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Why do others caramelize sugar and potassium nitrate in sugar rockets?


Zwalter
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Hello everyone. I am new to making sugar rockets and Ive been wondering, why do some youtube tutorials caramelize or heat up the potassium nitrate and sugar while other tutorials just simply refine and mix the  particles of sugar and the potassium nitrate? Does it give more overall thrust???

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2 minutes ago, Shpaget said:

Melting the mix allows for better mixing due to smaller particles of fuel and oxidizer being in contact and thus increasing surface contact area. This leads to faster and more uniform burn.

Ohhh okay thankss!!!

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1 hour ago, Shpaget said:

Melting the mix allows for better mixing due to smaller particles of fuel and oxidizer being in contact and thus increasing surface contact area. This leads to faster and more uniform burn.

Who makes perfect sense, pistols has very fine gunpowder while cordite used in artillery tend to use something more like spaghetti since you want an longer burn time because of the long barrel. 

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43 minutes ago, magnemoe said:

Who makes perfect sense, pistols has very fine gunpowder while cordite used in artillery tend to use something more like spaghetti since you want an longer burn time because of the long barrel. 

Interesting.  I've wondered how to make a "long burn" SRB for a final stage.  Since the "dry mass" of a SRB is entirely based on the pressure (and thus the thrust), having a long, low thrust burn would allow a better wet/dry mass ratio and thus a higher delta-v.  Of course, this would have limits as any "bursty" thrust would defeat the purpose.

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7 hours ago, Shpaget said:

Melting the mix allows for better mixing due to smaller particles of fuel and oxidizer being in contact and thus increasing surface contact area. This leads to faster and more uniform burn.

Shpaget is correct. According to a Wonderhowto article on making home-made solid fuel, melting the sugar improves the absorption of the Potassium Nitrate into the fuel mix.

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6 hours ago, magnemoe said:

Who makes perfect sense, pistols has very fine gunpowder while cordite used in artillery tend to use something more like spaghetti since you want an longer burn time because of the long barrel. 

If you pull old British .303 rifle rounds apart, they are actually filled with cordite spaghetti.

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A similar process is used for black powder production, where water is added during mixing and grinding. Not only it increases safety, since damp gunpowder doesn't catch fire nearly as easily as dry, but it also dissolves potassium nitrate which then can better coat porous surface of charcoal. It also helps in forming uniform grains, which are later dried.

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16 hours ago, wumpus said:

Interesting.  I've wondered how to make a "long burn" SRB for a final stage.  Since the "dry mass" of a SRB is entirely based on the pressure (and thus the thrust), having a long, low thrust burn would allow a better wet/dry mass ratio and thus a higher delta-v.  Of course, this would have limits as any "bursty" thrust would defeat the purpose.

In an solid fuel rocket this is usually done with changing the profile who is the surface area of the solid fuel. 
https://www.nakka-rocketry.net/th_grain.html
As you see you can have trust tapper off as rocket get lighter and yo can have an initial high trust to get up to velocity fast. 

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6 hours ago, magnemoe said:

In an solid fuel rocket this is usually done with changing the profile who is the surface area of the solid fuel. 
https://www.nakka-rocketry.net/th_grain.html
As you see you can have trust tapper off as rocket get lighter and yo can have an initial high trust to get up to velocity fast. 

Note that immediately afterwards it lists how to make a star profile with a neutral thrust by modifying the grain profiles or added inhibitors.  It also shows that a rod and cylinder naturally has a neutral profile, but you have to support the internal cylinder.  It appears that for minimum thrust, you need a rod and cylinder profile plus the lowest thrust grain profile you can find, although it might be better to use that star profile and some barely higher grain profiles + inhibitors.  No idea what the "inhibitors" do to your Isp.

2 hours ago, kerbiloid said:

They do this because the A. cookbook tells to do so.

More likely the youtuber who followed a youtuber who followed the A. Cookbook.  And since most of the youtubers appear to have lived, it must be one of the safer recipes in that book.

I think the Tech Ingredients channel does a similar thing, but skips the whole "sugar" process in favor of straight aluminum nitrate or similar "real" chemicals.  He appears to have the right background for such things and includes appropriate warnings (although likely geared for people who may have copied earlier designs, not necessarily for those the youtube algorithm thought they were looking for A. recipes).

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On 7/12/2021 at 10:19 AM, Zwalter said:

Ohhh okay thankss!!!

No one in this thread has said this yet, so imma say it....

Please for the love of all that is good and holy, observe some basic caution when cooking rocket candy.

Do NOT cook your rocket candy indoors. Do it outside, using a portable burner. Do NOT use a portable burner with an open flame; instead, use one that plugs in to an extension cord with an electric heating element. Make sure your area is well-ventilated. Follow instructions carefully. When cooking rocket candy, make sure you dissolve the ingredients in plenty of water. If possible, use an intermediate heat sink like a copper plate to maintain even heating and avoid the formation of hot spots. Hot spots tend to autoignite and then you WILL blow your face off.

WEAR PROTECTIVE EYEWEAR AT ALL TIMES. Preferably something with full coverage. Protecting your vision is the single most important thing you can do. If you screw up the cook and your mixture ignites, protective eyewear WILL make the difference between sustaining serious burns and sustaining permanent blindness.

I have made many sugar rockets. Grinding the ingredients (SEPARATELY) and then packing them together is the safest way to do it. Once you’re comfortable with that, you can start cooking. But please for the love of Thor be careful. 

Edited by sevenperforce
Forgot one important bit
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4 hours ago, sevenperforce said:

No one in this thread has said this yet, so imma say it....

Please for the love of all that is good and holy, observe some basic caution when cooking rocket candy.

Do NOT cook your rocket candy indoors. Do it outside, using a portable burner. Do NOT use a portable burner with an open flame; instead, use one that plugs in to an extension cord with an electric heating element. Make sure your area is well-ventilated. Follow instructions carefully. When cooking rocket candy, make sure you dissolve the ingredients in plenty of water. If possible, use an intermediate heat sink like a copper plate to maintain even heating and avoid the formation of hot spots. Hot spots tend to autoignite and then you WILL blow your face off.

WEAR PROTECTIVE EYEWEAR AT ALL TIMES. Preferably something with full coverage. Protecting your vision is the single most important thing you can do. If you screw up the cook and your mixture ignites, protective eyewear WILL make the difference between sustaining serious burns and sustaining permanent blindness.

I have made many sugar rockets. Grinding the ingredients (SEPARATELY) and then packing them together is the safest way to do it. Once you’re comfortable with that, you can start cooking. But please for the love of Thor be careful. 

I really appreciate all the precautions. Side note, I have successfully built my rocket motor yesterday, but I didn't caramelize it yet because I was not confident to do it so. And the good news, after 5 trial and error, my rocket flew. :))

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