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CuriousAmateur 03-03-2018 06:05 PM

Newbie failures - sugar rockets
 
Hello,

We are new to rocketry, and it shows from our results. I'm wondering if anyone has any advice. We are trying to make a basic (sugar) rocket motor. The results of which have thus far been smoke "bombs." If you have stopped groaning at another failing newbie and are still interested in helping, here are the details:

We're using 33% confectioners sugar and 66% Potassium Nitrate. Our sugar is pure, but I cannot verify the same for my KNO3. We're getting it from Gordon's stump remover, which we know contains a good concentration of KNO3, but we are strangely unable to find the MSDS info in it. We grind it up, and bake it to dry it out before mixing.

We then pack it into a 3/4'' PVC pipe, with a 3/4'' clay plug on each end and drill a 7/32'' nozzle through one plug, set it up, and light it off at the nozzle. It has a nice hot, fast burn, with a good amount of gas output. However, it comes in waves rather than a steady burn. It burns for probably about 20-40 seconds (we never timed) but never lifts off. It also has a small amount of white discharge which comes out liquid and quickly hardens into a hard, crumbly material. As expected, there is also a lot of white smoke. We originally thought that the white discharge might by melted PVC, but it is strange that it is crumbly.

As a couple other notes, we are not crystallizing the KNO3 before use; we don't know if that is needed or not, since we can't find the MSDS info. It does seem to act about right, except there is never enough thrust from rockets. We are packing the powders FIRMLY into the pipe, since it should be oxidized and not much matter. The nozzle is drilled all the way through the white mix to increase surface area though. On the first try, we had 1.5'' of fuel (not sure how many grains that comes to), and on the second attempt, we doubled it to 3'' of fuel, with the same 3/4'' plugs on each end. There is a fair amount of weight to the finished rocket, though we haven't thought to weight the finished product yet. The first one was 3'' long in total, and the second was 4.5''.

Any thought on what we should try? We've thought of perhaps packing it less tightly, but even as it is, some fuel tends to spill out when the nozzle is turned downward, multiple times after the hole is drilled. We've also thought of mixing in a little sulfur to the fuel, and also had it recommended elsewhere that a little iron oxide mixed in could help.

Any thoughts? Does anyone know if Gordon's stump remover is even a pure source? Thank you!

neil_w 03-03-2018 08:35 PM

I am not a motor builder myself so I can't help you out with your chemistry questions, but I do know enough to say that you should not use PVC as a casing, since it shatters unpleasantly.

CuriousAmateur 03-03-2018 09:39 PM

Quote:
Originally Posted by neil_w
I am not a motor builder myself so I can't help you out with your chemistry questions, but I do know enough to say that you should not use PVC as a casing, since it shatters unpleasantly.


Okay, good to know--any thoughts on what I should be using? Cardboard just isn't going to cut it.

jadebox 03-03-2018 09:40 PM

If you want to learn how to safely and legally make rocket motors that actually work, visit Jimmy Yawn's web site at:

http://www.jamesyawn.net

CuriousAmateur 03-04-2018 10:11 PM

Quote:
Originally Posted by jadebox
If you want to learn how to safely and legally make rocket motors that actually work, visit Jimmy Yawn's web site at:

http://www.jamesyawn.net


Thanks for the tip. He is making some very high-grade propellants, which I 'm sure are good. I will read through more of his material later.
To be honest, though, we don't need high-quality fuels, as long as they can provide a short burst of thrust. Perhaps we'll need to try a zinc/sulfur mix instead.

neil_w 03-05-2018 08:17 AM

Quote:
Originally Posted by CuriousAmateur
Okay, good to know--any thoughts on what I should be using? Cardboard just isn't going to cut it.

There are vendors out there selling cases, often aluminum.

Anyway, I'll bow out of this because although I've seen people say over, and over, and over, not to use PVC as a motor case, it looks like lots of sugar motor builders (that link Roger provided sure is a fun rabbit hole to go down) are in fact using PVC. So... I dunno, as I said I don't do it myself so I won't comment any further.

tbzep 03-05-2018 08:39 AM

I've made sugar motors in old cardboard motor casings. They are stronger than you think. Just don't use cardboard tubes that weren't designed for motors. Start small and work up.

ghrocketman 03-05-2018 10:46 AM

I have made sugar motors as well in old used 18mm and 24mm cardboard casings, and in used 29mm plastic/phenolic casings as well.
Many use PVC for sugar motors as well due to ease of availability; I have no comment on safety of using said PVC.

Don't mess around with zinc-sulfur aka "micrograin" propellants.

jadebox 03-06-2018 08:45 AM

As you can see on his web site, Jimmy Yawn has done some experimenting with using PVC to make motors, but he wouldn't recommend that for others. PVC is frangible. It breaks into small pieces when it fails.

The motors he actually uses to launch rockets use non-frangible metal casings as required by the Tripoli Research Safety code.

tmacklin 03-06-2018 09:20 AM

You might try your hand at rolling your own convolute wound paper tubes using Elmer's white glue. If you want a super strong tube, try West Systems epoxy which will produce a maple hard tube that you can drive nails with...almost. Like everything else in life there is a learning curve to be mastered.

If you want to buy some excellent paper tubes, here's a link:

http://www.hobbyhorse.com/pyro_tubes.shtml

CuriousAmateur 03-09-2018 02:03 AM

neil_w, thanks for the tip!

tbzep, good to know--we don't currently have and old casings, but we'll watch for some

ghrocketman, It does seem that a lot of people use PVC cases. There are also other non-PVC plasic options, but I don't know if they are any better. PVC can itself be a fuel, so it also makes some sense. I'm having a hard time finding safety infor on zinc/sulfur fuels. Any pointers?

tmacklin, I was wondering abount doing that, and of even wrapping our own paperboard with glue. we'll look for West Systems epoxy, too.

CuriousAmateur 03-09-2018 02:07 AM

So I finally found MSDS info on our Potassium Nitrate source. It is 99% KNO3, 1% Calcium Stearate.

I know that Calcium Chloride is a fire suppressant, and since Calcium Stearate is also a calcium salt, does it have a similar effect? If so, it's going to be a pain to remove, since it is also a crystal.

As always, thank you everyone!

ghrocketman 03-09-2018 06:47 AM

You are not going to find much in the way of "safety" information for zinc/sulfur propellant due to the simple fact it is NOT SAFE.

astronwolf 03-09-2018 11:15 AM

Quote:
Originally Posted by CuriousAmateur
So I finally found MSDS info on our Potassium Nitrate source. It is 99% KNO3, 1% Calcium Stearate.

I know that Calcium Chloride is a fire suppressant, and since Calcium Stearate is also a calcium salt, does it have a similar effect? If so, it's going to be a pain to remove, since it is also a crystal.

You are on the wrong forum. There are friendly folks who might give you some casual advise here, and maybe a couple here (who aren't talking) with actual expertise. It looks like you established an account here just to talk about sugar rocket propellant. No big a priori deal with that. But when you have to ask "...is calcium stearate like calcium chloride because they are both calcium salts?" I'm calling out "BS". I think you are too uneducated to be cook book mixing up propellants in your garage and trying to load it into cases. You're going to blow yourself up. At the very least your going to get the stuff all over your clothes. Wear gloves and an apron. Sheesh.

And stay the hec away from zinc/sulfur micrograin.

Rocketflyer 03-09-2018 12:36 PM

Quote:
Originally Posted by astronwolf
You are on the wrong forum. There are friendly folks who might give you some casual advise here, and maybe a couple here (who aren't talking) with actual expertise. It looks like you established an account here just to talk about sugar rocket propellant. No big a priori deal with that. But when you have to ask "...is calcium stearate like calcium chloride because they are both calcium salts?" I'm calling out "BS". I think you are too uneducated to be cook book mixing up propellants in your garage and trying to load it into cases. You're going to blow yourself up. At the very least your going to get the stuff all over your clothes. Wear gloves and an apron. Sheesh.

And stay the hec away from zinc/sulfur micrograin.



I agree with Wolfram. This is not the right forum to be asking questions about amataure rocketry motor making. Zn/S is not something you really don't want to mess with. All in all, if you aren't taking extreme measures to be safe, you can win a Darwin Award. Play it safe at all costs.

luke strawwalker 03-10-2018 09:54 AM

Quote:
Originally Posted by ghrocketman
You are not going to find much in the way of "safety" information for zinc/sulfur propellant due to the simple fact it is NOT SAFE.


Yeah it's essentially "flash powder" is it not... basically ANYTHING will set it off.

I think the problems with your motors are due to some error in the process... there's a video on YouTube of "The King of Random" where he makes similar motors. He uses the gray PVC hose nipples to make his motors because IIRC they're not as "brittle" and prone to shatter as regular PVC... IIRC they'd crack in two before they shatter. They say not to install air lines in shops with PVC (which I read a year after I'd installed my PVC air system) because if the pipe breaks under pressure basically it "explodes" with fragments of PVC blown all over the shop by the force of the compressed air behind it propelling it as it expands. Water and other liquids don't compress, so essentially if a water PVC pipe breaks the pressure is "instantly" relieved and therefore does not "propel" or continue to exert force on the pipe to shatter it into smaller fragments like air does.

Anyway, I haven't replaced my air system and it's been in there for most of 20 years... when it comes to air systems in shops they recommend either steel pipe or flex pipe (essentially, PEX or the black poly tubing with gray fittings...

Later! OL J R :)

tbzep 03-10-2018 08:51 PM

Quote:
Originally Posted by luke strawwalker
Yeah it's essentially "flash powder" is it not... basically ANYTHING will set it off.

It varies. It took effort to light it with a Bunsen burner to demonstrate synthesis reactions when I taught science. I mixed it on a small square of paper and set it on a mesh screen over the burner. I seldom had the perfect mix, which I recall was 6 to 1 by weight, but after the first time weighing it out, I always just estimated the size of each pile. It lit after the flame got on it a few seconds and provided quite the show, stinking up our whole wing. The other teachers hated it, which delighted the kids and myself. :cool:

The more fine the powder, the easier and quicker it went up. I used flowers of sulfur and I don't recall how fine the zinc was, but I didn't try to mill it down any finer. IIRC, it can be friction, static and shock sensitive to some degree depending on how it is prepared, particle size, the phase of Saturn and Uranus, how you hold your tongue, and whether or not your cat has recently puked up a hair ball.

ghrocketman 03-10-2018 09:42 PM

tbzep basically described ZnS to a tee.
It even under the best controlled conditions is very often unpredictable. That is what makes it so unsafe, if not downright foolish to use. There are so many better alternatives.
There is NOTHING good I can say about using ZnS for ANYTHING.

CuriousAmateur 03-12-2018 05:57 PM

Good to know
 
Okay, thank you everyone for your responses!
I do understand the instability of zinc/sulfur, and I would like to point out that if we were not taking safety precautions, I probably wouldn't be asking about safety concerns. :)

I know that most if not all of you are dealing with many other and more advanced topics, but I appreciate your time on this!

tbzep, that's good to know. I knew it could be unpredictable, which was why we hadn't tried it.

ghrocketman, I am curious what "many better alternatives" you might suggest. Good to know about the lack of safety though.

luke strawwalker, Thanks for the tip! We have seen several "The king of random" videos, although they provide minimal detail in certain situations. We did our best to follow those directions step-by-step, but had the same issue. I suspect it is a chemistry problem. We will consider and try looking for the hose nipples you suggested, although right now, the PSI our white mix generates is barely enough to even measure.

astronwolf, A bucket of cold water never hurts, and I do appreciate your concern. We are doing our best to take precautions and take it slow. (And yes, gloves and aprons are involved, as well as fire extinguishers, and more) As for blowing ourselves up, that is why we are talking and researching, instead of just trying blindly. One of "the right forums" couldn't help, which is why I was seeking some varied advice. If you have suggestions as to where this should be asked, we welcome them. Meanwhile, we are doing reading (offline as well as online). We entirely understand that the smallest chemical change can alter the molecule's properties immensely. It was a guess based on my lack of understanding of calcium stearate.

ghrocketman 03-12-2018 08:36 PM

APCP and ANCP are far safer alternatives to ZnS.

Messing around with ZnS is JUST PLAIN FOOLISH.

CuriousAmateur 03-23-2018 07:04 PM

Problem solved
 
Hi again,
I just wanted to let you folks and any future readers know--it WAS a chemistry problem. Perhaps burning Calcium Stearate was the problem, or perhaps there was something else odd going on. In any case, the problem was the stump remover.

After various experiments, we finally gave up and bought some lab grade 99.999% pure KNO3. We were not disappointed, as it worked quite well.

Thanks for your time and input! We are especially glad that you mentioned the risks of PVC casings.

tmacklin 03-23-2018 09:27 PM

You might try http://www.rocketryforum.com/ for additional information. They are always extremely helpful and courteous, especially when it comes to formulas. Just tell them "Uncle Ted sent me." :D

ghrocketman 03-24-2018 04:03 PM

Ted, that's a great idea.
I'm sure they will be extremely helpful in advising this endeavor.

tmacklin 03-24-2018 08:18 PM

Somehow I just knew you'd be pleased. ;)

CuriousAmateur 04-04-2018 12:48 PM

Quote:
Originally Posted by tmacklin
You might try http://www.rocketryforum.com/ for additional information. They are always extremely helpful and courteous, especially when it comes to formulas. Just tell them "Uncle Ted sent me." :D


Thanks for the suggestion! I'll take a look. :)

Ltvscout 04-04-2018 02:43 PM

Quote:
Originally Posted by CuriousAmateur
Thanks for the suggestion! I'll take a look. :)

I'd advise against it. Those guys were pulling your leg but asking for help at TRF. If you ask the question you asked here at TRF they're going to jump all over you in 2 milliseconds flat (and not in a good way).

FYI, I don't allow talk about experimental motors here either, but since you basically answered your own question I let it be.

tmacklin 04-15-2018 03:16 PM

http://www.rocketryforum.com/showth...s&p=1778191#top

Apparently, our newbie forgot to mention Uncle Ted. LOL!

ghrocketman 04-15-2018 06:57 PM

I'm REALLY surprised they were as gracious to him on TRF as they were.
I expected them to go off like a short-fused grenade.

CuriousAmateur 04-30-2018 12:04 AM

Quote:
Originally Posted by Ltvscout
I'd advise against it. Those guys were pulling your leg but asking for help at TRF. If you ask the question you asked here at TRF they're going to jump all over you in 2 milliseconds flat (and not in a good way).

FYI, I don't allow talk about experimental motors here either, but since you basically answered your own question I let it be.

Thanks for the advice, but they've actually been pretty friendly. My apologies for breaking the rules here, too! I was ignorant of this apparently common policy.

Quote:
Originally Posted by tmacklin
http://www.rocketryforum.com/showth...s&p=1778191#top
Apparently, our newbie forgot to mention Uncle Ted. LOL!

This does not seem to be a username there, but I assume it's an inside joke. I'll mention it if you were serious and it's safe, but I'm suspicious that there is something important that I'm missing.

Quote:
Originally Posted by ghrocketman
I'm REALLY surprised they were as gracious to him on TRF as they were.
I expected them to go off like a short-fused grenade.

I was slightly surprised as well, especially after the first response. However, they have been helping. It seems that the joke is on tmacklin!

CuriousAmateur 04-30-2018 12:20 AM

Updates
 
For those of you not following my progress on TRF, and are yet actually interested enough, here are some updates:
1. We've switched to poly casings. They don't insulate as well as we'd like, but they have not breached. The heat leakage is doing a little damage to the rocket body, but we can handle it.
2. We're having nozzle problems: they keep blowing out, and causing unpredictable flight.
3. Using a band-aid "solution" to these clay failures, we used some poly glue to help support the clay, and had some surprising success. We got about a 350-400 foot flight before the front plug blew, and the whole rig crashed. On recovery, all that was left was an empty tube, though we're not sure when the nozzle failed.
4. We set up and successful used a recovery charge, although the main nozzle blew out and the rocket crashed early, so it was in this case useless. Still, it's good to know that our delay system works.

We have been using diatomaceous clay rather than the usual bentonite for our plugs. Diatomaceous is quite rough, so we had hoped it would work as well or better. We couldn't find pure bentonite, but we have gotten some slightly contaminated stuff to try. Also, following some advice from TRF. we will probably begin forming our nozzles better, rather than just using cylinders.

aeppel_cpm 04-30-2018 08:44 AM

The wine industry uses bentonite as a fining agent to aid haze settling. It's available in a number of forms. KWK is cheap and grey. Champagne makers use forms purified to a white color.

tbzep 04-30-2018 09:09 AM

Quote:
Originally Posted by aeppel_cpm
The wine industry uses bentonite as a fining agent to aid haze settling. It's available in a number of forms. KWK is cheap and grey. Champagne makers use forms purified to a white color.

Estes nozzles seem to be better when the mottled grey clay is used. I've had issues with the nozzles made of the solid white clay. I've even photographed fairly severely vectored exhaust due to erosion.

tmacklin 05-01-2018 12:12 AM

1 Attachment(s)
Quote:
Originally Posted by CuriousAmateur


I was slightly surprised as well, especially after the first response. However, they have been helping. It seems that the joke is on tmacklin!


Now I know how Steve Harvey felt when he awarded the crown to the wrong chick at the 2015 Miss Universe contest! :o

At any rate, if you are looking for good information on building your own motors invest in some books and avoid those YouTube videos by sandal wearing teenagers igniting things with butane cigarette lighters. And don't smoke cigarettes!

Here's a good book on pressed powder motors by David Sleeter:
https://www.amazon.com/Amateur-Rock...e/dp/093038704X

And here's a bookset by John Wickman of CP Technologies:
http://www.space-rockets.com/newbook.html

And for "rocket candy", here's two good sources:
http://www.jamesyawn.net/
http://www.nakka-rocketry.net/

And finally, here's a picture of a Largemouth Bass....

ghrocketman 05-01-2018 12:27 PM

Ted-
That would have been a much better picture WITHOUT that fish.

tmacklin 05-01-2018 01:45 PM

Quote:
Originally Posted by ghrocketman
Ted-
That would have been a much better picture WITHOUT that fish.


Yes, but I'm told this is a "family friendly forum".

CuriousAmateur 05-01-2018 11:57 PM

Quote:
Originally Posted by aeppel_cpm
The wine industry uses bentonite as a fining agent to aid haze settling. It's available in a number of forms. KWK is cheap and grey. Champagne makers use forms purified to a white color.

I'd never heard of that usage! Interesting.....
I'm going to try the contaminated stuff first, and go from there. It's about 50 cents a pound, so I can't argue with the cost of trying it.


Quote:
Originally Posted by tbzep
Estes nozzles seem to be better when the mottled grey clay is used. I've had issues with the nozzles made of the solid white clay. I've even photographed fairly severely vectored exhaust due to erosion.

Any suggestions where I might be able to acquire mottled clay?


Someone suggested that we try adding grog to the clay, also. We haven not been able to test this yet.

CuriousAmateur 05-02-2018 12:01 AM

Quote:
Originally Posted by tmacklin
Now I know how Steve Harvey felt when he awarded the crown to the wrong chick at the 2015 Miss Universe contest! :o

That bad? Ouch. Sorry to disappoint you. :p

Thanks for the book suggestions. Your remark about YouTube sounds pretty accurate. I certainly don't trust such "resources." I have been using the websites you mentioned also. Most recently, I got some electronic detonators working using some advice from nakka-rocketry.net It's easier to just buy the wire ones, but this is progress.

CuriousAmateur 05-02-2018 12:09 AM

I should have asked this in my last posts, but I forgot.
I have another chemistry question, but I don't want to break any rules. Is it acceptable for me to ask simply what the functional/chemical difference is between red iron oxide and black iron oxide? Are they interchangeable in...whatever project one might be doing?

Where are the rules for this forum? I've been looking through pinned threads and FAQs, and not finding them.

Thanks!

tbzep 05-02-2018 07:31 PM

Quote:
Originally Posted by CuriousAmateur
I'd never heard of that usage! Interesting.....
I'm going to try the contaminated stuff first, and go from there. It's about 50 cents a pound, so I can't argue with the cost of trying it.



Any suggestions where I might be able to acquire mottled clay?

I'm afraid not. My EX experience is limited to APCP motors with graphite nozzles and just a little bit with sugar motors where I reused old Estes motors.


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