Problems with rocket compostions

[weknowpyro]

Hi,

I've been trying to make this 5 cent rocket mix and i have been using 6 parts kno3 4 parts sugar(powdered) and 1 part sulphur. Evertime i burn test it though it burns really poorly worse than just sugar and kno3. I doubt its my sulphur because i make bp fine. Anyone got any pointers?

Thanks

[keepkool79]

I never made sugar rockets but I will say that when I make bp rockets and test the bp it burns really shity. When you compress it in the rocket it works fine.

Hope that helps,

[aquaman]

If keepkool's advice doesn't work try this other sugar composition.:

 

Potassium Nitrate 63

 

Powdered Sugar 27

 

Sulfur 10

 

It's kind of like the one you're using but not exactly and at least I know this composition works (it's what I use). It should burn a little slower than BP.

[teknix]

You can't really just test rocket propellant in a pile in the open. It depends on the size of rocket your are using to as how fast you need it to burn. Larger rockets require a slower burn.

 

Also sugar rockets have a slow burning propellant in which there is a core through it to provide more surface area which increases the burn and also in the enigne there is pressure built up and with a higher pressure the propellant will burn faster. Basically your going to need to test the propellant in varying engine designs to determine if it is worth while. You can get a very slow burning mixture to work in a rocket if the core area is large enough but sometimes it might have to be too large for it to be economical (there are limits though).

[aquaman]

Teknix is right, to make a good rocket you're going to have to varrious test to figure out what composition is going to be the best in the engine that you're using. Make like 8 rockets, and say have 4 with one composition (slow) and the other four with another (fast). Then vary the core length in the group of four and keep track what each rocket's composition is and it's core length. Then light them off and see which ones flew.

 

The rockets design is another thing... you might find a good propellant but the rocket casing can't handle it or the end plug/nozzle shoots out. If you haven't made rockets before I believe this is going to be the hardest part.

[_DB_]

If you use the Kno3/sugar/sulfur fuel be sure to fill the core with BP. If you don't your rocket will probably burn most of it's composition before it even gets airborn. Mine always did with this composition anyway.

[Zippiot]

Sulfer won't add to the power. I have done some sulfer experimentation and research, sulfer just makes it ingite faster, doesn't increase the burn. Try 6 parts kno3 4 parts sugar and 1 or 1/2 part charcoal. This burns with enthusiasm!! But all parts much be finely ground up and mixed before melting.

Also undercook it, I have noticed that when 3/4 of it is melted and 1/4 is stil powder, stir it all up and it becoems mostly liquid. It takes an extra two seconds to light but seems to increase power output a little...

[chappers]

You don't say if you are melting your fuel or not you can either pour it molten or use a recrystallization method a dry mixture probably wont work in your rocket really.

As has been said you basically need to melt your sugar and dissolve your KNo3 in it. (about 190 degrees)and as also has been said use black powder to aid the ignition cany propellant is notoriously hard to ignite.

Have alook here

http://shadow.yak.net/125

[dragonman586]

Don't melt it and aquaman's is right that is the correct composition. Ball-mill the stuff with marbles for like an hour and the stuff gets considerably faster. Make sure that your sugar is extremely finely powdered before beginning. Run the Sugar through a coffee griner first.

[Mr.Dan]

With your propellant are you testing it right away or did you wait a while. If you wait the sugar will absorb water and also the same as the others said about in that if you burn it in a pile it will burn slowly if it doesnt your making a bomb

[ActionTekJackson]

Alright, I've been having problems with this particular Rocket comp

Rocket propellant #7 (Zinc/Sulfur)

Source: rec.pyrotechnics

Comments: Burns very fast, producing lots of smoke. It is not a very effective propellant due to its low energy density.

Preparation:

Zinc..............................................67.1%

Sulfur............................................32.9%

 

First, it is really hard to ignite. Secondly, it leaves a hellova lot of ash (Zinc Oxide?), and what appears to be a small amount of molten sulfur. Below is a video of one that I did in fact get to ignite, but as you can see it barely gets off the ground before it CATO's. A very small cato but none the less. Upon inspection I found the nozzle was completely shut with slag, the nozzle was 3/8" on a 3/4" ID tube, so I'm pretty sure the nozzle was plenty big. Another thing, the Rocket was fully cored. I never found any info stating whether or not this comp should be cored or not. Anyway, any help would be sweet, cuz the color of this comp is amazing. Anyone have any ideas?

 

Zinc/Sulfur Rocket ~Failed

[_DB_]

I've heard that it's hard to make a good rocket with this composition since Zinc is so heavy. How you tried a non-cored rocket? I don't figure one would perform well, but you never know.

[Yankie]

Would adding charcoal to KNSU propellant do anything?

[psyco_1322]

KNO3/Sugar kinda leaves a golden tail a bit from the carbon it makes burning. But the charcoal could add a bit of a nice tail if you dont add too much, other wise it will just slow it down. It would also aid a bit ignition but you wont be able to notice it since the fuel lights up pretty good by its self.

 

ActionTekJackson that is zinc sulfide that your making when burning that fuel and it will glow under UV. Old zinc powder tends to act differently than does new stuff so that may be your problem also. But Im unsure it it affect fuels like it does stars.