R-Candy

[dagabu]

This is why I recommended that you dissolve the ingredients into water first (2000g of each in 1000g of water) so that you can keep from having lumps. Corn syrup will not help with the cooking or the re-crystallization it only helps with the end result, it remains fluid a little longer.

 

Your fuel appears to be white still, no yellow, that means that you likely have the same result as a dry mixed fuel. It has to be held at the proper temp for the proper length of time to re-crystallize.

[TranslucentDragon]

I did dissolve the ingredients into water first, but the water wasn't boiling. Does that make a difference? Would the lack of yellow mean that my temp was too high, too low, or not determinable. It ended in an off-white almost yellow color. Could I put the fuel I have back in boiling water, and then redo the process, or must I start all the way over?

[BurritoBandito]

Probably too low. Water boils at 212 degrees F, Sugar melts at 367 degrees F, and KNO3 melts at 633 degrees F. You can't. Get the fuel hot enough to melt the KNO3 without igniting it (AFAIK). the idea is to dissolve the KNO3 in just enough water to dissolve it. If you boil the water it will take less, reducing the amount of time required to cook it out. Then you add the KNO3 water to the sugar and mix it thoroughly. The sugar will slightly melt from the heat of the water but not completely. Now you heat the fuel to drive off the water. It is better to do this at 212 until you start to see crystals forming, then bump it up to 367 to finish driving out the water and to melt the sugar. Doing it this way helps to reduce caramelization of the sugar. Caramelization is bad, but damned near impossible to avoid entirely.

 

This is the method that I would use. It may not be the best way to go, but it makes sense to me and has served me well.

[dagabu]

You gots some readin to do!!!!!

 

The basic Idea is to dissolve the KNO3 in water so that as it re-crystallizes, the sugar coats all of the crystals allowing the oxidizer and the fuel to be in intimate contact, allowing a complete and fast burn. The caramelized color is reached when the water is completely driven out and the mass reaches a "softball" stage.

 

Definition: Soft-ball stage refers to a specific temperature range when cooking sugar syrups. Soft-Ball Stage occurs at 235-245 degrees. This stage can be determined by dropping a spoonful of hot syrup into a bowl of very cold water. In the water, use your fingers to gather the cooled syrup into a ball. If it has reached soft-ball stage, the syrup easily forms a ball while in the cold water, but flattens once removed from the water.

 

If you don't get to the soft ball stage, there will still be way too much water left in the fuel causing it to slump and get sticky. It does not light well when in this condition.

 

If you get to the "hardball" stage, its too late and you have gone too far.

[BurritoBandito]

So... I'm overcooking it by around 100 degrees F? Well that sucks. It has worked (and been workable while hot), but what % efficiency have I lost? I thought caramelization was a bad thing, so I devised this cooking method to attempt to mitigate it. I cook off most of the water then bump the temp up to melt the sugar. It starts to bubble and once I can take a piece out and it cools to a warm, pliable mixture I take it off the heat and quickly start ramming it in small marble sized chunks (for a 1' ID). If it starts to get too cool then I heat it back to around 200 degrees F or so. It is generally pliable long enough for me to fill my casing. I store the extra in a desiccant box. Then I reheat it when I need it again, it usually takes 250 degrees F to get it pliable again at this point.

[TranslucentDragon]

I'm a bit confused. But this is what I understand:

• What I did: mixed 130g of dry KNO3 and 70g of dry Sucrose in a container, stirring slightly to make a heterogeneous mixture of sugar and saltpeter crystals. I boiled an unknown amount of water in en electric skillet at a temperature of about 300 degrees. I mixed the dry, crystalline mixture into the boiling water which was already in the skillet. The mixture dissolved into the water and I waited until all of the water evaporated or was boiled out of the skillet and was left with a slurry where you could see crystals in the water, gel-like mixture (a consistency slightly thicker than oil but less than molasses). This further boiled to a gritty, white paste; then to a gritty candy-like substance about the consistency of salt water taffy. I took this out of the pan and it cool, but was to floppy to do a break test. I lit it anyway, with a propane torch, and it burned, but you had to keep the torch on it. The energy to keep itself burning wasn't there. I went back to my skillet and by the time I got back, everything was hard. This did have the energy to keep itself burning and I was able to light it with a piece of visco. I crushed this with a hammer into a powder about that of what I started with (crystals) and that's where I'm at now.
  

• What I need to do: boil water and add potassium nitrate to the hot water to make a solution. Put sugar in a heating electric skillet and add the saltpeter to the skillet when the saltpeter has completely dissolved in the water. Boil off the water. Raise the temperature to a point where the mixture in the pan starts to bubble (not sure about this part, especially because my mixture didn't bubble at all, it just turned into a slurry). Lower the temperature and stir constantly. When the substance is yellow, it is done.
  

[BurritoBandito]

I would take dagabus advice. He is more knowledgeable about this than I am. But yeah that's pretty much what I do.

[BurritoBandito]

This is the point that I would turn the temp up. Again though, I would listen to dagabu if I were you. His method is probably better. I just started doing it this way and it worked so I kept doing it. I will be using dagabu's approach next time.

[TranslucentDragon]

So do I need to dissolve the potassium nitrate and the sugar in water (in separate containers) or just dissolve the potassium nitrate in water and heat the sugar in the skillet?

[BurritoBandito]

They don't need to be in separate containers.

[TranslucentDragon]

But that's what I did, I dissolved it in water first... does it have to be boiling?

[BurritoBandito]

Solubility is a function involving temperature, so boiling the water jut makes it dissolve the crystals easier. This means you can use less water. The way I have done it only dissolves the KNO3. I thought this was clever because it uses less water and I thought the whole purpose was to allow the KNO3 to be "decrysyalized" for lack of knowing the proper terminology. I thought the goal was just to make the two chemicals crystalize together... I was apparently wrong . I can say though that while my logic may have been incorrect and my method may not be the best, it DOES work... Well enough that I didn't continue to seek a better one.

[TranslucentDragon]

I understand why you use boiling water, but what I'm confused about is why my comp turned into a slurry and never bubbled. At first,I thought it was a mixture of the fact that the temps weren't right, and that I had to put KNO3 in boiling water, and keep it separated from the sugar, but, apparently, since you don't have to, that leaves the only variable for mistake as the temperature. I don't know where I went wrong with the temperature, that is my only issue.

[BurritoBandito]

Refer back to dagabu's last post. The one that starts with "You've gots some reading to do"

[dagabu]

I understand why you use boiling water, but what I'm confused about is why my comp turned into a slurry and never bubbled. At first,I thought it was a mixture of the fact that the temps weren't right, and that I had to put KNO3 in boiling water, and keep it separated from the sugar, but, apparently, since you don't have to, that leaves the only variable for mistake as the temperature. I don't know where I went wrong with the temperature, that is my only issue.

 

I don't know why your comp did not work out like others, you should write everything down and try again. I love to help with stuff like this but I am becoming exasperated with your lack of study and asking the same question time and time again in the seeming attempt to get the answer you want. R-candy is not difficult to make, to not get the results means that you did not follow the directions given.

 

Use your Google Foo and read up.

[TranslucentDragon]

Well, with the first crumbly batch I made, it didn't produce enough thrust to fly without a nozzle, as expected, but it flew with a nozzle to about 40 feet (I'm horrible at guessing distances so this could be way off). Not too shabby for a first batch.

[mikeee]

TranslucentDragon,

 

Go to the following website, Scott has built many R-Candy rockets and has tutorials and videos on how to make the fuel & rockets.

He has built some rockets that reach the 30,000 and 40,000 plus elevations.

http://www.thefintels.com/aer/propellants.htm

[Jonathan]

Translucent Dragon,

 

You might try this approach to rcandy. It works for me.

 

Dry mix 65g KNO3 + 20g sucrose + 15g dextrose. Dump into your cooking container with 100 ml of H2O and cook off all the water, stirring as James Yawn does. Add a pinch of Fe2O3 and stir some more. Scoop the hot glop onto a non-stick cookie sheet (if you don't intend to cast) or into a casting tube.

 

I like this method better than using corn syrup, because corn syrup (e.g., Karo) has unknown quantities of additives. Because dextrose is the central substance in corn syrup (it's corn sugar), using dextrose to replace some sucrose gives all the benefits of using junky corn syrup (more benefits, in fact).