R-Candy first burn test

[hummeldike]

I think I overcooked it, and I let it dry for about 5 minutes.

https://www.youtube.com/watch?v=AnQ8tIPZ-Fk&feature=youtu.be

 

Thanks.

[Oinikis]

It takes time and practice to get rcandy just right. The color of rcandy shouldn't be darker than/or be like this, preferably this. It also looks like it might be bit wet. How do you exactly cook your rcandy? Also note that stirring is very important, and when it starts to become like mashed potatoes, lower your heat, and stir non stop. When it star getting bit brown, take small sample, and put it aside while stirring. After a minute check it. If its not hard, and wet, throw it back in and try again after several minutes. Do not forget to stir furiously, and don't let it getting stuck to the bottom too long. When the sample is hard when cooled, you can start casting it, then let it cool and wrap it in plastic wrapper for storage. Common newbie mistake is not stiring enough. When not stirring enough your rcandy will be overcooked and wet at the same time, resulting in horrible burn characteristics. So, remember to lower the heat after big part of the water has evaporated, and then stir it frequently after that point. Most important part to stir is the bottom, the place where it touches the pan, the place where overcooking happens. Also, when you cook again, and want to check the burnrate roll a 5mm wide sausage, let it cool, and ignite it (Far away from the cooking place, obviously). It should burn at a rate of several seconds per centimeter, with ~4-5cm steady flame.

Edited August 8, 2014 by Oinikis

[hummeldike]

It takes time and practice to get rcandy just right. The color of rcandy shouldn't be darker than/or be like this, preferably this. It also looks like it might be bit wet. How do you exactly cook your rcandy? Also note that stirring is very important, and when it starts to become like mashed potatoes, lower your heat, and stir non stop. When it star getting bit brown, take small sample, and put it aside while stirring. After a minute check it. If its not hard, and wet, throw it back in and try again after several minutes. Do not forget to stir furiously, and don't let it getting stuck to the bottom too long. When the sample is hard when cooled, you can start casting it, then let it cool and wrap it in plastic wrapper for storage. Common newbie mistake is not stiring enough. When not stirring enough your rcandy will be overcooked and wet at the same time, resulting in horrible burn characteristics. So, remember to lower the heat after big part of the water has evaporated, and then stir it frequently after that point. Most important part to stir is the bottom, the place where it touches the pan, the place where overcooking happens. Also, when you cook again, and want to check the burnrate roll a 5mm wide sausage, let it cool, and ignite it (Far away from the cooking place, obviously). It should burn at a rate of several seconds per centimeter, with ~4-5cm steady flame.

I stirred it for the whole time it was cooking. The color was exactly this color. It was wet because it was raining.

[Oinikis]

Rain doesn't befriend pyro well. Which this color, light?

[hummeldike]

Rain doesn't befriend pyro well. Which this color, light?

It was the tan color you said it should be.

[cecil]

It takes time and practice to get rcandy just right. The color of rcandy shouldn't be darker than/or be like this, preferably this. It also looks like it might be bit wet. How do you exactly cook your rcandy? Also note that stirring is very important, and when it starts to become like mashed potatoes, lower your heat, and stir non stop. When it star getting bit brown, take small sample, and put it aside while stirring. After a minute check it. If its not hard, and wet, throw it back in and try again after several minutes. Do not forget to stir furiously, and don't let it getting stuck to the bottom too long. When the sample is hard when cooled, you can start casting it, then let it cool and wrap it in plastic wrapper for storage. Common newbie mistake is not stiring enough. When not stirring enough your rcandy will be overcooked and wet at the same time, resulting in horrible burn characteristics. So, remember to lower the heat after big part of the water has evaporated, and then stir it frequently after that point. Most important part to stir is the bottom, the place where it touches the pan, the place where overcooking happens. Also, when you cook again, and want to check the burnrate roll a 5mm wide sausage, let it cool, and ignite it (Far away from the cooking place, obviously). It should burn at a rate of several seconds per centimeter, with ~4-5cm steady flame.

 

 

Oinikis,

 

Thanks for this description; it should be very helpful to this guy just getting started. Also I liked your post on how you form your grains. Leaving room for the air to work its way out seems like a very good idea, but you might like to press uniformly the surface at the very end of the process to keep space between the grains. Check out the following, if you haven't already seen it:

 

 

The other posts in the series make my point clear.

 

I'd very much like to know how you made your static test stand and whether you use a computer program to work out your calculations. I'd also be interested in what your motor tubes are made of.

 

BTW, your English is so good I must compliment your competence. You're also the first Lithuanian I've ever met, so that's good. Don't let any suspicious types mess with your country.

 

cecil (USA)

Edited August 24, 2014 by cecil

[Oinikis]

The grains are usually cast in 2 increments, and uneven line between increments and massaging helps it become single "bone". The very top of the grain is made flat using fingers. My hands are like collective farm's worker, so I mold hot molten rcandy with my hands like clay, but the point is, my grains have no cracks and are of right geometry. Before assembly I use file to cut a cross on each end of the grain, to make sure ends ignite easier.

 

All the calculations are done by hand. Much more than a single day was spent reading articles on rocketry and stuff. Once you get basic idea how the science works you can basically calculate everything.

The tubes are homemade. I use heavy brown paper from hardware store, which was originally intended for covering stuff up to protect it during building etc. I do not know the exact weight but it is quite heavy. Tubes are rolled around 30mm dowel, which is covered in packing tape, so rolled tube slides of easier. I cut the paper in 17cmx2 meter strips, apply thin coat of diluted white wood glue, and then when rolling it, I press it hard, to make sure that layers stick to each other well, and basically form a single "bone". Tube is then cut into 2 8 cm tall ones. I cut my strip 1 cm longer, because when rolling 2 meters of paper, it's basically impossible to roll it perfectly without messy ends. The wall thickness is 6mm.

 

I got a little confused when you talked about grains, and poped a video of nozzle casting, however, I cast my nozzles in similar fashion. I cast them 32mm in diameter, and "sharpen" it a bit on the end which will come first into the paper tube. I coat both sides of the nozzle (or bulkhead) with epoxy/concrete mix (concrete dilutes epoxy, making in cheaper, and better at withstanding temperatures), and use vise as a press, to force in the ends.

As for tutorials, don't take every tutorial as god's commandment (myself included), watch some of them, and figure your own methods. Nobody showed me exactly how to do this, and how to do that, it will come with time.

Edited August 26, 2014 by Oinikis

[cecil]

The grains are usually cast in 2 increments, and uneven line between increments and massaging helps it become single "bone". The very top of the grain is made flat using fingers. My hands are like collective farm's worker, so I mold hot molten rcandy with my hands like clay, but the point is, my grains have no cracks and are of right geometry. Before assembly I use file to cut a cross on each end of the grain, to make sure ends ignite easier.

 

All the calculations are done by hand. Much more than a single day was spent reading articles on rocketry and stuff. Once you get basic idea how the science works you can basically calculate everything.

 

The tubes are homemade. I use heavy brown paper from hardware store, which was originally intended for covering stuff up to protect it during building etc. I do not know the exact weight but it is quite heavy. Tubes are rolled around 30mm dowel, which is covered in packing tape, so rolled tube slides of easier. I cut the paper in 17cmx2 meter strips, apply thin coat of diluted white wood glue, and then when rolling it, I press it hard, to make sure that layers stick to each other well, and basically form a single "bone". Tube is then cut into 2 8 cm tall ones. I cut my strip 1 cm longer, because when rolling 2 meters of paper, it's basically impossible to roll it perfectly without messy ends. The wall thickness is 6mm.

 

I got a little confused when you talked about grains, and poped a video of nozzle casting, however, I cast my nozzles in similar fashion. I cast them 32mm in diameter, and "sharpen" it a bit on the end which will come first into the paper tube. I coat both sides of the nozzle (or bulkhead) with epoxy/concrete mix (concrete dilutes epoxy, making in cheaper, and better at withstanding temperatures), and use vise as a press, to force in the ends.

 

As for tutorials, don't take every tutorial as god's commandment (myself included), watch some of them, and figure your own methods. Nobody showed me exactly how to do this, and how to do that, it will come with time.

 

Thanks Oinikis,

 

I really enjoyed reading about your methods. I'm especially impressed that you file a cross onto each end of a grain. Bet that was an original idea. A very good one. I once used rolled paper tubes in some of my rockets using brown grocery bag paper. They worked really well.

 

cecil