION: Undertake this project at your own risk. You are literally playing with fire, so understand what you’re getting into and don’t sell the dangerous aspects of this activity short. Sugar rocket fuel burns fiercely — do not ignite it until it’s contained in a completed motor. Follow all instructions and safety precautions carefully.
If you want more information than you can possibly use on DIY rockets – fuel mixes, motor designs, nozzles, fins, cones, recovery, telemetry there is one crucial source: Nakka.
http://www.nakka-rocketry.net/
Be safe. (maybe the most important safety tip is only ever mix as much fuel as you are going to be using immediately. Don’t store mixed fuel.
How about a safer remote ignition system for this. Take a strand of steel wool and fold it over the end of a paper match and tape it fast (leave a bit of each end of the steel wool exposed). Tuck that into the end of the rocket and wedge it in with a piece of the back end of the match. 30′ of wire and a couple alligator clips to attach it to the steel wool and a nine volt battery to set it off from a safe distance.
I’ve also used Nichrome wire (heating element wire) which I’ve salvaged from old toasters or bought at Radio Shack for this and it works well.
Make a U-shaped loop out of a small length and insert it into the core leave enough sticking out the bottom to attach those alligator clips. For juice I’ve used old train transformers etc, connected to an extension cord and household current to heat the wire red hot.
Alternatively, you can make an igniter by balling a small piece of the soft fuel on the wire which you can insert into the core when ready.
I wonder about the ‘with the nozzle pointed away’ part of the troubleshooting guide. If one takes that too literaly wouldn’t that mean pointing the rocket at oneself? I’d rather point the nozzle at the ground and the rocket up in the air, held out in front of me as far as I can reach. One could even use a pair of tongs.
I got to the last steps, still waiting to see how you suggested creating the nozzle.
Inserting the 6d nali through the nozzle to create the core is fine, but that solid 5/16″ plug of water putty isn’t going to let the nail though easily…
I don’t think you should push the nail through the sealed end. The opening in the core acts as the nozzle. If the sealed end is pierced, then combustion gases will also exit through the top of the rocket countering the thrust of the nozzle.
That’s right. The nail shouldn’t go through the putty. And it’s wise to work fast, since the fuel sets up and gets rock hard pretty quick.
Sorry, I guess my comment was too obscure; I wasn’t trying to be sarcastic, nor was I suggesting to push the nail through the water putty.
Unless I missed it (and again in re-reading), Bill never stated that we need to create a hole in the 5/16″ nozzle end plug. before loading in the fuel.
Whoops, sorry. Good catch, I updated the instructions.
silly/common question time: where can one acquire small quantities of potassium nitrate (in such a way as to not trigger the black helicopters)?
Try health food store for saltpetr as it is used for preserving beef jerky. The also sell it at the drugstore.
I have a jar I picked up at a country style butcher shop where they have their jerky seasonings.
I get all the potassium nitrate I need from the local garden supply shop, it’s one of the components of fertilizer. I also get my sulfur from the same place. Neither are controlled substances.
Potassium nitrate is commonly sold at hardware stores and garden supply stores as stump remover. It usually comes in half pound plastic jars and is labeled as such. You sprinkle the granules on old stumps to accelerate the decay process. I bought some at Menards.
Shame it’s illegal to make solid rocket motors in the UK :(
we cant get this from anywher…..
Hello, I need some help in a personal project of mine: I plan to use this recipe of fuel for my “booster rocket” for a pencil. I plan to add three (one if too much, which I think it is) 2″ casings in between each of the three fins. I want the casing to be reusable so what is a good material? PVC? Copper pipe? Also, I need a way to track it…(I plan to attach the booster to rocket by a tight fitting piping so I can take the pencil out and put a new one in the case it breaks during landing, the issue of tracking it is still being thought up on) Hope this get replies! Thanks.
Hey! If I wanted to make a bigger rocket, maybe double or triple the size, I know I could double the ingredients but would I have to just double the dimensions too? Thanks!
While I am not von Braun, I would assume so. The dimension should be in ratio of the propellant. While I myself is not qualified to say this, be careful where you ignite it to ensure minimal chance of contact with general population. And if it is legal to shoot a rocket of said size. Other than that, fire away!
Just a note – if you double the rocket dimensions (diameter and length of casing) you will need 8 times as much propellant mixture…
Where are you getting potassium nitrate?
http://www.spectracide.com/Products-and-Solutions/All-Products/Spectracide-Stump-Remover.aspx
WOW! I had no idea either!
today I tried to heat 150 g mixture outdoors on the gas burner- luckily weared safety googles and thermogloves- smoke and fire cloud was big enough to burn down the garage or even whole house :)
your a dumb dumb, you must not heat on open flame!!!!
Can I use simply N gas liquid and O2 gas liquid with a battery and bike spark plug for thrusters??
At what temperature the propellant should be cooked?? what is liftoff weight???
what kind of fuse should be used to ignite faster???
Packed powder motors work as well and are hecka easier. And why ball mill when you are melting it???
What is the best way to store extra sugar fuel so it don’t absorb moisture
Is this recipe/procedure scalable?
Fuses can burn at varying speeds, so a fuse would not be a very dangerous fuse, most fuses are shorter.
Be careful. I & my brother made a cooper tube jet with Salt Peter & Sugar mix 55 yrs ago. Used a 1/2 in. tube and soldered Wings & Wheels on it. Set it on the roadway. Lit the fuse and let it rip. Took off like a jet and then It went about 15′ and exploded throwing sharp medal (cooper) everywhere. Hurt my brother with sever cuts to his legs.
I was fine, stayed in the ditch we were hiding in.
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