Propellant Question

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Ray
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re: Propellant Question

Post by Ray » Sat Jul 02, 2005 12:56 am

ISP of Sugar/KNO3 is around 120-140
ISP of Black Powder KNO3/S/C is around 75-80

You'll get better performance from the sugar propellent. Less propellent for the same thrust (total impulse).

Sugar propellent burns slow, you'll need to make a BATES grain to really make it perform.

Black powder burns very fast...end burner is the way to go.

Or you can do what I do....move to Ammonium Perchlorate/HTPB rubber and get the ISP up to around 220. You motor will weigh slightly more than 1/2 of a sugar motor and slightly more than 1/3 of a black powder motor for the same performance.

Largest motor I've made (and flown) to date is about an "L" or 2600 Newton Seconds.

driveit
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re: Propellant Question

Post by driveit » Fri Oct 21, 2005 1:32 am

i have no clue if this will work but i heard if you mix SALTPETER..................113.2 GRAMS
SUGAR.......................48.5 GRAMS
SULFUR......................18.0 GRAMS
in a margerin container, break up the lumps and shake for 3 minutes its done and ready to be loaded!!!?!!!? :?

steve
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Post by steve » Fri Oct 21, 2005 5:56 pm

Greg O'Bryant wrote::) Go with the sugar and KNO3 I have had quite a bit experiance with working with the traditional blackpowder and the sugar, KNO3 engines. Yes the sucrose propellant is a bit slower but that is no problem if you just increase the core depth. If you use a ratio of about 70 parts KNO3 and 30 parts sucrose you will have an almost balanced chemical reaction although the propellant seems to burn a little better if you go a little heavy on the sugar. The reason why I like the sugar propellant is because of how consistently it performs and how easy it is to make, you can make several pounds of it in under 30 min. I would disolve the KNO3 and the sugar in water and cook it in an electric frying pan until all of the water evaporates and your done. Be careful about having a boil over and getting wet propellant on the plug. I have seen this ignite the propellant because of the electrical current. Anyways let me know how things go I used to make engines that would have been about the f size all of the time. The only problem with the sugar propellant is that unless you pack it when it is still hot it tends to be hard to press together, I think that a jack hooked up to an electric drill would be able to pack the cooled propellant into some aluminum tubes quite nicely. Just a thought.
Good luck
what if I was to pour the liquid directly into my motor casing? I would have a metal rod in the center that would be pulled out after the propellent had solidified, alternatively I could use a long drill bit after it had cooled instead. I have two casings, one is about C size and the other is around F.
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driveit
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re: Propellant Question

Post by driveit » Fri Oct 21, 2005 9:39 pm

would that idea work? here it is again:
Mix
SALTPETER..................113.2 GRAMS
SUGAR.......................48.5 GRAMS
SULFUR......................18.0 GRAMS
in a margerin container, break up the lumps and shake for 3 minutes its done and ready to be loaded

WILL THIS WORK?

El-Kablooey
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re: Propellant Question

Post by El-Kablooey » Sat Oct 22, 2005 1:52 am

Steve, if you do that (I've tried) it will never dry properly. No worries though, because when your Rcandy is just right it is still very pliable, seems brittle sometimes at first, just keep kneading until it softens up. If it stays brittle, throw it back in the pan with a few drops water and a drop or two more syrup, mix it up and dry again. When its done, just pack your engine. You may not even want to core the grain. If you leave it solid you'll get the same thrust throughout the burn, core it and thrust will increase until rocket burns out. (I don't know why I'm telling you this. I know you already know this)
On an endless quest in search of a better way.

driveit
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re: Propellant Question

Post by driveit » Sun Oct 23, 2005 10:10 pm

would that idea work? here it is again:
Mix
SALTPETER..................113.2 GRAMS
SUGAR.......................48.5 GRAMS
SULFUR......................18.0 GRAMS
in a margerin container, break up the lumps and shake for 3 minutes its done and ready to be loaded into a casing with a nozzle on it blah blah blah

WILL THIS WORK?

steve
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Re: re: Propellant Question

Post by steve » Sun Oct 23, 2005 10:29 pm

driveit wrote:would that idea work? here it is again:
Mix
SALTPETER..................113.2 GRAMS
SUGAR.......................48.5 GRAMS
SULFUR......................18.0 GRAMS
in a margerin container, break up the lumps and shake for 3 minutes its done and ready to be loaded into a casing with a nozzle on it blah blah blah

WILL THIS WORK?
CALM DOWN!!! we saw it the first time! if you haven't gotten an answer it is probably because no one here knows it. you are just going to have to try it yourself or go with a tried and true method instead of experimenting.
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El-Kablooey
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re: Propellant Question

Post by El-Kablooey » Sun Oct 23, 2005 10:51 pm

No doubt, Steve!

You don't need the sulfur, why make it more complex than it is? The Rcandy is easy enough, and it is generally considered one of the best fuels for an amateur rocket engine builder, by people who have tried different fuels in thousands of rockets.
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Mark
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re: Propellant Question

Post by Mark » Mon Oct 24, 2005 1:38 am

There is probably no advantage to using sulfur other than your smoke will smell awful. I prefer the candy smell. I have mixed sugar, sulfur, and KNO3 but I didn't care for it, although it makes a nice light lemon colored powder.
Mark
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marksteamnz
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Re: re: Propellant Question

Post by marksteamnz » Mon Oct 24, 2005 8:09 pm

WILL THIS WORK?[/quote]

You have received a reply in the other thread where you have also been spraying this question around. It was NO to refresh your memory.

You were given a link http://www.nakka-rocketry.net/ please use it.

As an example of how you can research, develope and build your own motors by buckling down and applying yourself rather than spraying questions at random see http://www.nzex.tk/ The three lads behind this site are 16 and started 2 years ago. I've been happy to help them with machining as they have researched and done careful work. They have now obtained there own lathe and are off and running.
Cheers
Mark Stacey
www.cncprototyping.co.nz

driveit
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re: Propellant Question

Post by driveit » Tue Oct 25, 2005 6:25 pm

never mind everybody the mix works!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Greg O'Bryant
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re: Propellant Question

Post by Greg O'Bryant » Fri Oct 28, 2005 8:25 pm

Sorry for the delay to answere your question about that propellant formula. Is that the same formula that the Teleflite corporation uses for it's 5 cent sugar rockets? If it is "as you already said" it works. I have made those little rockets with a similar mixture and came to the conclusion that you get a better and simpler propellant by just cooking the sugar and KNO3 together without the need for mechanical mixing or the sulpher. This is the same reason as to why I recomend the rocket candy over forms of black powder it is just easier, cheaper and more consistent for making engines. The only time I woukd cosider using a different type of propellant is if I were trying to increase the specific impluse of the propellant.

driveit
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re: Propellant Question

Post by driveit » Fri Oct 28, 2005 9:14 pm

the only reasone why im using the sulfur or red iron oxide is becuase i dont have a hot plate and im not to sure iwant to use the kitchen oven and ya, but im savin up.

(maybe at christmas i cant get one?!)

Zippiot
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re: Propellant Question

Post by Zippiot » Tue Jan 31, 2006 1:03 am

the harder u pack down the pwdered sugar sulfer and kno3 the better the performance. ima say its ok to whack it with a hammer, the way i pack thing sinto a 3/4 inch pipe is hammer a cork into it. there are more solid things to use, but they r more difficult to yank out.

if you ever want to know if your mixture will work, wrap it up in 8 layers of aluminum foil and launch it thru pvc pipe. u can quickly tell if it is a good mixture this way, even before cooking it (rcandy)
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Mike Kirney
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re: Propellant Question

Post by Mike Kirney » Wed Dec 06, 2006 5:32 am

Sulfur is added to black powder mainly to reduce the temperature of ignition:

http://www.musketeer.ch/blackpowder/recipe.html

The sulfur makes the mixture less 'energetic' but easier to ignite. The saltpeter acts as the oxidizer and it is the charcoal that provides the 'power' in the mixture. One can leave out the sulfur and play with the proportions of charcoal and saltpetre and come up with an optimum mixture for rocket fuel.
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