Homemade Rocketry

[The Optimist]

I have some experience in the field of model rocketry, but I realized that the price of any good-sized motor was actually ridiculously high. In response to this, I have come upon the idea of mixing my own solid propellant. I currently have 2 different concepts.

Mixed potassium nitrate and sugar

Combined without heating.

Pros: 

Safer to make and to handle

Simple to make

Easily scalable

Cons:

Very low specific impulse

Absorbs moisture in the air quickly and so loses effectiveness

Conventional R-candy 

A blend of potassium nitrate and granular sugar, with traces of magnesium metal added in

Pros:

Easier to package

Smells nice

Decent performance

Cons:

Heating what amounts to rocket fuel at a controlled temperature is not particularly safe

Slower burn time compared to other mixture

Requires a more durable vessel to contain the pressure

[AlmostNASA]

I think the video that i know about is here https://www.youtube.com/watch?v=yUYxk-y-tU8

[The Optimist]

8 minutes ago, AlmostNASA said:

I think the video that i know about is here https://www.youtube.com/watch?v=yUYxk-y-tU8

That's where I got the idea from

[StrandedonEarth]

*DIsclaimer*  A significant percentage of people who try to create rocket fuel at home tend to lose body parts.

[The Optimist]

20 minutes ago, StrandedonEarth said:

*DIsclaimer*  A significant percentage of people who try to create rocket fuel at home tend to lose body parts.

Perhaps, but a percentage of the people who try to create rocket fuel at home become NASA engineers.

[CAKE99]

2 hours ago, The Optimist said:

Perhaps, but a percentage of the people who try to create rocket fuel at home become NASA engineers.

Or developers of a popular game 

[The Optimist]

PVC pipes, which will act as the rocket's fuel tanks and fuselage have been purchased! The KNO3 necessary has also been purchased, in the form of stump remover.  It was apparently one of the last cans in the store.

[quasarrgames]

I've been wondering about this. Should be possible to break the sound barrier by taking a 1500g weather balloon up to 30km, then firing one or two E rocket motors downward, in a small streamlined shell made of paper or cardboard. Wouldn't be a particularly useful experiment, but it'd be fun!

Also, i've been pondering wether or not it'd be possible to make a homemade rocket that could get to orbit. Not with solid fuel, of course, but with liquid fuel. Apparently gasoline and gaseous oxygen can be combined into a decent fuel. With a liquid hydrogen upper stage, you might be able to get a vacuum isp in the 330s. You could weld some aluminum tanks to hold the fuel, use water cooling for the nozzle... Not sure how you'd make it able to turn though, maybe with some kind of tiny hydraulic gimballing system...

Oh jeez i've started daydreaming again

[The Optimist]

6 minutes ago, quasarrgames said:

I've been wondering about this. Should be possible to break the sound barrier by taking a 1500g weather balloon up to 30km, then firing one or two E rocket motors downward, in a small streamlined shell made of paper or cardboard. Wouldn't be a particularly useful experiment, but it'd be fun!

Also, i've been pondering wether or not it'd be possible to make a homemade rocket that could get to orbit. Not with solid fuel, of course, but with liquid fuel. Apparently gasoline and gaseous oxygen can be combined into a decent fuel. With a liquid hydrogen upper stage, you might be able to get a vacuum isp in the 330s. You could weld some aluminum tanks to hold the fuel, use water cooling for the nozzle... Not sure how you'd make it able to turn though, maybe with some kind of tiny hydraulic gimballing system...

Oh jeez i've started daydreaming again

I've been doing some reading lately, and it seems that liquid fuel engines are exceedingly dangerous and difficult to build, due to the high pressures and the difficulty of keeping the contained explosion contained for long.

[pTrevTrevs]

I'm currently slated for an Aerospace Engineering course this autumn, hopefully I'll get a chance to do some launches of my own.

I did make a water bottle rocket with a few others for a chemistry project once, we did it in honor of Yuri Gagarin and named it the Bolshevik Blastoff. Unfortunately it spun out of control because we didn't know how to secure the fins correctly and the parachute didn't work because we didn't know how to pack it properly.

Edited July 24, 2016 by pTrevTrevs

[Fluburtur]

I usually use water to cook my candy rocket fuel, don't know if it affects the performances too much.

Also I saw a lot of rocket engines that use parafin and nitrous oxyde and I want to make one, that stuff is pretty easy to get.

[lajoswinkler]

You made at least two very serious errors in your opening post that could even cost someone life. If I were you, I'd delete those lines. Most people will see your post and won't see mine and some of them will do it and get injured.

 

a) Mixing powdery sugar and potassium nitrate creates a very heterogeneous mixture that has extremely unreliable burning. It can easily detonate when confined in a rocket engine, but it will probably fart agressively and blow the nozzle out.

 

b) Adding metal powders, especially powerful reducers (aluminium, magnesium) into a mixture containing nitrates (even worse if it's ammonium nitrate) will cause two things - either the mixture will slowly degrade in time by surface phase reactions which will get gradually faster with increasing moisture and could heat up and ignite if larger amounts are present, or it will detonate on ignition.

 

Never mix powdered metals with oxidizing powders unless you're trying to make an explosive and I strongly urge you not to do that. There are combinations that lead to very sensitive mixtures that can ignite if just stressed with a spoon or by a tap on the table.